Audit 2A Pool.pdf

AUDIT POOL 2A Pag isusubmit, follow format sa syllabus. individual pasahan sa gdrive thru moodle. Naka-table lang to para organized. Mainly for review purposes CHAPTER 1: Group 1 Question Answer & Rationale Which of the following statements define...

AUDIT POOL 2A Pag isusubmit, follow format sa syllabus. individual pasahan sa gdrive thru moodle. Naka-table lang to para organized. Mainly for review purposes CHAPTER 1: Group 1 Question Answer & Rationale Which of the following statements defines a distinctive characteristic of prions in a. Prions are proteins that have been comparison to viruses and viroids? misfolded and do not contain any nucleic acids. a. Prions are composed of RNA and lack a protein covering. c.Prions are not made of RNA and are b. Prions are infectious proteins that abnormal form of a cellular protein, not an cause diseases but lack nucleic acids. c. Prions are made of RNA and require a host obligate intracellular agent. cell to replicate. d. Prions have both a protein coat and an d. Prions lack both a protein coat and an outer lipid envelope. outer lipid membrane. These characteristics are typical of viruses. Antimicrobial Resistance, the phenomenon Answer: b. Plasmid which occurs when microorganisms no longer respond to available antibiotic treatment, Rationale: Prokaryotes are capable of exchanging small packets of genetic persists as a global health concern due to the information which are carried on plasmids. extensive misuse and overuse of antibiotics. Plasmids are small and specialized genetic Drug-resistant microbes emerge as a result of elements which can replicate within at least genetic change due to the ability of one prokaryotic cell line, transferred from one prokaryotes to exchange genetic information, cell to another throughout a population, or in this case, drug resistance genes. What exhibit a broad host range, conveying sets of genetic element carries such information and genes to diverse organisms. Drug resistance plasmids are particularly recognized as they may convey these genes to diverse render diverse bacteria resistant to antibiotic organisms? treatment. a. Capsid Reference: Page 5-6, Jawetz, Melnick & b. Plasmid Adelberg’s Medical Microbiology, 28th edition c. Pheromones d. Prions Viruses are known to infect a wide variety of Answer: C plant and animal hosts. However, most viruses are restricted to infecting specific Rationale: Viruses are known to infect a wide types of cells of only one host species, a variety of plant and animal hosts as well as property known as ______. protists, fungi, and bacteria. However, most 1  a. Symbiosis viruses are restricted to infecting specific b. Parasitism types of cells of only one host species, a c. Tropism propert known as tropism. Symbiosis is an d. Maturation association of different organisms in which all contributing parties benefit. If the association primarily benefits one party, it is called parasitism, a relationship in which a host provides the primary benefit to the parasite. Maturation consists of assembling newly synthesized nucleic acid and protein subunits into mature viral particles. Reference: Page 1 - 2, Brooks GF, Jawetz E, Menick JL & Adelberg EA. (2016). Jawetz, Melnick & Adelberg’s Medical Microbiology, 27th ed, New York: London: McGraw-Hill Medical. A 35-year-old patient presents with a fungal Answer: C. Dimorphic infection that exhibits different growth forms at varying temperatures. In the laboratory, the Rationale: The fungus exhibits dimorphism, fungus grows as a mold at room temperature, meaning it grows as a mold at room but when incubated at body temperature, it temperature and as a yeast at body appears as a yeast. What is the best term to temperature, a characteristic of many describe the growth pattern of this fungus? medically important fungi. a. Yeast Reference: Page 8, Jawetz, Melnick & b. Mold Adelberg’s Medical Microbiology, 28th edition. c. Dimorphic d. Coenocytic Prion diseases that affect humans such as a. The PrPSc isoform has a higher Creutzfeldt-Jakob Disease (CJD) and proportion of Beta-sheet structures in Gerstmann-Sträussler-Schneiker disease are place of the normal alpha-helix structures thought to manifest when a conformational change involving the PrPSc isoform in the b. Alpha-synuclein prions were prion protein occurs. Which of the following is discovered to cause multiple system true regarding prion diseases: atrophy in humans a. The PrPC isoform has a higher proportion of Beta-sheet structures in c. “A common feature of all of these place of the normal alpha-helix diseases is the conversion of a structures host-encoded sialoglycoprotein to a b. Beta-synuclein prions were protease-resistant form as a discovered to cause multiple system consequence of infection.” atrophy in humans c. All prion diseases feature a conversion of host-encoded 2  sialoglycoprotein to a d. The conformational change from protein-resistant form PrPC to PrPSc alters the way in d. The conformational change from which proteins interconnect PrPSc to PrPC alters the way in which proteins interconnect Reference: Page 3-4, Jawetz, Melnick & Adelberg’s Medical Microbiology, 28th edition A 31 year old male is diagnosed with Human Answer: C. Maturation immunodeficiency virus (HIV). The last stage in the HIV life cycle is when the virus is Rationale: Maturation in viruses is the assembly of the newly synthesized proteins outside of the CD4 cell then releases into mature viral particles. This then permits protease which then breaks up long protein the non-infectious virus to transform into an chains in the virus, allowing the virus to be infectious virion and continue the spread of infectious. This process is called _______. the disease throughout its host. A. Assemble B. Budding C. Maturation D. Integration CHAPTER 2: Group 2 Question Answer & Rationale A 28-year-old man with a history of (A) Lipopolysaccharide: This is found in intravenous drug use presents with fever and Gram-negative bacteria, not in multiple abscesses. Blood cultures grow Gram-positive Staphylococcus Gram-positive cocci in clusters that are aureus. coagulase-positive. Which of the following (B) Teichoic acid: While present in virulence factors most likely contributes to the Gram-positive bacteria, it does not pathogen's ability to evade phagocytosis? primarily prevent phagocytosis. (C) Capsule: The capsule is a key virulence A. Lipopolysaccharide factor for Staphylococcus aureus that B. Teichoic acid prevents phagocytosis by the host's C. Capsule immune cells. D. Endospore formation (D) Endospore formation: S. aureus does not form spores; this feature is irrelevant to phagocytosis. A weakly gram-positive bacilli is identified in a Answer: C 50-year-old man presenting with a cough with sputum, fever, and night sweats. Upon further Rationale: This is a case of Mycobacterium 3 examination, the bacterium was found to be tuberculosis, which is an acid-fast bacteria. highly resistant to drying and decolorization. Acid-fast organisms contain wax and mycolic What is the probable organism? acid in their cell wall that renders the cells a. Neisseria resistant to decolorization even when b. Listeria decolorized with hydrochloric acid in alcohol. c. Mycobacterium Acid-fast bacteria include Cryptosporidium d. Legionella spp., Legionella micdadei, Isospora spp., Mycobacterium spp., and Nocardia spp. Reference: Page 39, Brooks GF, Jawetz E, Menick JL &Adelberg EA. (2016). Jewitz, Melnick & Adelberg’s Medical Microbiology, 27th ed, New York: London: McGraw-Hill Medical Answer: A Which of the following statements about bacterial cell walls is incorrect? Rationale: Gram-positive bacteria have a thick peptidoglycan layer while a. Gram-positive bacteria