Term
Staphylococci vs. Streptococci |
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Definition
Staph are grapelike stuctures Strep are chains Staph are Catalase +
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Term
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Definition
Diseases: - Inflammatory
- Abcesses, endocarditis, food poisoning, pneumonia
- Toxin mediated
- Toxic shock
- scalded skin syndrom
- rapid food poisoning
- sepsis
Characteristics: - Gram + cocci
- Coagulase +
- Catalase +
- β hemolysis
- β lactamase (penicillin resistance)
Habitat and Transmission: nose and skin. Transmitted by contact Pathogenesis: - Toxic shock toxin - uperantigen
- Enterotoxin - food poisoning superantigen
- scalded skin syndrome toxin - protease
- Protein A - virulence factor for binding Fc of IgG
- At risk: neutropenic, IV drug use, surgery
Clinical Features: - Systemic Infx
- Bacteremia
- Endocarditis
- Osteomyelitis and septic arthritis
- pnuemonia
- abscess
- Skin/Local
- Post-op infx
- Impetigo
- Furuncles and Carbuncles
- Mastitis
- Toxin mediated
- Toxic shock syndrome
- food poisoning
- scalded skin syndrome
Lab Dx: - Gram + cocci
- Coagulase +
- Catalase +
- β hemolysis
- Yellow or gold on BAP
Tx: Nafcillin for MRSA. Vancomycin for NRSA Prevention: prophylaxis before surgery
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Term
Staphylococcus epidermidis |
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Definition
Diseases: Endocarditis, prosthetic infection, IV cath infection, CSF shunt infection, neonatal sepsis Characteristics: - Gram + cocci in clusters
- Catalase +
- Coagulase NEGATIVE
- Nrl flora on skin
Pathogenesis: - Glycocalyx adhere to foreign bodies (i.e. hrt valves and prosthetics)
- Causes dz in mainly immunocompromised pts.
- NO exotoxins
Lab Dx: Gram +. Whitish, non-hemolytic, coagulase NEGATIVE, Sensitive to novobiocin (S. saprophyticus is not) Tx: Vancomycin plus either rifampin or aminoglycoside Prevention: None
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Term
Staphylococcus saprophyticus |
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Definition
Gram + cluster cocci Coagulase NEGATIVE Resistant to novobiocin (contrast to S. epidermidis) Causes URI's in young women |
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Term
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Definition
Diseases: Suppurative diseases: pharyngitis and cellulitis. Nonsuppurative diseases: rheumatic fever and acute glomerulonephritis Characteristics: - Gram + chains. Grp A Strep
- β-hemolytic
- Catalase NEGATIVE (as opposed to staph)
- Bacitracin-sensitive
Habitat and Transmission: Habitat is throat and skin. Transmisstion via respiratory droplets Pathogenesis: - Spreading factor - hyaluronidase
- erythrogenic toxin -> rash of scarlet fever
- M protein - antiphagocytic
- Rheumatic fever
- cross rxn of Ab's and human Ag in heart and joints.
- AGN
- Immune complexes b/w strep Ag's and Ab that get trapped in glomeruli, activate complement and recruit PMNs that lead to damage
Lab Dx: - Suppurative
- Gram + and culture
- β-hemolytic
- bacitracin sensitive
- Non-suppurative (i.e. RHF or AGN)
- ASO titer for ARF
- Anti-DNase B for AGN
Tx: Penicillin G Prevention: Penicillin in pts w/ RF. No vaccine |
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Term
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Definition
Diseases: Neonatal meningitis and sepsis Characteristics: - Gram + chains Grp B strep - B for Babies
- β-hemolytic
- Catalase Negative
- Bacitracin-resistant
Habitat and Transmission: Vagina. Transmitted at birth Pathogenesis: - pyogenic organism
- no exotoxins
- Predisposing factors
- rupture of membrranes >18hrs before delivery
- labor prior to 37 wks
- No maternal Ab
- heavy colonization
Lab Dx: - Gram +
- β-hemolytic
- Bacitracin resistant
- Hydrolyze hipurate and are CAMP test +
Tx:Penicillin G Prevention: No vaccine. Ampicillin to mothers with prolonged membrane rupture etc.
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Term
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Definition
Diseases: UTI and biliary tract infections. Abdomial Abscess.Rare endocarditis Characteristics: - gram + chains Grp D strep
- Grow in 6.5% NaCl - Hardy to live in gut!
- Grow in Bile - BLACK
- Non-hemolytic
- Catalase Negative
Habitat and Transmission: Colon, uretrhra and female genital tract. Bloodstream Pathogenesis: No exotoxins or virulence factors Lab Dx: - Gram + culture
- Grows in 6.5 % NaCl
- Hydrolyzes esculin in bile - BLACK
Tx: neicillin or vancomycin pus an aminoglycoside. Prevention: Penicllin and gentamicin should be given to pts with damaged heart valves prior to GI or UT procedures.
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Term
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Definition
Diseases: Meningitis, Otitis media (kids), Pneumonia and Sinusitis (children) = MOPS
Characteristics: - Gram + "lancet shaped", diplococci or short chains
- α-hemolytic
- Catalase negative
- Bile and Optochin sensitive (in contrast to viridans strep) MOPS - Most OPtochin Sensitive
- Capsulated
Habitat and Transmision:Upper respiratory tract. Transmitted through respiratory droplets Pathogenesis: - Inflammation
- No known exotoxins
- Capsule is antiphagocytic
- IgA protease
- Predisposers
- previous infection
- splenectomy
Clinical Features: - rusty sputom, sepsis in sickle cell anemia and splenectomy
Lab Dx: - gram + and culture
- α- hemolytic
- Inhibited by bile and optochin
- Quellung rxn
- Latex agglutination
Tx: Penicillin G Prevention: 2 vaccines. Adults - capsular polysaccharide. Children under 2 - conjugated.
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Term
Viridans Group Streptococci (S. Sanguis, S. Mutans) |
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Definition
Diseases: Endocarditis Characteristics: - Gram + chains
- α-hemolytic
- catalase negative
- Resistant to bile and optochin (unlike S. pneumococci)
Habitat and Transmission: Normal flora of mouth. Enters blood during oral procedures. Pathogenesis: - Bacteremia from dental procedures
- Protected within vegetations
- No known toxins
Lab Dx: - Gram + chains
- Catalase negative
- Resistant to bile and optochin
- a-hemolytic
Tx: Penicillin G Prevention: Pencillin in pts with damaged valves/dental procedures.
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Term
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Definition
Disease: Linked to COLON CANCER Characteristics: - Grp D strep non-enterococcus
- Growth on bile - BLACK
- NO GROWTH on 6.5% NaCl
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