342 Questions
Which process of reproduction is common in most bacteria?
Binary fission
What is the temperature range for psychrophiles and their optimum temperature?
-5 ° to 20 °, optimum between 15° and 35°
What type of bacteria live at high temperatures and are associated with volcanic activities or exposed directly to the sun?
Thermophiles
What is the target of Aminoglycosides antibiotics?
Protein synthesis in 30S ribosome
What is the generation time?
Time necessary to the duplication of a bacterial cell
What is the lowest concentration that kills 99.9% of the original inoculum in vitro?
Minimum bactericidal concentration (MBC)
What is the cause of resistance to antiviral drugs?
Changes in relevant part of the virus genome
Which of the following is true about transduction?
It transfers genes via a phage vector
Which bacterial species produces an alginate mucous layer for adherence?
Pseudomonas aeruginosa
What gives Streptococcus pyogenes its adhesion ability?
Protein F and lipotheic acid
Which type of bacteria are naturally resistant to hydrophobic antibiotics?
Gram-negative
What is the mode of action of quinolones?
They prevent supercoiling of DNA
Which type of bacteria are sulfamidics effective against?
Both Gram-positive and Gram-negative
What is MRSA?
A type of bacteria that is resistant to methicillin
What is the mechanism of resistance to beta-lactam antibiotics caused by bacterial enzymes?
Production of beta-lactamase
What is the mode of action of vancomycin?
Inhibiting cell wall synthesis
What is the mechanism of action of aminoglycosides?
Inhibiting protein synthesis
What do beta-lactamase inhibitors do?
Bind and inactivate beta-lactamase
Which type of bacteria is Thiomargarita namibiensis?
A gram-negative Proteobacterium
What is the function of the Mesosome in bacterial cells?
Anchorage and duplication of bacterial DNA
Which group of bacteria has teichoic acids in their cell walls?
Gram-positive bacteria
What is the main proposal to combat antimicrobial resistance mentioned in the text?
Use more narrow spectrum antibiotics
Which of the following is a possible cause of antibiotic resistance?
Inadequate surveillance
Which type of bacteria are penicillins most effective against?
Gram-positive bacteria
What is the difference between cephalosporins and cephamycins?
Cephamycins are more stable to beta-lactamase hydrolysis
What are the targets for penicillin and other beta-lactam antibiotics?
Penicillin-binding proteins (PBPs)
Which type of bacteria has a periplasmic space containing enzymes and is capable of producing beta-lactamase to disrupt antibiotics?
Gram-negative
Which component of the Gram-negative bacterial cell wall is responsible for inducing inflammation by promoting the release of acute phase cytokines?
Lipid A
Which staining method can be used to visualize Mycobacteria despite the presence of waxes in their cell walls?
Ziehl-Neelsen staining
What is the function of peptidoglycan in bacteria?
It is essential for the structure, form, replication, and survival of bacteria
What is the mode of action of spectinomycin?
It reversibly interferes with m-RNA interaction with the 30S ribosome
What is the spectrum of activity of tetracyclines?
Broad-spectrum against gram positive and some gram negative bacteria
What is the mode of action of chloramphenicol?
It binds to the 50S ribosome and blocks the peptide extension
What is the mode of action of rifampicin?
It binds to DNA-dependent RNA polymerase and inhibits initiation of mRNA synthesis
What is the role of bactoprenol in peptidoglycan synthesis?
Bactoprenol transports peptidoglycan monomers across the cytoplasmic membrane
What is the function of autolysins in peptidoglycan synthesis?
Autolysins break the glycosidic bonds between peptidoglycan monomers at the point of growth along the existing peptidoglycan
What is the role of transglycosidase enzymes in peptidoglycan synthesis?
Transglycosidase enzymes catalyze the formation of glycosidic bonds between the NAM and NAG of the peptidoglycan monomers and the NAG and NAM of the existing peptidoglycan
What is the process by which bacteria transfer genes from one cell to another by cell-to-cell contact?
Conjugation
What is the optimal growth temperature range for thermophilic bacteria?
45 ° and 80 °
What is the temperature range for psychrophiles?
-5 ° and 20 °
Which type of bacteria are responsible for the deterioration of chilled foods?
Optional psychrophiles
Which type of bacteria has a periplasmic space containing enzymes and is capable of producing beta-lactamase to disrupt antibiotics?
Gram-negative bacteria
Which bacterial species is the world's largest bacteria, found in the ocean sediments of the coast of Namibia?
Thiomargarita namibiensis
Which type of bacteria has teichoic acids in their cell walls that promote adhesion to target tissue and have antigenic properties?
Gram-positive bacteria
Which type of bacteria has a spiral form and a cell membrane without sterols, but with terpenoids that stabilize and compact it?
Spirochetes
Which of the following is a virulence factor of bacteria?
Alginate mucous layer
What is the role of protein F and lipotheic acid in Streptococcus pyogenes adhesion?
Mediate adhesion to skin cells
What is transduction in bacteria?
Transfer of genes from one cell to another via a phage vector
What is the mode of action of macrolides?
They inhibit translocation
Which antibiotic is used in the treatment of penicillin-resistant Neisseria gonorrhoeae?
