NAS agar is more suitable than McKay agar for primary culture of Streptococcus milleri group (SMG) fastidious bacteria, S-intermedius in particular

0473960 - ÚEB 2018 RIV CZ eng J - Journal Article
Raclavský, V. - Novotný, R. - Starý, L. - Navrátilová, Lucie - Zatloukal, J. - Jakubec, P. - Zápalka, M. - Kopřiva, F. - Kolek, V.
NAS agar is more suitable than McKay agar for primary culture of Streptococcus milleri group (SMG) fastidious bacteria, S-intermedius in particular.
Folia Microbiologica. Roč. 62, č. 1 (2017), s. 11-15. ISSN 0015-5632. E-ISSN 1874-9356
R&D Projects: GA MŠMT(CZ) LO1304
Institutional support: RVO:61389030
Keywords : cystic-fibrosis patients * disease
OECD category: Microbiology
Impact factor: 1.311, year: 2017

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.
Permanent Link: http://hdl.handle.net/11104/0271063