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67 Cards in this Set
- Front
- Back
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Clostridia
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Gram-positive anaerobic rods
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Gram positive
Rod shaped Spore former Anaerobe Strict to aerotolerant Bowel flora Animals and man Soil inhabitant Modest growth requirements |
Clostridia
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Clostridial species (4)
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C. tetani
-Tetanus C. perfringens -Food poisoning -Gas gangrene C. difficile -Enterocolitis C. botulinum -Botulism |
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Causative agent of tetanus (lockjaw)
Virulence factors production of tetanus toxin with systemic effects Infection process Introduction of spores into anaerobic site Puncture wound Generally does not spread Ear infections |
C. tetani
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Introduction into body
Germination of spore Growth of organism Small localized infection Production of toxin Systemic spread of toxin Acts on the anterior horn cells Results in rigor (inability to relax) Effects the masseter muscles first |
C. tetani
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C. tetani presentation
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Spasms
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C. tetani mortality
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15-60% due to respiratory failure
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C. tetani treatment
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tetanus immune globin - human
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C. tetani prevention
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DPT or DaPT
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Normal soil inhabitant
Grows on decaying material Proteases Lipases Toxin production Contaminates food Enterotoxin - superantigen Introduced into tissues Gas gangrene |
C. perfringens
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Food product contaminated with spores
Generally rice/meat dishes Food cooked followed by improper storage Spores germinate Enterotoxin is part of the spore coat Causes secretion of water and electrolytes into small intestine |
Clostridial food poisoning
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_________ is part of the spore coat for Clostridial in food poisoning
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enterotoxin
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Diarrhea ______ hours after ingestion
Accompanied with nausea, pain Treatment is time |
Clostridial food poisoning
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Rare form also produces a beta-toxin
Severe necrotizing enteritis Sudden onset Cramps, bloody diarrhea, shock High mortality |
Clostridial
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Trauma to deep tissue
Contamination with dirt or feces Spores germinate Deep-seated, spreading infection Large amounts of tissue destruction Large amount of gas production Tearing of weakened tissue |
gas gangrene
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Productions of exotoxins
Alpha-toxin Phospholipase C Hemolysin Oxygen labile Proteases Tissue destruction Vascular permeability and shock |
Clostridial
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Production of gas
Metabolic product |
Clostridial
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Usually a mixed infection
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Clostridial
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Clostridial treatment (3)
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Systemic wide spectrum antibiotics
Oxygen introduction Debridement |
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Normal bowel flora - 3%
Ubiquitous Not a food-associated infection Causes antimicrobial-associated diarrhea and pseudomembrane colitis Associated with fecal-oral contamination by hospital staff |
Clostridium difficile
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Virulence factors of C. difficile (2)
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enterotoxin A and cytotoxin B
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Virulence factor that
Causes infiltration of neutrophils Release of inflammatory factors that cause fluid secretion Hemorrhagic necrosis |
Enterotoxin A
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Virulence factor that
Disrupts microfilaments Blocks protein synthesis |
Cytotoxin B
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Patient treated with antimicrobials
Normal bowel flora repressed An over-growth of ________ occurs _______ causes watery diarrhea May proceed to pseudomembrane colitis Removal of antibiotics may reverse High frequency of reoccurrence High correlation with proton pump inhibitors |
C. difficile
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Common soil inhabitant
Produces neurotoxins Phage encoded Extremely toxic LD < 1µg for humans Heat labile (100ºC) Contaminates home-canned items Alkaline items |
C. botulinum
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Action of toxin
Blocks release of acetylcholine Flaccid paralysis Both voluntary and autonomic systems are effected |
C. botulinum
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Ingestion of toxin
Paralysis signs 18-96 hours after ingestion Ocular, pharyngeal, laryngeal respiratory first affected Dry mouth, constipation, urine retention 20% mortality |
C. botulinum
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C. botulinum treatment
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Horse antitoxin, large amounts
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C. botulinum prevention
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Proper canning techniques
Proper heating of foods |
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Gram-positive aerobic rods
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Bacillus species
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- Gram positive rods
- spore formers - most are obligate aerobes - soil organisms - ubiquitous |
Bacillus species
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Bacillus anthracis disease
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anthrax
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- spores from soil
- animal products goat hair wool infected carcasses |
Bacillus anthracis
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Bacillus anthracis virulence factors (4)
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capsule, D-glutamic acid
exotoxins -edema factor - adenylate cyclase -protective antigen, receptor -lethal factor - protease, MAPK |
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Bacillus anthracis exotoxin PA + EF causes
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EDEMA
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Bacillus anthracis exotoxin PA + LF causes
