Question

Disease Presentation : Food Poisoning

Causative agents:

Staphylococcus aureus

Bacillus cereus

Clostridium perfingens exotoxin

Questions:

. Signs and symptoms

. Causative agents

. Pathogenesis and virulence fators

.Transmission and epidemiology

.Culture and diagnosis

.Prevention and treatment

Answer 1

Bacillus cereus:

Signs and symptoms: nausea and vomit and diarrhoea and colic pain

Causative agents- Food products involved rice cooked at high temperatures, sauces, soups, and puddings.Contaminated include flours, meats, milk, cheese, vegetables, fish, rice and its derived products.

Pathogenesis and virulence factors- Virulence factor- hemolysin BL (HBL), nonhemolytic (NHE), cytotoxin K (CytK)

B. cereus reaches to the  small intestine and spore germination causes simultaneous production of the enterotoxin that cause diarrhoea. Symptoms appear soon after consuming food contaminated with the preformed toxin of B. cereus.

Transmission and epidemiology- Insects and  flies are the carrier for disease transmission by carrying contaminated food with pathogens Globally, there are figures where food poisoning caused by B. cereus pathogen occupies from 1 to 17.5% of the total cases of food poisoning caused by bacteria.

Culture and diagnosis- Real-time PCR to detect 16S ribosomal gene of B.cereus. Immunoassay or PCR to detect virulence gene

Prevention and treatment-It is suggested to store food at temperatures below  4°C or to cook food at temperatures higher than 100°C, and to reheat or cool food rapidly to minimize the risks of possible poisoning.

This can be treated with chloramphenicol, clindamycin, vancomycin, gentamicin, streptomycin, and erythromycin.

Clostridium perfringes exotoxin:

Signs and symptoms-severe abdominal cramps and diarrhoea after 8-22 h of food intake. It also include septicemia and necrotic enteritis.

Causative agents - Meat juice, stews, cooked beans, meat cooked at high temperatures.

Pathogenesis and virulence fators-Five different type of toxin -alpha, beta, epsilon, and iota.  CPE enterotoxin is responsible for causing diarrhea and Beta2-toxin is associated with enteritis.

Transmission and epidemiology:It is transmitted through flies and insects. Outbreak of C. perfringes  affect a large number of individuals and have a high range of morbidity. In total, 90% of the cases are caused by the intake of meat and poultry products.

Culture and diagnosis- Culture from the stools or the food sample involved or by molecular methods to detect following genes: cpe (CPE toxin), plc (Alpha-toxin), and etx (Epsilon-toxin)

Prevention and treatment- Better hygiene practices for food processing, cooking or storing and consumption prevents from the disease carrier flies and insects.

Administration of intravenous fluids, oral rehydration salts solutions, and medication for fever and pain control. Necrotizing enterocolitis is treated systemically with penicillin G, metronidazole or chloramphenicol.

Staphylococcus aureus :

Signs and symptoms- It includes Toxic shock syndrome which is characterized by high fever, hypotension, erythematous rashes similar to scarlet fever, peeling of the skin during recovery, flu-like symptoms, vomiting, and diarrhoea

Causative agents- Meat and meat products cooked at high temperatures, poultry, and salads with mayonnaise.

Pathogenesis and virulence fators- Pyrotoxins are superantigen which can cause immunosuppression and nonspecific T cell proliferation. Production of the Toxic Shock Syndrome Toxin 1 (TSST-1) and Enterotoxin Type B

Enterotoxins are highly stable and they resist high temperatures and proteolytic enzyme at low PH which favours the S. aureus in the digetsive tract after infection .

Transmission and epidemiology- It is being transmitted through flies and insect from contaminated food.

S. aureus can be responsible for up to 41% of food poisoning outbreaks and can affect people of any age, the variable range with the highest incidence from 20 to 49 years of age.

Culture and diagnosis- Enterotoxin is detected by bioassays, molecular biology, and immunological techniques

Prevention and treatment- Maintaining the cold chain of food can prevent the growth of the S. aureus. Food products should  be cooked above 60°C and refrigerated below 5°C to prevent favourable temperature of growth of S.aueus and by following good manufacturing and good hygiene practices.