Investigation of resistance of Salmonella spp. isolated from products and raw material of animal origin (swine and poultry)to antibiotics and disinfectants

ABSTRACT The genus Salmonella spp. Has worldwide geographical distribution, and represents a potential risk both to animal and human health. Inadequate use as well as continuous exposure to antibiotics and disinfectants might lead to the appearance of resistance of these microorganisms to antimicrobial compounds. The aims of this study were to investigate the occurrence of resistance in Salmonella spp., isolated from products and raw material of animal origin (swine and poultry), to antibiotics and disinfectants, and check whether the phenomenon of simultaneous resistance to disinfectants occurs among the antibiotic-resistant isolates. The test of susceptibility to antimicrobials (TSA) applied in 134 isolates indicated that 51 (38%) were resistant to at least one of the eight antibiotics used, and 28 (55%) of resistant isolates were multi-resistant. Resistant isolates were submitted to the test of quantitative suspension against four concentrations of disinfectants in three contact times, and the result was compared with that of the reference strain (Salmonella Choleraesuis ATCC 10.708). While the reference strain was sensitive considering the highest concentration (200 ppm) and the lowest contact time (5 min) as indicators, 12 (24%) isolates were resistant to cetyltrimethylammonium chloride (ammonia quaternary); the reference strain was resistant to chlorhexidine, which also occurred with 22 (43%) of the isolates; similar to the reference strain, all isolates were sensitive/inactivated by sodium hypochlorite and iodophore. There were no significant relations of simultaneous resistance between the antibiotics and the disinfectants tested.

摘要 沙门氏菌属（Salmonella spp.）在全球范围内均有地理分布，对动物与人类健康均构成潜在威胁。抗生素与消毒剂的不合理使用及持续暴露，可能导致此类微生物对抗菌化合物产生耐药性。本研究旨在调查从猪、禽源动物产品及原材料中分离的沙门氏菌属菌株对各类抗生素与消毒剂的耐药性发生情况，并验证耐药菌株中是否存在同时对消毒剂产生耐药性的现象。本研究对134株分离菌株开展抗菌药物敏感性试验（test of susceptibility to antimicrobials, TSA），结果显示51株（38%）对所用8种抗生素中的至少1种产生耐药性，其中28株（55%）耐药菌株呈现多重耐药性。将上述耐药菌株分别在3种接触时间下，针对4种不同浓度的消毒剂开展定量悬液试验，并将试验结果与参考菌株——猪霍乱沙门氏菌（Salmonella Choleraesuis）ATCC 10708进行比对。以最高浓度（200 ppm）与最短接触时间（5 min）作为判定标准时，参考菌株表现为敏感，而12株（24%）分离菌株对十六烷基三甲基氯化铵（季铵盐类消毒剂）产生耐药性；参考菌株对氯己定呈现耐药性，另有22株（43%）分离菌株同样对氯己定耐药；与参考菌株一致，所有分离菌株均对次氯酸钠与碘伏表现敏感（可被灭活）。本次研究所测试的抗生素与消毒剂之间，未发现显著的同时耐药相关性。