Salmonella

Family Salmonella

Enterobacteriaceae

Two species of Salmonella

S. bongori and S. enterica

Subspecies of S. enterica Salmonella

S. enterica subsp. enterica

• Which goes even into:

• Salmonella enterica ssp. enterica serovar Typhimurium
  Abbreviated to: S. Typhimurium

Gram +/- Salmonella

Gram negative

Shape Salmonella

Motile rod

Growth temperature Salmonella

5-47C, with optimum at 37C (Mesophile)

Minimum Aw Salmonella

0.93 is needed for growth, but can survive in lower Aw.

Does it form spores? Salmonella

No

Survival Salmonella

Has protection against gastric acid due to physical structure, for example in fatty products.

Disease Salmonella

Salmonellosis (Non-typhoidal)

• Nausea, vomiting, abdominal pain, diarrhoea

• Incubation time: 1-2 days

• Duration: 3-7 days

• D/R is high but can be low.

Can later lead to reactive arthritis (long term complications)

Trends Salmonella

There is a seasonal trend, therefore may be related to temperature.

Sources Salmonella

• Commonly found in food of animal origin: meat, poultry, raw milk, eggs, and (shell)fish

• Undercooking eggs is high risk

• Salmonella can persist in food factories and in stables.

• Darkling beetles are vectors.

• Environmental cycle is hard to break.

Transmission Salmonella

Prevention & control Salmonella

·        At the farm level: Implement national control programs, hygiene measures, separate animals from the outside, ensure Salmonella-free feed and water, and use vaccination.

·        To limit spread of contamination: Comply with microbiological criteria, practice logistic slaughter, and use hygienic equipment design.

·         General hygiene: Good general hygiene practices (GHP) in factories and retail, along with proper training, are essential.

·         Food preparation: Proper heating and storage (maintaining the cold chain) at retail, catering, and by consumers are vital.

·       heating to 70 °C is best  method for reducing Salmonella, as demonstrated by the reduction of CFU/g in egg yolks with increased boiling times

Even after being ill and recovering person is still a carrier for several days/months. Carriers can be treated with antibiotics

Optimum pH and pH resistance for Salmonella

• Optimally at 7, has a range of 6.5 to 7.5 optimally

• Broader: 4.0-9.0

• Can with stand 3.0-4.0 for limited periods