Catry B, Decostere A, Schwarz S, Kehrenberg C, de Kruif A, Haesebrouck F
Department of Reproduction, Obstetrics and Herd Health, Ghent University, Merelbeke, Belgium.
Vet Res Commun. 2006 Oct;30(7):707-15. doi: 10.1007/s11259-006-3347-8.
The aim of the present study was to determine which Pasteurella and Mannheimia species are present in the upper respiratory tract of healthy calves with no history of antimicrobial treatment prior to sampling. The presence of subpopulations of tetracycline-resistant Pasteurellaceae was also investigated. Nasal swabs from 61 loose group-housed, clinically healthy calves, 1 to 4 months old, from 16 dairy herds were inoculated aerobically on a selective medium (Columbia agar with 5% ovine blood and 16 mg/L bacitracin) with or without 4 mg/L oxytetracycline (OTC). A total of 43 strains belonging to the family Pasteurellaceae were isolated from 38 calves (62.3%) out of 13 herds (81.3%). The predominant organisms were Pasteurella multocida subsp. multocida (57.4%), Mannheimia varigena (4.9%) and M. haemolytica (3.2%). Growth of Pasteurellaceae on the OTC-containing medium was seen only with samples from two herds (6 animals; 9.8%), and on only one farm this proved to be an OTC-resistant subpopulation. Minimum inhibitory concentration (MIC) determinations by means of agar dilution confirmed a low prevalence of OTC-resistant Pasteurellaceae, with overall MIC(50) and MIC(90) values of 0.25 and 32 mg/L, respectively. These data do not support the hypothesis that the relative high frequency of tetracycline-resistant P. multocida isolates from fatal cases of bovine respiratory disease is related to the presence of minor tetracycline-resistance subpopulations within this species.
本研究的目的是确定在采样前无抗菌治疗史的健康犊牛上呼吸道中存在哪些巴斯德氏菌属和曼氏杆菌属物种。还研究了耐四环素巴斯德氏菌科亚群的存在情况。从16个奶牛场选取61头1至4月龄、临床健康、散养在群内的犊牛，采集鼻拭子，在添加或不添加4mg/L土霉素（OTC）的选择性培养基（含5%羊血和16mg/L杆菌肽的哥伦比亚琼脂）上进行需氧接种。从13个牛群（81.3%）的38头犊牛（62.3%）中总共分离出43株巴斯德氏菌科菌株。主要菌属为多杀巴斯德氏菌多杀亚种（57.4%）、变异曼氏杆菌（4.9%）和溶血曼氏杆菌（3.2%）。仅在两个牛群（6头动物；9.8%）的样本中观察到巴斯德氏菌科在含OTC的培养基上生长，并且仅在一个农场证明这是一个耐OTC的亚群。通过琼脂稀释法测定的最低抑菌浓度（MIC）证实耐OTC的巴斯德氏菌科患病率较低，总体MIC（50）和MIC（90）值分别为0.25和32mg/L。这些数据不支持以下假设，即从牛呼吸道疾病致死病例中分离出的耐四环素多杀巴斯德氏菌相对较高的频率与该物种内存在少量耐四环素亚群有关。