Spectinomycin
What is the spectrum of activity of rifampicin?
Broad-spectrum against gram-positive and some gram-negative bacteria
What is the mode of action of tetracyclines?
They reversibly bind to the 30S ribosome and inhibit binding of aminoacyl-t-RNA
What is the primary cause of antibiotic resistance?
Abuse of antibiotics in animals and foods
Which type of bacteria are penicillins most effective against?
Gram-positive bacteria
What is the difference between cephalosporins and cephamycins?
Cephalosporins contain oxygen in place of sulfur in the dihydrothiazine ring, while cephamycins contain sulfur
What is the mechanism by which bacteria become resistant to beta-lactam antibiotics?
Prevention of the interaction between the antibiotic and the target PBP
Which of the following is a mechanism of resistance to beta-lactam antibiotics?
Production of beta-lactamase that disrupts the beta-lactam ring of the antibiotic
What is the mode of action of vancomycin?
Inhibits proper cell wall synthesis in Gram-positive bacteria
What is the spectrum of activity of aminoglycosides?
Many gram-negative and some gram-positive bacteria
What is the function of beta-lactamase inhibitors such as clavulanic acid and sulbactam?
Bind and inactivate beta-lactamase, allowing penicillins to enter the bacterial cell without undergoing enzymatic degradation
What is the target of Macrolides antibiotics?
Elongation phase in 50S ribosome
Which bacterial strain requires a small number of cells to begin an infection?
Enterohemorrhagic strains of Escherichia coli
What is the minimum inhibitory concentration (MIC)?
The lowest concentration that results in inhibition of visible growth
What is the consequence of antibiotic treatment on the gastrointestinal tract?
Proliferation of Enterococcus, Pseudomonas, and fungi
What is the mode of action of quinolones?
They bind to the A subunit of DNA gyrase and prevent supercoiling of DNA
What is the spectrum of activity of sulfamidics?
Broad range activity against gram-positive and gram-negative bacteria
What is the mechanism of resistance to quinolones?
Modification of DNA gyrase that can not bind the drug anymore
What is the mode of action of sulfonamides?
They competitively inhibit formation of dihydropteroic acid
What is the key difference between the cell walls of Gram-positive and Gram-negative bacteria?
Gram-positive bacteria have teichoic and lypoteichoic acids, while Gram-negative bacteria do not
What is the function of Lipid A in Gram-negative bacteria?
It is the toxic part of LPS and promotes the release of acute phase cytokines inducing inflammation
What is the main function of Mycolic acids in Mycobacterium?
They allow bacterial survival for a prolonged time despite adverse conditions
What is the primary staining used in the Gram staining technique?
Crystal violet hydrophilic
Which temperature range do thermophiles live in?
45 ° and 80 °
What is the asexual process of reproduction in bacteria called?
Binary fission
Which type of bacteria are most microorganisms, including human pathogens?
Mesophiles
Which enzyme catalyzes the formation of glycosidic bonds between the NAM and NAG of peptidoglycan monomers and the existing peptidoglycan in bacteria?
Transglycosidase
What is the role of autolysins in peptidoglycan synthesis in bacteria?
Breaking peptide cross-bridges between rows of sugars
What is the mode of action of vancomycin against bacteria?
It binds the peptides of the peptidoglycan monomers and blocks the formation of glycosidic bonds between the sugars by the transglycosidase enzymes
What is the process of horizontal gene transfer by which some bacteria take up foreign genetic material (naked DNA) from the environment?
Transformation
Which bacterial species is associated with adhesion to heart valves or catheters due to its alginate mucous layer?
Pseudomonas aeruginosa
What is transduction in bacteria?
Transfer of genes from one cell to another via a phage vector without cell-to-cell contact
What are virulence factors?
Constituents of the bacterial cell or products of bacterial metabolism
Which of the following antibiotics is effective against gram-positive cocci and urinary tract infections?
Sulfamidics
What is the mode of action of quinolones?
Inhibit DNA synthesis
Which type of bacteria are broad-spectrum quinolones active against?
Both gram-positive and gram-negative
What is MRSA?
A type of bacteria that is resistant to several antibiotics
Which of the following is a mechanism of resistance to beta-lactam antibiotics?
Hydrolysis of the antibiotic by bacterial enzymes
What is the mode of action of Vancomycin?
Inhibiting proper cell wall synthesis in gram-positive bacteria
Which type of bacteria are aminoglycosides the first choice for treating?
Gram-negative bacilli
What is the mechanism of resistance to aminoglycosides?
Mutations in the binding site to the ribosome
What is the main cause of antibiotic resistance in bacteria?
Abuse of antibiotics in animals and foods
Which type of bacteria are penicillins most active against?
Gram-positive bacteria
What is the mechanism by which bacteria become resistant to beta-lactam antibiotics?
Prevention of the interaction between the antibiotic and the target PBP
What is the main characteristic of carbapenems compared to other beta-lactam antibiotics?
Very broad bacterial spectrum
Which of the following is a consequence of antibiotic treatment?
Decreased susceptibility of gastrointestinal tract microbes
Which of the following is a mechanism of resistance to antibacterial drugs?
Prevention of penetration of drug
What is the minimum infective dose for enterohemorrhagic strains of Escherichia coli?
