Enterotoxigenic Potential of Staphylococcus intermedius

Abstract

ABSTRACT Staphylococcal food poisoning (SFP) caused by enterotoxigenic staphylococci is one of the main food-borne diseases. In contrast to Staphylococcus aureus , a systematic screening for the enterotoxins has not yet been performed on the genomic level for the coagulase-positive species S . intermedius . Therefore, the enterotoxigenic potential of 281 different veterinary (canine, n = 247; equine, n = 23; feline, n = 9; other, n = 2) and 11 human isolates of S . intermedius was tested by using a multiplex PCR DNA-enzyme immunoassay system targeting the staphylococcal enterotoxin genes sea , seb , sec , sed , and see . Molecular results were compared by in vitro testing of enterotoxin production by two immunoassays. A total of 33 (11.3%) S . intermedius isolates, including 31 (12.6%) canine isolates, 1 equine isolate, and 1 human isolate, tested positive for the sec gene. In vitro production of the respective enterotoxins was detected in 30 (90.9%) of these isolates by using immunological tests. In contrast, none of 65 veterinary specimen-derived isolates additionally tested and comprising 13 (sub)species of coagulase-negative staphylococci were found to be enterotoxigenic. This study shows on both molecular and immunological levels that a substantial number of S . intermedius isolates harbor the potential for enterotoxin production. Since evidence for noninvasive zoonotic transmission of S . intermedius from animal hosts to humans has been documented, an enterotoxigenic role of this microorganism in SFP via contamination of food products may be assumed.