have a thin Gram-negative bacteria have thin peptidoglycan layer, while peptidoglycan layer. In Gram-positive Gram-negative bacteria have a bacteria, there are as many as 40 thick peptidoglycan layer. sheets of peptidoglycan, comprising up to b. Gram-positive bacteria appear purple 50% of the cell wall material; in after Gram staining, while Gram-negative bacteria, there appears to be Gram-negative bacteria appear only one or two sheets, comprising 5–10% of reddish-pink. the wall material. Bacteria owe their shapes, c. Most Gram-positive cell walls contain which are characteristic of particular significant amounts of teichoic and species, to their cell wall structure. teichuronic acids, whereas Gram-negative bacteria lack teichoic Reference: Page 24, Brooks GF, Jawetz E, acids. Menick JL &Adelberg EA. (2016). Jewitz, d. Gram-negative bacteria possess Melnick & Adelberg’s Medical Microbiology, periplasmic space, whereas 27th ed, New York: London: McGraw-Hill Gram-positive bacteria do not. Medical Which of the following is NOT a characteristic Answer: A. Integral part of the cell wall of of exotoxin? gram-negative bacteria A. Integral part of the cell wall of A. ENDOTOXINS, rather than exotoxins bgram-negative bacteria are lipopolysaccharides which are an B. Produced both gram-positive and integral part of the cell wall of gram-negative bacteria gram-negative bacteria and are C. Highly toxic liberated upon bacterial death, and D. Usually do not produce fever partly during growth. While produced by both gram-positive and gram negative bacteria, exotoxins are polypetides produced by living cells 4  which primarily play a role in evading host defense. Letters B, C, D are all characteristics of an exotoxin CHAPTER 3: Group 3 Question Answer & Rationale A gram positive spore-forming bacteria was Answer: B. Extremely resilient to disinfectants. cultured from a nutrient-rich medium. This type of bacteria was classified under gram-positive Rationale: eubacteria. What characteristics are applicable for A- These are characteristics of a gram-negative this type of bacteria? eubacteria. B- Spore forming gram positive organisms are A. Features a cell envelope with an outer highly resistant to common disinfectants. These membrane, a periplasmic space with a types of organisms are disinfected through heat thin peptidoglycan layer, and an inner sterilization or through the use of special chemical cytoplasmic membrane disinfectants. B. Extremely resilient to disinfectants. C- These are characteristics of mycoplasmas. C. These are microorganisms that lack cell D- These are characteristics of archaebacteria that walls and do not synthesize the precursors can be used to distinguish it from eubacteria. of peptidoglycan. D. They do not have a peptidoglycan cell wall, but can possess isoprenoid diether or diglycerol tetraether lipids, and has unique rRNA sequences Which of the following statement is Correct answer: C. CNA blood agar correctly described? (containing coliston and nalidixic acid) A. Lactose-fermenting members of the selects for Gram-positive cocci. 5  Enterobacteriaceae (eg, E. coli) form Rationale: white colonies, while pathogenic -A. Lactose fermenting members form salmonellae and shigellae (do not RED or PINK colonies, while Non ferment lactose) form red or pink lactose fermenting form white colonies. colonies. B. Examples of selective media are -B. MacConkey agar that contains bile MacConkey agar (containing bile) selects for Gram-NEGATIVE rods. selects for the Gram-positive rods Bile salts as an agent select for C. CNA blood agar (containing Gram-negative enteric bacteria and coliston and nalidixic acid) selects INHIBIT Gram-positive bacteria. for Gram-positive cocci -D. Nonselective media like blood or D. Nonselective Media such as blood or chocolate agar support the growth of chocolate agar are used to eliminate many different bacteria. It gives rise to (or reduce) the large numbers of colonies with DISTINCTIVE irrelevant bacteria in these MORPHOLOGIES. SELECTIVE specimens. MEDIA on the other hand, are used to ELIMINATE OR REDUCE the large numbers of IRRELEVANT bacteria in specimens. Reference: Page 44, Brooks GF, Jawetz E, Menick JL & Adelberg EA. (2019). Jewitz, Melnick & Adelberg’s Medical Microbiology, 28th ed, New York: London: McGraw-Hill Medica A hospital in Quezon City has reported an Answer: C. Plasmid Analysis outbreak of carbapenem-resistant Klebsiella pneumoniae (CRKP) in its intensive care unit Rationale: Plasmid Analysis is most useful (ICU). The infection control team discovered for examining outbreaks that are restricted that multiple patients, who were not in close in time and place, like in this case, an proximity, had been infected with CRKP. The outbreak in a hospital. In addition, this isolates from these patients are resistant to method is also crucial in determining if various antibiotics, including carbapenems, antibiotic-resistance genes are and preliminary tests indicate that a plasmid-mediated. transferable genetic element may cause the resistance. The team hypothesizes that the resistance genes may be on plasmids, allowing resistance to spread quickly within the hospital environment. Which of the following methods should the team use to determine whether antibiotic-resistant genes are present on a plasmid? a. Restriction Endonuclease Analysis b. Repetitive Sequence Analysis c. Plasmid Analysis 6  d. Genomic Analysis Which biochemical test would be useful in Answer: a) Oxidase test differentiating Pseudomonas aeruginosa from Escherichia coli? Rationale: The oxidase test detects the presence of the c component of the a) Oxidase test cytochrome–oxidase complex. The reagents used change from clear to colored when b) Indole test converted from the reduced to the oxidized state. The oxidase reaction is commonly c) Proteinase production demonstrated in a spot test, which can be done quickly from isolated colonies. d) Citrate utilization Pseudomonas aeruginosa is oxidase-positive, while Escherichia coli is oxidase-negative, making this test useful in differentiating between these two organisms. b) Indole test – used to detect the ability of an organism to produce indole, a benzopyrolle, from tryptophan. Tests positive for Proteus vulgaris. c) Proteinase production – detects proteolytic activity by growing bacteria in the presence of substrates such as gelatin or coagulated egg. Tests positive for P. aeruginosa and S. aureus d) Citrate utilization – detects ability of an organism to use citrate. Tests positive for Klebsiella pneumoniae. Reference: Reference: Page 45, Brooks GF, Jawetz E, Menick JL & Adelberg EA. (2019). Jewitz, Melnick & Adelberg’s Medical Microbiology, 28th ed, New York: London: McGraw-Hill Medical Question: Answer: D What type of media incorporates an inhibitory agent that specifically selects against the growth Rationale: of irrelevant bacteria? 