Streptococcus and Enterococcus Flashcards
What are the 4 important Streptococcus?
Strep pyogenes (Strep A) Strep agalactiae (Strep B) Strep anginosus Strep mitis (includes S. pneumoniae)
B-hemolytic strepococci
Group A- S. pyrogenes
Group B- S. agalactiae
Group D- Enterococcus
Group F- S. anginosus or S milleri
Strep A types of infections
Suppurative: Pharyngitis, skin infections
Non-suppurative- rheumatic fever, RF disease, acute glomerulonephritis
Strep A virulence factors
Protein M
Capsule
Surface Adhesions: LTA, protein M, protein F
Strep A toxins
Hemolysins (Streptolysin O and S)
Hemolysin O- form antibodies to this toxin
Streptococcal Pyogenic Extotocins (SpeA, B,C)
Strep A enzymes
DNases, Hyaluronidases
Streptokinase - degrades fibrin, used as a medication
C5a peptidase
specB- cleaves IgG
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
Pharyngitis treatment
complication if not treated
1st line: penicillin
2nd line: clindamycin or Macrolide (azithromycin, etc)
complication- scarlet fever
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
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
characteristic of B-hemolytic strepococcal infection?
Erysipelas: erythema, raised, sharp border
skin infections caused by GAS
Impetigo
Erysipelas
Cellulitis with lymphangitis
Necrotizing fascitis**
Complication of GAS skin infections?
Streptococcal toxic shock syndrome
GAS non-suppurative infections?
Rheumatic fever, Rheumatic heart disease
Acute glomerulonephritis
Acute Rheumatic fever: associated with what, incubation period?
10-30 days after GAS pharyngitits (not associated with skin infections)
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
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