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DEATH
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- cutaneous, from skin abrasion - papule to eschar, malignant pustule
- pulmonary, inhalation of spores - influenza-like symptoms proceeding to pneumonia to death - gastrointestinal, ingestion of contaminated foods - food poisoning symptoms to death - bacteremia and secondary infections (meningitis) from primary infection |
Bacillus anthracis
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Bacillus anthracis diagnosis, treatment, and control
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isolating, penicillin (cipro), herd vaccination
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- causes food poisoning
- ingestion of spore or toxin contaminated food -short term, nausea; long term, diarrhea - treatment is time, infection is self-limiting - may cause systemic infection in immunocompromised patients |
Bacillus cereus
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- small, Gram positive rods
- facultative anaerobe - grows at 5-40°C - motile at 25°C, less at 37°C - grows at all pHs - ubiquitous |
Listeria monocytogenes
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- Adult infections
- may be asymptomatic - Neonatal infections - Early onset - Late onset |
Listeria
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adult and neonatal - Both involve bacteremia and meningitis
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Listeria
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induces actin filament formation to move between cells
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actA
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allows escape from membrane vacuole
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- listeriolysin O
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-facultative intracellular parasite
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- highly invasive
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facilitates entry into cells
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internalin
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phospholipases in Listeria
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- beta-hemolytic
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Listeria Virulence factors (5)
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- highly invasive
- internalin - beta-hemolytic - listeriolysin O - actA |
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infects the very young, immunocompromised, and pregnant women
- requires CMI resistance - kidney transplant patients - asymptomatic carriers - food outbreaks |
Listeria
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ingested
- invades epithelial tissue and spreads - foci in many organs - tropism for the fetus, placenta, and CNS - meningitis, bacteremia, endocarditis |
Listeria
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Adult infections
- Bacteremia, meningitis, endocarditis - 30% mortality - Neonatal infections - Early onset - still birth, multiple foci, etc. - Late onset - meningitis |
Listeria
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Listeria diagnosis and treatment
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presence of listeria, tx: beta lacams
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Listeria sources
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unpasteurized milk, sof cheeses, and raw vegetables are sources.
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Listeria control
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USDA zero tolerance policy
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- small, Gram positive rod
- pleiomorphic shape with club ends - facultative anaerobe, prefers aerobic conditions |
Corynebacterium diphtheriae
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- only human reservoir
- droplet transmission - highly contagious - controlled with vaccination with DPT toxoid - carrier state may exist, not controlled by vaccination |
Corynebacterium diphtheriae
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Corynebacterium diphtheriae virulence factors (5)
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- not invasive
- local and systemic effects of exotoxin - toxin is bacteriophage encoded - toxin synthesis regulated by iron concentration - toxin blocks protein synthesis |
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- bacteria grow on the nasopharyngeal mucosa
- 2-6 days after infection, symptoms appear - toxin causes epithelial destruction - pseudomembrane forms, limits air passage - toxin goes systemic peripheral neuropathy myocarditis |
Corynebacterium diphtheriae
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Corynebacterium diphtheriae clinical signs (5)
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- pharyngeal infection most severe
- presence of pseudomembrane - bull neck - speech and swallowing problems - arrhythmia |
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Corynebacterium diphtheriae diagnosis and treatment
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- clinical presentation
- culture and isolation of pathogen - antitoxin - isolation of patient - penicillin is drug of choice |
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- Gram negative rod
- aerobic, non-fermentor - oxidase positive - encapsulated - pigmented - ubiquitous |
Pseudomonas aeruginosa
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Pseudomonas aeruginosa virulence factors (6)
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- alginate capsule, antiphagocytic
- pili, adhesions to epithelial cells - hemolysins, phospholipase C - proteases, includes elastase, tissue destruction - toxins (endotoxin, exotoxin A, exotoxin S) - antibiotic resistant |
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- causes opportunistic and nosocomial infections when predisposing conditions are present
burns, cystic fibrosis, cancer patients - localized infections may lead to disseminated infections 10% of all Gram negative systemic infections 50% mortality rate - endocarditis in IV drug users - UTI - eye infections - ear infections in children |
Pseudomonas aeruginosa
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- Gram negative evasion of immune system in immunocompromised host
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Pseudomonas aeruginosa
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Pseudomonas aeruginosa diagnosis
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includes culture and isolation
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Pseudomonas aeruginosa treatment
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Treatment involves antibiotic resistance profiles.
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Pseudomonas aeruginosa prevention
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Prevention is mainly good sanitary practices and use of the appropriate topical treatments.
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