Streptococci

Question 1

3 main gram positive cocci that cause disease

Answer 1

Streptococcus, Enterococcus, and Staphylococcus

Question 2

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

Answer 2

Phagocytosis (mainly) and neutrophils

Question 3

Empyema

Answer 3

Collection of pus in a body cavity, especially pleural cavity

Question 4

General characteristics of streptococci
Gram
Catalase?
Morphology
Oxygen environment

Answer 4

Gram positive
Catalase negative
Chains
Mostly facultative

Question 5

Reservoir for pneumococcus

Answer 5

Nasopharynx / throat

Question 6

Transmission of pneumococcus

Answer 6

Airborne

Question 7

Strep pneumoniae morphology

Answer 7

Lancet-shaped (elliptical) diplococci

Question 8

Hemolysis for strep pneumoniae

Answer 8

Alpha

Question 9

O2 conditions for pneumoniae

Answer 9

Grow better w/ 10% CO2 (capnophile)

Question 10

How do you differentiate pneumococcus from Strep Viridans?

Answer 10

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

Question 11

What is most common childhood illness?

Answer 11

Acute otitis media from Strep pneumoniae

Question 12

Major host defense against pneumococcus

Answer 12

Phagocytosis, augmented by IgG

Question 13

Effect of capsule in pneumococcus

Answer 13

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

Question 14

Hypogammaglobulinemia

Answer 14

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

Question 15

Who gets pneumococcal vaccine?

Answer 15

Children (> age 2), elderly, immunocompromised.

Question 16

Which diseases caused by pneumococcus are resistant to penicillin?

Answer 16

Meningitis and bacteremia

Question 17

Tx for otitis media

Answer 17

Amoxicillin or erythromycin

Question 18

Tx for sinusitis

Answer 18

Amoxicillin-clavulinate or FQ

Question 19

Tx for Meningitis

Answer 19

Ceftriaxone + Vancomycin

Question 20

Risk factors for acquiring penicillin-resistant pneumococcal infection

Answer 20

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

Question 21

Beta hemolytic strains

Answer 21

Group A, B, C, or G

Based on C-polysaccharide (in cell wall)

Question 22

What test is used to rule out GAS?

Answer 22

Bacitracin

Question 23

Alpha hemolytic strains

How do you differentiate?

Answer 23

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

Question 24

What test is used to rule out Group D strep?

Answer 24

Bile esculin test

Question 25

What determines Lancefield groupings?

Answer 25

C Polysaccharide

Question 26

What determines Lancefield typings?

Answer 26

M Protein

Question 27

``` Group A Strep Other Name Hemolysis Reservoir Transmission ```

Answer 27

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

Question 28

Susceptible hosts to GAS

Answer 28

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

Question 29

Function of Lipoteichoic acid and Protein F

Answer 29

Mediate attachment to epithelial cells by binding to fibronectin

Question 30

Cause of scarlet fever

Answer 30

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

Question 31

``` Erysipelas Caused by? Characteristics Population Location of rash ```

Answer 31

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

Question 32

Scarlet Fever Caused by Characteristics

Answer 32

Caused by GAS | Erythroderma, strawberry tongue, skin desquamation

Question 33

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

Answer 33

GAS is worse than Staph aureus

Question 34

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

Answer 34

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

Question 35

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

Answer 35

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

Question 36

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

Answer 36

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

Question 37

Which AB is GAS highly susceptible to?

Answer 37

Penicillin

Question 38

``` Group B Strep Other Name Reservoir Diseases Antigen Tx ```

Answer 38

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.

Question 39

2 main types of Group D Strep

Answer 39

Enterococci and Non-Enterocci (Strep bovis)

Question 40

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

Answer 40

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.

Question 41

Strep bovis 2 other names Association Tx

Answer 41

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

Question 42

Viridans Strep Hemolysis Normal microbiota of where? Diseases

Answer 42

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

Question 43

Tx for GAS endocarditis

Answer 43

Penicillin + gentamicin (aminoglycoside)

Question 44

Importance of spleen

Answer 44

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