G+ Cocci PDF - Microbiology Past Paper

Virulence factor of S. aureus with affinity for Fc of IgG --- Protein A Preferred growth medium for S. aureus on blood agar plates (BAP) --- Medium-large pinhead smooth convex opaque creamy yellow, β-hemolytic Colony color of MRSA on CHROMagar --- Mauve S. aureus identification genes detected by P...

Virulence factor of S. aureus with affinity for Fc of IgG --- Protein A Preferred growth medium for S. aureus on blood agar plates (BAP) --- Medium-large pinhead smooth convex opaque creamy yellow, β-hemolytic Colony color of MRSA on CHROMagar --- Mauve S. aureus identification genes detected by PCR --- nucA gene, mecA gene Sensitivity test result for Bacitracin (0.04 U) in Staphylococcus aureus --- Resistant Sensitivity of Staphylococcus species to Furazolidone (100µg) --- Sensitive Positive result in the Coagulase test for S. aureus using the slide method --- Clumping Test that differentiates Micrococcus from Staphylococcus --- Microdase (Modified Oxidase) test Color change indicating a positive Microdase test result --- Blue to purple-blue Positive indicator for DNase test on DNase agar for S. aureus --- Colorless or clearing Negative control organism for the DNase test on DNase agar --- E. coli Result in Coagulase test indicating Staphylococcus epidermidis using the tube method --- No clot Positive reaction color for PYR test --- Bright red Color of S. aureus colonies on Loeffler Serum Slant --- Golden yellow Temperature for Coagulase tube test overnight incubation --- Room temperature Test principle: H2O2 + O2 --- Catalase test S. aureus identification method for coagulase test if slide test is negative --- Tube coagulase test Color indication for a positive Voges-Proskauer test --- Red Staphylococcus species resistant to Novobiocin (5 µg) --- Staphylococcus saprophyticus Effect of Protein A on immune system components --- Binds to Fc of IgG Type of bacteria that are catalase positive and Gram-positive cocci --- Staphylococcus, Micrococcus Organism appearing as Gram-positive cocci in clusters --- Staphylococcus Expected zone of inhibition for Novobiocin sensitivity test (5 µg) for S. epidermidis --- >16 mm Medium color change when S. aureus grows on Mannitol Salt Agar (MSA) --- Yellow Colony appearance for Staphylococcus haemolyticus on blood agar plates --- β-Hemolytic Virulence factor responsible for inhibiting phagocytosis in S. aureus --- Capsule Virulence factor responsible for disrupting cell membranes in S. aureus --- Beta exotoxin Type of toxin in S. aureus that is heat stable and associated with food poisoning --- Enterotoxins A- E, G-I Virulence factor that allows S. aureus to break down fibrin clots --- Staphylokinase Staphylococcus species commonly associated with urinary tract infections in sexually active young women --- Staphylococcus saprophyticus Virulence factor that acts as a spreading factor by breaking down connective tissues --- Hyaluronidase Positive result indicator for Staphylococcus aureus in the Catalase test --- Copious bubbles/effervescence Temperature range for the Catalase test --- 22-25°C Result for Micrococcus luteus in the Modified Oxidase (Microdase) test --- Blue to purple-blue Reagent used in the Catalase test --- 3% or 30% hydrogen peroxide Preferred colony color of S. citreus on Loeffler Serum Slant --- Lemon yellow Result for a Staphylococcus aureus sample in the Coagulase tube test after 1-4 hours at 35-37°C --- Clot formation Coagulase-negative result in Staphylococcus saprophyticus for Novobiocin susceptibility test --- Resistant (16 mm ZOI) Concentration of KOH solution used in the Voges-Proskauer test --- 40% Sensitivity threshold for Bacitracin in Micrococcus --- Sensitive at ≥15 mm Glucose metabolism classification for Micrococcus species --- Oxidizers Expected Coagulase test result for Staphylococcus saprophyticus --- Negative Staphylococcus species associated with transient colonization without multiplication --- Transient colonizer (e.g., Micrococcus) Bacterial response to Modified Oxidase test in Staphylococcus species --- Negative (no color change) Incubation time and temperature for DNase test using methyl green agar --- 13-24 hours at 35-37°C S. aureus exotoxin causing direct cytotoxicity to red blood cells (RBCs) --- Delta toxin Medium that encourages colony differentiation between mannitol-fermenting and non-fermenting staphylococci --- Mannitol Salt Agar (MSA) Expected result for S. aureus colonies on MSA due to mannitol fermentation --- Yellow colonies and halo Expected reaction for S. aureus in the DNA/Toluidine Blue DNase test --- Deep pink Effect of hydrochloric acid addition in