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MICROBIOLOGY MICROBIOLOGY PHYSICIAN LICENSURE EXAM MICROBIOLOGY...

MICROBIOLOGY MICROBIOLOGY PHYSICIAN LICENSURE EXAM MICROBIOLOGY TABLE OF CONTENTS Introduction and Bacterial Recombination (Dr. Dacanay) ……………………………………………..1 Introduction to Bacteriology and Gram-Positive Bacteria (Dr. Dacanay) …………………………….5 Streptococci (Dr. Dacanay) ………………………………………………………………………………..9 Gram-Negative Bacteria (Dr. Dacanay) …………………………………………………………………11 Spore-forming and Non-Spore-Forming Rods (Dr. Dacanay) ………………………………………...13 Enterics (Dr. Dacanay) …………………………………………………………………………………….16 Zoonotic Infections, Spirochetes and Atypical Organisms (Dr. Dacanay) …………………………...19 Medical Mycology and Pharmacology of Antifungals (Dr. Dacanay) …………………………………22 ᐧ Medical Virology (Dr. Cruz) ……………………………………………………………………………...26 MEDICAL PARASITOLOGY (Dr. Cruz) Introduction to parasitology ………………………………………………………………………...36 Protozoan Infections ………………………………………………………………………………...37 Nematode Infections ………………………………………………………………………………...47 ᐧ Cestode Infections …………………………………………………………………………………...56 Trematode Infections ………………………………………………………………………………..60 Arthropods of Medical Importance …………………………………………………………………64 D M Medical Parasitology (Dr. Pata) …………………………………………………………………………65 r t p e RA 8293 E x INTELLECTUAL PROPERTY CODE OF THE PHILIPPINES THE FOLLOWING ARE STRICTLY PROHIBITED 1. Unauthorized distribution of handouts 2. Unauthorized recording, downloading and distribution, in ANY FORM, of all Live and pre-recorded Video Lectures 3. All violative acts as stated in RA 8293 WE CAN SEE YOU. All violators will face legal and administrative action which may affect eligibility to take the Licensure exam. EXPERTMD MICROBIOLOGY Unauthorized copying, sharing or distribution is strictly prohibited..  Introduction and Bacterial Recombination MICROBIOLOGY Christopher Rey Dacanay, RPh, MD PHYSICIAN LICENSURE EXAM INTRODUCTION BACTERIAL RECOMBINATION Transformation Conjugation Transduction Transposition INTRODUCTION BACTERIAL CELL WALL ANATOMY PREVIOUS BOARD EXAM RECALL Which of the following is true regarding bacterial capsule? a. Always made up of a carbohydrate molecule b. One type is capsid c. Evades immune response through bypassing the formation of antigen-antibody complex CAPSULE d. Contains D-glutamic acid in Bacillus anthracis Polysaccharide or polypeptide Evasion of phagocytosis, adherence/attachment, resistant to Meningococcemia is a fatal disorder affecting multiple organ desiccation systems. This is due to the evasion of Neisseira meningitides of Contains K antigen which component of the complement cascade? a. Classical pathway Includes: b. Alternative pathway Strep pneumoniae (and Group B Strep) c. Formation of antigen-antibody complex Neisseria meningitides d. Membrane Attack Complex Klebsiella pneumoniae Haemophilus influenzae type B Which of the following refers to C3 convertase? Salmonella typhi a. Part of the coagulation cascade Cryptococcus neoformans (fungi) b. C4b2a complex Pseudomonas aeruginosa c. C4b2aC3b complex d. C5bC6C7C8C9 complex Some Nasty Killers Have Serious Capsule Protection Mnemonic doesn’t include E. coli which also has some encapsulated strains Answers given in the lecture video. CELL WALL Gives shape and resistance to lysis by osmotic shock Made up of peptidoglycan Endotoxin PREVIOUS BOARD EXAM RECALL Which of the following is TRUE regarding bacterial cell wall? a. Thick peptidoglycan in gram positive, which is absent in gram negative b. Periplasmic space is absent in gram positive C3 convertase - C4b2a and C3bBb c. LPS, specifically the polysaccharide portion is also known C3a and C5a - inflammation as endotoxin C3b - opsonization d. Teichoic acid is present only in gram positive C5b to C6-C9 - membrane attack complex Answers given in the lecture video. C5 convertase - C4b2aC3b and C3bBbC3b SPACE FOR SIDE NOTES CYTOPLASMIC MEMBRANE Maintains cell integrity Regulates transport Specialized function (respiration, photosynthesis, protein secretion) PILUS Hair-like structures on cell, -pilin (protein) For adherence, bacterial mating in conjugation, virulence factor of Neisseria gonorrhea FLAGELLUM Flagellin (protein), motility, chemotaxis, run and tumble movement Flagellar arrangement: atrichous, monotrichous, amphitrichous, lophotrichous, peritrichous EXPERTMD MICROBIOLOGY DR. DACANAY Unauthorized copying, sharing or distribution is strictly prohibited.. 1 of 89  EXPERTMD MEDICINE BOARD REVIEW Introduction and Bacterial Recombination DIFFERENCE BETWEEN FLAGELLA AND PILI ACID-FAST STAINING Inhalational Intravenous Pili Ziehl-Neelsen (Hot) Kinyoun (Cold) Purpose (C-A-M) (C-A-M) Long, whip like, helical Short, straight, hair like Definition appendages made up of filamentous appendages, Primary stain Carbol – Fuchsin Carbol – Fuchsin flagellin that protrude made up of pilin that protrude through cell membrane from the surface of the cell Mordant Heat Phenol Length, width 3-20µm long 0.5µm long 3% acid alcohol Decolorizer 3% acid alcohol (Nocardia – 1% H2SO4) Thickness 0.01-0.03µm 10mm thick Counterstain Methylene blue Malachite green Can also be one in Number Numerous number AFO – Red AFO – Red Result NAFO – Blue NAFO – Green Polar, lateral or Occurrence Throughout the surface peritrichous Both gram (+) and gram Exclusively on gram (-) Present in PREVIOUS BOARD EXAM RECALL (-) bacteria bacteria Which of the following is least likely used as a special staining method? Required for a. Leifson No Yes conjugation b. Welch Function Motility Attachment, transfer of DNA c. Gram’s stain d. Schaeffer-Fulton Motion Wave life, undulating Twitching motility FLAGELLAR ARRANGEMENT In gram staining procedure, what decolorizer is being used? - Atrichous a. Acetone alcohol - Monotrichous b. Acid