Listeria and coagulase-positive Staphylococci have been found during inspections of fruit salads in Switzerland, according to the Swiss Association of Cantonal Chemists (ACCS).

Cantonal chemists analyzed the microbiological quality of fruit salads by taking 205 samples.                                                                                                         

During the control, organized from May to September 2022, the samples of fruit salads were taken throughout Switzerland and Liechtenstein to check the microbial quality and for the presence of bacteria that could pose a health risk.

Food control is done by cantons, which carry out inspections and laboratory analyses with the help of cantonal chemists. Switzerland is made up of 26 regions called cantons.

Fruit salads can represent a health risk, particularly if storage temperatures and times are not adequate and products are intended for vulnerable people in retirement homes, nursing homes, or hospitals.

Targeted sampling looked at types of fruit more likely to be contaminated by bacteria such as low-acid fruits like melon or watermelon and followed criteria set in food legislation.

Unexpected findings
Ten products were contaminated with bacteria. This result was worse than what was expected by cantonal chemists.

The acidity of fruit salads did not prevent the presence and development of coagulase-positive Staphylococci and Listeria monocytogenes, which were detected in five samples each.

Actions were taken at companies producing these fruit salads to identify the source of contamination, improve self-checks and guarantee food safety.

No Salmonella was detected but officials said it was still important to test for this pathogen in such products, as it has been found previously.

Cantonal chemists said findings show looking for pathogens in foods that are not conducive to bacterial development can be worth doing and that a strengthening of controls seems necessary to ensure food safety.

There are eight coagulase-positive Staphylococci (CPS) species and Staphylococcus aureus is the most pathogenic. It produces toxins including staphylococcal enterotoxins (SEs) responsible for staphylococcal food poisoning outbreaks. Unlike the bacterium, SEs can survive heat treatment used during food processing. People who carry Staphylococcus aureus can contaminate food if they don’t wash their hands before touching it.

The incubation period and severity of symptoms depend on the number of enterotoxins ingested and the susceptibility of each person. Initial symptoms such as nausea followed by vomiting occur within 30 minutes to eight hours after eating contaminated food.

Other common symptoms are abdominal pain, diarrhea, dizziness, shivering, and general weakness sometimes associated with moderate fever. In severe cases, headaches and low blood pressure have been reported. In most cases, recovery occurs within 18 to 24 hours without specific treatment.