7  The prevention of growth of vast numbers of A. Non-selective differential irrelevant bacteria in specimens is done by using B. Non-selective media selective media. This is done by adding inhibitory C. Differential media agents that would selectively choose against the D. Selective Media growth of certain species or types of bacteria. Reference: Page 44, Brooks GF, Jawetz E, Menick JL & Adelberg EA. (2016). Jawetz Melnick & Adelberg's Medical Microbiology, 27th ed, New York: London: McGraw-Hill Medical. CHAPTER 4: Group 4 Question Answer & Rationale Dr. Caballero is preparing surgical instruments for an upcoming procedure. She wants to achieve sterilization to prevent any risk of infection. What process of microbial control should she consider? A. Eliminating many or all pathogenic microorganisms, except bacterial spores, A. DISINFECTION from the instruments. B. PASTEURIZATION B. Applying heat to the instruments for a C. SANITIZATION specified period to kill or retard the D. STERILIZATION growth of pathogenic bacteria. C. Reducing pathogenic organisms to safe levels on the instruments, thereby reducing the likelihood of cross-infection. D. Completely eliminating all forms of microbial life, including highly resistant bacterial spores, from the instruments. Dr. Moran, a hospital infection control Answer specialist, is evaluating various products for Antibiotic is incorrect use in the hospital’s sterilization protocols. ○ Antibiotics are substances that She needs to choose a product that is either kill or inhibit the growth 8 effective against a wide range of of bacteria, not all microorganisms, including bacteria, fungi, microorganisms. and viruses. After reviewing the available Bactericidal is incorrect options, she finds several that can inactivate ○ Bactericidal is an agent that microorganisms, but she needs the one that kills bacteria, not a broad works across a broad spectrum. spectrum of microorganisms. A. Antibiotic Biocide is correct B. Bactericidal ○ Broad spectrum agent that C. Biocide inactivates microorganisms, D. Antiseptic including bacteria, fungi, and viruses. Antiseptic is incorrect ○ Antiseptic is an agent that destroys or inhibits microorganisms on living tissue, but they may not be effective against a wide range of microbes. A. A process that destroys or eliminates all forms of microbial life from an object or environment. This includes highly resistant bacterial spores. B. A specific term referring to the property by which biocide can kill bacteria, Bactericidal action differs It is a specific term referring to the property from bacteriostasis only in being by which biocide can kill bacteria, wherein the irreversible (i.e, the killed organism killed organism can no longer reproduce even can no longer reproduce even after after being removed from contact with the being removed from contact with the agent. agent). In some cases, the agent A. Sterilization causes lysis (dissolution) of cells; in B. Bactericidal other cases, the cells remain intact C. Bacteriostatic and may even continue to be D. Sanitization metabolically active. (The terms fungicidal, sporicidal, and virucidal refer to the property whereby biocides can kill fungi, spores, and viruses, respectively.) C. A specific term referring to the property by which a biocide inhibits bacterial multiplication; upon removal of the agent, multiplication resumes. 9  (The term fungistatic and sporostatic refer to biocides that inhibit the growth of fungi and spores, respectively.) D. The process whereby pathogenic organisms are reduced to safe levels on inanimate objects, thereby reducing the likelihood of cross-infection. A. Glutaraldehyde is correct. Glutaraldehyde, an aldehyde, is commonly used for low-temperature sterilization of surgical instruments. It is bactericidal and sporicidal when used as a 2% solution, A 45 year old patient is scheduled for surgery making it the most suitable choice for involving the use of various medical ensuring sterilization of instruments. instruments and surfaces that must be thoroughly disinfected or sterilized. The B. Chlorhexidine is incorrect. healthcare team needs to select the most Chlorhexidine is a biguanide widely used for appropriate biocide for different purposes, hand washing and as a disinfectant. While it including instrument sterilization, hand is bactericidal, it is not sporicidal, making it antisepsis, and preventing fungal unsuitable for sterilizing instruments where contamination in the operating room. sporicidal activity is required. Among the following biocides, the MOST C. Triclosan is incorrect. suitable for sterilizing surgical instruments Triclosan is a bisphenol used in antiseptic and ensuring sporicidal activity is.. soaps and hand rinses. It is bactericidal and sporostatic but not sporicidal, making it less A. Glutaraldehyde effective for sterilizing surgical instruments B. Chlorhexidine compared to glutaraldehyde. C. Triclosan D. Benzoic acid D. Benzoic acid is incorrect. Benzoic acid is an organic acid used as a fungistatic preservative. It is not bactericidal or sporicidal, and therefore not appropriate for sterilizing surgical instruments. Using a microscope, you have observed that Answer: C the batch culture you have inoculated a few days ago now shows slow loss of cells A. Lag Phase - A period wherein cells adapt through death but growth equally persists. to their new environment. Enzymes and Which phase of the microbial death curve is intermediates are formed and accumulate 10 this? until they are present in concentrations that A. Lag Phase permit growth to resume. B. Log Phase B. Log Phase - Exponential phase - cells are C. Stationary Phase in a steady state of growth. New cell material D. Decline Phase is being synthesized at a constant rate, but new material is catalytic, and the mass increases in an exponential manner. C. Stationary Phase - Cell turnover takes place: Slow loss of cells through death which is balanced by formation of new cells through growth and division. Total cell count slowly increases although the viable count stays constant. D. Decline Phase - Cell viability begins to decrease at a defined rate; death rate increases until it reaches a steady level. Answer: D Rationale: A. Agent removal - Cells that are inhibited by the presence of Mercuric ions can be inactivated by the bacteriostatic agent are removed by addition of methanethiol. What kind of centrifugation or flushing the surface mechanism of reversing biocide action is B. Competitive inhibition - When a present? chemical antagonist of the analog type binds reversibly to an enzyme A. Agent removal C. Antimicrobial index - Its the B. Competitive inhibition concentration of the substrate that C. Antimicrobial index reverses the inhibition D. Agent inactivation D. Agent inactivation - It's an agent that can be inactivated by adding a substance that combines to the medium, thus preventing its interaction with cellular components. CHAPTER 5: Group 5 Question Answer & Rationale 11 A botanist is examining a type of algae that C is correct because, in the dark, the algae thrives in well-lit environments. The algae are can use organic molecules provided capable of converting light energy into externally to generate energy through aerobic chemical energy, producing organic respiration, which relies on oxygen and does molecules. However, the botanist observes not require light. that the algae can also survive and grow in the dark if provided with an external source of A is incorrect because it occurs in the organic molecules. absence of oxygen and does not fully utilize the organic molecules for energy, which is Which metabolic process are the algae likely less efficient for growth. using to generate energy in the dark? B is incorrect because it is a process that A. Fermentation occurs without oxygen, unlike aerobic B. Anaerobic respiration respiration, which is likely in play if oxygen is C. Aerobic respiration available. D. Photophosphorylation D is incorrect because it is a light-dependent process used to produce energy and is irrelevant in dark conditions. A medical student studying for his prelim Answer: C examination is having difficulty understanding the nutritional source needed in cultivating Rationale: microorganisms. Which of the following would A. Heterotrophs require organic carbon for best describe the difference between growth. Carbon dioxide is an example of autotrophs and heterotrophs? inorganic carbon. B. Autotrophs do not require organic carbon. A. Autotrophs do not require organic carbon Thiosulfate is an inorganic substrate that acts for growth, while heterotrophs require carbon as a reductant, which can be observed in dioxide as their carbon source. other autotrophic microorganisms such as B. Autotrophs require organic carbon, while chemolithotrophs. heterotrophs require substrate such as C. Autotrophs do not require organic carbon thiosulfate to act as a reductant for growth. nutrients for growth, but other autotrophic C. Autotrophs may require inorganic microorganisms, such as chemolithotrophs, substrates and carbon dioxide as a may use inorganic substrates and carbon carbon source, while heterotrophs require dioxide as a carbon source. Heterotrophs organic carbon for growth. require organic carbon for growth. D. Both autotrophs and heterotrophs require D. Only heterotrophs require organic carbon organic carbon, but autotrophs also require for growth, while other autotrophic an inorganic substrate. microorganisms may require an inorganic substrate. Reference: Page 70, Brooks GF, Jawetz E, Melnick JL & Adelberg EA. (2019). Jawetz, Melnick & Aldeberg’s Medical Microbiology, 28th ed, New York: London: McGraw-Hill Medical. 