Anaerobes And C Difficile Flashcards
Clinical presentation for anaerobic infections
Clostridia: toxin mediated disease (enterotoxins, Histotoxins, neurotoxins)
Endogenous infection with skin and mucosal flora
Clinical bacteriology
Specimen: blood, fluid aspirate, tissue
Culture: anaerobic chamber, special media
Identification: MALDI-TOF, colony characteristics, Gram stain, phenotypic test, toxin detection (antigen immunoassay, PCR
Anaerobic gram positive rods
Clostridium
Actinomyces
Anaerobic gram-negative rods
Bacteriodes
Fusobacterium
Clostridium
Environmental, some present in human intestinal flora
Spores: Facilitate persistence in the environment, important for a transmission
Toxins: important in Pathophysiology
Clostridial species that produce enterotoxins
C perfingens
C. difficile
Clostridial species that produce neurotoxins
C botulinum
C tetani
All Clostridium produce
Histotoxins, hemolysis, proteases
Clostridium perfingens
Clostridial myonecrosis (gas gangrene)
traumatic injury containing clostridium spores
Severe pain, rapid progression, edema with discoloration, crepitus, Bullard, systemic toxicity
Requires prompt surgical debreadment
High mortality rate
Cellulitis
Abdominal/biliary tract infection
Female genital tract infections
Food poisoning
Clostridium perfringens lab features
Gram +
Box car rods
rapid growth
Double zone of hemolysis
Clostridium botulinum
Botulism: paralytic illness
Neurotoxin blocks release of Ach at neuromuscular junctions
Acute onset, febrile, without altered mental status
Blurred vision, ptosis, difficulty swallowing/speaking, symmetric descending weakness, difficulty breathing
Types of botulism
Food: associated with improperly canned foods
Infant: internal colonization followed by toxin production after ingestion of spores (raw honey)
Wound: black-tar heroine injection
Inhalation: contaminated cocaine
Clostridium botulinum lab features
Mouse bioassay
ELISA, PCR
Clostridium tetani
Tetanospasmin neurotoxin blocks release of inhibitory neurotransmitters in motor neurons leading to muscle spasms and rigidity
Uncommon in countries with vaccination programs
Lockjaw followed by spasms
Neonatal: Follows infection of umbilical stump
Clostridium tetani clinical features
Spores president in environment resistant alcohol based sanitizers
Spores germinate and proliferate in the colon
Produces inflammatory diarrhea be a toxin production
TcdA, TcdB damage mucosal epithelium
Disrupts cell cytoskeleton leading to death
Inflammatory cytokines
Colonic pseudomembrane
Diarrhea, toxic mega colon, perforation, shock, death
Factors controlling C diff infection
Colonization resistance
bile acid composition
increased IgA levels
bacteriocin secretion
C diff infection risk factors
Anti-microbial exposure
underlying illness severity
immunosuppression
inflammatory bowel disease
gastric acid suppression
NAP1/B1/O27
Flouroquinolone resistant C diff increased sporulation
Increased toxin production
C diff diagnostics
Cell cytotoxic assay
Stool culture
glutamate dehydrogenase antigen detection
Tonic A/B antigen or nucleic acid detection
C diff treatment
Stop antibiotics
Supportive care
Fecal transplants
Actinomyces
Gram +
Branched filaments
Normal flora
actinomyosis (sulfur granules)
Pelvic infection associated with IUD
A israelii: soft tissue
A viscosus, A naeslundii: caries, periodontal disease
Anaerobic Gram - rods
Bacteriodes
Fusobacterium
Porphyromonas
Provo tells
Normal flora
predilection for abscess formation
Lab ID: colony morphology, Gram stain, antibiotic susceptibility, biochemical tests
Bacteriodes fragilis
Polysaccharide capsule
Intraabdominal infection, SSTI, bacteremia
Rapid growth, bile resistant, hydrolysis esculin
Produce beta lactamase
Fusobacterium
Head and neck infections, bacteremia
F nucleatum- dental plaque flora, head/neck infections, fusiform rods
F necrophorum- pharyngeal, peritonsillar abscess, Lemierre syndrome (jugular vein thrombophlebitis)
