畜牧業抗生素使用與微生物對人用抗生素產生抗藥性之關聯性初探

Influence of the usage of antibiotics in animal husbandries on the emergence of drug-resistant microorganisms.

陳右儒(Yu-Zu Chen)

指導教授 ： 洪慶宜

長榮大學/健康科學學院/職業安全與衛生研究所/碩士(2007年)

摘要

近年來國內外研究顯示微生物對人用抗生素產生抗藥性與畜牧業抗生素大量使用有關，更有部份文獻顯示致使感染症發生的高抗藥性致病菌來自於畜牧活動。本研究初探國內養豬場相關檢體的腸胃道細菌對人用抗生素的抗藥情形，在台灣南部共採集六家不同型態及規模的養豬場、一個養豬廢水共同處理場與二家傳統市場肉品，由豬糞便、廢水、生物氣膠與肉品中，總共分離出254株腸球菌、492株大腸桿菌與120株大腸桿菌群。
抗藥性測試結果顯示腸球菌對Vancomycin產生抗藥性(VRE)的比例，在其中的一家養豬場為4%，在雞肉的檢體為13%。六家養豬場中豬糞便分離的大腸桿菌，對Tetracycline的抗藥性中位數為100%，對Ampicillin的中位數為33~100%、Trimethoprim / sulfamethoxazole為33~90%、Chloramphenicol為20~100%、Nalidixic acid為0~100%、Ciprofloxacin為0~100%、Cephalothin為0~100%、Gentamicin為0~50%、Cefotaxime為0%、Amikacin為0%與Imipenem為0%，養豬場使用抗生素的方式，影響糞便中大腸桿菌在養豬場的抗藥性表現，抗生素使用種類較多的養豬場糞便大腸桿菌抗藥性的比例較高。生物氣膠中大腸桿菌有類似的抗生素抗藥性情形，可能成為養豬工人的職場危害。養豬廢水共同處理場放流水分離的大腸桿菌群，對Tetracycline的抗藥性比例為94%，對Nalidixic acid為94%、Trimethoprim / sulfamethoxazole為81%、Cephalothin為50%、Ampicillin為44%、Chloramphenicol為44%、Ciprofloxacin為44%與Gentamicin為6%，對Cefotaxime、Amikacin與Imipenem則完全無抗藥性，抗藥性狀況與養豬場豬隻糞便樣本類似，而養豬廢水雖已經過標準處理流程，放流水中仍有高抗藥性的微生物。
本研究初探臺灣畜牧業抗生素使用與各種養豬場相關環境檢體中微生物對人用抗藥性產生抗藥性的程度，因豬隻糞便、廢水及空氣樣本中普遍有較高微生物抗生素抗藥性的發生率，此顯示畜牧業抗生素的大量使用對職場及環境衛生的危害可能高於食用安全問題。未來進一步掌握養豬工人糞便檢體細菌抗藥情形及養豬場中環境檢體抗生素定性與定量，將能更清楚建立畜牧用抗生素及職場暴露的關係。而針對養豬場廢水承受水體上、中、下游的細菌抗藥情形與抗生素檢測，將能作為評估環境風險的基礎。

關鍵字

抗生素抗藥性 ； 環境衛生 ； 養豬場

並列摘要

Recent studies have suggested that the progressively wide spread of antibiotic-resistant bacteria in the environments might cause the inefficiency of drug administrations. The source of resistance might come from the routine usage of antibiotics in animal husbandries. Few investigations abroad have linked the drug-resistance patients directly to the usage of antibiotics in farms. This study investigated the antibiotic resistance of enteric bacteria from various pig-farm related samples. There were totally 254 Enterococcus, 492 Escherichia coli, and 120 fecal coliforms isolated in pig-stool and aerosol samples from 6 pig farms with various types and scales, in wastewater and aerosol samples from a swine sewage treatment plant, and on meat samples from 2 conventional markets.
Antibiotic sensitivity tests to these isolated enteric microorganisms indicated that the incidence of Vancomycin-resistant Enterococcus (VRE) is 4% in stool samples from one of the pig farms, and 13% on the chicken samples from one of the markets. The incidences of Escherichia coli in stool samples from pig farms that expressed resistance to Tetracycline, Ampicillin, Trimethoprim / sulfamethoxazole, Chloramphenicol, Nalidixic acid, Ciprofloxacin, Cephalothin, Gentamicin, Cefotaxime, Amikacin, Imipenem were 100%, 37-96%, 33-90%, 20-100%, 0-100%, 0-100%, 0-100%, 0-50%, 0%, 0%,and 0%, respectively. Different farm types, with different ways of drug administration, apparently affect the incidence of antibiotic resistant Escherichia coli. Escherichia coli with similar drug-resistant patterns to medical antibiotics were isolated from aerosol samples. This might pose an occupational hazard to farm workers. The incidences of fecal coliforms in effluent of the swine wastewater treatment plant that expressed resistance to Tetracycline, Nalidixic acid, Trimethoprim / sulfamethoxazole, Cephalothin, Ampicillin, Chloramphenicol, Ciprofloxacin, Gentamicin were 94%, 94%, 81%, 50%, 44%, 44%, 44%, and 6%, respectively. No resistance was found to Cefotaxime, Amikacin, and Imipenem. The drug-resistant patterns of fecal coliforms in discharged wastewater were similar to those of Escherichia coli in stool samples of pig farms. Common wastewater treatment process was proved to be ineffective with respect to eliminate drug-resistant genes.
The present study provides preliminary information to examine the influence of the usage of antibiotics in animal husbandries of Taiwan on the emergence of drug-resistant microorganisms in various environmental samples. Generally higher incidences of drug-resistant microorganisms in stool, wastewater, and aerosol samples suggested that the routine usage of antibiotics in husbandry might cause even more harms to occupational and environmental health, comparing with the concern for food safety. Future studies focusing on microbial resistance to antibiotics in farmers’ fecal samples and on chemical analyses of antibiotics in the pig farms will further establish the relationship between feed antibiotics and occupational exposure. Investigation on microbial resistance to antibiotics and on concentrations of antibiotics in water samples of upstream, discharge point, and downstream of swine wastewater effluent will serve as a ground work for the assessment of environmental risk of feed antibiotics.

並列關鍵字

antibiotic resistant ； environmental hygiene ； pig farm

參考文獻

行政院農業委員會 (2002) 動物用藥品管理手冊。動物用藥品管理法。

行政院農業委員會 (2005) 動物用藥品使用準則。動物用藥品管理法。

行政院農業委員會 (2005) 屠宰作業準則。畜牧法。

行政院勞工委員會 (2002) 勞工安全衛生法。

行政院勞工委員會 (2004) 勞工安全衛生設施規則。勞工安全衛生法。