Department of Public Health and Pediatrics, University of Turin, 10126, Turin, Italy.
BMC Microbiol. 2021 Feb 16;21(1):48. doi: 10.1186/s12866-021-02109-1.
This study illustrates for the first time the performance (sensitivity and selectivity) of the selective medium BCYEα +AB suggested by the new edition of ISO 11731 for legionella isolation and enumeration. We compared the efficacy of the selective BCYEα +AB medium with that of the highly selective MWY medium.
Legionella spp. was detected in 48.2 and 47.1% of the samples by BCYEα +AB and MWY agar, respectively. For optimal detection of Legionella spp., most protocols recommend using selective media to reduce the number of non-Legionella bacteria. Agreement between the two media was 86.7%.
According to the results, both media have a very similar performance and they both have advantages and disadvantages over each other. In AB medium there is the risk of being less selective so more interfering microbiota may grow but in MWY medium there is the risk of being too selective. The low selectivity of the AB medium could be resolved if other treatments are applied after filtration, e.g. acid and/or heat treatment, but it must be taken into account that these treatments still reduce the number of viable Legionella. In conclusion, we recommend using MWY as a selective medium for the detection of Legionella spp. as it is easier discern suspected colonies and facilitate the final Legionella spp.
本研究首次说明了 ISO 11731 新版本中建议的用于军团菌分离和计数的选择性培养基 BCYEα+AB 的性能（灵敏度和选择性）。我们比较了选择性 BCYEα+AB 培养基与高度选择性 MWY 培养基的功效。
通过 BCYEα+AB 和 MWY 琼脂，分别检测到 48.2%和 47.1%的样品中存在军团菌属。为了最佳检测军团菌属，大多数方案建议使用选择性培养基来减少非军团菌的数量。两种培养基之间的一致性为 86.7%。
根据结果，两种培养基的性能非常相似，彼此都有优点和缺点。在 AB 培养基中，选择性较低的风险是可能会有更多干扰微生物生长，但在 MWY 培养基中，选择性过高的风险是可能会有。如果在过滤后应用其他处理方法（例如酸处理和/或热处理），AB 培养基的低选择性可以得到解决，但必须考虑到这些处理方法仍然会降低活的军团菌的数量。总之，我们建议使用 MWY 作为选择性培养基来检测军团菌属，因为它更容易识别可疑的菌落，并有助于最终鉴定军团菌属。