DNase test on DNA --- Precipitates DNA Differentiating feature of Micrococcus in Gram-positive cocci tests --- Forms tetrads, obligate aerobe Species considered a resident colonizer with ability to multiply --- Resident colonizer (e.g., Staphylococcus) Virulence factor of S. aureus that targets white blood cells (WBCs) --- Gamma exotoxin Appearance of Micrococcus colonies on Modified Oxidase test plate --- Blue to purple-blue (positive reaction) Expected result for Serratia on DNase test using methyl green --- Colorless What is the shape of Streptococcus and Enterococcus organisms? — Gram-positive cocci in pairs or chains Are Streptococcus and Enterococcus catalase and oxidase positive or negative? — Negative What temperature range does Streptococcus pyogenes grow at? — 37°C only Which Streptococcus group is known to grow at both 10°C and 37°C? — Streptococcus lactis What hemolytic pattern does Streptococcus pneumoniae display? — Alpha-hemolytic Name a disease caused by Group A Streptococcus (GAS). — Acute pharyngitis What test can confirm the presence of Streptococcus pyogenes? — Taxo A Sensitive What is the main virulence factor responsible for post-streptococcal sequelae in Group A Streptococcus? — M protein What laboratory test is sensitive to Group B Streptococcus (GBS)? — CAMP test What enzyme allows S. pneumoniae to autolyze in the presence of bile? — Amidase Which organism is typically PYR positive? — Enterococcus faecalis, S. pyogenes What indicates a positive result in the Bile Esculin Hydrolysis test for Enterococcus? — Growth with blackening How are Streptococcaceae and Enterococcaceae classified in Rebecca Lancefield grouping? — By groups (e.g., Group A, B, etc.) What virulence factor does Streptococcus pyogenes have that binds to Factor H? — M protein What does the virulence factor C5a peptidase in Streptococcus pyogenes do? — Destroys chemotactic factors What is the typical Gram stain appearance of Gemella haemolysans? — Easily decolorizes, may appear as Gram-negative cocci What type of medium is used for the Bacitracin susceptibility test for S. pyogenes? — Supported Media or Blood agar plate (BAP) What temperature range is required for incubation in the Bacitracin susceptibility test? — 35-37°C with 5-10% CO₂ for 18-24 hours What color indicates a positive result in the PYR test for Enterococcus faecalis and S. pyogenes? — Bright red What type of medium is used in the Bile Esculin Hydrolysis test? — Bile esculin slant What type of indicator is used in the Bile Esculin Hydrolysis test? — Ferric ammonium citrate What is the other name of Taxo P in Optochin susceptibility test? — Ethylhydrocupreine hydrochloride What does a zone of inhibition greater than 14 mm in the Optochin test indicate? — Susceptibility, typically for S. pneumoniae What does a positive Bile solubility test look like? — Colony disintegration in agar or a clear broth culture What color does the LAP test turn if Enterococcus faecalis is present? — Red What medium is used for the CAMP test? — Blood agar plate (BAP) What type of hemolysis pattern is associated with Group B Streptococcus in the CAMP test? — Arrowhead hemolysis What reagent is added to the Hippurate Hydrolysis test for detection? — Ninhydrin reagent What color change indicates a positive result in the Hippurate Hydrolysis test? — Purple What type of broth is used in the Pyruvate test? — Pyruvate broth What does a yellow color in the Salt Tolerance test indicate for Enterococcus faecalis? — Growth in high salinity What temperature range and time are required for the Salt Tolerance test incubation? — 35-37°C for 24-48 hours What is the primary purpose of the CAMP test? — To differentiate Group B Streptococcus from other Streptococci What organism is positive in the Hippurate Hydrolysis test? — Streptococcus agalactiae What type of infections is Aerococcus urinae commonly associated with? — Urinary tract infections (UTIs) Which organisms (Gram-positive cocci in pairs or chains, Catalase and Oxidase negative, Facultative anaerobe) show intrinsic resistance to vancomycin? — Leuconostoc and Pediococcus What odor does Viridans Streptococci produce on CAP? — Butterscotch smell What organisms are considered Nutritionally Variant Streptococci (NVS)? — Abiotrophia spp. and Granulicatella spp. What is required for Nutritionally Variant Streptococci to grow on CAP? — Pyridoxal (Vitamin B6) or cross-streak with S. aureus What is the primary virulence factor of Streptococcus pneumoniae? — Capsule What hemolytic pattern does Streptococcus bovis exhibit? — Gamma-hemolytic What color change in the Bile Esculin Hydrolysis test indicates a negative