10 cells
What is the difference between an antibiotic and an antimicrobial agent?
An antibiotic kills microorganisms, while an antimicrobial agent only inhibits their growth
What is the world's largest bacteria and where is it found?
Thiomargarita namibiensis found in ocean sediments off the coast of Namibia
Which of the following bacteria are classified as cocci?
Streptococcus pneumoniae and Staphylococcus aureus
Which type of bacteria has a cell membrane without sterols, but with terpenoids that stabilize and compact it?
Gram-negative bacteria
What is the composition of the cell wall of gram-positive bacteria?
Peptidoglycan and teichoic acids
Which type of bacteria has a periplasmic space between the cytoplasmic membrane and the external membrane?
Gram-negative bacteria
What is the endotoxin that characterizes the pathogenic feature of Gram-negative bacteria?
LPS
What is the function of mycolic acids in the cell wall structure of Mycobacteria?
To form waxes that protect the bacteria from drying and disinfectants
What is the primary staining agent used in Gram staining?
Crystal violet
What is the mode of action of spectinomycin?
Spectinomycin reversibly interferes with m-RNA interaction with the 30S ribosome.
What is the spectrum of activity of chloramphenicol?
Narrow-spectrum, only used in the treatment of typhoid fever or bacterial meningitis.
What is the mode of action of fusidic acid?
Fusidic acid binds to elongation factor G and inhibits release of EF-G from the EF-G/GDP complex.
What is the mechanism of action of rifampicin?
Rifampicin binds to DNA-dependent RNA polymerase and inhibits initiation of mRNA synthesis.
What is the role of bactoprenol in peptidoglycan synthesis?
It transports the peptidoglycan monomers across the cytoplasmic membrane
What is the mechanism of action of vancomycin?
It binds the peptides of the peptidoglycan monomers and blocks the formation of glycosidic bonds between the sugars by the transglycosidase enzymes
What is the function of autolysins in peptidoglycan synthesis?
They break the glycosidic bonds between the peptidoglycan monomers and the peptide cross-bridges that link the rows of sugars together
What is bacterial transformation?
The process of horizontal gene transfer by which some bacteria take up foreign genetic material (naked DNA) from the environment
What is the process of asexual reproduction in bacteria called?
Binary fission
What is the temperature range for thermophiles?
45 ° to 80 °
Which group of bacteria are responsible for the deterioration of chilled foods?
Psychrophiles
Which of the following is a mechanism of transduction?
Transfer of genes from one cell to another via a phage vector without cell-to-cell contact
Which bacterial species produces an alginate mucous layer that allows the anchoring of bacteria to the cell surface, particularly in patients suffering from cystic fibrosis or other respiratory diseases?
Pseudomonas aeruginosa
Which two constituents of bacteria can act as virulence factors?
Bacterial cell and bacterial metabolism
What is the main reason for the emergence of bacterial resistance to antibiotics?
Abuse of antibiotics in animals and foods
Which of the following antibiotics is active against most gram-positive bacteria such as staphylococci and streptococci?
Penicillins
What is the general mechanism by which bacteria become resistant to beta-lactam antibiotics?
Prevention of the interaction between the antibiotic and the target PBP
Which of the following is a characteristic of Carbapenems?
Hydrolytically stable to almost all beta-lactamase enzymes
Which type of bacteria has a periplasmic space containing enzymes and is capable of producing beta-lactamase to disrupt antibiotics?
Gram-negative bacteria
What is the endotoxin that characterizes the pathogenic feature of gram-negative bacteria?
Lipid A
What is the primary staining used in Gram staining?
Crystal violet
What is the function of peptidoglycan in bacteria?
It protects bacteria from drying and disinfectants
Which of the following is NOT a way to combat antimicrobial resistance?
Use broad spectrum antibiotics
Which of the following is the world's largest bacteria?
Thiomargarita namibiensis
Which of the following is NOT a way to classify bacteria?
By their habitat preference
Which of the following is a characteristic of gram-positive bacteria?
The cell wall contains teichoic acids
Which type of bacteria can begin an infection with only a small number of cells in the initial inoculum?
Escherichia coli
What is the principal mechanism of resistance to antibacterial drugs that involves enzymatic drug destruction or inactivation?
Enzymatic drug destruction or inactivation
What is the difference between an antibiotic and an antimicrobial agent?
Antibiotics kill microorganisms, while antimicrobial agents inhibit their growth
What is the minimum bactericidal concentration (MBC)?
The lowest concentration that kills 99.9% of the original inoculum
What is the mode of action of vancomycin against Gram-positive bacteria?
It inhibits proper cell wall synthesis.
What is the mechanism of resistance to beta-lactam antibiotics caused by mutations in the PBPs?
They do not allow the binding with the antibiotic.
What is the mode of action of aminoglycosides against bacteria?
They inhibit protein synthesis.
What is the function of beta-lactamase inhibitors like clavulanic acid and sulbactam?
They bind and inactivate beta-lactamase.
What is the mode of action of Spectinomycin?
Inhibits protein synthesis by interfering with m-RNA interaction with the 30S ribosome
What is the spectrum of activity of Chloramphenicol?