alcohol - Amphitrichous c. Gram’s iodine - Lophotrichous d. Crystal violet - Peritrichous Answers given in the lecture video. PREVIOUS BOARD EXAM RECALL A straight filamentous appendage which is involved in twitch-like CULTURE MEDIA motility in some bacteria a. Lateral spine Causative Agent Medium Used b. Flagellum Neisseria Thayer Martin / NYC c. Operculum Clostridium d. None of the above Thioglycollate Bacteroides Answers given in the lecture video. Vibrio cholerae TCBS Corynebacterium diphtheriae Loeffler’s medium CYTOPLASM Helicobacter pylori Skirrow Viscous aqueous suspension of protein, nucleic acid, dissolved in Mycobacterium Lowenstein-Jensen organic compounds, mineral salts Gengou Contains the enzymes, storage granules Bordetella pertussis Bordet-Gengou RIBOSOMES Leptospira Fletcher’s Protein synthesis: 70s made up of 50s and 30s subunits H. influenza Chocolate Agar Plate Giemsa, Wright and Silver stain Spirochete Malachite green Spores Fuelgen Nuclei M. fadyean B. anthracis Lowenstein medium M. tuberculosis Modified Thayer Martin Neisseris Mac Conkey Agar Fletcher’s Media Leptospira interrogans Chocolate agar Haemophilus influenzae SELF STUDY TOPICS GENOME CLASSIFICATION OF CULTURE MEDIUM Nuclear area or nucleoid Based on Consistency Bacterial chromosome Contains no agar ○ Single DNA molecule Liquid medium e.g. brain heart infusion (BHI), tryptone soya ○ Circular chromosome broth (TSB), thioglycate Plasmids (self-replicating piece of circular DNA) Contains 0.5-1% agar Semi-solid medium e.g. sulfide indole motility (SIM) SPORE Contains 2-3% agar Function: survival during conditions of desiccation, nutrient Solid medium e.g. triple sugar iron (TSI), Mac Conkey & depletion, and waste buildup Chocolate agar Resistant to heat, cold, drying, and chemicals Based on Composition Synthetic / Defined All substances are known to the user Bacterial Staining Methods medium For research purposes 1. Simple stain Composed of some unknown substances 2. Differential stain Non-synthetic / For isolation of bacteria a. Gram stain Complex medium e.g. nutrient browth, TSB, MacConkey b. Acid fast stain agar 3. Special stain a. Nigrosin stain Tissue culture Isolate obligate intracellular bacteria b. Schaeffer fulton medium W 138, HELA 229 cells & Mc Coy cells c. Welch method d. Fuelgen stain Based on Dispensing e. Leifson Test tube-butt, Butt-slant, Slant and Liquid Tubed media f. L.A.M.B media 4. Negative stain: Nigrosin Plated media Petri dish EXPERTMD MICROBIOLOGY DR. DACANAY Unauthorized copying, sharing or distribution is strictly prohibited.. 2 of 89  EXPERTMD MEDICINE BOARD REVIEW Introduction and Bacterial Recombination Based on Use NUTRITION Routinely used in the laboratory and Macronutrients - acquired in the form of CO2, organic carbon Simple / General without added supplement compounds, nitrates, ammonia, sulfates and phosphates Purpose e.g. nutrient agar & broth, TSB Micronutrients - required as trace elements and are components of Contain specific nutrients enzymes and cofactors e.g. alkaline peptone water, Selenite F, Enrichment media buffered charcoal yeast extract (BCYE), thioglycate ENERGY PRODUCTION w/ added supplement necessary for the Fermentation growth of fastidious organism Respiration Enriched media ex. Blood agar plate (BAP) → nutrient agar Photosynthesis (only in minority of bacteria) + 5% sheep red blood cell, chocolate agar plate (CAP) Allows visualization of metabolic BACTERIAL RECOMBINATION differences between group of species of TRANSFORMATION Differential media bacteria Donor cells lyse, a fragment of DNA is released and passed into a Ex. Mac Conkey, BAP, eosin methylene recipient cell. Enzyme dissolves one strand of the fragment, and blue, hektoen enteric agar the other stand displaces a homologous segment of the recipient’s Incorporated with antibiotics, dyes or DNA. The recipient then has a recombinant DNA. chemicals to inhibit the growth of other Involves direct uptake of donor DNA by recipient cells which organisms while promoting the growth of depends on their competence for transformation. the desired organism Selective media e.g. Hektoen enteric (HE) agar, MacConkey (INH, G+ but not G-_ xylose lysine decarboxylase (XLD) agar, Bismuth sulfate agar (BSA) Mannitol salt afar (7.5% salt) Oxidase test targets which specific bacterial chemical component? CYTOCHROME Enzyme Activity Bacteria Result Oxidase Cytochrome G- rods Black Catalase H2O2 Staph Bubbles Hydrolysis Urease Urea H. pylori pH change UTI orgs hydrolysis Coagulase Fibrin clot Staph Clots serum Temperature requirement Mesophilic bacteria Grow best at temperatures ranging from 20⁰C-40⁰C. most human pathogens belong to this type Thermophilic bacteria Grow best at 50⁰C-60⁰C Psychophilic bacteria CONJUGATION Grow best at 0⁰C-10⁰C It involves two live bacteria, donor and recipient, with transfer of genetic material from a plasmid. Oxygen Requirement The donor is F+, has a fertility factor and codes for sex pilus. Obligate aerobes bacteria w/ oxygen Once there is contact with the F- or recipient, plasmid DNA begins Facultative bacteria w/ or w/o oxygen to replicate by the rolling circle method. DNA is transferred and the F- is converted to F+. Microaerophilic bacteria Requires small amount of oxygen Aerotolerant Doesn’t require oxygen but can survive in oxygen Obligate anaerobes w/o oxygen HIGH-YIELD TABLE FOR BOARDS Obligate Facultative Microaerophilic Obligate Aerobes aerobes anaerobes Have all Aerobic, can Fermentation, Can’t grow in enzymes, grown in the No ETC, (+), (-) presence in TCA, ETC absence of catalase presence of oxygen oxygen Neisseria, Staph, B. Streptococcus, Clostridium, Pseudomonas, anthracis, Campylobacter, Bacteroides Legionella Listeria, Leptospira Mycoplasma Based on carbon and Energy Source AUTOTROPHS Are organisms that can produce their own food from the substances available in their surroundings using light (photosynthesis) or chemical energy (chemosynthesis) HETEROTROPHS Cannot synthesize their own food and rely on other organisms – both plants and animals – for nutrition ON BACTERIAL GROWTH AND NUTRITION Physical requirements: Temperature, pH, osmotic pressure TRANSDUCTION Chemical requirements: Water, sources of carbon and nitrogen, The transfer of genetic material from one organism to another by a minerals, oxygen, carbon dioxide, organic growth factors transducing phase or ________________. EXPERTMD MICROBIOLOGY DR. DACANAY Unauthorized copying, sharing or distribution is strictly prohibited.. 