Gram positive

Question 1

M Protein

Answer 1

S. pyogenes
2 exotoxins
Streptolysin S
Streptolysin O

Question 2

Group D Streptococcus
Strep bovis
Strep equines

Answer 2

Colony morph: white to grey gamma hemolytic
gram stain: gram + cocci in pairs or chains
catalase =
BE +
6.5% NaCl =
Clinical: Bacterial endocarditis, bactermia, UTI’s, wound infections

Question 3

Staphylococcus aureus

Answer 3

Colony morph: white-creamy opaque colonies on BAP, BETA HEMOLYSIS
gram stain: gram positive cocci in clusters
Biochemical tests: catalase positive, coagulase positive

Question 4

Protein A

Answer 4

Cell wall component in S. aureus that prevents phagocytosis by binding IgG Fc portion

Question 5

Micrococcus luteus

Answer 5

Colony morph: BAP - large, yellow colonies
gram stain: gram + cocci in tetrads or clusters
catalase +
coagulase -
modified oxidase +
Bacitracin susceptible

Question 6

Staphylococcus saprophyticus

Answer 6

NF - UTI's of child bearing age women
Colony morph: smooth, buttery-like, STRINGY when picked off place
Gram positive cocci in clusters
Catalase POSITIVE
Coagulase NEG
Novobiocin Resistant

Question 7

What are virulence factors of S. agalactiae?

Answer 7

Sialic acid capsule
CAMP factor
Hyaluronidase (spreading factor)

Question 8

Streptococcus agalactiae

Answer 8

Colony morph: small/tiny grey/white mucoid colonies
narrow zone beta hemolysis
gram stain: gram positive cocci in pairs and chains
catalase =
CAMP +
Hippurate +
Bacitracin R
Clinical: neonatal meningitis
Treatment: Penicillin + Cephalosporin
ex. Ampicillin + Gentamycin

Question 9

What is in a beta strep run?

Answer 9

Bacitracin (A) disc
OR PYR
CAMP
OR Hippurate
Bile esculin
6.5% NaCl

Question 10

Lactobacillus

Answer 10

NF "Good guys" of female Genitourinary tract
lowers pH
pleiomorphic g+ rods
catalase =
H2S =

Question 11

Lancefield group antigen A

Answer 11

Streptococcus pyogenes

Question 12

Streptococcus pyogenes

Answer 12

GROUP A Strep
colony morph: small-tiny semi translucent
wide zone Beta hemolysis
gram stain: gram positive cocci pairs or chains
Catalase negative
Biochemical Test: Bacitracin sensitive
PYR +
Clinical: STREP THROAT, Rheumatic fever, Scarlett Fever, Necrotizing fasciitis
Treatment: Amoxicillin, azithromycin if allergic to amox

Question 13

Enterococcus

Answer 13

Colony morph:  white to grey colonies with disappearing borders
mostly gamma hemolysis
sometimes alpha
rarely beta
Catalase weak +
BE +
PYR +
6.5% NaCl +
Clinical: NF --- nosocomial infections
Endocarditis in patients w/ prosthetic heart valves
Treatment: vancomycin, unless VRE

Question 14

What antibiotics do you use to treat MRSA?

Answer 14

Vancomycin, clindamycin, levofloxacin

Question 15

What is in an alpha strep run?

Answer 15

Optichin (P) disc
Bile Esculin
6.5% NaCl

Question 16

Lancefield group antigen B

Answer 16

Streptococcus agalactiae

Question 17

Staphylococcus epidermidis

Answer 17

NF - Often nosocomial
Colony morph: white, smooth colonies, GAMMA HEMOLYTIC
gram stain: gram positive cocci in clusters
catalase positive
COAGULASE NEGATIVE
NOVOBIOCINN SENSITIVE

Question 18

Corynebacterium diptheriae

Answer 18

causative agent of DIPTHERIA
    tough grey-white pseudomembrane in sputum
Diptheria toxin (bacteriophage) tox gene
Colony morph: BAP small waxy, narrow beta hemolysis
    CTBA selective for g+ differential grey-black colonies
    MTM black colonies w/ brown halo
Gram stain: pleimorphic g+ rods
    V forms, pickett fences
Methylene blue smear
      Babes-Ernst granules
Modefied Elek test ---- arch of identity
Catalse +
Urease =

Question 19

What is in a gamma strep run?

Answer 19

gamma hemolysis (nonhemolytic)
bile esculin
6.5% NaCl

OR PYR

Question 20

Gardenella vaginalis

Answer 20

NF female vagina
BAP colony morph: pinpoint, nonhemolytic colonies
aerobic gram variable short rods, gamma hemolysis
HBT (Human bilayer Tween), V-Agar = BETA HEMOLYSIS
Catalase =
Hippurate +
Urea +
clinical: bacterial vaginosis: pH >4.5
Clue cells w/ foul smelling whiff test + KOH

Question 21

Strep veridans

Answer 21

colony morph: pinpoint grey colonies usually alpha hemolytic
gram stain: gram positive cocci in pairs and chains
catalase =
optichin R
BE =
6.5% NaCl =
ID BY EXCLUSION

Question 22

Streptococcus pneumoniae

Answer 22

Colony morph: coin shape raised rim alpha hemolytic grows best with increased CO2
gram stain: gram positive diplococci
Catalse negative
Optichin (P) Disc Susceptible
Bile Esculin +
Clinical: Lobar Pneumonia, Meningitis
Treatment: Penicillins

Question 23

Listeria monocytogens

Answer 23

3rd trimester flu like leading to stillbirth
neonatal meningitis
food poisoning
BAP --- beta hemolysis
gram stain: short, NON BRANCHING, g+ rods
Tumbling motility
Catalase +
BE +
CAMP + (BLACK, NOT ARROWHEAD)

Question 24

Erysipelothrix rhusiopthiae

Answer 24

Collect from skin biopsy, lesion aspirate
Colony morph: pleiomorphic between 24-48 hrs
gram stain: pleiomorphic g+ rods
Catalse =
Nonmotile
H2S production on TSI

Question 25

Nocardia

Answer 25

Rare in humans — immunocompromised
Pulmonary, Cutaneous —- sulfur granules
Gram + filamentous, branched, beaded
Weakly acid fast —- light pink

Question 26

Bacillus anthracis

Answer 26

Cause of anthrax
cutaneous anthrax —- eschar lesion
inhalation anthrax—– nonspecific flu sudden severe
extreme precaution —- BSC3
Large g+ rods w/ square ends w/ central spore
“bamboo chutes”
non hemolytic, quick growth on BAP
beaten egg white appearance
test = capsule detection, anthracis toxin
treatment : cirpo, doxycycline IV

Question 27

Bacillus cereus

Answer 27

Clinical: food poisoning 2 forms
diarrheal - self limiting
emetic toxin - rice tables disease (similar to staph.)

colony morph: beta hemolytic small, shiny spreading
Gram + rod same as b. anthracis
MOTILE

Question 28

Bacillus subtillis

Answer 28

common contaminant
BAP very large gray, beta hemolytic
motile
large g+ rods, shorter than B. anthracis, and B. cereus