Pulsed-field gel electrophoresis (PFGE) and coagulase gene restriction profile (CRP) analysis techniques were used to analyze 71 Staphylococcus aureus isolates recovered from nine food-borne disease outbreaks. Twenty-two PFGE profiles and 11 CRPs were identified, with discrimination indices of 0.86 and 0.72, respectively. In addition, the variable regions of the coagulase genes of 39 isolates were sequenced and showed extensive identity, indicating that this is not an efficient alternative for the molecular typing of S. aureus.

Pulsed-field gel electrophoresis (PFGE) and coagulase gene restriction profile (CRP) analysis techniques were used to analyze 71 Staphylococcus aureus isolates recovered from nine food-borne disease outbreaks. Twenty-two PFGE profiles and 11 CRPs were identified, with discrimination indices of 0.86 and 0.72, respectively. In addition, the variable regions of the coagulase genes of 39 isolates were sequenced and showed extensive identity, indicating that this is not an efficient alternative for the molecular typing of S. aureus. Staphylococcus aureus is one of the major causative agents of food poisoning. In Taiwan, S. aureus was responsible for 30% of cases of bacterial food-borne outbreaks between 1986 and 1995 (17). Staphylococcal food poisoning is characterized by nausea, vomiting, abdominal pain, and diarrhea and has an incubation period of 30 min to 8 h after ingestion of the contaminated food (8). Enterotoxins produced by the bacteria are believed to be wholly responsible for the symptoms of food poisoning (3); therefore, only enterotoxigenic strains of S. aureus are thought to be able to cause food poisoning. To date, nine S. aureus enterotoxins, designated SEA, SEB, SEC, SED, SEE, SEG, SEH, SEI, and SEJ, have been identified (4, 16, 22, 26). The first five of these (SEA through SEE [SEA-E]) can be detected with commercially available antisera. Tests with such antisera are routinely performed with staphylococcal isolates in the laboratories of the Taiwanese health department in order to confirm the source of a food-borne outbreak. However, while these tests can identify SEA-E-producing isolates, they do not address the possibility that non-SEA-E-producing isolates may be the cause of a food-poisoning outbreak. Another problem of S. aureus identification is that, because the scale of food-borne outbreaks in which S. aureus could be involved is frequently small, only very limited numbers of isolates are usually recovered. Molecular typing of staphylococcal isolates can provide useful clonality information for confirmation of a staphylococcal food-borne outbreak. Numerous such methods for S. aureus typing have been described (5, 6, 7, 12, 19, 23, 25, 27). Among these methods, pulsed-field gel electrophoresis (PFGE) has been demonstrated to have advantages in discriminatory power, typeability, and reproducibility and has been taken as the "gold standard" for the typing of S. aureus (2, 18, 20), even though it is labor-intensive and time-consuming. Compared to PFGE, coagulase gene restriction profile (CRP) analysis, a PCR-based method, is easy to perform and has high levels of specimen typeability and reproducibility, and it has been used successfully for the typing of a large number of methicillinresistant S. aureus isolates (9, 13). In this study, we compared PFGE and CRP analysis for the characterization of staphylococcal isolates recovered from nine food-borne outbreaks. The relationship between the staphylococcal isolates and the foodborne outbreaks is also discussed.