Fact sheet on Pseudomonads and Pseudomonas aeruginosa

General
Pseudomonads belong to the family Pseudomonaceae. Many Pseudomonas species are food spoilage organisms, as they can cause unpleasant odors and altered taste. This group of bacteria does not cause foodborne illness. The species Pseudomonas aeruginosa is a common cause of wound or urinary tract infections.

Characteristics

• Rod-shaped bacterium
• Gram-negative
• Oxidase-positive
• Catalase-positive

Origin / Occurrence

• Widespread in our environment (e.g. soil, water, plants and animals)
• Occur particularly in plant- and animal-derived foods with high water content

Importance

• Pseudomonads play an important role as potential spoilage organisms in high-moisture foods such as fresh meat, fish, cream and chopped vegetables
• In water hygiene, Pseudomonas aeruginosa serves an important function as an indicator organism. It indicates contamination and biofilms in drinking and mineral water, as well as in bathing water. In bathing water it can also cause infections (e.g. wound infections)
• In medical facilities and hospitals, Pseudomonas aeruginosa is a feared pathogen causing e.g. wound and urinary tract infections (a cause of hospital-acquired infections)

Growth conditions

• Temperature:
  • Optimum: +25 °C to +30 °C
  • Minimum: +5 °C
  • Generally no growth above +50 °C
• pH value: growth at pH 5.0 to 8.0
• a_w value: growth at a water activity of at least 0.95
• Oxygen requirement: obligate aerobic

Inactivation by heating

• At +72 °C for at least 2 minutes exposure time (Attention: check core temperature)

1. Check the execution of cleaning and disinfection:
   1. Hygiene plan
   2. Execution of cleaning and disinfection, e.g. dosing of the disinfectant, contact time, use of suitable and clean materials and cleaning cloths
2. Avoid residual moisture and biofilms. Ensure thorough drying of equipment, appliances and surfaces
3. Train staff regarding potential errors and corrective measures
4. Repeat cleaning and disinfection
5. Verify effectiveness by visual on-site inspections, environmental testing and follow-up testing

1. Check work organization in the operation
   1. Separate work areas, utensils and implements for raw and processed foods
   2. Separation of "clean" and "unclean" areas and activities
2. Train staff regarding potential errors and corrective measures
3. Verify effectiveness by visual on-site inspections and follow-up tests

1. Check processes, production logs and documentation
2. Most bacteria are killed at a core temperature of +72 °C for at least 2 minutes. Exceptions include 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 the correctness of processes and temperatures
   1. In general, holding temperatures above +60 °C are required
   2. Rapid cooling: after 3 hours a core temperature of at least +7 °C must be reached (special care is required for large quantities)
4. Verify effectiveness by follow-up tests

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

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

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