Gumber S, Whittington R J
The University of Sydney, Private Bag 3, Camden 2570, NSW, Australia.
Vet Microbiol. 2007 Jan 17;119(1):42-52. doi: 10.1016/j.vetmic.2006.08.009. Epub 2006 Aug 14.
To compare the utility and diagnostic accuracy of BACTEC and MGIT culture systems, a total of 41 pooled faecal samples, each containing faeces from one sheep infected with the S strain of Mycobacterium paratuberculosis and four uninfected sheep was cultured. The MGIT culture system did not support the growth of the S strain of M. paratuberculosis from faeces within the time frame of the experiments, although a laboratory adapted S strain grew slowly in MGIT provided that sufficient bacteria were inoculated. In contrast, C strain grew rapidly in MGIT. The sensitivity of culture was calculated relative to the infection status of the animals, none of which had clinical signs of ovine Johne's disease. The overall sensitivity of pooled faecal culture in the BACTEC culture system was 21.9% (95% confidence limits, 10.5-37.6), a figure dependant on the proportion of multibacillary cases. The sensitivities of the BACTEC culture system for pools containing animals with multibacillary and paucibacillary lesions were 100.0% (95% confidence limits, 47.2-100.0) and 17.8% (95% confidence limits 6.06-36.8), respectively. The contamination rate of BACTEC cultures was 9.7% compared to 14.3% for MGIT. The effect of 100 microg/ml ampicillin on the S strain of the M. paratuberculosis was examined and in both BACTEC and MGIT media it delayed growth by about 1 week. The composition of MGIT medium, particularly presence of vancomycin hydrochloride, slowed the growth of the S strain. The low content of egg yolk was considered to be another possible factor. The radiometric BACTEC culture system remains the best alternative for the culture of S strain and is recommended in circumstances where the genotype (s) of the strains present in a region/farm is either unknown or S strain.
为比较BACTEC和MGIT培养系统的实用性及诊断准确性，共培养了41份混合粪便样本，每份样本包含来自1只感染副结核分枝杆菌S菌株的绵羊和4只未感染绵羊的粪便。在实验时间范围内，MGIT培养系统无法支持粪便中副结核分枝杆菌S菌株的生长，不过实验室适应的S菌株在接种足够细菌的情况下能在MGIT中缓慢生长。相比之下，C菌株在MGIT中生长迅速。培养的敏感性是相对于动物的感染状态计算的，这些动物均无绵羊副结核病的临床症状。BACTEC培养系统中混合粪便培养的总体敏感性为21.9%（95%置信区间，10.5 - 37.6），该数值取决于多菌型病例的比例。BACTEC培养系统对含有多菌型和少菌型病变动物的混合样本的敏感性分别为100.0%（95%置信区间，47.2 - 100.0）和17.8%（95%置信区间6.06 - 36.8）。BACTEC培养物的污染率为9.7%，而MGIT为14.3%。研究了100μg/ml氨苄青霉素对副结核分枝杆菌S菌株的影响，在BACTEC和MGIT培养基中它都使生长延迟约1周。MGIT培养基的成分，特别是盐酸万古霉素的存在，减缓了S菌株的生长。蛋黄含量低被认为是另一个可能因素。放射性BACTEC培养系统仍然是培养S菌株的最佳选择，在一个地区/农场中存在的菌株基因型未知或为S菌株的情况下推荐使用。