12  Answer: D Which of the following statements correctly describes how microorganisms regulate their Rationale: internal pH? A. Incorrect. Acidophiles maintain an internal A. Acidophiles maintain an internal pH close to pH of about 6.5, even though the external 7.5, despite external pH conditions as low as pH can be as low as 1.0. 1.0. E. Incorrect. Neutralophiles do use a primary, ATP-driven proton pump and a B. Neutralophiles have a proton transport system K+/H+ exchanger, but the K+/H+ that includes a secondary, ATP-driven proton exchanger is not the primary system. pump and a K+/H+ exchanger. F. Incorrect. Alkaliphiles maintain an internal pH of about 9.5, not 6.5, despite external C. Alkaliphiles regulate their internal pH to about pH conditions as high as 11.0. 6.5, even when external pH conditions are as G. Correct. Microorganisms regulate their high as 11.0. internal pH using proton transport systems to maintain a stable internal pH D. Microorganisms use proton transport across a range of external pH conditions. systems to maintain internal pH within a narrow range, relative to the external pH range they can tolerate. There are different stages in the growth curve Answer: B of cell cultures and these stages describe the In the stationary phase, there is a slow loss of typical growth cycle of microbial cultures in a cells through death, which is balanced by the closed system, like a batch culture. Which formation of new cells through growth and division. While the total cell count gradually phase is where the rate of death and rate of rises, the viable count remains stable. growth are equal? A is not the correct answer because in the log A. Log phase phase, cells start to divide at a constant and B. Stationary phase exponential rate.This phase is characterized by C. Death Phase rapid cell growth and division, leading to an D. Lag phase exponential increase in the number of cells. C is not correct for a very obvious reason. In the death phase, the rate of cell death exceeds the rate of cell division, leading to a decline in the overall population. D is also incorrect because lag phase is the initial phase of growth when microorganisms or cells are introduced to a new environment or medium. A lab technician is culturing bacteria for use Answer: C. in an antimicrobial susceptibility test and wishes to incubate them at a temperature of 13 30°C. Unfortunately, the temperature was Rationale: The range for growth of carelessly set to 80°. When the technician thermophilic bacteria is from 40-80°C with checked the culture, they found that the the optimum being around 50-60°C. If the bacteria have not denatured but also have not bacteria were mesophilic it would have grown grown much. They tried culturing another at 30°C and if it were hyperthermophilic it plate of the same bacteria at 30° and found would have grown at 80°C. Psychrophilic that it failed to thrive. The lab technician bacteria grow best at very low temperatures, concluded that the bacteria were: so this bacteria is clearly not psychrophilic. A. Mesophilic B. Psychrophilic C. Thermophilic D. Hyperthermophilic CHAPTER 6: Group 6 Question Answer & Rationale These enzymes directly use the potent A. Depolymerase: These enzymes break oxidant molecular oxygen as a substrate down polymers (such as in reactions that con- vert a relatively polysaccharides or nucleic acids) into intractable compound to a form in smaller units, but they do not directly which it can be assimilated by use molecular oxygen as a substrate. thermodynamically favored reactions. B. Proteases: These enzymes hydrolyze peptide bonds in proteins, converting A. Depolymerase them into smaller peptides or amino B. Proteases acids, but they do not use molecular C. Oxygenases oxygen as a substrate. D. lipases C. Oxygenases: These enzymes incorporate molecular oxygen into organic compounds, facilitating their conversion into more manageable forms for further metabolism. This process helps in transforming relatively intractable compounds into forms that can be assimilated through subsequent, thermodynamically favorable reactions. D. Lipases: These enzymes break down lipids into fatty acids and glycerol, but they do not use molecular oxygen as 14  a substrate in their reactions. The conversion of the compound Correct Answer: fructose-6-phosphate into A. Catabolism, because it cleaves fructose-1,6–diphosphate presents what fructose-6-phosphate into metabolic process? fructose-1,6-diphosphate and utilizes A. Catabolism, because it cleaves ATP. fructose-6-phosphate into B. Catabolism, because it cleaves fructose-1,6-diphosphate and utilizes fructose-6-phosphate into ATP. fructose-1,6-diphosphate and B. Catabolism, because it cleaves synthesizes ATP. fructose-6-phosphate into C. Anabolism, because it synthesizes fructose-1,6-diphosphate and fructose-6-phosphate into synthesized ATP. fructose-1,6-diphosphate and C. Anabolism, because it synthesize utilizes ATP. fructose-6-phosphate into D. Anabolism, because it synthesizes fructose-1,6-diphosphate and fructose-6-phosphate into utilizes ATP. fructose-1,6-diphosphate and D. Anabolism, because it synthesize synthesizes ATP. fructose-6-phosphate into fructose-1,6-diphosphate and Rationale: synthesize ATP. Anabolism refers to the metabolic processes that build up larger molecules from smaller ones, often requiring energy input. In this case, fructose-6-phosphate is converted into fructose-1,6-diphosphate by adding a phosphate group, which requires ATP. This makes the process anabolic, as it involves synthesis and energy consumption. Reference: Carroll, K. C., Butel, J. S., & Morse, S. A. (2019). Jawetz Melnick & Adelberg’s Medical Microbiology (28th ed., p. 81). McGraw Hill Professional. The formation of phosphoenolpyruvate is Answer: C crucial for identifying clinically significant bacteria. Which organism can directly Rationale: phosphorylate pyruvate using ATP? 15  Escherichia coli is an organism capable of directly A. Bacillus subtilis phosphorylating pyruvate with ATP, which results B. Listeria monocytogenes in the production of adenosine monophosphate C. Escherichia coli (AMP) and inorganic phosphate (Pi). This process D. Corynebacterium diphtheriae differs from that of other organisms, which require an additional metabolic step to accomplish the same phosphorylation. Reference: Brooks, G. F., Jawetz, E., Menick, J. L., & Adelberg, E. A. (2016). Jawetz, Melnick & Adelberg’s Medical Microbiology (27th ed., p. 84). New York, NY; London, UK: McGraw-Hill Medical. CHAPTER 7: Group 7 & 10 Question Answer & Rationale Which of the following is TRUE about A. Frameshift mutation is caused by