title: Possible horizontal transmission of Salmonella via reusable egg trays in Thailand.
abstract: Salmonella contamination of eggshells, egg contents, reusable egg trays, and various environmental samples was assessed. Although the overall Salmonella contamination rate from egg farms was low (3.2%), over a quarter (26.7%) of egg trays from farms and more than one third (36.7%) of trays from the market were contaminated. Salmonella strains isolated from reusable egg trays were analyzed by serotyping, antimicrobial susceptibility test and XbaI pulsed-field gel electrophoresis (PFGE) typing. Five serovars (S. Braenderup, S. Emek, S. Weltevreden, S. Stanley, and S. Derby) were isolated, and half of the strains assessed were found to be resistant to one or more of the six antimicrobial agents examined. The overall resistance rates to nalidixic acid, trimethoprim-sulfamethoxazole, tetracycline, and ampicillin were 40.7%, 36.0%, 26.7% and 3.5%, respectively. The PFGE types were matched against sample location and drug resistance. S. Braenderup PFGE type A2 (susceptible to all tested drugs) was isolated from all sample sites; PFGE type A2 (resistant to nalidixic acid) was isolated from Farm C and the market. S. Braenderup PFGE type A1 (resistant to four drugs) was isolated from Farms A and C. S. Weltevreden PFGE type C3 (susceptible to all tested drugs) was isolated from Farms A and B and type C4 (susceptible to all tested drugs) was isolated from Farm A and the market. The distribution of the related genotypes and resistance patterns of Salmonella in egg farms and the market indicate drug-resistant strains of Salmonella may be spread on reusable egg trays.
authors.affiliation: Department of Microbiology, Faculty of Public Health, Mahidol University, Bangkok, Thailand.
authors.forename: Fuangfa
authors.initials: F
authors.lastname: Utrarachkij
authors.forename: Srirat
authors.initials: S
authors.lastname: Pornraungwong
authors.forename: Kanokrat
authors.initials: K
authors.lastname: Siripanichgon
authors.forename: Chie
authors.initials: C
authors.lastname: Nakajima
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Orasa
authors.initials: O
authors.lastname: Suthienkul
mesh_terms: D000383:Agriculture; D000667:Ampicillin; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects / Q000235:genetics; D004531:Eggs / Q000382:microbiology*; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D004866:Equipment Contamination; D005506:Food Contamination; D008826:Microbial Sensitivity Tests; D009268:Nalidixic Acid; D012475:Salmonella / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D012480:Salmonella Infections; D012703:Serotyping; D013752:Tetracycline; D013785:Thailand
chemical_list: D000900:Anti-Bacterial Agents; D009268:Nalidixic Acid; D000667:Ampicillin; D013752:Tetracycline