Broad-spectrum, effective against gram-positive and some gram-negative bacteria
What is the mode of action of Macrolides?
Inhibits protein synthesis by binding to the 50S ribosome
What is the mode of action of Rifampicin?
Inhibits RNA synthesis by binding to DNA-dependent RNA polymerase
Which of the following antibiotics is effective against gram-positive cocci and urinary tract infections?
Quinolones
What is the mode of action of sulfonamides?
They inhibit the synthesis of folic acid
What is the mechanism of resistance to quinolones?
Decreased drug entry into bacterial cell due to alteration of membrane porin
What is MRSA?
A type of pathogen that is resistant to methicillin and several other antibiotics
Which enzyme catalyzes the formation of glycosidic bonds between the NAM and NAG of the peptidoglycan monomers and the NAG and NAM of the existing peptidoglycan?
Transglycosidase enzymes
What is the role of bactoprenol in peptidoglycan synthesis?
Transport peptidoglycan monomers across the cytoplasmic membrane
What is the function of autolysins in peptidoglycan synthesis?
Break the glycosidic bonds between the peptidoglycan monomers
Which process of gene transfer requires the presence of a sex pilus on the donor cell?
Conjugation
What is binary fission in bacteria?
The asexual process of reproduction involving cell division
What is the optimal growth temperature range for mesophilic bacteria?
10 ° to 50 °
Where are thermophilic bacteria commonly found?
In soils or waters associated with volcanic activities or exposed directly to the sun
What is the mode of action of Rifampicin against bacteria?
Inhibits mRNA synthesis
Which antibiotic is used in the treatment of penicillin-resistant Neisseria gonorrhoeae?
Spectinomycin
What is the spectrum of activity of Fusidic acid?
Active against gram-positive cocci
What is the common adverse effect of Tetracyclines?
Destruction of normal intestinal flora
Which of the following is a virulence factor?
Products of bacterial metabolism
What is the mechanism of adhesion for Pseudomonas aeruginosa?
Pili
Which of the following bacteria has adhesion ability given by protein F and lipotheic acid?
Streptococcus pyogenes
Which type of bacteria requires a large number of cells in the inoculum to successfully infect a host?
Vibrio cholerae
What is the difference between an antibiotic and an antimicrobial agent?
Antibiotics kill microorganisms, while antimicrobial agents only inhibit their growth
What is the target of Aminoglycosides?
Protein synthesis in 30S ribosome
What is the minimum bactericidal concentration (MBC)?
The lowest concentration that kills 99.9% of the original inoculum
What is the mode of action of quinolones?
They bind to the A subunit of DNA gyrase and prevent DNA synthesis
Which type of bacteria are quinolones most effective against?
Gram-negative bacilli
What is the mode of action of sulfonamides?
They competitively inhibit formation of dihydropteroic acid
What is the primary mechanism of resistance to quinolones and sulfonamides?
Increased drug entry into bacterial cell due to alteration of membrane porin
What is the mode of action of beta-lactam antibiotics?
Inhibition of cell wall synthesis
What is the mechanism of resistance to beta-lactam antibiotics?
Enzymatic modification of the antibiotic
What is the mode of action of vancomycin?
Inhibition of cell wall synthesis
What is the mechanism of resistance to aminoglycoside antibiotics?
Enzymatic modification of the antibiotic
What is the world's largest bacteria found in ocean sediments of the coast of Namibia?
Thiomargarita namibiensis
Which of the following bacterial species is NOT spherical (cocci)?
Escherichia coli
What is the function of teichoic acids in the cell walls of gram-positive bacteria?
All of the above
What is the difference between spirilla and spirochetes?
Spirilla are bend-shaped while spirochetes are cylindrical
Which type of bacteria are penicillins most active against?
Gram-positive bacteria
What is the mechanism by which bacteria become resistant to beta-lactam antibiotics?
Prevention of the interaction between the antibiotic and the target PBP
What is the difference between cephalosporins and cephamycins?
Cephalosporins contain oxygen in place of sulfur in the dihydrothiazine ring while cephamycins contain sulfur
What is the primary cause of antibiotic resistance according to the text?
Abuse of antibiotics in animals and foods
What is the key difference between the cell walls of Gram-positive and Gram-negative bacteria?
Gram-negative bacteria have a periplasmic space containing enzymes
What is Lipid A and how does it interact with the immune system?
It is the toxic part of LPS in Gram-negative bacteria and interacts with CD14 receptors on immune cells to induce inflammation
What is the function of mycolic acids in the cell wall of Mycobacterium?
They are linked to peptidoglycans and form waxes that protect the bacteria from adverse conditions
What is the mode of action of lysozyme in bacteria?
It degrades peptidoglycan in the cell wall
What is the role of autolysins in peptidoglycan synthesis?
They break glycosidic bonds between peptidoglycan monomers and peptide cross-bridges
What is the mechanism of action of vancomycin?
It binds to the peptides of the peptidoglycan monomers and blocks the formation of glycosidic bonds
What is bacterial transformation?
The process of horizontal gene transfer by which some bacteria take up foreign genetic material from the environment
What is the function of plasmids in bacteria?
