| Summary: | 碩士 === 國立嘉義大學 === 生物科技研究所 === 93 === Food poisoning caused by the newly identified enterotoxins of Staphylococcus aureus has been demonstrated by the food microbiologists based on food safety concern. The transmitting route of Staphylococcus aureus is largely due to contamination from workers who directly contact and handle foods. In this study, whether the recent identified enterotoxins playing an important role in food poisoning was investigated. The mucosal membranes from 143 workers involved in making lunch boxes in the Unified Schools in Chiayi City were collected and cultured for isolation and identification. As a result, these workers harbored 27 isolates belonging to Staphylococcus aureus. When subjected to polymerase chain reaction (PCR) to detect seg and sei genes involved in new enterotoxin synthesis, only 4 out 27 (14.8%) clones were positive. This indicates that these two toxins might play a minor role in food poisoning. When the 27 clones were respectively cultured overnight and cells were subjected to analysis of fatty acid composition by Gas Chromatography (GC). In general, fatty acid profiles of these Staphylococcus aureus clones were mainly composed of 14:0, a-15:0, i-15:0, 16:0, 17:0, 18:0, 19:0 and 20:0 fatty acids. As estimated, a-15:0 content was around 37.63% and the rest contents of i-15:0, 18:0, and 20:0 were 11.76, 8.16 and 11.52% respectively. The differences of fatty acid composition among isolates were very limilted. In order to imitate hand washing of food handlers prior to contact foods, all isolates were subjected to mix with triclosan solutions with various concentration for 30 sec and followed by pour-plate enumeration of the survival cells. When 104 CFU/mL of Staphylococcus aureus were respectively incubated with 2.5, 5 and 30 ppm of triclosan for 30 sec, 24 (88.8%), 26 (96.3%) and 27 (100%) isolates were effectively eliminated. This indicates that triclosan is effective in elimination of Staphylococcus aureus. When the isolated cultures were subjected to disk diffusion susceptibility test with various antibiotics, 96.3% of Staphylococcus aureus isolates were resistant to penicillin, 37% were resistant to erythromycin, 29.6% were resistant to clindamycin and tetracycline, and 25.9% were resistant to oxacillin. All isolates were susceptible to vancomycin, fusidic acid, rifampin and sulfamethozaole. In conclusion, isolates harboring new enterotoxin types were minor. Fatty acid composition among isolates varied very limited. Tricolsan could effectively inhibit growth of Staphylococcus aureus at low concentrations. Thus, washing hands with cleaners containing triclosan to prevent food poisoning caused by Staphylococcus aureus was strongly encouraged.
|
|---|