3 of 89  EXPERTMD MEDICINE BOARD REVIEW Introduction and Bacterial Recombination BACTERIAL GROWTH 1. Lag phase Organisms are adjusting to the environment (little or no division) There are synthesizing DNA, ribosomes and enzymes to breakdown nutrients, and to be used for growth 2. Log or logarithmic phase Division is at a constant rate (generation time) but varies with species, temperature and media Cells are most susceptible to inhibitors 3. Stationary phase Dying and dividing organisms are at an equilibrium 4. Death or decline phase The population is dying in a geometric fashion so there are more deaths than new cells TRANSPOSITION Process of transferring genes through “jumping genes” PREVIOUS BOARD EXAM RECALL In what phase of bacterial growth are ANTIBIOTICS most effective? LOG PHASE SPACE FOR SIDE NOTES PREVIOUS BOARD EXAM RECALL In an experiment, a bacterial chromosome, coming from an unknown organism with gene-coded fertility factor, was transferred to another prokaryotic cell observing a rolling circle method. This describes a. Transposition b. Transduction c. Transformation d. Conjugation In bacterial conjugation, the recipient bacteria at the termination of bacterial recombination becomes a. F- b. F+ c. Gram negative d. Phage-infected These are mobile segments of a bacterial DNA which contributes to bacterial DNA recombination resulting to emergence of antibiotic resistance. a. Phage b. Jumping jeans c. Fertility factor d. None of the above In a patient presenting with skin abscess, Ureidopenicillin was the treatment of choice. In order to treat the patient, this antibacterial agent should be administered prior or during which phase of the bacterial growth curve? a. Lag b. Log c. Plateau d. Decline Answers given in the lecture video. EXPERTMD MICROBIOLOGY DR. DACANAY Unauthorized copying, sharing or distribution is strictly prohibited.. 4 of 89  Bacterial Classification & Gram-Positive Bacteria PHARMACOLOGY Christopher Rey Dacanay, RPh, MD PHYSICIAN LICENSURE EXAM Bacterial classification TESTS FOR IDENTIFICATION OF GRAM-POSITIVE BACTERIA A. By Morphology For Gram positive with Branching Filaments Gram Positive Bacteria Acid Fast stain A. Gram Positive Bacteria with Branching Filaments ○ Weakly acid fast: ___________ B. Gram Positive Cocci – Staphylococci ○ Not acid fast: ___________ a. Staphylococcus aureus b. Staphylococcus saprophyticus For Gram positive Cocci → c. Staphylococcus epidermidis Catalase Test ○ H2O2 → H2O + O2 ○ Bubbles indicate production of oxygen gas by catalase BACTERIAL CLASSIFICATION ○ (+) Catalase: ___________ BACTERIAL MORPHOLOGY ○ (-) Catalase: ___________ For Staphylococci (Catalase positive) → Coagulase Test ○ Coagulase positive bacteria promote clothing of serum ○ (+) Coagulase: ___________ ○ (-) Coagulase: ___________ or ___________ Novobiocin sensitivity Sensitive: ___________ Resistant: ___________ For Streptococci (Catalase negative) → Hemolysis Test ○ Alpha hemolytic: partial hemolysis Causes greenish discoloration due to ___________ → hemoglobin to hematin Optochin sensitivity Sensitive: ___________ Resistant: ___________ Diplococci - Lancet-shaped bacteria – Streptococcus pneumoniae ○ Beta hemolytic: complete hemolysis Streptococci – Streptococcus pyogenes (GAS) Clearing due to: _________________ Peritrichous arrangement of flagella – flagella around the bacteria Bacitracin sensitivity Sensitive: ___________ Vibrio cholerae – comma-shaped bacillus with single, long, polar Resistant:___________ flagellum, monotrichous ○ Gamma hemolytic: no hemolysis Spirilla – 2 curves, H. pylori, tuff of flagella on one end Growth in hypertonic solution (6.5% NaCl) (lophotrichous). H. pylori- can cause gastric ulcer, and gastric With growth: ___________ adenocarcinoma No growth: ___________ PREVIOUS BOARD EXAM RECALL GRAM-NEGATIVE BACTERIA This organism, known for its unique morphology, is a gram positive, anaerobic bacteria that survives on low pH culture. Sarcina ventriculi usually causes pathology of which of the following? a. Cardiac b. GIT c. Meninges d. Endometrium Answer given in the lecture video. TESTS FOR IDENTIFICATION OF GRAM-NEGATIVE BACTERIA For Gram negative Diplococci Maltose utilization For Gram negative Bacilli Lactose fermentation Oxidase test H2S (hydrogen sulfide) - black colonies For comma-shaped, oxidase positive Grows in 42C Grows in alkaline media Urease producing PREVIOUS BOARD EXAM RECALL GRAM-POSITIVE BACTERIA All of the following statements are correct except: Propionibacterium – Cutibacterium a. Novobiocin is an agent used to differentiate Staphylococci Fite faraco stain – modified acid-fast staining method species. Clinical implication of Nocardia – Immunocompetent (cutaneous b. Viridans group causes incomplete hemolysis observed in infection); Immunocompromised (TB-like manifestation) BAP. c. Nocardia is weakly-acid fast and can be detected using the TB-like manifestation, branching filament - Nocardia Fite-Faraco staining Actinomyces – cutaneous infection, drainage → yellow-sulfur d. Strep mutans is optochin-sensitive granules EXPERTMD MICROBIOLOGY DR. DACANAY Unauthorized copying, sharing or distribution is strictly prohibited.. 