To carry genes that encode toxins or proteins that promote the transfer of the plasmid to other cells
What is the optimal temperature range for mesophilic bacteria?
Between 10°C and 50°C
What is the temperature range for psychrophiles?
Between -5°C and 20°C
What is the asexual process of reproduction in bacteria called?
Binary fission
Which type of bacterial transfer is referred to as transduction?
Transfer of genes from one cell to another via a phage vector
What is the mechanism of adhesion for Streptococcus pyogenes?
Adhesion to skin cell is mediated by protein F
What is the function of virulence factors in bacteria?
To cause disease in the host
What is the primary target of penicillin and other beta-lactam antibiotics?
Peptidoglycan synthesis
Which of the following is a possible cause of antibiotic resistance?
Defective susceptibility assays
Which of the following is a characteristic of carbapenems?
Very broad bacterial spectrum
Which of the following is a mechanism of resistance to beta-lactam antibiotics in gram-negative bacteria?
Prevention of interaction with target PBP
What is the target of Aminoglycosides like streptomycin and gentamicin?
Protein synthesis
What is the minimum infective dose for enterohemorrhagic strains of Escherichia coli?
10 cells
What is the principal mechanism of resistance to antibacterial drugs that involves rapid ejection of the drug?
Activation of efflux pumps
What is the difference between antibiotics and antimicrobial agents?
Antibiotics kill microorganisms, while antimicrobial agents inhibit their growth
Which type of bacteria has a periplasmic space containing hydrolytic enzymes and lithic factors of infection?
Gram-negative bacteria
What is the endotoxin that characterizes the pathogenic feature of gram-negative bacteria?
Lipid A
What is the primary function of mycolic acids in Mycobacterium?
To protect from disinfectants
What is the primary function of peptidoglycan in bacteria?
To stabilize and compact the cell membrane
Which of the following is the world's largest bacteria?
Thiomargarita namibiensis
Which of the following is NOT a method for classifying bacteria?
Gram-staining properties
Which of the following is a characteristic of gram-positive bacteria?
The cell wall contains teichoic acids
Which of the following is a characteristic of spiral-shaped bacteria?
They have a site for the anchorage and duplication of bacterial DNA called the mesosome
What is the mode of action of quinolone antibiotics?
They prevent supercoiling of DNA, thereby inhibiting DNA synthesis
What is the spectrum of activity of sulfonamide antimicrobials?
Broad range activity against gram-positive and gram-negative bacteria
What is the mechanism of resistance to quinolone antibiotics?
Decreased drug entry into bacterial cell due to alteration of membrane porin
What is MRSA?
A bacterium that is naturally resistant to methicillin antibiotics
What is the mode of action of spectinomycin?
It reversibly interferes with m-RNA interaction with the 30S ribosome
What is the spectrum of activity of chloramphenicol?
Broad-spectrum against gram positive and some gram negative bacteria
What is the mode of action of macrolides?
They inhibit translocation
What is the mode of action of rifampicin?
It inhibits initiation of mRNA synthesis by binding to DNA-dependent RNA polymerase
Which enzyme is responsible for catalyzing the formation of glycosidic bonds between peptidoglycan monomers and the existing peptidoglycan?
Transglycosidase
What is the process by which bacteria transfer genes from one cell to another by cell-to-cell contact?
Conjugation
Which antibiotic is effective against Staphylococchi oxacillin-resistant and other gram+ resistant to beta-lactam antibiotics?
Vancomycin
Which group of bacterial enzymes break the peptide cross-bridges that link the rows of sugars together in peptidoglycan synthesis?
Autolysins
Which of the following is a mechanism of resistance to beta-lactam antibiotics?
Enzymatic modification of the antibiotic by phosphorylation
What is the mode of action of vancomycin?
Interacts with D-alanine D-alanine terminal of lateral pentapeptidic chains
What is the mechanism of action of aminoglycosides?
Binds to the 16S ribosomal RNA and freezes the 30S initiation complex
What is the function of beta-lactamase inhibitors?
To bind and inactivate beta-lactamase
Which of the following is NOT a step involved in bacterial growth via binary fission?
Formation of nucleolus
Which type of bacteria lives at temperatures between -5°C and 20°C, and is responsible for the deterioration of chilled foods?
Psychrophiles
Which type of bacteria lives at high temperatures between 45°C and 80°C, and is associated with volcanic activities or direct exposure to the sun?
Thermophiles
Which bacteria is considered the world's largest?
Thiomargarita namibiensis
Which type of bacteria is responsible for causing gonorrhea?
Neisseria gonorrhoeae
What is the function of teichoic acids in gram-positive bacteria?
They promote adhesion to target tissue
What is the function of the mesosome in bacterial cells?
It is a site for bacterial DNA duplication
Which of the following is a method of gene transfer in bacteria that occurs via a phage vector without cell-to-cell contact?
Transduction
Which bacterial strain is able to adhere to skin cells via pili and produce an alginate mucous layer that allows it to anchor to cell surfaces, particularly in patients suffering from cystic fibrosis or other respiratory diseases?
Pseudomonas aeruginosa
Which bacterial strain has adhesion ability given by protein F and lipotheic acid on its surface?
Streptococcus pyogenes
Which of the following is NOT a mechanism of resistance to antibacterial drugs?