frameshift mutation? INSERTIONS or DELETIONS of several nucleotides in a DNA sequence A. Frameshift mutation is caused by rearrangement of several nucleotides in a B. TRUE DNA sequence. C. Frameshift mutation is a mutation of DNA B. This mutation is caused by polymerase sequence that is NOT divisible by 3. slippage. D. This mutation is FAVORED by exposure to C. Frameshift mutation is a mutation of DNA acridine dye sequence that is divisible by 3. D. Exposure to acridine dye is not favored in this type of mutation. Dr. de Guzman wants to use a hybridization A. TRUE probe that will give him quantitative data regarding RNA synthesis. Which probe B. Southern blots are used to discern 16 should he use? specific DNA sequences. A. Northern blots C. Western blots are used to detect expressions of proteins. B. Southern blots D. While Eastern blots exist, it is not C. Western blots covered in the book. D. Eastern blots Reference: Carroll, K. C., Butel, J. S., & Morse, S. A. (2019). Jawetz Melnick & Adelberg’s Medical Microbiology (28th ed., p. 123). McGraw Hill Professional. In DNA sequencing, the original method used A. It mostly relies on the relative the Maxam-Gilbert technique which has chemical liability of different nucleotide largely moved to the Sanger method. Which bonds. -Maxam-Gilbert technique of the following statements best describes the B. It introduces DNA into bacteria using Sanger method? an electrical gradient. -Electroporation under "Cloning of DNA Restriction A. It mostly relies on the relative Fragments" chemical liability of different nucleotide C. It interrupts elongation of DNA bonds. sequences by incorporating B. It introduces DNA into bacteria using dideoxynucleotides into the an electrical gradient. sequences. C. It interrupts elongation of DNA D. It allows the separation of DNA sequences by incorporating fragments containing up to 100 kbp dideoxynucleotides into the that are separated on high-resolution sequences. polyacrylamide gels - Pulsed-field gel D. It allows the separation of DNA electrophoresis under "Physical fragments containing up to 100 kbp Separation of Differently Sized DNA that are separated on high-resolution Fragments" polyacrylamide gels. Reference: Page 122. (2019). Riedel S, & Hobden J.A., & Miller S, & Morse S.A., & Mietzner T.A., & Detrick B, & Mitchell T.G., & Sakanari J.A., & Hotez P, & Mejia R(Eds.), Jawetz, Melnick, & Adelberg's Medical Microbiology, 28e. McGraw-Hill Education. A) A stable form for survival outside a host Dr. Lin is examining a mysterious virus that B) A mechanism for invading a host cell has caused an outbreak in a small population C) Ability to replicate without a host of animals. The virus is highly resilient D) Genetic information for viral replication outside the host, can efficiently invade host within the host cells, and carries all the necessary genetic material to reproduce once inside. However, Dr. Lin notes that the virus cannot replicate Rationale: on its own without infecting a host. Which of 17 the following is NOT required for successful viral propagation? Option A is incorrect. A virus must be stable outside the host to survive and reach another host. A) A stable form for survival outside a host B) A mechanism for invading a host cell Option B is incorrect. A mechanism to C) Ability to replicate without a host invade a host cell is necessary to access the D) Genetic information for viral replication cell's machinery for replication. within the host Option C is correct. Viruses cannot replicate without a host, making this the correct answer. Option D is incorrect. Genetic information is essential for creating new viral components. Reference: Page 109-110, Riedel, S., Hobden, J. A., Miller, S., Morse, S. A., Mietzner, T. A., Detrick, B., Mitchell, T. G., Sakanari, J. A., Hotez, P., & Mejia, R. (2019). Jawetz, Melnick & Adelberg’s medical microbiology (28th edition). New York: London: McGraw-Hill Education. A bacterial strain of Staphylococcus aureus A. Specialized transduction develops methicillin resistance. It is observed B. Transformation that this resistance is transferred rapidly C. Conjugation within a hospital setting, even among different D. Transposons bacterial species. Laboratory tests confirm that this resistance is associated with the acquisition of a large plasmid. Rationale: Option A is incorrect. Specialized transduction involves the transfer of specific What is the most likely mechanism of bacterial genes from one bacterium to resistance gene transfer? another via a bacteriophage. A. Specialized transduction Option B is incorrect. Transformation B. Transformation involves the uptake of free DNA from the C. Conjugation environment, not the movement of genes within a bacterium. D. Transposons Option C is correct. Conjugation involves the transfer of genetic material between bacteria through direct cell-to-cell contact, typically spreading plasmids between different cells. 18  Option D is incorrect. Transposons describe the movement of genetic elements within a single bacterium, not between different bacteria. It is not involved in inter-bacterial transfer Reference: Page 111, Riedel, S., Hobden, J. A., Miller, S., Morse, S. A., Mietzner, T. A., Detrick, B., Mitchell, T. G., Sakanari, J. A., Hotez, P., & Mejia, R. (2019). Jawetz, Melnick & Adelberg’s Medical Microbiology. McGraw-Hill Education. Bacteriophages are viruses associated with A. The bacteriophage is a filamentous prokaryotes which are distinguished based on phage their mode of propagation. Dr. M is studying a B. The bacteriophage enters a nonlytic certain bacteriophage where its replication of prophage state nucleic acid is linked to replication of host cell C. The bacterial host is debilitated but DNA. Which of the following is True regarding not killed by the phage infection this phage? D. Bacteria carrying prophages are A. The bacteriophage is a filamentous termed “Lytic”. phage B. The bacteriophage enters a Rationale: nonlytic prophage state Correct answer is B: The question pertains C. The bacterial host is debilitated but to Temperate phages which are not killed by the phage infection bacteriophages that enter a non-lytic D. Bacteria carrying prophages are prophage state. termed “Lytic” Option A and C pertains to Filamentous phage Option D: Bacteria carrying prophages are termed “Lysogenic” Reference: Page 109-110, Riedel, S., Hobden, J. A., Miller, S., Morse, S. A., Mietzner, T. A., Detrick, B., Mitchell, T. G., Sakanari, J. A., Hotez, P., & Mejia, R. (2019). Jawetz, Melnick & Adelberg’s Medical 19  Microbiology. McGraw-Hill Education. In the laboratory, a bacterial strain is Answer: C. Nonsense Mutation observed to exhibit termination of protein synthesis and loss of function due to a Rationalization: spontaneous mutation. Genetic analysis reveals that this point mutation causes a A. Missense Mutation results from a premature stop codon into the coding substitution of one amino acid for a sequence of the bacterial gene. There is also different one, which can lead to no a presence of a truncated protein at the site discernable phenotypic effect. There of mutation. What type of mutation is most is only a change in the amino acids likely responsible for this effect? that are being incorporated into a protein and does not completely stop A. Missense Mutation its synthesis B. Rearrangement B. Rearrangement results from deletions C. Nonsense Mutation that remove large portions or sets of D. Frameshift Mutation genes C. Nonsense Mutation is the answer as it is a type of point mutation where a single nucleotide change converts the amino acid into a premature stop codon which ends protein synthesis. This also causes the formation of a non functional truncated or shortened protein