Staphylococcus Aureus

Symptoms specific to staph

cramps

Staph quick facts

Quick contagion, present in low-moisture food, can survive in warm food, can survive salt and sugar, quick recovery

Staph characteristics

Group of small, spherical, bunch of cells (like grapes), gram-positive (peptidoglycan and teichoic acid), catalase positive

Catalase

Enzyme found in all living organisms which catalyzes decomposition of hydrogen peroxide into water and oxygen

Gram-positive

thicker cell walls

Several species of staphylococcus can produce

staphylococcal enterotoxins

Nearly all staphylococcal food poisoning is from

S. aureus

Toxin-mediated syndromes

Toxemias

Invasive and pyogenic infection

Direct tissue destruction

Staphylococcal food poisoning

Enterotoxins A-E

Key virulence drives of SFP

Enterotoxins, TSST-1 Superantigen

SFP

Staphylococcal food poisoning

Intoxication

Ingesting toxin released by bacterial cells; bacteria is dead but toxin is active - rapid onset (1-6 hours)

Staphylococcal toxins are highly

high stable and can survive commercial sterilization

Staphylococcal enterotoxins require _____ for _____ for inactivation

heat of 121C (250F); 30-60 minutes

Sources of S. aureus - humans

Reside in exterior surface, most common in nose and skin, spread by physical contact, skin fragments, and respiratory droplets

Most staphylococcal food poisoning is traced

back to food contaminated by humans during preparation

Animals as a source of S. aureus

Inadequate refrigeration, poor hygiene, inadequate cooking, prolonged warming, preparation of food too far in advance

Osmotolerant

can survive up to 20% salt

Under aerobic conditions

Can grow at 0.86 aw

Under anaerobic conditions

Can grow at 0.90 aw

S. aureus is highly resistant to

temperature, low water activity, and high salt

Osmoprotectant system

the cell accumulates compounds that allow it to lower its aw and match its surroundings

Characteristics of disease

Vomiting a very short time after consumption (30m to 6hr), resolves within 24 to 48 hours

Vomiting, nausea, CRAMPS, diarrhea, headaches

Common symptoms of disease

S. aureus Toxins

Staphylococcal enterotoxins are heat stable and not destroyed by heating or canning

Enterotoxins involved in outbreak

B, A, D

Osmotolerant S. aureus toxins

Can survive in low water activity but produce less enterotoxin

Petri dish characteristics

Yellow pigment, clumping, fermentation

Ineffective dose of S. aureus

10^5 to 10^8 CFU/g

Enterotoxin A causes

more outbreaks

Enterotoxin B causes

more severe symptoms