Increased susceptibility to antibiotics
Which of the following is an example of an antimicrobial agent?
Chloramphenicol
What is the minimum number of cells required for Vibrio cholerae to successfully infect a host?
Around 1000 cells
What is the consequence of antibiotic treatment on the gastrointestinal tract?
Proliferation of antibiotic-resistant organisms
Which type of bacteria has a periplasmic space containing enzymes such as protease, lipase, and phosphatase?
Gram-negative bacteria
What is the function of Mycolic acids in Mycobacterium?
They allow bacterial survival in adverse conditions
Which of the following is a characteristic of Gram-negative bacteria?
Allow passive diffusion of small hydrophobic molecules through porins
What is the toxic part of LPS in Gram-negative bacteria?
Lipid A
What is the mode of action of quinolones?
They bind to the A subunit of DNA gyrase and prevent supercoiling of DNA.
What is the spectrum of activity of sulfamidics?
Broad range activity against gram-positive and gram-negative bacteria.
What is the primary cause of antibiotic resistance in MRSA?
An alternative enzyme for folic acid synthesis encoded by a plasmid.
What is the mode of action of trimethoprim against bacteria?
They bind to dihydrofolate reductase and inhibit formation of tetrahydrofolic acid.
What is the primary difference between cephalosporins and cephamycins?
Cephalosporins contain sulfur in the dihydrothiazine ring while cephamycins contain oxygen.
What is the primary mechanism by which bacteria become resistant to β-lactam antibiotics?
Prevention of the interaction between the antibiotic and the target PBP.
Which of the following antibiotics is characterized by a rapid bactericidal action due to a faster crossing of porins D2 of the bacterial wall?
Carbapenems
What is the primary reason for the emergence of bacterial resistance to penicillins?
Production of enzymes (penicillinases or β-lactamase) by bacteria.
Which antibiotic is used primarily for the treatment of typhoid fever or bacterial meningitis due to its bone marrow toxicity?
Chloramphenicol
Which antibiotic has a rare resistance in Neisseria gonorrhoeae and is used in the treatment of penicillin-resistant strains?
Spectinomycin
Which antibiotic has a bactericidal effect and inhibits DNA-dependent RNA polymerase, making it most effective during cell division, and is used primarily in the treatment of tuberculosis?
Rifampicin
Which antibiotic has a mode of action that involves inhibiting translocation, is broad-spectrum against gram positive and some gram negative bacteria, and has common resistance?
Macrolides
What is the mode of action of vancomycin?
It inhibits proper cell wall synthesis in gram-positive bacteria
What is the mechanism of resistance to aminoglycoside antibiotics?
Mutations in the binding site to the ribosome
What is the spectrum of activity of aminoglycosides?
Many gram-negative and some gram-positive bacteria
What is the function of beta-lactamase inhibitors like clavulanic acid and sulbactam?
They bind and inactivate beta-lactamase and allow penicillins to enter the bacterial cell without undergoing enzymatic degradation
Which enzyme catalyzes the formation of glycosidic bonds between the NAM and NAG of the peptidoglycan monomers and the NAG and NAM of the existing peptidoglycan?
Transglycosidase
What is the function of the capsule in many bacteria?
It allows adherence to the tissue and protects bacteria from phagocytosis.
What is the mechanism of action of vancomycin against Staphylococchi oxacillin-resistant and other gram+ bacteria?
It binds the peptides of the peptidoglycan monomers and blocks the formation of glycosidic bonds between the sugars by the transglycosidase enzymes.
What is the process of bacterial transformation?
It is a process of horizontal gene transfer by which some bacteria take up foreign genetic material (naked DNA) from the environment.
Which of the following is NOT involved in bacterial growth through binary fission?
Formation of cilia for cell movement
Which type of bacteria is responsible for the deterioration of chilled foods?
Psychrophiles
Which of the following temperature ranges is optimal for mesophilic bacteria growth?
10 ° to 50 °
Which of the following is a virulence factor of Pseudomonas aeruginosa?
Pili
What is transduction in bacterial genetics?
The transfer of genes from one cell to another via a phage vector without cell-to-cell contact
Which of the following is a virulence factor of Streptococcus pyogenes?
Protein F
What is the minimum infective dose required for enterohemorrhagic strains of Escherichia coli to begin an infection?
Less than 10 cells
What is the lowest concentration that kills 99.9% of the original inoculum in antibiotic susceptibility testing?
Minimum bactericidal concentration (MBC)
What is the primary mechanism of resistance to antibacterial drugs that involves enzymatic drug destruction or inactivation?
Enzymatic drug destruction or inactivation
What is the consequence of antibiotic treatment on the most common microbes that colonize the gastrointestinal tract?
They can cause the proliferation of antibiotic-resistant organisms
Which of the following bacterial cell wall components is absent in Gram-negative bacteria?
Teichoic acids
What is the function of waxes in the cell wall structure of Mycobacteria?
To protect from drying and disinfectants
What is the toxic part of LPS in Gram-negative bacteria?
Lipid A
What is the mode of action of beta-lactamase enzymes?
To disrupt antibiotics and make bacteria resistant to the drug
Which group of bacteria is penicillin most active against?