due to premature termination of protein synthesis D. Frameshift Mutation is caused by insertions or deletions of nucleotides in numbers that are not divisible by 3. This shift results in misreading of the gene and will result in a completely different sequence of amino acid after the point of mutation What statement is true regarding the Answer: A gene expression between an eukaryotic and prokaryotic organism? Rationale: A) In both eukaryotes and prokaryotes, A) In both eukaryotes and prokaryotes, mRNA is synthesized using RNA mRNA is synthesized using RNA polymerase, which transcribes DNA polymerase, which transcribes DNA into a into a polyribonucleotide strand with a polyribonucleotide strand with a sequence 20 sequence complementary to the DNA complementary to the DNA template template strand. strand. B) The process of translation in both B) Translation involves mRNA and tRNA eukaryotes and prokaryotes involves the in both eukaryotes and prokaryotes, not direct formation of polypeptide chains by direct polypeptide formation by DNA. DNA without the involvement of mRNA or tRNA. C) In eukaryotes, translation occurs in the cytoplasm, not in the nucleus, and C) Unlike in prokaryotes, eukaryotic involves mRNA, tRNA, and ribosomes. translation occurs entirely in the nucleus where mRNA and tRNA interact with D) The triplet codons are largely used by ribosomes to form polypeptides. both eukaryotic and prokaryotic D) Eukaryotic organisms use triplet organisms and they generally specify the codons during translation as compared to same amino acids during translation. prokaryotic organisms that use only double codons which leads to distinct Reference: amino acid sequences. Riedel, S., Morse, S. A., Mietzner, T. A., & Miller, S. (2019). Jawetz Melnick The triplet codons used during translation & Adelberg's Medical Microbiology (28th in eukaryotic organisms differ significantly ed.). McGraw Hill LLC. Chapter 7: from those used in prokaryotic organisms, Microbial genetics: Gene expression (pp. leading to distinct amino acid sequences. 115-116). During Bacterial DNA replication, enzyme Rationale: helicase separates the two strands of a DNA A. This is the function transposases in double helix, creating a replication fork where facilitating transposon mobility. the new DNA is synthesized. This unwinding B. This is the function of helicase in of the DNA double helix results in the unwinding dsDNA. formation of a mechanical tension which can C. [CORRECT ANSWER] further lead to supercoiling. Which of the Topoisomerase alters the following describes the enzyme involved in supercoiling of dsDNA by transiently managing supercoiling? cutting the strands of DNA to relax the coil and extend the DNA molecule. 21  A. Allows transposons to integrate within D. This is how restriction the same replicon or an independent endonucleases provide bacteria with replicon. a mechanism to distinguish between B. Breaks down hydrogen bonds of their own DNA and DNA from other complementary base pairs. biologic sources which is essential in C. Temporarily disrupts the the transfer of DNA. phosphodiester bond of DNA's backbone by breaking it. Reference/s: Pages 109 -111, Riedel, S., D. Modifies DNA through methylation of Hobden, J. A., Miller, S., Morse, S. A., adenine or cytosine residues within Mietzner, T. A., Detrick, B., Mitchell, T. G., the site Sakanari, J. A., Hotez, P., & Mejia, R. (2019). Jawetz, Melnick & Adelberg’s medical microbiology (28th edition). New York: London: McGraw-Hill Education. Which of the following statements about Answer: C bacterial DNA replication is correct? Rationale: A) Replication of the bacterial chromosome A. Replication begins at the ori locus not begins at the ter locus and is unidirectional. the ter locus, and the replication is bidirectional B) The replication of bacterial DNA is B. Bacterial DNA replication is unidirectional and involves the separation of bidirectional the two new strands before cell division. C. Process of bacterial DNA replication starts at the ori locus, C) The replication of bacterial DNA begins proceeding bidirectionally, and at the ori locus and is bidirectional, involving topoisomerases to involving topoisomerases to manage manage supercoiling supercoiling. D. Plasmid replication can be tightly controlled, but mutations can cause D) Bacterial plasmids always replicate with relaxed control, leading to a higher tight control, ensuring there are no more than number of plasmid copies, sometimes 30 copies in a bacterial cell. exceeding 30. A 65-year-old woman presents to the Answer: B emergency department with a two-week history of persistent cough, fever, and Rationale: Lipopolysaccharide (LPS), found shortness of breath. A chest X-ray shows in the outer membrane of Gram-negative bilateral infiltrates, suggestive of pneumonia. bacteria like Klebsiella pneumoniae, acts as Sputum samples are sent for culture and an endotoxin that triggers a strong immune sensitivity testing. The culture results reveal response, leading to inflammation. It doesn’t the presence of Klebsiella pneumoniae, a Gram-negative rod. The outer membrane of 22 Gram-negative bacteria like Klebsiella play a role in spore formation, acid survival, pneumoniae contains lipopolysaccharide or biofilm production. (LPS). What role does LPS play in the pathogenicity of these bacteria? Reference: Page 238-255, Brooks GF, Jawetz E, Menick JL & Adelberg EA. (2019). A) It helps in the formation of spores. Jewitz, Melnick & Adelberg’s Medical Microbiology, 28th ed, New York: London: B) It induces a strong inflammatory McGraw-Hill Medical response. C) It enables the bacteria to survive in acidic environments. D) It allows the bacteria to produce biofilms. CHAPTER 8: Group 8 Question Answer & Rationale 1. A 9-year old boy got sick with a e. Innate immunity which includes common cold and presented humoral antibody that is mediated by symptoms such as sore throat, antibodies low-grade fever, cough, sneezing and f. Adaptive immunity which is an rhinorrhea. This has caused him to immediate response to a pathogen miss 5 school days. After a few that does not confer long-lasting months, the boy got exposed to a protective immunity. classmate with symptoms of common g. Innate immunity with a hallmark of cold. The mother noticed that his son antigen processing and presentation. only developed a low-grade fever and h. Adaptive immunity which is highly cough which only lasted for a day. specific, has immunologic memory What type of immune response is the and can respond rapidly and reason for the second scenario? vigorously to a second antigen exposure. a. Innate immunity which includes humoral antibody that is mediated by Rationale: antibodies This case shows the difference between the b. Adaptive immunity which is an way our body typically reacts to primary and immediate response to a pathogen second exposure to infecting that does not confer long-lasting microorganisms. The immune responses that protective immunity. explain these mechanisms are the innate and c. Innate immunity with a hallmark of adaptive immunity. Main difference is that antigen processing and presentation. innate immunity is a nonspecific response to d. Adaptive immunity which is highly primary exposure, while adaptive immunity is specific, has immunologic memory a specific response that occurs during second and can respond rapidly and exposure. With this, the answer to the 23  vigorously to a second antigen question is adaptive immunity because the exposure. one described in the second scenario is a second exposure of the boy to the infection. Letter A and C are wrong because it’s innate immunity, also the following description pertains to that of adaptive. Letter B is also wrong because even