microbiology ch 13, actinomycetes, clostridia, bacillus Flashcards
2 important genera of actinomycetes?
actinomyces, nocardia
Actinomyces
major component of dental plaque, Femal genital tract
Actinomyces isralii
major agent of human actinomycosis, has yellowish sulfur granules, colonies appear as bread crumbs or molars, sensative to penicillin and amoxicillin
where are the infections for israelii usually found?
60-65% are in cervicofacial region
10-20% are abdominal
some are thoracic
Nocardia
cause nocardiosis in humans
clostridia in general
gram positive spore forming bacilli found in soil, water, decaying animal and plants
clostridia welchii
spores are in soil, vegetative cells in colon and vagina
what does c welchii cause?
gas gangrene, good poisening
what toxin does c welchii make?
alpha toxin- lyses phospholipids of eukaryotic cell membranes
whats the name of the test that uses egg yolk to neutralize the alpha toxin?
naglers reaction
clostridium tetani
Intestinal tract of herbivores, spores in soil, look like drumstick,
c. tetani toxiins
tetanospasmin- potent neurotoxin from vegatative cells
tetanolysin- haemolytic toxin
what do the toxins cause?
trismus( lockjaw), risus sardonicus ( facial muscle spasm), opisthotonos( arching body)
how do the toxins cause these?
blocks inhibitory mediators at spinal synapses
clostridium difficile
faeces of adults and kids, up to 25% of common antibiotic associated diarrhoea is from C difficile