5 of 89  EXPERTMD MEDICINE BOARD REVIEW Bacterial Classification & Gram-Positive Bacteria Which test can differentiate Beta-hemolytic Lancefield group A and CATALASE TEST – test to differentiate Streptococcus and B bacteria? Staphylococci a. Catalase Test o Bubbles indicate production of oxygen gas by catalase b. Coagulase Test o Catalase (+) – Staphylococci c. Optochin sensitivity test o Catalase (-) - Streptococci d. Bacitracin sensitivity test COAGULASE TEST All of the following are lactose fermenters except: ○ Coagulase positive bacteria promote clothing of serum a. Enterococcus ○ (+) Coagulase: Staphylococcus aureus b. Klebsiella ○ (-) Coagulase: S. saprophyticus or S. epidermidis c. Enterobacter Novobiocin sensitivity d. Escherichia Sensitive: S. epidermidis Resistant: S. saprophyticus Meningitis in sexually active teenagers is most commonly caused by Neisseria meningitidis. Which of the following is not true about the said organism? GRAM POSITIVE COCCI - STAPHYLOCOCCI a. Humans are the only natural hosts b. Ferments glucose c. Mannose fermenter d. Non-lactose fermenter A 56/F complained of sharp chest pain accompanied with undocumented fever. History of previous valve repair and was noted in her medical records. Transesophageal echogram showed vegetations in the valve cusps. Blood GSCS yielded positive results. The microorganism involved is known to possess hydrogen Staphylococcus aureus peroxide. Which of the following is the most likely pathogen Gram positive cocci in clusters a. Staphylococcus aureus Colonies: golden yellow b. Staphylococcus epidermidis Catalase positive, Coagulase positive c. Enterococcus sp Protein A binds to Fc of Ig inhibiting phagocytosis; d. Streptococcus viridans Mannitol salt agar (+) Colonizes mucosa Answers given in the lecture video. Increased colonization in health workers, DM, neutropenic VIRULENCE FACTORS GRAM POSITIVE BACTERIA Protein A: GRAM POSITIVE WITH BRANCHING FILAMENTS ○ Prevents complement activation ○ Binds IgG, preventing opsonization and phagocytosis Coagulase ○ Allows insoluble fibrin formation around organism, protecting it from phagocytosis Hemolysins (cytotoxins): toxic to hematopoietic cells Leukocidin/Panton-Valentine Leukocidin (PVL): specific for WBCs Catalase: detoxifies hydrogen peroxide Penicillinase ○ Secreted form of beta-lactamase ○ Disrupts the beta lactam portion of the penicillin molecule, Nocardia asteroides Actinomyces israelli thereby inactivating the antibiotic Aerobe Anaerobe PENETRATE THROUGH TISSUES Weakly acid fast Hyaluronidase Not acid fast (Fite-Faraco stain) ○ Spreading factor Normal oral, reproductive and GI ○ Breaks down the proteoglycans in connective tissue (hyaluronic Found in soil acid) flora Staphylokinase Pulmonary infections in Oral/facial abscesses that Lipase immunocompromised (can drain through the sinus tracts Protease mimic TB but with negative PPD) Often associated with dental Cutaneous infections after caries/extraction EXOTOXINS trauma in immunocompetent Forms yellow sulfur granules Exofoliatin Toxin Can spread to CNS → brain ○ causes epidermal separation (stratum granulosum) in Scalded abscesses (orange colonies) Can cause PID with IUDs Skin Syndrome (aka Ritter Disease) Treatment: Sulfonamides ○ Cleaves Desmoglein (TMP-SMX Treatment: Penicillin Enterotoxins (heat-stable): superantigens causing food poisoning ○ Common food sources: poultry, ham, meat, potato salad Treatment is a SNAP: ○ short incubation period: 1-6 hours Sulfonamides – Nocardia; Actinomyces - Penicillin Toxic shock syndrome toxin (TSST-1): superantigen leading to toxic shock syndrome Alpha toxin: causes marked necrosis of the skin and hemolysis PREVIOUS BOARD EXAM RECALL Staphylococcal enterotoxicosis is associated with eating all but which of the following food? a) Custard b) Ham and processed meat c) Hamburger d) Chicken salad 7 schoolchildren sought consult at your clinic due to non-bilious vomiting, fever and loose watery stools. Parents reported that they consumed chicken egg salad 24 hours back which apparently is “sour taste”. The most probable cause of food poisoning in this scenario is: A. Salmonella B. Staphylococcus aureus C. EHEC D. Bacillus aureus EXPERTMD MICROBIOLOGY DR. DACANAY Unauthorized copying, sharing or distribution is strictly prohibited.. 6 of 89  EXPERTMD MEDICINE BOARD REVIEW Bacterial Classification & Gram-Positive Bacteria A 19/F was rushed to the ER, febrile, hypotensive with scarlatiniform PREVIOUS BOARD EXAM RECALL rash, with areas of desquamation in her arms which were 8/M from Bulacan presents with fever, cough and respiratory insignificant. She has had abdominal pain and loose bowel distress. In the ER the patient was unstable and in tripod position. movement since yesterday. She is on her D4 of menses and uses CXR showed hazy infiltrates in bilateral lower lung fields with area of tampons for the first time. She improved and was discharged. What cystic lucency in the middle lobe. AFB sputum smear (-), What is the is the most likely diagnosis most likely causative agent? a. Scarlet fever a. Streptococcus pneumoniae b. Scalded Skin Syndrome b. Klebsiella pneumoniae c. Toxic Shock Syndrome c. Legionella pneumophila d. Food poisoning d. Staphylococcus aureus In the previous case, what pathophysiologic mechanism is most In the previous case, what pathophysiologic mechanism is most important in the progression of the clinical manifestation? important in the progression of the clinical manifestation? a. Exfoliatin toxin cleaves desmoglein a. Exfoliatin toxin cleaves desmoglein b. Presence of TSST-1, a superantigen, in the systemic b. Presence of TSST-1, a superantigen, in the systemic circulation circulation c. Consumption coagulopathy c. Consumption