strep and enterococci

Question 1

Staph versus strep characteristics?
Catalase?
cocci arrangement?
growth media and temp?
aerobic or anaerobic?
appearance when plated?

Answer 1

Staph/Strep
catalase pos/neg
cocci clusters/pairs and chains
minimal media at 35-37C/complex media at 35-37C
aerobic/anaerobic or CO2 atmosphere
cream or gold colored/translucent or clear

Question 2

Bacteria of Group A Strep? Group B?

Answer 2

Strep pyogenes

Strep agalactiae

Question 3

6 clinical manifestations of Strep throat?

Answer 3

Acute Pharyngitis
Impetigo
Erysipelas
Scarlet Fever
Necrotizing Fasciitis
Toxic Shock-like syndrome
puerperal sepsis

Question 4

Why is Acute Pharyngitis (strep throat) recurrent?

Answer 4

Diff M proteins (each strain has a diff M protein, ABs are made specifically for a specific M protein, so you are now resistant to that strain, but not other strains)

Question 5

Erysipelas characteristics?

Answer 5

erythematic lesions with well demarcated border on face and legs (looks like severe burn, peeling skin)

Question 6

Scarlet Fever characteristics?

Answer 6

Caused by erythrogenic exotoxin
Strawberry Tongue
rash first appears as tiny red bumps on the chest and abdomen
fine, red, and rough-textured, blanches upon pressure
appears 12–48 hours after fever
generally starts on the chest, armpits, and behind the ears

Question 7

Necrotizing Fasciitis characteristics?

Answer 7

Infection deep in cutaneous tissue

extensive destruction of muscle and fat

Question 8

Toxic Shock-like Syndrome Toxin?

Answer 8

SPE toxin (TSST-1 with staph aureus)

Question 9

what is puerperal sepsis?

Answer 9

colonization of upper genital tract from strep pyogenes in genital tract or obstetrical personnel

Question 10

2 post-strep sequelae?

Answer 10

Rheumatic fever

acute glomerulonephritis

Question 11

Rheumatic fever clinical manifestation?

Answer 11

Fever, carditis, subcutaneous nodules, chorea, polyarthritis
Lesions on the heart valves (Aschoff bodies, as result of AB-antigen interactions injuring the heart) damage the valves and lead to endocarditis

Question 12

Acute glomerulonephritis clinical manifestation?

Answer 12

antigen-AB-compliment response complexes go through glomerulus and cause damage
causes edema, hypertension, hematuria, and proteinuria

Question 13

4 types of Strep pyogenes virulence factors?

Answer 13

Adherence (Lipteichoic acid and M protein)
Avoid opsonization and phagocytosis (capsule)
invade into epithelial cells
produce enzymes and toxins to cause cell destruction and lysis (hemolysins, hyaluronidase, streptokinase, nuclease)

Question 14

Effects of SPE?

Answer 14

super antigens that cause cytokine response leading to shock and organ failure
responsible for scarlet fever rash

Question 15

M protein actions?

Answer 15

binds to epithelial cells (adherence) allowing survival
required for virulence
degrades C3b complement component

Question 16

How do you treat strep pyogenes?

Answer 16

penicillin/ampicillin/amoxicillin

Erythromycin if allergic to penicillin

Question 17

Cause of Neonatal disease? Early vs Late onset?

Answer 17

Caused by Strep agalactiae
Early: First week of life
bacteremia, pneumonia, or meningitis (often fatal)
Late: 1week to 3mo
bacteremia with meningitis (better survival rate)

Question 18

Strep agalctiae in neonatal disease?

Answer 18

If pregnant mother’s vagina or rectum is colonized with strep agalactiae, then it can be spread to the baby upon birth because the baby has no immune protection.
So pregnant mothers are tested at 35-37weeks for this, and if positive, then give penicillin/ampicillin (clindamycin if allergic) to prevent spread of neonatal disease.

Question 19

Limitation of Group A strep kit?

Answer 19

70% sensitivity (so 30% chance of false neg), so need to follow negatives up with further testing

Question 20

Bovis Group (viridians strep) clinical significance?

Answer 20

Isolation from the loos indicates carcinoma of the colon

Question 21

Strep Milleri group species?

plated appearance and characteristic?

Answer 21

S anginosus, intermedius, constellatus

pinpoint colonies, have distinct butterscotch smell

Question 22

Clinical manifestation of strep milleri infection?

Answer 22

Pyogenic (pus-forming) abscesses, found in majority of brain abscesses

Question 23

Nutritionally deficient strep group species?

what do they lack?

Answer 23

abiotrophia and granulicatella

Vit B6

Question 24

What is the most common cause of meningitis?

Answer 24

Strep pneumoniae

Question 25

Strep pneumo lab characteristics?
gram+ or -? 
Shape?
occur on their own? pairs? chains?
catalase + or -?

Answer 25

gram+
lancet-shaped (pointed at one end)
diplococci normally (sometimes short chains)
catalase neg

Question 26

Strep pneumo blood agar characteristics?

Answer 26

2 appearances: Runny mucoid colony and flat with indented center

Question 27

Why Optochin test for strep pneumo?

Describe test?

Answer 27

Strep pneumo is inhibited by optochin.

plate strep pneumo on blood agar plate with optochin disc, incubate, and results will show dead zone around disc.

Question 28

enterococcus characteristics?
gram+ or -?
pairs or chains?
PYR + or -?

Answer 28

gram+ cocci in pairs or chains
PYR pos (indicates that it has pyrodonal peptidase)

Question 29

2 major disease causing entercocci species?

Answer 29

E. Faecium and E. Faecalis

Question 30

3 most common diseases of enterococci?

Answer 30

Urinary tract
Mixed bacterial wound infections and decubiti
Sepsis, endocarditis

Question 31

Enterococci treatment?

Answer 31

Intrinsically resistant to cehalosporins, aminoglycosides, and trimthoprim-sulfa(bactram)
treat with ampicillin (and amino glycoside for synergy)
or treat with Linezolid