Manie T, Khan S, Brözel V S, Veith W J, Gouws P A
Department of Zoology, University of the Western Cape, Bellville, South Africa.
Lett Appl Microbiol. 1998 Apr;26(4):253-8. doi: 10.1046/j.1472-765x.1998.00312.x.
Animal feed is increasingly being supplemented with antibiotics to decrease the risk of epidemics in animal husbandry. This practice could lead to the selection for antibiotic resistant micro-organisms. The aim of this study was to determine the level of antibiotic resistant bacteria present on retail and abattoir chicken. Staphylococci, Enterobacteriaceae, Salmonella and isolates from total aerobic plate count were tested for resistance to vancomycin, streptomycin, methicillin, tetracycline and gentamicin using the disc diffusion susceptibility test; resistance to penicillin was determined using oxacillin. Results from the antibiotic code profile indicated that many of the bacterial strains were displaying multiple antibiotic resistance (MAR). A larger proportion of resistance to most antibiotics, except for vancomycin, was displayed by the abattoir samples, therefore suggesting that the incidence of MAR pathogenic bacteria was also higher in the abattoir samples. This resistance spectrum of abattoir samples is a result of farmers adding low doses of antibiotics to livestock feed to improve feeding efficiency so that the animals need less food to reach marketable weight. The lower incidence of MAR pathogenic bacteria in the retail samples is a result of resistance genes being lost due to lack of selective pressure, or to the fact that the resistant flora are being replaced by more sensitive flora during processing. The use of subtherapeutic levels of antibiotics for prophylaxis and as growth promoters remains a concern as the laws of evolution dictate that microbes will eventually develop resistance to practically any antibiotic. Selective pressure exerted by widespread antimicrobial use is therefore the driving force in the development of antibiotic resistance. This study indicated that a large proportion of the bacterial flora on fresh chicken is resistant to a variety of antibiotics, and that resultant food-related infections will be more difficult to treat.
动物饲料中越来越多地添加抗生素，以降低畜牧业中疫病爆发的风险。这种做法可能导致对抗生素耐药微生物的选择。本研究的目的是确定零售鸡肉和屠宰场鸡肉中存在的抗生素耐药细菌的水平。使用纸片扩散药敏试验检测葡萄球菌、肠杆菌科细菌、沙门氏菌以及总需氧平板计数分离株对万古霉素、链霉素、甲氧西林、四环素和庆大霉素的耐药性；使用苯唑西林测定对青霉素的耐药性。抗生素编码谱的结果表明，许多菌株表现出多重抗生素耐药性（MAR）。除万古霉素外，屠宰场样本对大多数抗生素的耐药比例更高，因此表明屠宰场样本中MAR病原菌的发生率也更高。屠宰场样本的这种耐药谱是由于农民在牲畜饲料中添加低剂量抗生素以提高饲养效率，从而使动物达到可上市体重所需的食物减少。零售样本中MAR病原菌的发生率较低，是由于缺乏选择压力导致耐药基因丢失，或者是由于在加工过程中耐药菌群被更敏感的菌群所取代。使用亚治疗水平的抗生素进行预防和作为生长促进剂仍然令人担忧，因为进化规律表明微生物最终会对几乎任何抗生素产生耐药性。因此，广泛使用抗菌药物所施加的选择压力是抗生素耐药性发展的驱动力。这项研究表明，新鲜鸡肉上的大部分细菌菌群对多种抗生素耐药，并且由此导致的与食物相关的感染将更难治疗。