coagulopathy d. Ingestion of heat-stable toxin d. Ingestion of heat-stable toxin In the previous case, which of the following is correct regarding the In the previous case, which of the following is correct regarding the causative agent? causative agent? a. Catalase (-) Coagulase (+) a. Catalase (-) Coagulase (+) b. Gram positive cocci in tetrads b. Gram positive cocci in tetrads c. Possesses penicillinase enzyme c. Possesses penicillinase enzyme d. Optochin and Bacitracin Sensitive d. Optochin and Bacitracin Sensitive A 23/M was seen at the OPD with generalized erythematous macular Answers given in the lecture video. and popular lesions with areas of skin necrosis. Large areas of skin at the back of the abdomen, including lips are noted to be sloughing off. (+) fever, (+) altered sensorium. What is the most likely Staphylococcus saprophyticus diagnosis? Non-hemolytic A. Staphylococcal scalded skin syndrome Coagulase negative B. SJS Novobiocin resistant C. Toxic epidermal necrolysis Causes “honeymoon cystitis” D. Toxic shock syndrome ○ Common cause of UTI among sexually active young women Answers given in the lecture video. Staphylococcus epidermidis Novobiocin sensitive BACTERIAL FOOD POISONING Has the ability to adhere to artificial materials in the body (e.g. catheters and prosthetic heart valves) Frequently isolated in ○ Infected indwelling catheters ○ Prosthetic heart valve endocarditis BOARD EXAM PABAON Most common cause of: ○ Prosthetic valve endocarditis DISEASE ENTITIES ○ Septic arthritis in prosthetic joints Diseases by exotoxin release ○ Ventriculoperitoneal shunt infections ○ Gastroenteritis - enterotoxin ○ Toxic shock syndrome – TSTT-1 ○ Scalded skin syndrome – Exfoliatin toxin PREVIOUS BOARD EXAM RECALL 76/F CKD Stage 5 patient undergoing Hemodialysis for 1 week now, Direct skin invasion suddenly presents with hypotension, high-grade fever, chills. CBC ○ Skin infections (cellulitis, impetigo, carbuncle, furuncle, SSI, showed marked leukocytosis and >10% bands. (+) purulent material mastitis, folliculitis) around the site of IJ cath. What is the next best step? ○ Acute bacterial endocarditis a.Remove IJ cath and use AVF instead ○ Urinary tract infection b.Do a culture in 2 sites ○ Pneumonia c.Ultrasound of IJ cath insertion site Empyema – pus in the pleural space d.Complete neurologic exam Consolidation PNEUMATOCOELE - cavity filled with air in lung parenchyma In the case above, what is the most likely diagnosis? ○ Osteomyelitis a.Catheter exit site infection BRODIE ABSCESS b.Tunnel infection Sequestered focus of infection found at the metaphysis of c.CRBSI long bones d.None of the above ○ Septic arthritis EXPERTMD MICROBIOLOGY DR. DACANAY Unauthorized copying, sharing or distribution is strictly prohibited.. 7 of 89  EXPERTMD MEDICINE BOARD REVIEW Bacterial Classification & Gram-Positive Bacteria In the above case, what is the most likely causative agent? DIFFERENTIATION OF SPECIES Organism Hemolysis a) Staphylococcus epidermidis Catalase Coagulase Novobiocin Colony on blood production production sensitivity b) Staphylococcus saprophyticus appearance agar S. aureus Golden Positive Positive Sensitive Positive c) Staphylococcus pneumoniae S. epidermidis White Gray Positive Negative Sensitive Negative d) Staphylococcus aureus S. saprophyticus White Gray Positive Negative Resistant Negative Answers given in the lecture video. EXPERTMD MICROBIOLOGY DR. DACANAY Unauthorized copying, sharing or distribution is strictly prohibited.. 8 of 89  Streptococci MICROBIOLOGY Christopher Rey Dacanay, RPh, MD PHYSICIAN LICENSURE EXAM STREPTOCOCCI PYOGENIC INFECTION Impetigo contagiosa: perioral blisters with honey colored crust; accumulation of neutrophils beyond the stratum corneum; complication includes PSGN Erysipelas: superficial infection extending into dermal lymphatics Cellulitis: deeper infection involving subcutaneous/dermal tissues; facilitated by hyaluronidase (spreading factor) Pharyngitis: most common bacterial cause of sore throat TOXIGENIC Scarlet fever: due to erythrogenic toxin; fever, strawberry tongue, sandpaper-like centrifugal rash, Pastia’s lines, desquamation ○ Dick test for susceptibility Streptococcal Toxic Shock Syndrome Necrotizing fasciitis - rapidly progressive infection of deep subcutaneous tissues; facilitated by exotoxin B IMMUNOLOGIC For Streptococci (Catalase negative) → Acute Rheumatic Fever Hemolysis Test (using Blood Agar) Acute Post Streptococcal Glomerulonephritis ○ Alpha hemolytic: partial hemolysis Causes greenish colonies due to hydrogen peroxide → hemoglobin to hematin Optochin sensitivity Sensitive: S. pneumoniae Resistant: Viridans Streptococci (contain H2O2) ○ S. angionosus ○ S. salivarius ○ S. mutans ○ S. sanguis ○ S. mitis ○ Beta hemolytic: complete hemolysis Clearing due to: Streptolysin Bacitracin sensitivity Sensitive: S. pyogenes Resistant: S. agalactiae ○ Gamma hemolytic: no hemolysis Growth in hypertonic solution (6.5% NaCl) With growth: Enterococci (Group D– E. faecium, E. faecalis) No growth: S. bovis LANCEFIELD CLASSIFICATION Serologic classification of streptococci based on their antigenic PREVIOUS BOARD EXAM RECALL characteristics A 4 year old boy presents in the ER with scarlatiniform rash, red Group A Streptococcus pyogenes eyes, strawberry tongue, painless lymphadenopathy, high grade Group B Streptococcus agalactiae fever with no relief when given Paracetamol 12 mg/kg/dose. What is Streptococcus equisimilis, S. zooepidemicus, the most likely diagnosis? Group C a. Scalded Skin Syndrome Streptococcus dysgalactiae Group D Enterococci, Streptococcus bovis b. Scarlet Fever c. Kawasaki Disease Group A Streptococci d. Measles Streptococcus pyogenes Beta hemolytic In the previous case, what sequela is most important to watch out Sensitive to bacitracin