Chapter 6: bacillus and clostridium Flashcards
bacillus is aerobic/anaerobic
aerobic
clostridium is aerobic/anaerobic
anaerobic
2 species of bacillus
bacillus anthracis
bacillus cereus
4 species of clostridium
botulinum
tetani
perfringens
difficile
bacillus anthracis is unique that it is the only bacterium with _____
-fnct?
a capsule composed of protein (poly-D-glutamic acid)
-prevents phagocytosis
transmission of anthrax usually from
direct contact with infected animals or soil or when handling infected animal products, such as hides or wool
-no human to human
where can anthrax spores germinate
skin (cutaneous anthrax)
inspired into lungs (respiratory anthrax)
ingested into the GI tract (GI anthrax)
the exotoxin from bacillus anthracis causes what on localized tissue
necrosis
painless round black lesion with a rim of edema called a malignant pustule
respiratory anthrax pathogology
spores taken up by macrophages in lungs and transported to hilar and mediastinal LNs
mediastinal hemorrhage occurs resulting in mediastinal widening
GI anthrax occurs how often, and clinically
rare but often cuases death
exotoxin causes necrotic lesion within intestine
vomiting abdominal pain and bloody diarrhea
antrax exotoxin is encoded on a plasmid called ___ which has 3 seperate proteins?
pXO1
edema factor (A subunit) increases cAMP which impairs neutrophil fnct and causes massive edema
protective antigen: promotes entry of EF into phagocytic cells
Lethal factor: zinc metalloprotease that inactivates protein kinase
-stimulates mactrohpage to release TNF-a and interleukin-1B
second plasmid in anthrax ____ encodes 3 genes necessary for synthesis of ___
pXO2
poly-glutamyl capsule
bacillus cereus clinically
food poisoning releaseing enterotoxin
nausea, vomiting, diarrhea
-antibiotics won’t help
bacillus cereus enterotoxins
heat labile toxin
-nausea, abdrominal pain and diarrhea lasts 12-24 hours
heat stable toxin: nausea and vomiting, limited diarrhea
clostridium botulinum produces
lethal neurotoxin, blocks release of Ach from presynaptic nerve terminals in ANS = flaccid muscle paralysis
adult botulism
-how does one get it and symptoms
smoked fish or home canned veggies
potent neurotoxin ingested
pts afebrile
initially develop bilateral cranial nerve palsies: double vision and dysphagia
then muscle weakness which leads to repiratory paralysis and death
-pts need ventilator
infant botulism
how do babies get it and symptoms
fresh honey contaminated with spores
-spores colonize GI tract
infant constipted for 2-3 days then dysphagia and muscle weakness
“floppy” babies must be hospitalized and given supportive therapy
wound botulism presentation
longer incubation period
pts more likely to have a fever and elevated white count
clostridium tetani spores are often found where
soil and animal feces
what is the exotoxin released by clostridium tetani
tetanospasmin
-inhibits GABA and glycine
taken up at NMJ and transported to CNS
pts with tetanus present with
severe muscle spasms especially in the muscles of the jaw
-trismus or lockjaw
risus sardonicus (spasm of facial muscles)
-high mortality once this occurs
clostridium perfringens
in anerobic conditions it matures and produces gas
3 classes of infection with clostridium perfringens
cellulitis/wound infection: palpation reveals moist, spongy, crackling consistency called crepitus
clostridial myonecrosis: trauma into muscles secretes exotoxins that destory adjacent muscle, gas formation pockets in the muscles and subcutaneous tissue
-as enzymes degrade the muscles, a thin, blackfish fluid exudes from skin
diarrheal illness: watery diarrhea
-more severe type can lead to hemorrhagic necrosis of the jejunum
C diff toxins
toxin A causes diarrhea
toxin B is cytotoxic to colonic cells
