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Flashcards in Streptococci Deck (44):
1

3 main gram positive cocci that cause disease

Streptococcus, Enterococcus, and Staphylococcus

2

What is main host defense of GPC (gram positive cocci)?

Phagocytosis (mainly) and neutrophils

3

Empyema

Collection of pus in a body cavity, especially pleural cavity

4

General characteristics of streptococci
Gram
Catalase?
Morphology
Oxygen environment

Gram positive
Catalase negative
Chains
Mostly facultative

5

Reservoir for pneumococcus

Nasopharynx / throat

6

Transmission of pneumococcus

Airborne

7

Strep pneumoniae morphology

Lancet-shaped (elliptical) diplococci

8

Hemolysis for strep pneumoniae

Alpha

9

O2 conditions for pneumoniae

Grow better w/ 10% CO2 (capnophile)

10

How do you differentiate pneumococcus from Strep Viridans?

Both are Gram positive and alpha hemolytic. Pneumococcus is highly susceptible to Optochin disk (Cu compound). Strep viridans is NOT.

11

What is most common childhood illness?

Acute otitis media from Strep pneumoniae

12

Major host defense against pneumococcus

Phagocytosis, augmented by IgG

13

Effect of capsule in pneumococcus

Antiphagocytic by inhibiting complement opsonization (C3b)
Stimulates intense inflammatory response
Main immunogen (Ab detection)
Conjugated vaccine uses capsule

14

Hypogammaglobulinemia

Can’t make Abs to opsonize / phagocytose organisms; includes myeloma, lymphoma, leukemia, and nephritic syndrome

15

Who gets pneumococcal vaccine?

Children (> age 2), elderly, immunocompromised.

16

Which diseases caused by pneumococcus are resistant to penicillin?

Meningitis and bacteremia

17

Tx for otitis media

Amoxicillin or erythromycin

18

Tx for sinusitis

Amoxicillin-clavulinate or FQ

19

Tx for Meningitis

Ceftriaxone + Vancomycin

20

Risk factors for acquiring penicillin-resistant pneumococcal infection

Prior becta-lactam AB therapy (amoxicillin / oral cephalosporins)
Contact w/ kids in daycare
Exposure to healthcare setting
Recent respiratory infection

21

Beta hemolytic strains

Group A, B, C, or G
Based on C-polysaccharide (in cell wall)

22

What test is used to rule out GAS?

Bacitracin

23

Alpha hemolytic strains
How do you differentiate?

Strep viridans and Strep pneumoniae
Optochin testing (pneumococcus is vulnerable)

24

What test is used to rule out Group D strep?

Bile esculin test

25

What determines Lancefield groupings?

C Polysaccharide

26

What determines Lancefield typings?

M Protein

27

Group A Strep
Other Name
Hemolysis
Reservoir
Transmission

Strep Pyogenes
Beta-hemolytic
5-10% of people are carriers in throat, skin, anus, and vagina
Transmitted via air or direct contact

28

Susceptible hosts to GAS

College students, military recruits, neonates, post-partum women, damaged skin (burns, measles, chickenpox, impetigo), surgery

29

Function of Lipoteichoic acid and Protein F

Mediate attachment to epithelial cells by binding to fibronectin

30

Cause of scarlet fever

GAS erythrogenic toxin (exotoxin) is produced after virulence factor is added by lysogenic phage.

31

Erysipelas
Caused by?
Characteristics
Population
Location of rash

Caused by GAS
Erythema / edema w/ well-demarcated edges
Most common in kids and elderly
More common on legs than face

32

Scarlet Fever
Caused by
Characteristics

Caused by GAS
Erythroderma, strawberry tongue, skin desquamation

33

What 2 strains cause Toxic Shock Syndrome and which is worse?

GAS is worse than Staph aureus

34

GAS Toxic Shock Syndrome
Initial site of infection?
Cytokine
Complications (4 things)
Tx

Most often due to soft tissue infection or bacteremia
TNF
May cause necrotizing fasciitis, strep gangrene, bacteremia, or shock
Tx w/ penicillin and surgical debridement

35

Rheumatic Fever
Due to which strain?
Diagnostic criteria
Location of prior infection
Tx
Prophylaxis for RHD

Due to GAS
Jones Criteria: 2 major or 1 major + 1 minor + lab evidence of GAS
Due to prior pharyngitis (not skin)
Tx w/ aspirin, steroids, or penicillin
Prophylaxis w/ penicillin or sulfadiazine

36

Post-streptococcal glomerulonephritis
Strain
Location of prior infection
Population
Sxs
Prevention
Tx

GAS
Typically skin infection (sometimes pharyngitis)
Most common in kids
Sxs: oliguria (due to renal failure), dark urine, hematuria, proteinuria, seizures, HTN, edema.
Not preventable
Only supportive tx

37

Which AB is GAS highly susceptible to?

Penicillin

38

Group B Strep
Other Name
Reservoir
Diseases
Antigen
Tx

Strep agalactiae
Asymptomatic colonization of genital tract and lower GI tract. 30% of women are carriers in vagina.
Diseases: #1 cause of bacterial sepsis in newborns. Can also cause puerperal sepsis (in pregnant mother). SSTIs / UTIs in diabetics.
Capsule interferes w/ phagocytosis and complement activation
Tx w/ pencillin. Vancomycin if allergic.

39

2 main types of Group D Strep

Enterococci and Non-Enterocci (Strep bovis)

40

Enterococci
2 types
Characteristics
Catalase?
Reservoir
Transmission
Risk factors
Antigens
Diseases
Tx

E. Faecalis and E Faecium
Major cause of nosocomial infections. Grow in bile and salt. Catalase negative
Catalase negative
Reservoir: soil, food, water, animals. Normal microbiota of GI and Gyn tracts.
Transmission: endogenous, contact, surfaces
Risk factors: invasive devices, broad spectrum AB's, surgery, >60 y/o
Antigens – adhesins and bacteriocins inhibit competing flora
Diseases: catheter-associated UTI's, endocarditis, surgical infections (especially after colonic / vaginal surgery).
Does NOT cause pneumonia
Tx w/ ampicillin or vancomycin (however resistance is growing). Linezolid / Daptomycin if VRE.

41

Strep bovis
2 other names
Association
Tx

Non-enterococci, Strep gallolyticus
Associated w/ colon cancer
Penicillin is tx of choice. Erythromycin / vancomycin if allergic.

42

Viridans Strep
Hemolysis
Normal microbiota of where?
Diseases

Alpha hemolytic
Normal microbiota of mouth, GI, and GU
Causes dental carries, bacteremia, and SBE

43

Tx for GAS endocarditis

Penicillin + gentamicin (aminoglycoside)

44

Importance of spleen

Protects against encapsulated bacteria that immune system has not seen before. Most important in kids