for? Possesses an M protein a. Guillain Barre syndrome Erythrogenic toxins b. RHD Produces Streptolysin S and O c. Glomerulonephritis d. Coronary aneurysm VIRULENCE FACTORS Answers given in the lecture video. Hyaluronidase - aids in the invasion and dissemination of the bacteria within the host (spreading factor) Streptokinase (fibrinolysin) ○ binds to and activates plasminogen, converting it into plasmin Group B Streptococci ○ Plasmin then acts to break down fibrin in blood clots, leading to Streptococcus agalactiae their dissolution Part of the normal flora of the vagina, mouth, urethral mucous ○ Anti-Streptokinase membrane, GIT DNAse (streptodornase) Group B Lancefield ○ degrades DNA in exudates or necrotic tissue Beta hemolytic ○ anti-DNAse – document antecedent strep skin infection) Capsule - major virulence factor C5a peptidase - inactivates complement C5a Causes neonatal meningitis, pneumonia, and sepsis M protein CAMP test Positive: CAMP factor enlarges the area of hemolysis ○ it contributes to the bacterium's ability to adhere to and invade formed by S. aureus host tissues TOXINS Streptococcus pneumoniae Erythrogenic toxin - scarlet fever Encapsulated cocci, non-motile, lancet shaped, fastidious Streptolysin O (oxygen labile) - highly antigenic, causes antibody Polysaccharide capsule: retards phagocytosis, major virulence formation; destroys RBCs and WBCs and is the reason for factor, has 84 serotypes; antigenic hemolysis Part of oropharyngeal flora Streptolysin S (oxygen stable) - not antigenic Alpha hemolytic ○ Anti-streptolysin O antibody – used to document antecedent strep Lancet shaped diplococcus throat infection Determined by Quellung reaction and Optochin test Pyogenic exotoxin A - superantigen similar to TSST Major cause of adult pneumonia Exotoxin B - protease that rapidly destroys tissue (necrotizing Most common cause of otitis media fasciitis) Most common cause of adult meningitis EXPERTMD MICROBIOLOGY DR. DACANAY Unauthorized copying, sharing or distribution is strictly prohibited.. 9 of 89  EXPERTMD MEDICINE BOARD REVIEW Streptococci Viridans Streptococci PREVIOUS BOARD EXAM RECALL S. mutans A 34 year old male from Tondo, Manila, an IV heroin user, presents ○ Dental caries with a 3 day history of fever T>39, chest pain, “pinching” in character; ○ Commonly found in the oral cavity, particularly on the surfaces of nausea, vomiting. Troponins are low. CKMB negative. ECG shows teeth where it forms biofilms or dental plaque sinus tachycardia. Blood culture on 2 sites were positive. PMHx: ○ It thrives in an environment where there are sugars available for tricuspid valve repair in 2003. What is the most likely diagnosis? fermentation a) Acute endocarditis S. sanguis b) Subacute endocarditis ○ While S. sanguinis is generally considered a commensal, it has c) Myocarditis been associated with infective endocarditis, a serious infection of d) Takotsubo cardiomyopathy the heart valves. ○ This can occur when bacteria enter the bloodstream, often during In relation to the case above, which is true regarding the causative dental procedures, and adhere to damaged heart valves. agent? S. intermedius a) Gram negative bacilli ○ Most common cause of brain abscess b) Coagulase negative c) Optochin resistant d) Inhibited by Novobiocin In the above case, what in the cardiac physical examination is MOST LIKELY noted? a) Dynamic precordium b) (+) muffled heart sounds c) Diastolic murmur d) Holosystolic murmur Answers given in the lecture video. PREVIOUS BOARD EXAM RECALL What is the causative agent? Dental carries: S. mutans Subacute bacterial endocarditis (SBE): S. sanguis – most common cause of Subacute and native valve endocarditis PREVIOUS BOARD EXAM RECALL Brain abscess: S. intermedius A 34 year old male from Tondo, Manila, a heroin user, presents with sudden onset of fever T> 39, RLQ pain, nausea, vomiting. Emergency appendectomy was done. 2 days post-op, (+) pinching chest pain. Troponins are low. CKMB negative. ECG shows sinus tachycardia. Blood culture on 2 sites were positive. (+) bacterial MODIFIED DUKE CRITERIA FOR INFECTIVE ENDOCARDITIS vegetations on tricuspid area seen in TEE. What is the most likely causative agent? a. Staphylococcus epidermidis b. Staphylococcus aureus c. Clostridium spp. d. Enterococcus spp. A 34 year old male from Tondo, Manila, a heroin user, presents with sudden onset of fever T> 39, vague abdominal pain, nausea, vomiting. Emergency laparotomy was done. Diagnosis of colon cancer was noted. 2 days post-op, (+) pinching chest pain. Troponins are low. CKMB negative. ECG shows sinus tachycardia. Blood culture on 2 sites were negative. (+) sterile vegetations on tricuspid area seen in TEE. What is the most likely causative agent? a. Staphylococcus epidermidis b. Staphylococcus aureus c. Streptococcus bovis d. Enterococcus spp. Answers given in the lecture video. Group D Streptococci Enterococcus faecalis Streptococcus bovis (Non enterococci) Part of the intestinal and oral flora Produces gamma hemolysis (majority) Causes endocarditis (Infective and Marantic) SPACE FOR SIDE NOTES Acute Subacute Toxic looking With underlying heart problem No underlying heart problem Gradual development Native valve =S. aureus Native/Prosthetic = Viridans group Prosthetic valve = S. epidermidis Endocarditis after GIT surgery = Enterococcus Marantic endocarditis = Streptococcus bovis EXPERTMD MICROBIOLOGY DR. DACANAY Unauthorized copying, sharing or distribution is strictly prohibited.. 