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Microbio Gram Pos > Streptococci > Flashcards

Streptococci Flashcards

1
Q

3 main gram positive cocci that cause disease

A

Streptococcus, Enterococcus, and Staphylococcus

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2
Q

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

A

Phagocytosis (mainly) and neutrophils

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3
Q

Empyema

A

Collection of pus in a body cavity, especially pleural cavity

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4
Q 
General characteristics of streptococci
Gram
Catalase?
Morphology
Oxygen environment
A

Gram positive
Catalase negative
Chains
Mostly facultative

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5
Q

Reservoir for pneumococcus

A

Nasopharynx / throat

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6
Q

Transmission of pneumococcus

A

Airborne

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7
Q

Strep pneumoniae morphology

A

Lancet-shaped (elliptical) diplococci

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8
Q

Hemolysis for strep pneumoniae

A

Alpha

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9
Q

O2 conditions for pneumoniae

A

Grow better w/ 10% CO2 (capnophile)

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10
Q

How do you differentiate pneumococcus from Strep Viridans?

A

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

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11
Q

What is most common childhood illness?

A

Acute otitis media from Strep pneumoniae

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12
Q

Major host defense against pneumococcus

A

Phagocytosis, augmented by IgG

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13
Q

Effect of capsule in pneumococcus

A

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

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14
Q

Hypogammaglobulinemia

A

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

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15
Q

Who gets pneumococcal vaccine?

A

Children (> age 2), elderly, immunocompromised.

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16
Q

Which diseases caused by pneumococcus are resistant to penicillin?

A

Meningitis and bacteremia

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17
Q

Tx for otitis media

A

Amoxicillin or erythromycin

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18
Q

Tx for sinusitis

A

Amoxicillin-clavulinate or FQ

19
Q

Tx for Meningitis

A

Ceftriaxone + Vancomycin

20
Q

Risk factors for acquiring penicillin-resistant pneumococcal infection

A

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

21
Q

Beta hemolytic strains

A

Group A, B, C, or G

Based on C-polysaccharide (in cell wall)

22
Q

What test is used to rule out GAS?

A

Bacitracin

23
Q

Alpha hemolytic strains

How do you differentiate?

A 
Strep viridans and Strep pneumoniae
Optochin testing (pneumococcus is vulnerable)
24
Q

What test is used to rule out Group D strep?

A

Bile esculin test

25
Q

What determines Lancefield groupings?

A

C Polysaccharide

26
Q

What determines Lancefield typings?

A

M Protein

27
Q 
Group A Strep
Other Name
Hemolysis
Reservoir
Transmission
A

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

28
Q

Susceptible hosts to GAS

A

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

29
Q

Function of Lipoteichoic acid and Protein F

A

Mediate attachment to epithelial cells by binding to fibronectin

30
Q

Cause of scarlet fever

A

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

31
Q 
Erysipelas
Caused by?
Characteristics
Population
Location of rash
A

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

32
Q

Scarlet Fever
Caused by
Characteristics

A

Caused by GAS

Erythroderma, strawberry tongue, skin desquamation

33
Q

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

A

GAS is worse than Staph aureus

34
Q 
GAS Toxic Shock Syndrome
Initial site of infection?
Cytokine
Complications (4 things)
Tx
A

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

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

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
Q

Which AB is GAS highly susceptible to?

A

Penicillin

38
Q 
Group B Strep
Other Name
Reservoir
Diseases
Antigen
Tx
A

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
Q

2 main types of Group D Strep

A

Enterococci and Non-Enterocci (Strep bovis)

40
Q 
Enterococci
2 types
Characteristics
Catalase?
Reservoir
Transmission
Risk factors
Antigens
Diseases
Tx
A

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
Q

Strep bovis
2 other names
Association
Tx

A

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

42
Q

Viridans Strep
Hemolysis
Normal microbiota of where?
Diseases

A

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

43
Q

Tx for GAS endocarditis

A

Penicillin + gentamicin (aminoglycoside)

44
Q

Importance of spleen

A

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

Microbio Gram Pos (11 decks)

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