if it’s adaptive, immediate response and short-lasting response are characteristics of innate immunity. The answer is letter D because the description matches the definition of adaptive immunity, as well as explains the reason as to why the boy presented symptoms for a shorter time than the first exposure. Reference: Carroll, K. C., Butel, J. S., & Morse, S. A. (2019). Jawetz Melnick & Adelberg’s Medical Microbiology (28th ed., pp. 127-135). McGraw Hill Professional. A 26-year-old female was involved in a e. Type I hypersensitivity severe car accident, sustaining extensive f. Type II hypersensitivity injuries that led to massive blood loss. Upon g. Type III hypersensitivity arrival at the emergency room, the medical h. Type IV hypersensitivity team noted that she was hypotensive and urgently needed a blood transfusion. The staff Rationale: retrieved her driver's license, which indicated Type II hypersensitivity occurs when her blood type as A. This information was antibodies bind to cell surface antigens, promptly relayed to the blood bank. However, triggering the complement system. This due to an overwhelming number of patients activation can lead to complement-mediated requiring transfusions, the blood bank cell lysis, as seen in conditions like hemolytic mistakenly provided a bag of B blood instead anemia, ABO transfusion reactions, and Rh of the correct type. The patient was hemolytic disease. transfused with the incorrect blood type, and hours later, she developed symptoms In this scenario, the patient, with blood type including fever, chills, nausea, and shock, A, possesses A antigens on the surface of ultimately resulting in her death. What type of her red blood cells (RBCs) and naturally has hypersensitivity reaction did the patient anti-B antibodies in her plasma. Upon experience? receiving a transfusion of type B blood, her anti-B antibodies recognized the B antigens a. Type I hypersensitivity on the transfused RBCs as foreign, leading to b. Type II hypersensitivity the activation of the complement system and c. Type III hypersensitivity subsequent destruction of these cells d. Type IV hypersensitivity (hemolysis). A woman recently exposed to someone with D) Type IV hypersensitivity (delayed-type) active tuberculosis underwent a PPD test to 24 check for latent TB infection. Forty-eight Rationale: hours later, she returns with a swollen, red, and itchy area on her forearm where the test Type IV hypersensitivity, also known as was given. delayed-type hypersensitivity, T cell-mediated response. The interaction of an Which type of hypersensitivity reaction is antigen with specifically sensitized T cells most likely causing this reaction? results in T-cell proliferation, release of potent inflammatory cytokines (IFN-γ and IL-2), and A) Type I hypersensitivity (IgE-mediated) activation of macrophages. This inflammatory response most often begins 2 or 3 days after B) Type II hypersensitivity (cytotoxic) contact with the antigen and typically lasts for several days. C) Type III hypersensitivity (immune complex-mediated) Delayed hypersensitivity to antigens of microorganisms occurs in many infectious D) Type IV hypersensitivity (delayed-type) diseases and it has been used as an aid in diagnosis. The tuberculin reaction is a good example of a delayed-type hypersensitivity (DTH) response. When a small amount of tuberculin is injected into the epidermis of a patient previously exposed to Mycobacterium tuberculosis, there is little immediate reaction. Gradually, however, induration and redness develop and reach a peak in 24–72 hours. In this case, the woman developed a swollen, red, and itchy area on her forearm 48 hours after the PPD test, which is characteristic of a Type IV hypersensitivity reaction. The immune response involves T-helper 1 (Th1) cells and macrophages reacting to the TB-specific antigens. This delayed response indicates that the immune system has been sensitized to these antigens, either from a past TB infection or exposure. U Answer: D Selectins and integrins are examples of adhesion molecules. The primary role of Rationale: Adhesion molecules, such as adhesion molecules in the inflammatory selections and integrins, are crucial for the response is to: inflammatory responses. They are expressed on the surface of the endothelial cells and a. Directly destroy microorganisms leukocytes. Their primary function is to b. Stimulate the production of antibodies mediate the binding of leukocytes to the c. Promote the formation fibrin clots endothelial lining of blood vessels, a critical 25  d. Facilitate the attachment of step in the process of leukocyte migration leukocytes to endothelial cells from the bloodstream to the site of injury or infection. Page 130, Riedel S, & Hobden J.A., & Miller S, & Morse S.A., & Mietzner T.A., & Detrick B, & Mitchell T.G., & Sakanari J.A., & Hotez P, & Mejia R(Eds.), Jawetz, Melnick, & Adelberg's Medical Microbiology, 28th ed. McGraw-Hill Education. CHAPTER 28: Group 9 Question Answer & Rationale A 40-year-old patient is diagnosed with a Answer:D bacterial infection, and the doctor prescribes an antibiotic that binds reversibly to the 50S Chloramphenicol is a known bacteriostatic subunit of the 70S bacterial ribosome, drug that inhibits protein synthesis in bacteria inhibiting peptidyl transferase. This drug by binding to the 50S subunit of the 70S hinders the binding of new amino acids to the bacterial ribosome. Particularly, it inhibits nascent peptide chain and its action is peptidyl transferase causing interference with reversible upon discontinuation, as it is the binding of new amino acids to the nascent bacteriostatic. peptide chain. Which antibiotic is most likely being described in this scenario? A. Penicillin B. Erythromycin C. Tetracycline D. Chloramphenicol Which of the following statements correctly Rationale: describes the mechanism of action or resistance Option A is incorrect because aminoglycosides for a class of antimicrobial drugs that inhibit bind to the 30S ribosomal subunit, not the 50S, protein synthesis? 26  and block the initiation complex and cause A. Aminoglycosides bind to the 50S ribosomal misreading of mRNA. subunit and prevent the formation of the initiation complex. Option B is incorrect because chloramphenicol B. Chloramphenicol inhibits protein synthesis by binds to the 50S ribosomal subunit and inhibits interfering with the peptidyl transferase activity on peptidyl transferase activity, not the 30S subunit. the 30S ribosomal subunit C. Tetracyclines inhibit protein synthesis by Option C is correct. Tetracyclines bind to the 30S blocking the attachment of aminoacyl-tRNA to ribosomal subunit and inhibit protein synthesis by the 50S ribosomal subunit. blocking the attachment of aminoacyl-tRNA. D. Glycylcyclines are synthetic analogues of macrolides and primarily bind to the 50S Option D is incorrect because glycylcyclines, ribosomal subunit to inhibit protein synthesis. like tigecycline, are synthetic analogues of tetracyclines, not macrolides, and they bind to the 30S ribosomal subunit. Which of the following statements correctly Answer: D describes drug-resistant organisms and their effective wide-spread use of antimicrobial Rationale: drugs? Option A is incorrect: Sulfonamides, penicillin, and rifampin were previously used a. Rifampin, penicillins, and quinolones drugs to treat meningococci. Currently, are previously used drugs for both Fluoroquinolones have largely replaced therapy and prophylaxis in treating rifampin for prophylaxis. Quinolones are used meningococci. to treat gonorrhea. b. Pneumococcal become resistant to quinolone due to mutations in the Option B is incorrect: Pneumococcal RNA polymerase or GyrA/GyrB of become resistant to quinolone due to DNA Gyrase. mutations in the DNA topoisomerase IV or c. Oral-third generation cephalosporins GyrA/GyrB of DNA Gyrase. are recommended as first-line treatment of gonorrhea rather than Option C is incorrect: Parenteral parenteral third-generation quinolones third-generation cephalosporins or quinolones due to rising MICs among N. remain the agents of choice for gonorrhea. gonorrhoeae d. A 35 year old male is known to have Enterococci infection. REFERENCE: Riedel, S., Hobden, J. A., Penicillin and ampicillin are Miller, S., Morse, S. A., Mietzner, T. A., rendered ineffective due to some Detrick, B., Mitchell, T. G., Sakanari, J. A., enterococci having acquired a Hotez, P., & Mejia, R. (2019). Jawetz, Melnick plasmid which encodes for & Adelberg’s Medical Microbiology. β-lactamase. McGraw-Hill Education. 