10 of 89  Gram Negative Bacteria MICROBIOLOGY Christopher Rey Dacanay, RPh, MD PHYSICIAN LICENSURE EXAM OUTLINE CLINICAL DISEASES Gram Negative Diplococci – Neisseria Gonococcal urethritis Neisseria gonorrhoeae ○ Urethritis and epididymitis in men Neisseria meningitidis ○ Most common cause of urethritis Haemophilus influenzae Cervical gonorrhea Bordetella pertussis ○ In women, can progress to pelvic inflammatory disease Legionella pneumophila ○ Complications: Ectopic pregnancy Sterility GRAM NEGATIVE DIPLOCOCCI - Neisseria Chronic pelvic pain Non motile diplococcus Dyspareunia Aerobic, non-aerobic environment Peritonitis Oxidase (+), ferment CHO (acid) Perihepatitis: Fitz-Hugh Curtis Syndrome: “violin string” adhesions Culture: ○ Thayer-Martin/MTMA ○ NYC ○ Treatment; Ceftriaxone (IM) + Doxycycline / Azithromycin N. gonorrhoeae N. meningitidis Gonococcal Arthritis ○ The most common cause of septic arthritis in sexually active individuals Ophthalmia Neonatorum ○ Purulent conjunctivitis in newborns ○ Prophylaxis: Erythromycin eye ointment Bacterial conjunctivitis ○ N. gonorrhea is the most common cause of hyperacute bacterial conjunctivitis in adults Insignificant capsule Encapsulated Ferments glucose only Ferments maltose and glucose PREVIOUS BOARD EXAM RECALL In which of the following exudate specimen can a positive smear for Neisseria gonorrhoeae be a basis for presumptive diagnosis of Neisseria gonorrhoeae gonorrhea and start treatment without additional laboratory test? Virulence Factor Biological Functions a. Throat b. Endocervical Capsule Prevents phagocytosis c. Urethral Mediate attachment of gonococci to d. Rectal nonciliated epithelial cell; Pili Answers given in the lecture video. Prevent ingestion and killing of gonococci by neutrophils Confer resistance to serum killing of DIAGNOSIS Por proteins gonococci by preventing fusion of Specimen Significance Further testing phagolysosome in neutrophils Urethra Presumptive Diagnosis: No dx testing necessary Mediate the bacterial adherence to each other Opa proteins (+) Diplococci within pus cells NAAT or culture and to the eukaryotic cells Endocervix Produce antibodies that block serum Conjunctiva Can also be diagnostic Rmp proteins bactericidal activity against gonococci Throat Lipo- Generally, not helpful Rectum oligosaccharides Possesses endotoxic activity of the bacteria (LOS) Synovial fluid IgA protease Destroys IgA immunoglobulin Beta-lactamase Degrades beta-lactam rings in the penicillin Neisseria meningitidis Plasmid-borne virulence determinants are Virulence factors Plasmids ○ Capsule associated with antimicrobial resistance ○ Pili ○ IgA protease Humans are the only natural host 12 strains ○ Serotypes A, B, C cause most cases Most common form of infection: Asymptomatic carriage ○ Most common anatomic site: nares Disease begins when bacteria enter bloodstream, pass into cranial circulation, multiply in meninges ○ Very rapid onset ○ Endotoxin causes hemorrhage and shock ○ Can be fatal Treatment ○ Penicillin ○ Chloramphenicol EXPERTMD MICROBIOLOGY DR. DACANAY Unauthorized copying, sharing or distribution is strictly prohibited.. 11 of 89  EXPERTMD MEDICINE BOARD REVIEW Gram-Negative Bacteria CLINICAL DISEASES Possible complications: Pharyngitis/pneumonia → sepsis ○ Pneumonia ○ Meningococcemia with or without meningitis usually with ○ Seizure complement C5-C9 deficiency) ○ Encephalitis Death within 24 hours Treatment: Hemorrhage; DIC ○ DOC: Erythromycin Meningococcemia with petechial bleeding Can cause hypertrophic pyloric stenosis Waterhouse Friderichsen Syndrome ○ Alternative: Azithromycin ○ Also known as hemorrhagic adrenalitis ○ Fulminant meningococcemia ○ Adrenal gland failure due to bleeding into the adrenal glands Legionella pneumophila caused by severe bacterial infection, most commonly due to Facultative intracellular Neisseria meningitidis Aerobic, fastidious ○ Manifests as: Natural habitat is water Hyponatremia  no aldosterone produced Causes Legionnaires’ disease and Pontiac fever Hyperkalemia Poorly Gram staining → Dieterle’s silver stain Hypoglycemia_______________ Grows intracellularly Grown on buffered charcoal yeast extract agar PREVIOUS BOARD EXAM RECALL ○ Contains: L-cysteine and Iron In a patient infected with Neisseria meningitidis presenting with hemorrhagic adrenalitis, this is called Specimen Legionnaires’ Pontiac Fever a. Cushing Pneumonia Flu-like illness (fever, b. Waterhouse-Friderichsen Clinical features Cough chills, malaise) c. Weil Fever WITHOUT pneumonia d. Fitz-Hugh-Curtis Radiographic Yes No Which of the following is the most widely used prophylactic drug for pneumonia meningococcemia in the local setting? 24-72 hours after a. Rifampicin Incubation period 2-14 days after exposure exposure b. Ceftriaxone c. Ciprofloxacin d. Penicillin G PREVIOUS BOARD EXAM RECALL Answers given in the lecture video. 23/M fishpond cleaner developed fever, cough, and body weakness. If you are suspecting Pontiac fever because of the occupational history, which of the following CXR findings would you expect? Haemophilus influenzae a. Hazy infiltrates on upper and middle lobes Small uniform coccobacillus b. Consolidation, empyema, pneumatoceles Encapsulated c. Doughnut signs 6 distinct antigenic types (A, B, C, D, E, F) d. Negative chest ○ Type B: most virulent Vaccine contains polyribitol ribose phosphate Answers given in the lecture video. Growth factors (X, V) ○ H. influenzae satellitism in culture: S. aureus produces factor V via hemolysis → H. influenzae can grow in the hemolytic zone SPACE FOR SIDE NOTES around and between the large, white hemolytic staphylococci H. influenzae is incapable of hemolysis on its own. It requires blood components hemin (factor X) and NAD+ (factor V) for its growth X-factor (hemin): Heat-stable substance V-factor (NAD): Heat-labile ○ Coenzyme I ○ Nicotinamide adenine dinucleotide ○ Found in the blood or secreted by certain organisms Causes: Meningitis, Epiglottitis, Septic arthritis, Sepsis, Sinusitis, Otitis media Lab diagnosis: isolation on Chocolate agar_____________ Bordetella pertussis Fastidious coccobacilli (+) capsule in virulent strains Oxidase (+), urease (-) Agglutination property Strict aerobe Produces whooping cough Can be plated on: ○ Regan-Lowe or ○ Bordet-Gengou medium Component of acellular vaccine (DTaP) CLINICAL COURSE – WHOOPING COUGH 1. Catarrhal (1-2 weeks) 2. Paroxysmal (1-6 weeks) 3. Convalescent (weeks to months) EXPERTMD MICROBIOLOGY DR. DACANAY Unauthorized copying, sharing or distribution is strictly prohibited.. 