城市污水处理系统中沙门氏菌对四环素和磺胺甲恶唑的耐药性

耐药性病原菌的出现对人类健康构成潜在威胁.为揭示耐药性沙门氏菌在城市污水处理系统中的存在和分布特征,从2座城市污水处理厂的不同处理单元中分离得到81株沙门氏菌,采用Kirby-Bauer纸片琼脂扩散法考察它们对四环素和磺胺甲恶唑的耐药性.利用PCR检测方法,分析耐药基因tetA、tetB、sul1、sul2和sul3在耐药沙门氏菌中的分布情况.结果表明:分离得到的沙门氏菌对四环素和磺胺甲恶唑的耐药率分别为53.1%和40.7%,其中大部分菌株同时对这2种抗生素具有耐药性;从氯消毒出水中分离到的沙门氏菌对四环素和磺胺甲恶唑的二重耐药率比原污水中的高30.7%;城市污水中耐四环素和耐磺胺甲恶唑沙门氏菌中主要的耐药基因分别为tetA和sul3,经过污水处理系统之后耐药基因的分布发生了显著变化.研究表明,污水处理厂的原水和排放水中沙门氏菌的耐药性问题已十分突出,可能对人类健康造成较大的风险.

Tetracycline and Sulfamethoxazole Resistance and Distribution of Resistance Genes in Salmonella Isolated from Municipal Wastewater Treatment Plants

Antibiotic resistant pathogenic bacteria pose a potential threat to human health. In order to investigate the antibiotic resistance of Salmonella in municipal wastewater, 81strains were isolated from two municipal wastewater treatment plants. The analysis of antibiotic resistance to tetracycline and sulfamethoxazole in these isolates was conducted by Kirby-Bauer disc agar diffusion method. The presence of antibiotic resistance genes, tetA, tetB, sul1, sul2and sul3, in antibiotic resistant Salmonella were investigated by the PCR method. The results showed that the antibiotic resistance rates to tetracycline and sulfamethoxazole were 53.1% and 40.7% respectively, and most of antibiotic resistant Salmonella showed a dual resistance. The rate of dual resistance to tetracycline and sulfamethoxazole in Salmonella isolated from effluent after chlorination was 30.7% higher than in isolates from raw wastewater. The genes tetA and sul3were frequently detected in antibiotic resistant Salmonella in the raw wastewater, while the distribution of antibiotic resistance genes in Salmonella changed significantly after wastewater treatment process. The results implicated that the prevalence of antibiotic resistance of Salmonella in municipal wastewater and effluent may be a major risk to human health.