Raclavsky Vladislav, Novotny Radko, Stary Lubomir, Navratilova Lucie, Zatloukal Jaromir, Jakubec Petr, Zapalka Martin, Kopriva Frantisek, Kolek Vitezslav
Department of Microbiology, Faculty of Medicine and Dentistry, Palacký University Olomouc, Hnevotinska 3, Olomouc, Czech Republic.
Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, Hnevotinska 5, Olomouc, Czech Republic.
Folia Microbiol (Praha). 2017 Jan;62(1):11-15. doi: 10.1007/s12223-016-0470-y. Epub 2016 Sep 16.
Streptococcus milleri group (SMG) is a group of three streptococcal species (S. anginosus, intermedius and constellatus) that act as opportunist pathogens, among others in cystic fibrosis. Due to their fastidious character, they are both difficult to cultivate and to differentiate from less pathogenic streptococcal species, therefore being most probably underdiagnosed. Semi-selective McKay agar and NAS agar were developed to facilitate SMG recovery from clinical samples; however, direct comparison of recovery rates has not been published yet. We tested the performance of both media on 123 patient samples and demonstrated general superiority of NAS agar for SMG recovery during primary cultivation convincingly. This observation was also confirmed by quantitative drop tests during subculture. Despite the undisputed overall superiority of NAS agar over McKay agar, a smaller fraction of strains grew better on McKay agar. Inter-strain differences were the most probable explanation. Therefore, when economic conditions are not limiting and maximum recovery rate is desirable, both plates are advised to be used in parallel for primary cultivation of clinical samples.
米勒链球菌群（SMG）由三种链球菌（咽峡炎链球菌、中间链球菌和星座链球菌）组成，它们是机会致病菌，在囊性纤维化等疾病中较为常见。由于其苛求的特性，它们既难以培养，又难以与致病性较低的链球菌区分开来，因此很可能存在诊断不足的情况。开发了半选择性麦凯琼脂和NAS琼脂，以促进从临床样本中分离出SMG；然而，尚未发表回收率的直接比较。我们在123份患者样本上测试了这两种培养基的性能，并令人信服地证明了NAS琼脂在初次培养期间回收SMG方面的总体优势。继代培养期间的定量点滴试验也证实了这一观察结果。尽管NAS琼脂在总体上优于麦凯琼脂，但仍有一小部分菌株在麦凯琼脂上生长得更好。菌株间差异是最可能的解释。因此，在经济条件允许且希望获得最高回收率时，建议在临床样本的初次培养中同时使用这两种平板。