12 of 89  Spore-Forming and Non-Spore-Forming Rods MICROBIOLOGY Christopher Rey Dacanay, RPh, MD PHYSICIAN LICENSURE EXAM OUTLINE PREVIOUS BOARD EXAM RECALL INTRODUCTION A 28/M worker has a 2 day history of fever, cough, dyspnea. He SPORE-FORMING RODS presents in the ER in tripod position, altered sensorium with O2 sat BACILLUS of 86% at room air. ABG showed metabolic acidosis. Patient was CLOSTRIDIUM intubated but still unstable. Patient then expired at the ER. PMHx (+) NON-SPORE-FORMING RODS DM uncontrolled (+) asthma. Personal Hx: alcoholic drinker, worker CORYNEBACTERIUM in a factory of linen and fabric from sheep fleece. What is the most LISTERIA likely diagnosis? a. CAP b. Asthma exacerbation INTRODUCTION c. Diabetic ketoacidosis BACTERIAL SPORE POSITION d. Anthrax In relation to the case above, which of the following is true regarding the causative agent? a. Gram (+) cocci in chains b. Has a capsule made up of D-aspartic acid c. Forms medusa head morphology in gram staining d. None of the above In relation to the case above, what is the MOST LIKELY cause of death? a. Pulmonary hemorrhage Bacterial spores are reproductive structures formed by certain types b. Pleural effusion of bacteria as a means of surviving adverse environmental c. Hemorrhagic stroke conditions. d. Cardiac tamponade They are highly resistant to heat, desiccation, chemicals, and radiation allowing the bacteria to endure harsh conditions that would What radiologic finding would be compatible with the case above? otherwise be lethal. a. Meniscus sign The position of bacterial spores within a bacterial cell can vary b. Widened mediastinum depending on the species. c. “Thumbprint sign” In general, bacterial spores are typically located in the central part d. Lemon shaped hyperdensity of the bacterial cell e.g. Bacillus anthracis ○ Terminal - Clostridium tetani To which of the following clinical entities is the expected cause of the ○ Subterminal - Clostridium botulinum death of the patient in the above case similar to? The process of spore formation is called sporulation, and it involves a. Weil’s syndrome the transformation of a vegetative bacterial cell into a spore. During b. Congenital rubella sporulation, the spore is usually positioned centrally within the cell c. Legionnaires disease and is surrounded by a thick, protective layer known as the spore d. All of the above coat. Which of the following drugs have coverage for the causative agent of Woolsorter’s disease? SPORE-FORMING RODS a. Penicillin and Ciprofloxacin BACILLUS b. Monoclonal antibody Bacillus anthracis c. Doxycycline Only bacteria with amino acid capsule (D-glutamic acid) d. All of the above Identified by McFadyean Reaction ○ Polychrome methylene blue capsule – pink Answers given in the lecture video. ○ Bacilli - dark blue ○ Diagnostic staining for B. anthracis CUTANEOUS ANTHRAX Causes ANTHRAX Most common route of entry (95%) ○ Cutaneous: exotoxin causes localized tissue necrosis Direct epidermal contact with spores causes localized tissue Eschar formation with edema necrosis, evidenced by a painless round black lesion with a rim of ○ Respiratory: Woolsorter’s disease→ pulmonary hemorrhage edema (malignant pustule) Radiologic finding: widened mediastinum ○ GI: rare but fatal INHALATIONAL/PULMONARY ANTHRAX Virulence factors: inhaled spores from animals (Woolsorter’s disease) or from ○ Protective antigen weaponized preparations (bioterrorism) ○ Edema factor ○ Lethal factor prolonged latent period (2mos) before rapid deterioration Treatment: Raxibacumab massively enlarged mediastinal lymph nodes; pulmonary hemorrhage (MCC of death); meningeal symptoms 100% mortality rate without immediate treatment GASTROINTESTINAL ANTHRAX: ingestion of live spores leads to UGI ulceration, edema, and sepsis vomiting abdominal pain, bloody diarrhea rapidly progressive course mortality approaches 100% Bacillus cereus Found in starchy food (fried rice) ENTEROTOXINS: 2 types Heat-labile - similar to the enterotoxin of cholera and the LT of E. coli; causes ADP ribosylation increasing cAMP Heat-stable - Staphylococcal-like enterotoxin functions as a superantigen Emetic Diarrheal Rice Meat, vegetables Short IP: 6 hours (mean: 9h) EXPERTMD MICROBIOLOGY DR. DACANAY Unauthorized copying, sharing or distribution is strictly prohibited.. 13 of 89  EXPERTMD MEDICINE BOARD REVIEW Spore-forming and Non-Spore-forming Rods Emetic Diarrheal Vomiting, nausea, abdominal Diarrhea, nausea, abdominal cramps cramps Shorter duration: 8-10 hours Longer duration: 20-36 hours (mean: (mean: 9h) 24h) Heat-stable enterotoxin Heat-labile enterotoxin Similar to staphylococcal food Resembles clostridial gastroenterities poisoning CLOSTRIDIUM Clostridium perfringens Clostridium botulinum Common cause of food poisoning Produces the most potent neurotoxin (blocks the release of Gas gangrene or pig bel disease acetylcholine from presynaptic nerve terminals) which causes flaccid Possesses an alpha-toxin (lecithinase) → Nagler’s reaction paralysis Fatal food poisoning Botulinum toxin Clostridium difficile Toxin is identified through the Mouse Neutralization Test Most common cause of superinfection Pseudomembranous colitis Severe diarrhea, abdominal cramping, fever PREVIOUS BOARD EXAM RECALL Which of the following drugs can precipitate pseudomembranous colitis? a. Clindamycin b. Cephalexin c. Amoxicillin