27  Answer: A An ideal antimicrobial agent exhibits selective toxicity, which means that the drug is harmful A. Inhibition of cell wall synthesis: This is to pathogens without being harmful to the the correct answer because penicillin and its host. What is the primary mechanism of derivatives inhibit the transpeptidation action by which penicillin exerts its process, which is essential for bacterial cell bactericidal effect? wall synthesis. By preventing the formation of peptidoglycan, the cell wall becomes weak A. Inhibition of cell wall synthesis and eventually ruptures, leading to cell death. B. Disruption of cell membrane integrity B. Disruption of cell membrane integrity: This is incorrect. While some antibiotics C. Inhibition of protein synthesis target the cell membrane, penicillin does not. D. Interference with nucleic acid metabolism C. Inhibition of protein synthesis: This is incorrect because antibiotics like aminoglycosides and macrolides inhibit protein synthesis, but not penicillin which inhibits cell wall synthesis. D. Interference with nucleic acid metabolism: This is incorrect. Antibiotics like quinolones and sulfonamides interfere with nucleic acid metabolism. Question: C. To inhibit β-lactamase is correct. Amoxicillin is a beta-lactam antibiotic effective in treating Dr. Kong thinks of using amoxicillin and bacterial infections, however, certain bacteria clavulanic acid together on treating his patient’s produce an enzyme known as β-lactamase, which infectiom. He explains to his patient that can degrade amoxicillin and make it inactive, clavulanic acid helps amoxicillin to work better by while clavulanic acid is a β-lactamase inhibitor. preventing it from being degraded. What is the By inhibiting β-lactamase enzymes, clavulanic primary reason for this combination? acid prevents these enzymes from breaking down or degrading amoxicillin. This ensures that amoxicillin remains effective against bacteria that produce β-lactamase, protecting it from A. To block sequential metabolic degradation, and enhancing its therapeutic effect. pathways The keyword here is “preventing it from being degraded” as clavulanic acid inhibits β-lactamase B. To enhance drug entry into bacteria from breaking down amoxicillin. C. To inhibit β-lactamase A. To block sequential metabolic pathways is incorrect. Blocking sequential metabolic pathways D. To affect the cell membrane and means using two drugs that interfere with different facilitate the entry of the second drug. steps in the microbial metabolic pathway, like sulfonamides and trimethoprim. This is not applicable to amoxicillin and clavulanic acid as they do not act by sequentially blocking a 28  microbial metabolic pathway. B. To enhance drug entry is incorrect. Some drug combinations may enhance the entry of one drug into bacteria like penicillin with aminoglycosides, this is not the mechanism for amoxicillin and clavulanic acid as it does not facilitate the entry of amoxicillin into bacteria; instead, it inhibits the enzyme that would degrade amoxicillin. D. To affect the cell membrane and facilitate the entry of the second drug is incorrect. This is applicable to amphotericin with flucytosine. The combination of amoxicillin and clavulanic acid does not involve altering the bacterial cell membrane to enhance drug entry. In peptidoglycan synthesis, what Answer: B. peptidoglycan monomer is attached to the growing end of a peptidoglycan chain which Rationale: helps increase the length of the chain by one (A) UDP-NAM pentapeptide - attached to repeat unit? bactoprenol (a lipid of the cell membrane) and receives a molecule A. UDP-NAM pentapeptide of N-acetylglucosamine from UDP B. NAG-NAM pentapeptide formed via condensation. C. NAM pentapeptide (B) NAG-NAM pentapeptide– during D. Bactoprenol-NAM pentapeptide polymerization or glycosylation, glycosylase enzyme the disaccharide units of the Lipid II precursors to form long chains of peptidoglycan. (C) NAM- Pentapeptide – formed from the sequential addition of amino acids to UDP-NAM (D) Bactoprenol-NAM pentapeptide - (Lipid I) upon the synthesis of UDP-MurNAc-pentapeptide, it is transferred to a membrane bound lipid carrier called bactoprenol. The pyrophosphate group of UDP is replaced by the bactoprenol phosphate, forming lipid I or bactoprenol-NAM-pentapeptide. 29 Miguel, a 30 year old patient, is recently given Answer: B. Bactericidal – is the correct 500 mg of ampicillin during a consultation answer because ampicillin directly kills with a gastroenterologist due to his chief Listeria monocytogenes by inhibiting bacterial complaint of diarrhea that is later verified of wall synthesis, which is a method employed an acute GI infection caused by Listeria by bactericidal agents (biocides). monocytogenes from eating smoked salmon. Which of the methods in establishing microbial control characterizes the general A. Bacteriostatic – is incorrect mechanism of action of ampicillin as an because while it may also be present antibiotic for the patient’s condition? in biocides, its mechanism of action involves inhibiting bacterial cell division, in which case if the biocide is A. Bacteriostatic removed, the cell can resume its B. Bactericidal proliferative phase. C. Biocide C. Biocide – is incorrect because it is D. Antiseptic the ampicillin itself that describes this term, not related to the mechanism of action that this biocide (antibiotic) provides to treat the patient’s condition. D. Antiseptic – is incorrect because while it shares the inhibition of growth of microorganisms like with Bactericidal agents, it is only applicable for sterility techniques such as betadine and 70% isopropyl alcohol that eliminates biologic fluid that can be pathogenic to the patient. A 28 year old female presents nausea due to Rationale: head ache, stiff neck, and high fever temperature above 38 degrees Celsius. A and D. Are gram positive cocci which stains Patient samples was tested in the purple microbiology section which was stained pink in gram staining and circular organism on the B. Is a gram negative cocci, which stains pink the microscope view. What could be the in gram staining and show circular cells in possible bacteria? microscope C. Is a gram positive which stains purple in A. Staphylococcus gram staining and they are also Bacilli which show Cylindrical shape cells in microscope B. Neisseria C. Bacillus D. Streptococcus 30 This test is used to identify an antigen in a Immunoblot or Western blot is used to identify complex mixture of proteins subjected to an antigen in a complex mixture of proteins. SDS-polyacrylamide gel electrophoresis The complex mixture of proteins (eg, (PAGE) microorganism) is subjected to sodium dodecyl sulfate (SDS)– polyacrylamide gel A. Flow Cytometry electrophoresis (PAGE). This separates the B. Immunofluorescence proteins according to charge and molecular C. Immunoblot size. D. Enzyme-Linked Immunosorbent Assay 31