Staphylococcal food poisoning is caused by ingestion of enterotoxins preformed in the food contaminated essentially through human manipulation or raw material obtained from animals. Although coagulase-positive Staphylococcus aureus is the main agent responsible for food intoxication, some researches emphasise that coagulase-negative staphylococci (CNS) are able to produce staphylococcal enterotoxins and may be a potential cause of food poisoning. In the present study CNS were isolated from foods and the toxigenic capacity of the strains determined. A total of 88 food samples were analysed and 22.7% were positive for CNS strains. Staphylococcal counts ranged from 3.0 x 10 2 to 1.4 x 10 6 CFU/g or mL of food examined. S. epidermidis predominated among the isolates (40%). Further isolates included S. xylosus (20%), S. warneri (20%), S. saccharolyticus (15%), and S. hominis (5%). Four isolates were positive for enterotoxin genes, as detected by polymerase chain reaction, with sea being the predominant gene. Although no enterotoxin production was detected by the reverse passive latex agglutination method, the data showed that the toxigenic capacity of CNS should not be ignored, requiring investigation of this group of microorganisms in food.

Within the genus Staphylococcus, S. aureus, a coagulase-positive species which produces a series of other enzymes and toxins, is the most widely known and has frequently been implicated in the etiology of a series of infections and intoxications in man and animals, while coagulase-negative staphylococci (CNS) have been considered to be saprophytic or rarely pathogenic (21).Before the 1970s, reports of infections caused by CNS were rare, with these bacteria being recognized by clinicians and microbiologists as contaminants of clinical samples (22). However, this detection, widely used for clinical diagnosis, has posed a challenge regarding the role that these microorganisms play in infectious processes.CNS are currently known to be essentially opportunistic microorganisms that take advantage of numerous organic situations to produce severe infections (22)(23)(24)(25)(26). The emergence of CNS as etiological agents might also be the result of the recognition of this group as opportunistic pathogens and of the increasing use of invasive procedures such as intravascular catheters and prostheses in immunocompromised patients, and in intensive treatment, premature children, patients with neoplasia and transplant patients (22).Several virulence factors are responsible for the symptoms and severity of infections caused by S. aureus. These factors include hemolysins α, β, γ and δ, leukocidin, exfoliative toxins A and B, and a group of Abstract: The detection of staphylococcal enterotoxins is decisive for the confirmation of an outbreak and for the determination of the enterotoxigenicity of strains. Since the recognition of their antigenicity, a large number of serological methods for the detection of enterotoxins in food and culture media have been proposed. Since immunological methods require detectable amounts of toxin, molecular biology techniques represent important tools in the microbiology laboratory. In the present study, polymerase chain reaction (PCR) was used to identify genes responsible for the production of enterotoxins and toxic shock syndrome toxin 1 (TSST-1) in S. aureus and coagulase-negative staphylococci (CNS) isolated from patients and the results were compared with those obtained by the reverse passive latex agglutination (RPLA) assay. PCR detection of toxin genes revealed a higher percentage of toxigenic S. aureus strains (46.7%) than the RPLA method (38.3%). Analysis of the toxigenic profile of CNS strains showed that 26.7% of the isolates produced some type of toxin, and one or more toxin-specific genes were detected in 40% of the isolates. These results suggests the need for further studies in order to better characterize the pathogenic potential of CNS and indicate that attention should be paid to the toxigenic capacity of this group of microorganisms.

Representatives of the Staphylococcus genus are the most common pathogens found in hospital environments, and they are etiological agents for a large variety of infections. Various virulence factors are responsible for the symptoms and severity of infections caused by Staphylococcus aureus. Among them are staphylococcal enterotoxins (SEs), which cause staphylococcal food poisoning, and toxic shock syndrome toxin-1 (TSST-1). Some reports indicate that TSST-1 and staphylococcal enterotoxins are also produced by coagulase-negative staphylococci (CNS). The present review aimed to discuss general aspects of staphylococcal toxins as well as the epidemiology, genetics and detection of toxins in Staphylococcus aureus and coagulase-negative staphylococci, since these microorganisms are becoming more and more frequent in nosocomial infections.

No abstract