result? — No blackening What is the Gram stain reaction of Streptococcus pyogenes? — Gram-positive Which hemolysin produced by Streptococcus pyogenes is oxygen stable? — Streptolysin S What type of hemolysis does Streptolysin O cause? — Subsurface (stab) hemolysis What disease is caused by antibody cross-reactivity of M protein to heart muscle in Streptococcus pyogenes infections? — Rheumatic fever What are the two post-streptococcal sequelae of Streptococcus pyogenes infection? — Rheumatic fever and Acute glomerulonephritis What infections are commonly caused by Group B Streptococcus (Streptococcus agalactiae) in neonates? — Meningitis, sepsis, and pneumonia What medium is used for detecting Group B Streptococcus? — Todd-Hewitt, Granada medium, LIM, Carrot medium What selective medium is used to isolate Enterococcus species? — Enterococcosel agar Which diagnostic test is positive for Enterococcus in the presence of 6.5% NaCl? — Salt Tolerance test What shape are Streptococcus pneumoniae cells under the microscope? — Encapsulated, bullet/lancet-shaped diplococci What diagnostic test differentiates Streptococcus pneumoniae from other alpha-hemolytic Streptococci? — Optochin susceptibility test What enzyme of Streptococcus pneumoniae mediates oxidative bursts during phagocytosis? — Pneumolysin What extracellular polysaccharides are produced by Viridans Streptococci to aid in cell attachment? — Glucans and dextrans What result does the LAP test turn for Pediococcus spp.? — Positive What additional nutrient is required for Abiotrophia spp. to grow on CAP? — Cystein, Pyridoxal (Vitamin B6) What clinical condition is most associated with Helcococcus spp.? — Foot infections What indicates a positive result in the Optochin susceptibility test for Streptococcus pneumoniae? — Zone of inhibition greater than 14 mm What organism is Hippurate positive and produces arrowhead hemolysis in the CAMP test? — Streptococcus agalactiae What condition is a common sequela of Streptococcus pyogenes skin infections? — Acute glomerulonephritis What is the Gram stain reaction of Helcococcus spp.? — Gram-positive What diagnostic test is specifically used to differentiate Group D Enterococci? — Bile Esculin Hydrolysis test What clinical symptoms are associated with Acute Glomerulonephritis following Streptococcus infection? — Edema, hypertension, hematuria, proteinuria What diagnostic test is used to confirm Streptococcus pneumoniae in cerebrospinal fluid? — CSF latex agglutination test What medium is used for the CAMP test to enhance hemolysis of S. aureus? — Blood agar plate (BAP) Which virulence factor in Streptococcus pyogenes is responsible for epithelial cell attachment? — Protein F What Streptococcus group includes S. dysgalactiae and S. equi? — Group C and G Which test uses a filter paper disk and detects β-naphthylamine? — PYR test What is the incubation condition for the Bile Esculin Hydrolysis test? — 35-37°C for 48 hours What does the Optochin disk test differentiate? — Differentiates S. pneumoniae from other alpha- hemolytic Streptococci What appearance on culture does Streptococcus pneumoniae have due to its capsule? — Mucoidal, umbilicate colonies Which streptococcus is known as 'flesh-eating bacteria'? — Streptococcus pyogenes What type of hemolysis is characteristic of Streptococcus bovis? — Gamma-hemolytic What temperature and duration are required for the LAP test? — 22-25°C for 5 minutes Which organism is positive for the 6.5% NaCl tolerance test? — Enterococcus faecalis What color indicates a positive reaction in the Salt Tolerance test for Enterococcus faecalis? — Yellow What virulence factor in S. pneumoniae allows for spreading and invasion in host tissues? — Phosphorylcholine What organism (Gram-positive cocci in pairs or chains, Catalase and Oxidase negative, Facultative anaerobe) may be mistaken for Gram-negative due to decolorization in Gram stain? — Gemella haemolysans What is the defining symptom of Scarlet Fever caused by Streptococcus pyogenes? — Rash What test confirms the presence of Enterococcus faecalis using esculin hydrolysis? — Bile Esculin Hydrolysis test What type of infections does Streptococcus agalactiae primarily cause in neonates? — Meningitis and sepsis What substance is released by S. pneumoniae that lyses red blood cells? — Pneumolysin What is the catalase reaction of all Streptococcus species? — Catalase negative What is the purpose of the Pyruvate test in Enterococcus identification? — To distinguish Enterococcus faecalis from Enterococcus faecium What diagnostic test is used to confirm Rheumatic fever caused by Streptococcus pyogenes? — ASO titer What Streptococcus