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a.Gram positive, non-encapsulated
b. Rod-shaped
c. Motile – flagella
d. β-hemolytic
a. Facultative anaerobe
b. Forms heat resistant, hydrophobic spores
c. Diarrheal
i. Viable cells and secrete endotoxins
ii. Enterotoxins – all three required for maximal enterotoxin activity
1.Hemolysin BL – dermonecrotic and vascular permeability
a. Primary virulence factor in diarrhea
2. Non-hemolytic enterotoxin
3. Cytotoxin K
d. Emetic
i. Toxin produced in foods when warmedii. Cereulid – resistant to heat, pH, proteolysis
a. Ubiquitous in nature – normal soil anaerobeb. Generally foodborne, usually due to survival of endospores in improperly cooked foodc. Often associated dishes that are cooked and warmed for several hours such as rice
a. Isolation of > 105 organisms per gram in implicated foodb. Testing usually not done due to self-limiting and relatively harmless nature
a. Symptoms
i. Emetic – short-incubation
1. Nausea, vomiting, abdominal cramps2. 1-2 hour incubation, 24 hour duration
ii. Diarrheal – long-incubation
1. Diarrhea, abdominal pain, cramps2. Incubation period of up to one day in GI, 24 hour duration
iii. Also known to cause skin infections and keratitis
b. Diagnosis
i. Usually diagnosed based on symptoms and possible exposure
c. Differential diagnoses
i. Clostridium perfringens – almost identical presentation to diarrheal
1. Fever is uncommon in B. cereus
d. Therapy
i. Generally resolves after 24 hours – treat symptoms (supportive)
1. Rest and fluids/electrolytes – severe dehydration may require IV fluids
ii. Drug therapy for more severe cases
1. Susceptible to vancomycin, ciprofloxacin, erythromycin, gentamicin, clindamycin, tetracycline2. Resistant to β-lactams
e. Prevention and control
i. Cook foods thoroughlyii. Maintain food storage at < 40 °F and > 140 °Fiii. Refrigerate food immediately after cooking