Gram-positive bacteria
What is the mechanism by which bacteria can become resistant to beta-lactam antibiotics?
Prevention of the interaction between the antibiotic and the target PBP
Which of the following is a characteristic of carbapenems?
Very broad bacterial spectrum
What is the difference between cephalosporins and cephamycins?
Cephamycins contain oxygen in place of sulfur in the dihydrothiazine ring
What is the mode of action of chloramphenicol?
It binds the 50S ribosome and blocks the peptide extension.
What is the spectrum of activity of tetracyclines?
Broad-spectrum against gram positive and some gram negative bacteria.
What is the mode of action of macrolides?
They reversibly interfere with m-RNA interaction with the 30S ribosome.
What is the mode of action of rifampicin?
It binds to DNA-dependent RNA polymerase and inhibits initiation of mRNA synthesis.
Which of the following antibiotics inhibits DNA synthesis by binding to the A subunit of DNA gyrase in gram-negative bacteria?
Quinolones
Which of the following antimetabolite antimicrobials inhibits the synthesis of folic acid by binding the enzyme involved in folic acid synthesis in place of the natural substrate (PABA)?
Sulfamidics
What is the mechanism of action of trimethoprim, methotrexate, and pyrimethamine?
Inhibition of folic acid synthesis
What is MRSA?
A type of gram-positive bacteria
Which of the following is the world's largest bacteria?
Thiomargarita namibiensis
Which of the following is a characteristic of gram-positive bacteria?
The cell wall contains teichoic acids
Which of the following is NOT a characteristic used to classify bacteria?
Antibiotic resistance
What is the difference between spiral and cylindrical/rod-shaped bacteria?
Spiral bacteria have a bend shape, while cylindrical/rod-shaped bacteria are straight
Which enzyme catalyzes the formation of glycosidic bonds between the NAM and NAG of the peptidoglycan monomers and the NAG and NAM of the existing peptidoglycan?
Transglycosidase
What is the function of bactoprenol in peptidoglycan synthesis?
Transport peptidoglycan monomers across the cytoplasmic membrane
What is the mode of action of Vancomycin?
It binds the peptides of the peptidoglycan monomers and blocks the formation of glycosidic bonds between the sugars
What is the process of bacterial transformation?
Horizontal gene transfer by which some bacteria take up foreign genetic material from the environment
What is the mode of action of vancomycin?
It inhibits proper cell wall synthesis in Gram-positive bacteria by interacting with D-alanine D-alanine terminal of lateral pentapeptidic chains interfering with the formation of bridges.
What is the main mechanism of resistance to beta-lactam antibiotics?
Mutations in the PBPs that do not allow the binding with the antibiotic.
What is the mode of action of aminoglycosides?
They irreversibly bind to the 16S ribosomal RNA and freeze the 30S initiation complex (30SmRNA-tRNA) so that no further initiation can occur. They also slow down protein synthesis that has already initiated and induce misreading of the mRNA.
What is the function of beta-lactamase inhibitors such as clavulanic acid and sulbactam?
They bind and inactivate beta-lactamase and allow Penicillins to enter the bacterial cell without undergoing enzymatic degradation.
Which of the following is NOT a characteristic of mesophilic bacteria?
They can survive in cold environments.
What is the temperature range for hyperthermophiles?
Between 80°C and 115°C.
Which type of bacteria are responsible for the deterioration of chilled foods?
Psychrophiles
What is the target of Aminoglycosides?
Protein synthesis
What is the difference between Antibiotics and Antimicrobial agents?
Antibiotics inhibit growth while Antimicrobial agents kill microbes
What is the Minimum Inhibitory Concentration (MIC)?
The lowest concentration that results in inhibition of visible growth
What is the primary cause of the proliferation of antibiotic-resistant organisms?
Antibiotic treatment
Which type of antibiotic inhibits DNA synthesis by binding to the A subunit of DNA gyrase in bacteria?
Quinolones
Which type of bacteria are naturally resistant to hydrophobic antibiotics due to their external wall?
Gram-negative
Which type of antimicrobial inhibits the synthesis of folic acid in bacteria by binding to the enzyme involved in the process?
Sulfamidics
What is the mode of action of trimethoprim, methotrexate, and pyrimethamine in bacteria?
Inhibition of folic acid synthesis
What is the primary cause of antibiotic resistance due to heavy use of penicillin?
Production of enzymes by bacteria
Which type of bacteria are penicillins most active against?
Spirochetes
Which antibiotics are known to cause antagonism when used together?
Penicillins and aminoglycosides
What is the primary mechanism by which bacteria become resistant to β-lactam antibiotics?
Prevention of the interaction between the antibiotic and the target PBP
What is transduction in bacteria?
Transfer of genes from one cell to another via a phage vector without cell-to-cell contact
What is the function of virulence factors in bacteria?
They are constituents of the bacterial cell or products of bacterial metabolism that aid in causing disease
How does Pseudomonas aeruginosa adhere to skin cells?
Adhesion is mediated by pili and an alginate mucous layer
Which enzyme is responsible for breaking the glycosidic bonds between the peptidoglycan monomers at the point of growth along the existing peptidoglycan?
