Johansson A, Greko C, Engström B E, Karlsson M
Department of Bacteriology, National Veterinary Institute, SE-751 89 Uppsala, Sweden.
Vet Microbiol. 2004 Apr 19;99(3-4):251-7. doi: 10.1016/j.vetmic.2004.01.009.
This study was undertaken to determine the in vitro susceptibility of Clostridium perfringens, isolated from poultry to antimicrobials used in poultry production. The minimal inhibitory concentration (MIC) of eight antimicrobials, including the ionophoric coccidiostat narasin, was determined for 102 C. perfringens isolates, 58 from Sweden, 24 from Norway and 20 from Denmark. Susceptibility to each antimicrobial compound was determined by broth microdilution. The isolates were obtained from broilers (89), laying hens (9) and turkeys (4), affected by necrotic enteritis (NE) or by C. perfringens associated hepatitis (CPH), and from healthy broilers. All strains, regardless of origin, proved inherently susceptible to ampicillin, narasin, avilamycin, erythromycin and vancomycin. A low frequency of resistance to virginiamycin and bacitracin was also found. Resistance to tetracycline was found in strains isolated in all three countries; Sweden (76%), Denmark (10%) and Norway (29%). In 80% of the tetracycline-resistant isolates, the two resistance genes tetA(P) and tetB(P) were amplified by PCR whereas in 20% only the tetA(P) gene was detected. No tetM gene amplicon was obtained from any of the tetracycline-resistant isolates. The uniform susceptibility to narasin revealed in this study shows that the substance can still be used to control clostridiosis. In this study, C. perfringens also showed a low degree of resistance to most other antimicrobials tested. Despite the small amounts of tetracycline used in poultry, a considerable degree of resistance to tetracycline was found in C. perfringens isolates from Swedish broilers.
本研究旨在确定从家禽中分离出的产气荚膜梭菌对家禽生产中使用的抗菌药物的体外敏感性。对102株产气荚膜梭菌分离株测定了8种抗菌药物的最低抑菌浓度（MIC），其中58株来自瑞典，24株来自挪威，20株来自丹麦。这8种抗菌药物包括离子载体类抗球虫药那拉菌素。通过肉汤微量稀释法测定各分离株对每种抗菌化合物的敏感性。这些分离株取自患有坏死性肠炎（NE）或产气荚膜梭菌相关性肝炎（CPH）的肉鸡（89株）、蛋鸡（9株）和火鸡（4株），以及健康肉鸡。所有菌株，无论来源如何，对氨苄西林、那拉菌素、阿维拉霉素、红霉素和万古霉素均表现出固有敏感性。对维吉尼亚霉素和杆菌肽的耐药频率也较低。在所有三个国家分离出的菌株中均发现了对四环素的耐药性；瑞典（76%）、丹麦（10%）和挪威（29%）。在80%的四环素耐药分离株中，通过聚合酶链反应（PCR）扩增出了tetA(P)和tetB(P)两个耐药基因，而在20%的分离株中仅检测到tetA(P)基因。从任何一株四环素耐药分离株中均未获得tetM基因扩增产物。本研究中所显示的对那拉菌素的一致敏感性表明该物质仍可用于控制梭菌病。在本研究中，产气荚膜梭菌对大多数其他测试抗菌药物的耐药程度也较低。尽管家禽中使用的四环素量较少，但在瑞典肉鸡的产气荚膜梭菌分离株中发现了相当程度的对四环素的耐药性。
