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Microbiology

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Gram Positive Cocci

Question
50 out of 78
 

Which one of the following procedures is most likely to reduce the incidence of group B streptococcal disease in an infant?



A Identification of possible high-risk births

B Intrapartum antibiotic treatment

C Screening of pregnant females at the first office visit, usually during the first trimester

D Screening of pregnant females in the last trimester

Ans. B Intrapartum antibiotic treatment

a. The incidence of group B streptococcal (GBS) disease is 1 to 3 cases per 1000 births. Neonates acquire the disease during birth from mothers who harbor the organism.

b. Risk factors include prematurity, premature rupture of membranes, and group B streptococcal carriage. GBS can be reduced by intrapartum administration of penicillin.

c. While GBS is relatively more resistant to penicillin than group A streptococci, the great majority of GBS isolates are still penicillin-susceptible.

d. An aminoglycoside such as gentamicin may be added to GBS treatment regimens due to the relative reduced susceptibility of some strains.

ENTEROCOCCUS

EXTRA EDGE

Previously referred as enterococcal group D streptococci

Characteristic:

a. Normal flora of lower intestinal tract

b. Non motile, non capsulated, gram + cocci in pairs, short chains

c. , or non- hemolytic on sheep blood agar

d. MacConkey’s agar: tiny magenta colored colonies (LF)

e. Grow in presence of 6.5% NaCl, pH 9.6, at 10C & 45°C

f. Grow in presence of 40% bile, hydrolyze aesculin

g. PYRase test +

h. Survive 60c for 30 min

i. Resistant to penicillin (altered PBP’s) and aminoglycosides (decreased uptake)

i. E. faecalis: most common; E. faecium , E. durans

ii. Most common infections-UTI, wound infection, endocarditis, Peritonitis, Septicemia

Gram Positive Cocci Flashcard List

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