MLS: Microbiology Final Exam
Questions and All Correct Answers
2026 Updated.
National Fire Protection Association Hazard colors - Answer Red-> fire
Blue-> health
Yellow-> reactivity
White-> special
Exotoxin - Answer excreted by organisms. found in both GP & GN organisms. (ex: S. aureus, B.
anthracis, S. pyogenes, tetanus, diphtheria, botulism)
Endotoxin - Answer integral part of cell wall. found mostly in GN organisms. (ex: E. coli, S.
typhi, Shigella, V. cholera, meningococcemia, GNR sepsis)
blood culture bottles - Answer minimum: 5-10 mL blood
SPS as preservative
SPS - Answer sodium polyanethol sulfinate
kills Neisseria species
CSF bacterial storage - Answer room temp (20C)
CSF viral storage - Answer <5 days: fridge (2-6C)
>5 days: freezer (-70C)
Sputum rejection - Answer >10 squamous epithelial cells per low power field
Staph aureus - Answer Beta hemolytic, GPC in clusters, lipochrome pigment (dull yellow),
catalase & coagulase/staph latex (+)
MRSA - Answer methicillin resistant staph aureus
PBP2a mutation from mecA gene
S. aureus toxin causing food poisoning - Answer enterotoxin
,coagulase negative staph (CNS) - Answer large creamy white colonies. usually non-hemolytic,
coagulase/staph latex (-)
S. saprophyticus - Answer pearly white, UTI, novobicin resistant
S. lugdunensis - Answer similar to S. aureus
PYR (+)
S. epidermidis - Answer grey colonies
skin & periodontal infections
S. intermedius - Answer PYR (+) & latex (+)
skin/wound infections
stomatococcus - Answer capsule
coagulase (-)
needles/drug abusers
micrococcus - Answer gram positive cocci in tetrads
oxidase & microdase disk (+)
bright lemony yellow pigment
hemolytic patterns - Answer beta: complete lysis (ex: Step A, B, C, etc.)
alpha: partial hemolysis (ex: Strep. pneumo & viridans)
gamma: no hemolysis (ex: enterococcus)
beta strep A - Answer Strep pyogenes
S. pyogenes - Answer strep throat (A, C, & G)
necotizing fasciitis-> M protein
S. pyogenes secondary sequalae - Answer rheumatic fever, glomerulonephritis, scarlet fever,
cellulitis, erysipelas (full body rash)
, beta strep B - Answer Strep agalactiae
Strep agalactiae - Answer neonatal meningitis & septicemia
CAMP (+), carrot broth (+)
Enterococci - Answer bile esculin (+) & 6.5% NaCl (+) & PYR (+)
E. faecalis & E. faecium
Strep viridans - Answer Bile esculin, 6.5% NaCl, & PYR (-)
most common cause of SBE (subacute bacterial endocarditis)
Strep Bovis - Answer Bile esculin (+), 6.5% NaCl, (-) & PYR (-)
associated w/ GI cancer
Step pneumoniae - Answer GPC, lancet shape, checker colonies (autolytic enzymes)
alpha hemolytic
community pneumonia & meningitis
susceptible to optochin
bile solubility (pneumolysin suppresses phagocytes)
Abiotrophia defectiva - Answer nutritionally deficient Strep
require B6
satellite S. aureus
cause endocarditis
ex: S. defectivus & S. adjacent
aerobic GPR, non-spore forming - Answer Erysipelothrix rhusiopathiae
Listeria
Corynebacterium
Lactobacillus
Listeria monocytogenes - Answer systemic: meningitis, bacteremia, encephalitis
localized: conjunctivitis, lymphadenopathy, skin infections
motility: tumbling, umbrella (agar). nonmotile at 37C
intracellular & hydrolyze esculin
Questions and All Correct Answers
2026 Updated.
National Fire Protection Association Hazard colors - Answer Red-> fire
Blue-> health
Yellow-> reactivity
White-> special
Exotoxin - Answer excreted by organisms. found in both GP & GN organisms. (ex: S. aureus, B.
anthracis, S. pyogenes, tetanus, diphtheria, botulism)
Endotoxin - Answer integral part of cell wall. found mostly in GN organisms. (ex: E. coli, S.
typhi, Shigella, V. cholera, meningococcemia, GNR sepsis)
blood culture bottles - Answer minimum: 5-10 mL blood
SPS as preservative
SPS - Answer sodium polyanethol sulfinate
kills Neisseria species
CSF bacterial storage - Answer room temp (20C)
CSF viral storage - Answer <5 days: fridge (2-6C)
>5 days: freezer (-70C)
Sputum rejection - Answer >10 squamous epithelial cells per low power field
Staph aureus - Answer Beta hemolytic, GPC in clusters, lipochrome pigment (dull yellow),
catalase & coagulase/staph latex (+)
MRSA - Answer methicillin resistant staph aureus
PBP2a mutation from mecA gene
S. aureus toxin causing food poisoning - Answer enterotoxin
,coagulase negative staph (CNS) - Answer large creamy white colonies. usually non-hemolytic,
coagulase/staph latex (-)
S. saprophyticus - Answer pearly white, UTI, novobicin resistant
S. lugdunensis - Answer similar to S. aureus
PYR (+)
S. epidermidis - Answer grey colonies
skin & periodontal infections
S. intermedius - Answer PYR (+) & latex (+)
skin/wound infections
stomatococcus - Answer capsule
coagulase (-)
needles/drug abusers
micrococcus - Answer gram positive cocci in tetrads
oxidase & microdase disk (+)
bright lemony yellow pigment
hemolytic patterns - Answer beta: complete lysis (ex: Step A, B, C, etc.)
alpha: partial hemolysis (ex: Strep. pneumo & viridans)
gamma: no hemolysis (ex: enterococcus)
beta strep A - Answer Strep pyogenes
S. pyogenes - Answer strep throat (A, C, & G)
necotizing fasciitis-> M protein
S. pyogenes secondary sequalae - Answer rheumatic fever, glomerulonephritis, scarlet fever,
cellulitis, erysipelas (full body rash)
, beta strep B - Answer Strep agalactiae
Strep agalactiae - Answer neonatal meningitis & septicemia
CAMP (+), carrot broth (+)
Enterococci - Answer bile esculin (+) & 6.5% NaCl (+) & PYR (+)
E. faecalis & E. faecium
Strep viridans - Answer Bile esculin, 6.5% NaCl, & PYR (-)
most common cause of SBE (subacute bacterial endocarditis)
Strep Bovis - Answer Bile esculin (+), 6.5% NaCl, (-) & PYR (-)
associated w/ GI cancer
Step pneumoniae - Answer GPC, lancet shape, checker colonies (autolytic enzymes)
alpha hemolytic
community pneumonia & meningitis
susceptible to optochin
bile solubility (pneumolysin suppresses phagocytes)
Abiotrophia defectiva - Answer nutritionally deficient Strep
require B6
satellite S. aureus
cause endocarditis
ex: S. defectivus & S. adjacent
aerobic GPR, non-spore forming - Answer Erysipelothrix rhusiopathiae
Listeria
Corynebacterium
Lactobacillus
Listeria monocytogenes - Answer systemic: meningitis, bacteremia, encephalitis
localized: conjunctivitis, lymphadenopathy, skin infections
motility: tumbling, umbrella (agar). nonmotile at 37C
intracellular & hydrolyze esculin
