Anaerobes Flashcards
What is the proper way to get Anaerobic cultures?
Collect in STERILE manner! Can’t be contaminated with normal flora
(Can’t swab, need aspirate/surgical specimen/biopsy)
What is the morphology of Peptostreptococcus?
Gram positive cocci
What is the morphology of Clostridium?
Gram positive rod (spore forming)
What is the morphology of Actinomyces?
Gram positive rod
What is the morphology of Lactobacillus?
Gram positive rod
What is the morphology of Bacteroides?
Gram negative rod
What is the morphology of Fusobacterium?
Gram negative rod
What is the morphology of Mobiluncus?
Gram positive rod
What is the morphology of Propionibacterium?
Gram positive rod
What diseases are caused by Peptostreptococcus (gram positive cocci)?
Polymicrobial (lots of other bacteria involved)
What diseases are caused by Actinomyces (Gram pos rod)?
Acinomycosis - chronic lesions associated with abscess
What is a sign of actinomycosis?
“sulfur granules” in abscess material
- Often get mistaken for malignancies, hard and fibrous
How does Actinomyces appear in culture?
“molar tooth” colonies
What is the treatment for Actinomyces?
Penicillin
What diseases are caused by Lactobacillus?
Septicemia in immunocompromised patients
Endocarditis in persons with underlying valve abnormalities
What is the treatment for Lactobacillus?
Penicillin or combo with aminoglycoside
What diseases are caused by Mobiluncus?
Bacterial vaginosis
What diseases are caused by Propionibacterium?
Acne
Opportunistic infections of prosthetic device
What is the major virulence factor in Bacteroides fragilis?
Polysaccharide capsule
What diseases are caused by Bacteroides fragilis?
Abscess formation
What is the treatment of Bacteroides fragilis?
Metronidazole
Resistant to penicillins
What is the treatment of Mobiluncus?
Penicillin
Resistant to metronidazole, so probably not cause of bacterial vaginosis since metronidazole treats that
What diseases are caused by Fusobacterium?
Oropharyngeal infections
- Gingivitis - trench mouth
- Pharyngitis
- Jugular venous thrombophleitis - Lemierre’s syndrome
What is Lemierre’s syndrome?
Pharyngitis due to Fusobacterium -> peritonsillar abscess -> spread of bacteria through parapharyngeal spaces -> thrombophlebitis of internal jugular vein
(Clots can embolize)
What is treatment of Fusobacterium?
Beta lactam-beta lactamase inhibitor
Ampicillin-sulbactam
What characterizes Clostridium?
Spore-producing
What is the toxin released by Clostridium tetani?
Tetanospasmin
What is the mechanism of action of Tetanospasmin?
Gets internalized into motor neurons and cleaves proteins necessary for release of inhibitory transmitters
Hence, stay in state of excitatory synaptic activity (constant contraction = tetanus)
What are the four forms of tetanus?
Generalized tetanus
Localized tetanus
Cephalic tetanus
Neonatal tetanus
What are some major clinical presentations of tetanus?
Spastic paralysis
Trismus (inability to open mouth due to masseter contraction)
Opisthotonos (contraction of back muscles)
Apnea (contraction of pharyngeal muscles)
What is the treatment for C. tetani?
Metronidazole
(don’t use Penicillin, can theoretically worsen muscle issues)
Vaccination
Ventilation support
What diseases are caused by Clostridium botulinum?
Botulism from release of botulinum toxin
What are the forms of botulism?
Foodborne (usually home canned vegetables or fermented tofu)
Wound
Infant
Inhalation (biological weapon)
What is the mechanism of action of botulinum toxin?
Inhibits release of acetylcholine at neuromuscular junctions, so don’t get any excitatory input.
Results in flaccid paralysis (opposite of tetanus)
What is the major clinical presentation of botulism?
Cranial neuropathies with DESCENDING paralysis (in contrast to Guillain-Barre syndrome caused by Campylobacter), progressing to respiratory failure
No major sensory deficits or unresponsiveness (also unlike Guillain-Barre)
What is the treatment of botulism?
Metronidazole
Trivalent botulinum antitoxin (anti-A,B,E) to bind circulating toxin
Ventilation support
How do Clostridium perfingens colonies appear when plated?
Double zone of hemolysis
What toxins are produced by C. perfingens?
“Lethal” toxins: alpha, beta, epsilon, iota
Enterotoxin
What diseases are caused by Clostridium perfingens?
Food poisoning
Soft tissue infections (classically myonecrosis [gas gangrene])
Bacteremia
What is the treatment of Clostridium perfingens?
For serious infection, need surgery and debridement
Penicillin + clindamycin
What toxins are produced by Clostridium difficile?
Enterotoxin
Cytotoxin
What diseases are caused by C. diff?
Range from diarrhea to pseudo-membranous collitis, can progress to toxic megacolon
Usually from suppression of normal flora due to antibiotics
Which antibiotics are most commonly implicated in C. diff infection?
CLINDAMYCIN
How does pseudomembranous colitis appear on histo?
Denuded epithelium
Psuedoplaque
How can you test for C. diff infection (not just colonization)?
PCR amplification of toxin genes
Can’t do culture
What is the treatment for C. diff colitis?
Metronidazole + vancomycin
