Chuanchuen Rungtip, Pathanasophon Pornpen, Khemtong Sirintip, Wannaprasat Wechsiri, Padungtod Pawin
Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
J Vet Med Sci. 2008 Jun;70(6):595-601. doi: 10.1292/jvms.70.595.
Salmonella enterica isolates from poultry (n=125) and swine (n=132) in Thailand were investigated for antibiotic resistance, susceptibility to disinfectants (benzalkonium chloride (BKC), chlorhexidine digluconate (CHX), zinc chloride and copper sulfate) and cyclohexane tolerance. Forty-two percent were of multiple resistance to antibiotics. The minimum inhibitory concentrations (MICs) of all antibiotics against isolates from swine were higher than that against the isolates from poultry. There were generally few variations in MICs to all disinfectants, indicating that the isolates had either no or only a limited degree of developed resistance to the disinfectants tested. Only 5 isolates (1.9%) were tolerant to cyclohexane. The proton-dependent efflux systems did not play a major role in the reduced susceptibility to BKC and CHX, since susceptibility was not restored when an efflux inhibitor, carbonyl cyanide m-chlorophenylhydrazone (CCCP) was present. Successive exposure to subinhibitory concentrations of BKC and CHX generated mutants resistant to BKC and CHX. A spontaneous BKC-resistant derivative expressed cross-resistance to antibiotics, chloramphenicol and erythromycin. The mechanism responsible for cross-resistance between BKC and antibiotics was not driven by the proton motif force (PMF).
对泰国家禽（n = 125）和猪（n = 132）分离出的肠炎沙门氏菌进行了抗生素耐药性、对消毒剂（苯扎氯铵（BKC）、葡萄糖酸氯己定（CHX）、氯化锌和硫酸铜）的敏感性以及环己烷耐受性调查。42%对多种抗生素耐药。所有抗生素对猪分离株的最低抑菌浓度（MIC）高于对家禽分离株的最低抑菌浓度。对所有消毒剂的MIC一般变化不大，表明分离株对所测试的消毒剂要么没有耐药性，要么耐药程度有限。只有5株分离株（1.9%）对环己烷耐受。质子依赖性外排系统在对BKC和CHX敏感性降低方面不起主要作用，因为当存在外排抑制剂羰基氰化物间氯苯腙（CCCP）时，敏感性并未恢复。连续暴露于亚抑菌浓度的BKC和CHX会产生对BKC和CHX耐药的突变体。一株自发的BKC耐药衍生物对氯霉素和红霉素等抗生素表现出交叉耐药性。BKC与抗生素之间交叉耐药的机制不是由质子动力（PMF）驱动的。