Autolysins
What is the process of horizontal gene transfer by which some bacteria take up foreign genetic material (naked DNA) from the environment?
Transformation
What is the mechanism of action of vancomycin against bacteria?
It blocks the formation of glycosidic bonds between the NAM and NAG of the peptidoglycan monomers
Which type of bacteria does not have peptidoglycan?
Mycoplasma
What is the mode of action of spectinomycin?
It reversibly interferes with m-RNA interaction with the 30S ribosome.
What is the spectrum of activity of chloramphenicol?
Broad-spectrum against gram positive and some gram negative bacteria.
What is the mode of action of macrolides?
It inhibits translocation.
What is the mode of action of rifampicin?
It inhibits initiation of mRNA synthesis by binding to DNA-dependent RNA polymerase.
Which of the following is NOT a characteristic used to classify bacteria?
Color
Which of the following bacterial species is NOT cylindrical/rod-shaped?
Streptococcus pneumoniae
Which of the following is a characteristic of gram-positive bacteria?
Cell wall composed of peptidoglycan
What is the function of the mesosome in bacteria?
Portion of the cytoplasmic membrane invaginations
What is the main difference between the cell walls of Gram-positive and Gram-negative bacteria?
Gram-positive bacteria have teichoic and lypoteichoic acids, while Gram-negative bacteria do not.
What is the function of Lipid A in Gram-negative bacteria?
It is the toxic part of LPS and promotes the release of acute phase cytokines, inducing inflammation.
What is the role of mycolic acids in Mycobacterium?
They are linked to peptidoglycans through a bridge of arabinogalactans and can bind different glycolipids, forming waxes that protect the bacteria from drying and disinfectants.
What is the primary staining agent used in Gram staining?
Crystal violet
What is the mode of action of Vancomycin?
It interacts with D-alanine D-alanine terminal of lateral pentapeptidic chains interfering with the formation of bridges.
What is the mechanism of resistance to beta-lactam antibiotics?
Mutations in the PBPs that do not allow binding with the antibiotic.
What is the mode of action of aminoglycosides?
They irreversibly bind to the 16S ribosomal RNA and freeze the 30S initiation complex.
What is the function of beta-lactamase inhibitors such as clavulanic acid and sulbactam?
They allow Penicillins to enter the bacterial cell without undergoing enzymatic degradation.
Study Notes
Bacterial Reproduction
- Binary fission is the common process of reproduction in most bacteria.
Bacterial Temperature Ranges
- Psychrophiles have a temperature range of 0-10°C and an optimal temperature of 2-5°C.
- Thermophiles have a temperature range of 50-80°C and are associated with volcanic activities or exposed directly to the sun.
Antibiotics
- Aminoglycosides target the 30S ribosomal subunit.
- The minimum inhibitory concentration (MIC) is the lowest concentration of an antibiotic that kills 99.9% of the original inoculum in vitro.
- Quinolones target the enzyme DNA gyrase.
- Sulfamidics are effective against Gram-positive bacteria.
- Vancomycin targets the peptidoglycan layer of the bacterial cell wall.
- Beta-lactamase inhibitors, such as clavulanic acid and sulbactam, inhibit the action of beta-lactamase enzymes.
Bacterial Structure and Function
- Mesosomes are cell membrane infoldings that increase the surface area for cellular respiration.
- The Gram-negative bacterial cell wall contains Lipid A, which induces inflammation.
- Peptidoglycan is a key component of bacterial cell walls that provides structural support.
- Transglycosidase enzymes catalyze the formation of glycosidic bonds between peptidoglycan monomers.
- Bactoprenol is a carrier lipid that plays a role in peptidoglycan synthesis.
Bacterial Infections and Resistance
- MRSA (Methicillin-resistant Staphylococcus aureus) is a type of antibiotic-resistant bacteria.
- The primary cause of antibiotic resistance is the overuse and misuse of antibiotics.
- Beta-lactamase production is a mechanism of resistance to beta-lactam antibiotics.
- Aminoglycoside resistance can occur due to mutations in the ribosomal binding site.
Other Bacterial Facts
- Thiomargarita namibiensis is a type of bacteria that produces sulfur compounds.
- Streptococcus pyogenes has a M protein that gives it adhesion ability.
- Some bacteria have teichoic acids in their cell walls, which promote adhesion to target tissue and have antigenic properties.
- Some bacteria have a spiral form and a cell membrane without sterols, but with terpenoids that stabilize and compact it.
Virulence Factors
- Virulence factors are molecules that contribute to the pathogenicity of bacteria.
- Examples of virulence factors include protein F and lipotheic acid in Streptococcus pyogenes.
Horizontal Gene Transfer
- Conjugation is the process of horizontal gene transfer by which bacteria transfer genes from one cell to another through direct cell-to-cell contact.
- Transformation is the process of horizontal gene transfer by which some bacteria take up foreign genetic material (naked DNA) from the environment.
Test your knowledge on peptidoglycan synthesis and cell division machinery in bacteria with this quiz! Learn about the role of bactoprenol in transporting peptidoglycan monomers and how new peptidoglycan is synthesized at the cell division plane. Keywords: peptidoglycan, bactoprenol, cytoplasmic membrane, cell division machinery.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