group is S. agalactiae classified under? — Group B Which species requires cysteine or Vitamin B6 to grow and is classified as Nutritionally Variant Streptococci? — Abiotrophia spp. and Granulicatella spp. What species is known to cause slow-evolving bacterial endocarditis in the oral cavity? — Viridans Streptococci (e.g., S. sanguis) What reagent is used to detect β-naphthylamine in the PYR test? — N,N-methylamino- Cinnamaldehyde What temperature and duration are required for the Hippurate Hydrolysis test? — 35°C for 2 hours What organism's colonies appear umbilicate on Blood Agar Plate? — Streptococcus pneumoniae What species is identified using Granada medium? — Group B Streptococcus (Streptococcus agalactiae) What does a positive CAMP test result look like for S. agalactiae? — Arrowhead hemolysis near S. aureus streak What organism is identified by resistance to 0.04 units of Bacitracin? — Streptococcus agalactiae, S. aureus What species of Viridans Streptococci is associated with bacterial endocarditis? — Streptococcus sanguis What two organisms are compared in the LAP test using color changes? — Enterococcus faecalis (red) and Aerococcus viridans (yellow/no color) Which organism is a major cause of pneumonia in the community? — Streptococcus pneumoniae What Streptococcus species is known for causing necrotizing fasciitis? — Streptococcus pyogenes What virulence factor in Group B Streptococcus aids in evading the immune system? — Capsule What Lancefield group does Streptococcus dysgalactiae belong to? — Group C What test uses a Taxo A disk for detecting susceptibility? — Bacitracin susceptibility test What is the defining test for differentiating Streptococcus pneumoniae from other alpha-hemolytic streptococci? — Optochin susceptibility test What is the primary component of Streptococcus pyogenes that inhibits phagocytosis? — Hyaluronic acid What color indicates a positive Bile Esculin test for Enterococci? — Blackening Which organism is identified by the presence of a capsule and alpha hemolysis on BAP? — Streptococcus pneumoniae What test is commonly used to differentiate Enterococcus faecalis from Enterococcus faecium? — Pyruvate test What Streptococcus species is identified with a positive Neufeld quelling reaction? — Streptococcus pneumoniae What disease is characterized by edema, hypertension, hematuria, and proteinuria after Streptococcus infection? — Acute Glomerulonephritis Which Streptococcus requires a 5-10% CO₂ atmosphere for optimal growth in culture? — Streptococcus pyogenes Bile Esculin Hydrolysis: Growth but NO blackening — E. coli Bile Esculin Hydrolysis: NO growth & blackening — S. pyogenes What is the reagent/indicator of Bile solubility test in BAP? — 10% Na deoxycholate What is the reagent/indicator of Bile solubility test in broth? — 2% Na deoxycholate What does a zone of inhibition (ZOI) greater than 10 mm indicate in the bacitracin susceptibility test? — Susceptible (S. pyogenes, Micrococcus luteus) Which organism shows no zone of inhibition (ZOI) in the bacitracin susceptibility test? — S. agalactiae, S. aureus What color indicates a positive result in the PYR test within 5 minutes? — Bright Red (E. faecalis, S. pyogenes) What result indicates a negative PYR test? — No color change (S. agalactiae, S. aureus) What color change indicates a positive result in the bile esculin test? — Growth and Blackening (E. faecalis) What is the zone of inhibition (ZOI) threshold for optochin susceptibility to indicate a positive test for S. pneumoniae? — >14 mm ZOI Which organism is resistant in the optochin susceptibility test with a ZOI of less than 14 mm? — S. pyogenes What indicates a positive result in the bile solubility test for S. pneumoniae on agar? — Colony disintegration Which organism shows intact or insoluble colonies in the bile solubility test? — E. faecalis, Viridans What is observed in a positive CAMP test for S. agalactiae? — Arrowhead hemolysis Which organism does not show enhanced arrowhead hemolysis in the CAMP test? — S. pyogenes What indicates a positive result in the hippurate hydrolysis test for S. agalactiae? — Purple color Which organism shows no color or yellow-pink in the hippurate hydrolysis test? — S. pyogenes What color change indicates a positive result in the LAP test for E. faecalis? — Red What color indicates a positive pyruvate test for E. faecalis? — Yellow Which organism shows no color change or weak yellow-green in the pyruvate test? — S. gallolyticus What indicates a positive salt tolerance test for E. faecalis? — Growth with yellow color Which organism shows little or no growth in the salt tolerance test? — S. gallolyticus