Anaerobes (gram pos. and neg.) Flashcards
What are some of the clinical characteristics of gas gangrene?
- rapid onset
- necrosis of muscle (myonecrosis) and skin
- tense edema
- bullae formation
- gas formation (fermentation)
- shock
- hyper or hypothermia
What is the main treatment for gas gangrene?
debridement! (antibiotics, like clindamycin, can also be used, but they act on the toxins and not the bacteria itself)
Why does food poisoning caused by C. perfringens take a longer time to appear than food poisoning caused by Staph?
C. perfringens food poisoning involves an enterotoxin produced FOLLOWING germination of large #s of organisms (toxin is NOT pre-formed).
What does the tetanospasmin toxin do in the brain?
blocks postsynaptic inhibition (GABA) of spinal motor reflexes, causing spasmotic contractions
What are the key clinical features of tetanus?
- trismus (lockjaw)
- risus sardonicus (incr. tone of orbicularis oris)
- opisthotonus (arm flexion, leg extension)
- respiratory distress (diaphragm not functional)
What is the treatment for tetanus?
- human tetanus immunoglobulin
- sedation
- control of spasms
- supportive care (airway)
Describe some key features of the botulinum toxin.
- single large polypeptide
- cleaved by bacterial protease to become active
- blocks ACh and NT release –> paralysis
- permanently damages synapse
- can travel through axons
- heat labile
What are some of the clinical features of botulism?
- GI symptoms (nausea, dry mouth, diarrhea)
- Descending paralysis (flaccid)
- Wound botulism
Do patients affected by botulinum have sensory defects?
No! The effect of the toxin is purely paralytic.
What is one of the first signs of C. diff?
leukocytosis (elevated WBC count)
What is the key clinical feature associated with C. diff infection?
pseudomembranous colitis
Which strain of C. diff is the most severe and why?
- BI (Nap1) strain
- Has increased Toxin A production and higher mortality (esp. among elderly)
What is the treatment for C. diff?
- stop antibiotics
- treat w/ oral vancomycin
- colon resection
- fecal transplant (FCT)
What is the best treatment for infection w/ actinomyces?
penicillin (but clindamycin and erythromycin can also be used)
Why do we care about Propionibacterium acnes?
Although it is not an important pathogen, it is a common contaminant in blood cultures.
