Clostridium, legionella and vibrio Flashcards
Clostridium
- obligate anaerobe
- fermentation
- killed by oxygen
Endogenous infection
-normal human flora
Exogenous infection
-enviroment
sites of anaerobes in the normal flora
- intestine
- mouth
- genitourinary tract
strict anaerobe infectious disease
- sites throughout the body
- muscle, cutaneous/ sub-cutaneous
- abscesses
Clostridia
Gram-positive rods
- human intestine
- soil
- spore formers
C. perfringens
- soil, fecal contamination
- wound contamination WWI
- gas gangrene
- gas production
- growth on sheep blood agar
Clostridial cellulitis
-introduces into tissue during surgery by a traumatic injury
Pathogenisis C. perfringens
-enterotoxins released on sporulation
-tissue degrading enzymes
=lecithinase- massive hemolysis
=proteolytic enzymes
=saccharolytic enzymes
-destruction of blood vessels
-tissue necrosis
-creates anaerobe environment
Diagnosis C. perfringens
-Laboratory identification
=lecithinase production
=gram stain
=x rays, resonance image
Treatment C. perfringens
-penicillin
-debridement
-anti-toxin
-amputation and death is rare
=Hyperbaric chamber (oxygen)
Clostridium tetani
- non-invasive
- tetanus
- lockjaw
Tetanus toxin: tetanospasmin
- deseminates systematically
- binds to ganglioside receptors
- glycine- neurotransmitter
- stops nerve impulse to muscles
- spastic rigid paralysis
- severe muscle contractions
Vaccination Tetanus
-DTP (diphtheria, pertussis, tetanus)
-booster every 10 years
-tetanus toxoid
=antigenic
=no exotoxic activity
Treatment Tetanus
- immunization with tetanus immune globulin TIG
- active immunization with tetanus toxoid
- control muscle spams
Legionella pneumophila
-gram-negative rod
-stains poorly silver stain is better
-non-spore-forming
-oxidase and catalase positive
frow on a charcoal disk
Legionnaire’s disease
- pneumonia 2-10 days after exposure
- requires antibiotic treatment
- more frequently on elderly , hospitals
Pontiac fever
- acute onset flu-like illness
- no pneumonia
- myalgia (muscle pain)
Legionella pneumonia transmission
- environmental reservoir
- natural bodies of water
- hor water towers
- not spread person to person
Diagnostic legionella
- poor isolation from clinical specimens
- antigens tests for serogroup 1
- PCR
- plate on buffered charcoal yeast extract with iron salts, l-cysteine, colonies can be visualized with UV
Identification of legionella
- 2 blood specimens taken at least 4 weeks apart
- Positive indirect FA test for L. pneumonia in a patient septum
Treatment Legionnaire’s disease
-Macrolides (azithromycin, clarithromycin, erythromycin) or fluoroinolones (ciprofloxaci, levofloxin)
Pontiac fever treatment
-self-limiting, only need supportive care
vibrios
- gram-negative rods
- comma-shaped
- oxidase-positive
- readily cultivates
- all species required NaCl
- V. cholerae CAN GROW W/O SALT
