Streptococcus and Enterococcus Flashcards by Megan Miles

What are the 4 important Streptococcus?

Strep pyogenes (Strep A)
Strep agalactiae (Strep B)
Strep anginosus
Strep mitis (includes S. pneumoniae)

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B-hemolytic strepococci

Group A- S. pyrogenes
Group B- S. agalactiae
Group D- Enterococcus
Group F- S. anginosus or S milleri

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Strep A types of infections

Suppurative: Pharyngitis, skin infections

Non-suppurative- rheumatic fever, RF disease, acute glomerulonephritis

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Strep A virulence factors

Protein M
Capsule
Surface Adhesions: LTA, protein M, protein F

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Strep A toxins

Hemolysins (Streptolysin O and S)
Hemolysin O- form antibodies to this toxin
Streptococcal Pyogenic Extotocins (SpeA, B,C)

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Strep A enzymes

DNases, Hyaluronidases
Streptokinase - degrades fibrin, used as a medication
C5a peptidase
specB- cleaves IgG

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Pharyngitis:
clinical features
diagnosis

Strep A- S. pyrogenes
clinical features: fever, NO cough, purulent exudate, cervical lymphadenopathy
diagnosis: Rapid antigen test, Culture
negative Rapid antigen test, must get culture

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Pharyngitis treatment

complication if not treated

1st line: penicillin
2nd line: clindamycin or Macrolide (azithromycin, etc)
complication- scarlet fever

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uncommon complication of Strep A infection (pharyngitis)?

clinical manifestations?

Scarlet Fever
usually due to GAS pharyngitis
due to Spec A and C exotoxins
trunk rash, strawberry tongue**, capillary fragility, desquamation of skin

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Impetigo:
what 2 bacteria cause this
clinical manifestation
treatment options

S.aureus or S.pyogens
honesty colored crusting
topically: Bacitracin or Mupirocin
extensive disease: PO- amoxicillin-clavulanic acid or cephalexin

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characteristic of B-hemolytic strepococcal infection?

Erysipelas: erythema, raised, sharp border

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skin infections caused by GAS

Impetigo
Erysipelas
Cellulitis with lymphangitis
Necrotizing fascitis**

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Complication of GAS skin infections?

Streptococcal toxic shock syndrome

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GAS non-suppurative infections?

Rheumatic fever, Rheumatic heart disease

Acute glomerulonephritis

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Acute Rheumatic fever: associated with what, incubation period?

10-30 days after GAS pharyngitits (not associated with skin infections)

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Acute Rheumatic fever: clinical syndrome:

2 major OR 1 major +2 minor
major criteria: carditis, chorea, subcutaneous nodules, polyarthritis, erythema marginatum

Minor criteria: fever, 1st degree heart block, arthralgia, elevated CRP/ESR

AND evidence of recent infection with Strep

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Rheumatic fever treatment: Symptoms, primary and secondary treatment

Symptoms: aspirin or corticosteroids

primary: treatment of pharyngitis (penicillins OR marcrolids/clindamycin)
secondary: penicillin G monthly or oral penicillin daily

Post-streptococcal glomerulonephtritis?
incubation period?
associated with what infection?

1-2 weeks after pharyngitis
2-3 weeks after skin infection
associated with deposition of immune complex

Strep B species?
most common infection in which age group?
colonizer of what?
onset?

Streptococcal agalactiae
neonates
GI tract, female genital tract
early onset; in utero, at birth
late onset

Strep B infection causes what?

sepsis, meningitis, or pneumonia

Strep B diagnosis?

Strep B treatment?

culture or nucleic acid amplification test
1st line: penicillin
2nd line: vancomyocin or clindamycin

S. anginosus
belongs to which group?
causes what?
what type of hemolysis?

belongs to bigger group S. milleri
Abscesses: liver, brain, peridontal
alpha, beta, or gamma hemolysis

Viridans Streptococci:
what hemolysis?
colonize what?
S. bovis?
treatment?

alpha and gamma hemolysis
mucosal surfaces NOT skin
S. bovis/S.gallolyticus = increase risk of colon cancer, do colonoscopy
treatment: penicillin or vancomycin (no penicillin for mitis group)

Streptococci pneumoniae general characteristics

Viridans group, mitis group
Gram positive, catalase negative
Alpha-hemolysis

Streptococci pneumoniae laboratory idendification

Alpha hemolysis catalase negative suseptible to optochin solubility in bile salts

S. pneumoniae virulence factors

Evasion of host immunity: capsule, Pneumolysin (lysis of phagocytic cells) Adherence: phosphocholine, surface adhesion proteins FEW toxins

S. pneumoniae resistance

some resistance to penicillin (not anywhere near rates of other bacteria) mechanism: alteration of PBP some resistance to macrolides, TMP/SMX no resistance to fluoroquinolones

S. pneumoniae pathogenesis? where does S. pneumoniae cause infections? What is a predisposing factor?

disease presents when S. pneumoniae moves from the oropharynx to normally sterile sites lower airways= pneumonia or bronchitis paranasal sinuses= sinusitis ears= otitis meninges= meningitis viral infection precedes S. pneumoniae infection, trapping bacteria bacteremia usually associated with pneumonia or meningitis

Where does S. pneumoniae colonize?

Nasopharyx

Otitis media cause and treatment

S.pneumoniae is most common cause treatment: no treatment over 2 yrs with mild symptoms more severe symptoms, amoxicillin

Meningitis cause, treatment, diagnosis

S. pneumonia most common cause (2nd cause Neisseria gonorrhea) Treatment: both Ceftriaxone and vancomycin (good CNS penetration) Diagnosis: lumbar puncture

Risk factors for S. pneumoniae infection?

lack of pneumococcal vaccine splenectomy immunodeficiencies (inability to form antibodies, PMN deficiency) inflammatory condition- COPD, asthma, smoking

Pneumonia treatment:

Ceftriaxone (to cover S. pneumoniae) | Macrolid (to cover atypicals)

2 types of pneumococcal vaccinations

Prevnar- children | pneumovax- over 65yo

Enterococcus general features

Gram positive in pairs and chains Facultative anaerobes E. faecium, E. faecalis

Laboratory identification of Enterococci

Catalase negative PYR positive LAP positive

Enterococci colonization

GI track

Enterococci virulence factors

Antibiotic resistance** inherent resistance: cephalosporins, semi-synthetic penicillins acquired resistance: vancomycin, aminoglycosides, fluoroquinolones other: surface proteins, cytolysins, proteases, Gis protein

Treatment of E. faecalis

treatment of choice: ampicillin or penicillin | Endocarditis: ampicillin + aminoglycoside

Treatment of E. Faecium

Treatment of choice: vancomycin Endocarditis: vancomycin + aminoglycoside if VRE: use Linezolid or daptomycin instead (both Gram positive, VRE)

what infections do Enterococci cause?

Intra-abdominal and pelvic infections UTIs bacteremia Endocarditis (along with S. aureus, psuedomonas)

Enterococci UTI

Common in males | common in hospitalized patients with urinary catheter