Gram Positive Cocci

gram positive cocci that grow in clusters and are catalase positive

staphylococcus spp

coagulase positive staph spp

s. aureus

what is the clinical significance of s. aureus

bacteremia/sepsis, toxic shock syndrome, scalded skin syndrome

key ID info: coagulase positive, beta hemolytic, golden colonies, salt tolerant, ferments mannitol

s. aureus

what gene causes MRSA

mecA that produces PBP2a

how is MRSA detected

PCR or cefoxitin disk

what is MRSA treated with

vancomycin

key ID info: coag neg, non-hemolytic, white/gray colonies, novobiocin susceptible, grows in 6.5% NaCl, mannitol non-fermenter

staph epidermidis

what is the clinical significance of s. epidermidis

prosthetic valve endocarditis, catheter associated infections, hospital acquired opportunist

key ID info: coag negative, non-hemolytic, novobiocin resistant, grows in 6.5% NaCl, white/cream colonies

staph saprophyticus

clinical significance of staph saprophyliticus

common cause of UTI in sexually active females

gram positive cocci that is part of normal skin flora, usually a contaminant, and looks like staph

micrococcus

key ID info: catalase positive, coagulase negative, bacitracin susceptible, modified oxidase positive

micrococcus

gram positive cocci in chains, catalase negative

streptococcus species

group A strep

strep pyogenes

key ID info: PYR positive, bacitracin susceptible, beta hemolytic, streptolysin O and S

s. pyogenes

clinical significance of S. pyogenes

strep throat, scarlet fever, post streptococcal sequelae

Group B strep

Strep agalactiae

key ID info: CAMP positive, Hippurate Hydrolysis, PYR negative, Bacitracin resistant, weakly beta hemolytic

S. agalactiae

clinical significance of S. agalactiae

baby strep; sepsis, meningitis, pneumonia in neonates; normal flora of genitourinary tract that can be transmitted to baby

when are pregnant women screened for s. agalactiae and what is the treatment if positive

35-37 weeks gestation; intrapartum IV antibiotics

what feature of S. agalactiae is the main cause of neonatal infections

polysaccharide capsule that protects it from phagocytosis; contains sialic acid

gram positive lancet shaped diplococci

strep pneumoniae

key ID info: optochin sensitive, bile esculin positive, alpha hemolytic

strep pneumoniae

clinical significance of S. pneumoniae

meningitis, otitis, pneumonia and sinusitis

what is the virulence factor of S. pneumoniae

polysaccharide capsule that prevents it from phagocytosis

strep species that is part of normal oral flora

s. viridans

key ID info: optochin resistant, bile esculin negative, alpha hemolytic

S. viridans

clinical significance of S. viridans

can cause subacute bacterial endocarditis, bacteremia after dental procedures

Group D strep

strep bovis

key ID info: bile esculin positive, 6.5% NaCl negative, non-hemolytic, bile solubility negative

Group D strep

clinical significance of Group D strep

strong association with colon cancer

beta-hemolytic strep (not A, B or D)

groups C, F, and G

key ID info: PYR negative, bacitracin resistant, CAMP negative, catalase negative, beta hemolytic

Beta hemolytic strep (not A, B or D)

clinical significance of S. anginosus (beta-hemolytic strep, not A, B or D)

may be found in abscesses of brain, liver or abdomen

virulence factor of group A strep (S. pyogenes)

M protein

key ID info: catalase negative, bile esculin positive, grows in 6.5% NaCl, PYR positive, non-hemolytic

Enterococcus spp

which enterococcus species is vancomycin resistant and a major hospital-acquired pathogen

Enterococcus faecium

hemolytic reaction: complete lysis of RBCs, clear zone around colony

beta hemolysis

hemolytic reaction: partial lysis of RBCs, green zone around colony

alpha hemolysis

colonies on SBA: 1-3 mm, round, smooth, convex, glistening, opaque, butter-like (butyrous)

staphylococcus spp

colonies on SBA: < 1 mm, white to gray, translucent or semiopaque

streptococcus spp