Fact sheet on Salmonella

General information
Salmonella (= Salmonella) are bacteria of the family Enterobacteriaceae. As causes of gastrointestinal diseases, Salmonella play an important role worldwide. These bacteria are most often transmitted through raw animal foods, especially poultry meat, eggs and pork. However, plant-based foods can also be affected.

People excrete Salmonella in their stool, both during an illness and, under certain circumstances, for a long time thereafter. "Salmonella carriers" must not be employed in the production and sale of easily perishable foods, because otherwise, with inadequate personal hygiene, transmission to foods can occur.

Characteristics

• Rod-shaped bacteria
• Gram-negative
• Oxidase-negative
• Catalase-positive
• Toxin producers

Note: Typhoid and paratyphoid fever, caused by the two Salmonella serovars S. typhi and S. paratyphi, differ markedly in their clinical presentation from other salmonelloses and are not covered here, since the cases reported in Germany are predominantly travel-associated or acquired abroad.

Origin / occurrence

• Intestinal tract of birds, reptiles, mammals and humans
• Primarily in animal but also in plant-based foods

Significance

• Pathogen: common cause of foodborne gastrointestinal diseases
• Ready-to-eat foods contaminated with Salmonella are classified as hazardous to health
• To cause illness, multiplication of Salmonella in the food is usually required in healthy people. In immunocompromised persons, lower numbers of organisms can also cause disease
• Salmonella are capable of surviving in the environment for several months and therefore can also be found in plant-based foods → multiple contamination sources should be considered

Clinical picture

• Incubation period: 12 to 48 hours
• Duration of illness: usually 1 to 4 days
• Symptoms: diarrhea, vomiting, abdominal pain, headache, usually fever. Symptoms generally last only a few days. In exceptional cases, however, they can lead to multi-day hospital stays
• Severe complications with fatal outcome are rare but can occur, especially in immunocompromised individuals such as infants, young children, elderly people and patients with chronic diseases
• Mortality: approx. 0.1% (considerably higher in risk groups)

Examples of affected foods

• Poultry meat, offal, game meat and the liquids released during thawing
• Chicken eggs, egg-containing dishes such as desserts, homemade mayonnaise…
• Pork, beef, minced meat, meat preparations, fresh Mettwurst, raw sausage
• Raw milk
• Fish
• Spices and herbs, herbal teas
• Salad, sprouts, sprouting seeds
• Deli salads, cream- and dessert-based dishes
• In rare cases also chocolate (special case: can cause illness even at lower organism numbers)

Growth conditions

• Temperature:
  • Optimum: +37 °C
  • Minimum: +7 °C
  • No multiplication above +50 °C
• pH value: growth at 4.5 to 9.0
• a_w value:
  • Multiplication at high water activity of at least 0.95
  • Survival also at low a_w values down to 0.43 (e.g., dried foods)
• Oxygen requirement: growth with and without oxygen (facultative anaerobe)

Inactivation by heating

• At +72 °C for at least 2 minutes contact time the bacterial cells and heat-labile toxins are inactivated (Note: monitor core temperature)

1. Check incoming products for e.g. delivery/transport temperature, shelf life, packaging, deviations or abnormalities
2. This also applies to the goods before use in production. In case of doubt, do not use the food and consult a supervisor
3. Review microbiological specifications. If necessary, arrange laboratory testing of suspicious products or request results from the supplier
4. Verify effectiveness by follow-up testing

1. Review workplace organization in the company
   1. Separate work areas, equipment and utensils for raw and processed foods
   2. Separation of "clean" and "unclean" areas and activities
2. Train employees regarding potential errors and improvement measures
3. Verify effectiveness by visual on-site inspections and follow-up testing

1. Review execution of cleaning and disinfection:
   1. Hygiene plan
   2. Execution of cleaning and disinfection, e.g. disinfectant dosing, contact time, use of suitable and clean materials and cleaning cloths
2. Avoid moisture residues and biofilms. Ensure good drying of equipment, utensils and surfaces
3. Train employees regarding potential errors and improvement measures
4. Repeat cleaning and disinfection
5. Verify effectiveness by visual on-site inspections, environmental sampling and follow-up testing

1. Train employees regarding potential errors and improvement measures
2. Regular cleaning and disinfection of hands and/or regular glove changes
3. Regular change of work clothing. Ensure cleanliness of work clothing
4. Train employees on the requirements for infection control
5. Verify effectiveness by visual on-site inspections and follow-up testing

Deficiencies in infection control:
This creates a risk of transmission of pathogenic microorganisms from humans to product-contact surfaces or directly to foods

Examples:

Salmonella from carriers or ill employees

Staphylococcus aureus from employees with inflamed or purulent wounds or with colonization of the nasopharynx

1. Employees who are ill with or suspected of infections by Salmonella, EHEC/STEC, Shigella, Vibrio cholerae, hepatitis A or E viruses or other infectious gastrointestinal diseases, or who shed the above-mentioned bacterial pathogens, are not allowed to work in food businesses handling perishable foods and kitchens according to the Infection Protection Act (IfSG) (see IfSG § 42)
2. The same applies to employees who have inflamed or purulent wounds. Non-infected wounds must be hygienically properly covered
3. Regular training/instruction of employees regarding the required infection control measures
4. Verify effectiveness by visual on-site inspections, checks of training records and follow-up testing

1. Check processes, production protocols and documentation
2. Inactivation of most bacteria at a core temperature of +72 °C for at least 2 minutes. Exceptions are e.g. heat-stable spores and toxins. In these cases significantly higher temperatures and exposure times are required. Further information can be found, for example, in the respective information sheets (fact sheets)
3. Check correctness of processes and temperatures
   1. In general, hot-holding temperatures of over +60 °C are required
   2. Rapid cooling: after 3 hours a core temperature of at least +7 °C must be reached (special caution is required for large quantities)
4. Verify effectiveness by follow-up testing

1. Request traceability of the cold chain during transport or from the supplier
2. Check incoming and storage temperatures
3. Control refrigeration temperatures/cold chains during processing, transport and sale
4. If overaging (or excessive shelf life) is suspected, perform appropriate storage tests
5. Verify effectiveness by follow-up testing

1. Check processes, environmental conditions, production protocols and documentation
2. Verify effectiveness by follow-up testing

1. Maintain distance from fields with animal husbandry; keep wild animals away from fields by e.g. fences or nets
2. Water hygiene: contaminated water must not be used for irrigation. Irrigation and drainage systems must be suitable. Regular monitoring of microbiological water quality
3. No use of microbially contaminated fertilizers in crop production
4. Personnel and work hygiene during harvest and post-harvest steps
5. Remove soil or contamination by washing
6. Verify effectiveness by follow-up testing