title: NAS agar is more suitable than McKay agar for primary culture of Streptococcus milleri group (SMG) fastidious bacteria, S. intermedius in particular.
abstract: 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.
authors.affiliation: Department of Microbiology, Faculty of Medicine and Dentistry, Palacký University Olomouc, Hnevotinska 3, Olomouc, Czech Republic. vladislav.raclavsky@upol.cz.|Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, Hnevotinska 5, Olomouc, Czech Republic. vladislav.raclavsky@upol.cz.
authors.forename: Vladislav
authors.initials: V
authors.lastname: Raclavsky
authors.affiliation: Department of Microbiology, Faculty of Medicine and Dentistry, Palacký University Olomouc, Hnevotinska 3, Olomouc, Czech Republic.
authors.forename: Radko
authors.initials: R
authors.lastname: Novotny
authors.affiliation: Department of Surgery I, University Hospital Olomouc, I. P. Pavlova 6, Olomouc, Czech Republic.
authors.forename: Lubomir
authors.initials: L
authors.lastname: Stary
authors.affiliation: Department of Microbiology, Faculty of Medicine and Dentistry, Palacký University Olomouc, Hnevotinska 3, Olomouc, Czech Republic.|Laboratory of Growth Regulators, Palacký University Olomouc & Institute of Experimental Botany AS CR, Slechtitelu 11, Olomouc, Czech Republic.
authors.forename: Lucie
authors.initials: L
authors.lastname: Navratilova
authors.affiliation: Department of Respiratory Medicine, University Hospital Olomouc, I. P. Pavlova 6, Olomouc, Czech Republic.
authors.forename: Jaromir
authors.initials: J
authors.lastname: Zatloukal
authors.affiliation: Department of Respiratory Medicine, University Hospital Olomouc, I. P. Pavlova 6, Olomouc, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Jakubec
authors.affiliation: Department of Pediatrics, University Hospital Olomouc, I. P. Pavlova 6, Olomouc, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Zapalka
authors.affiliation: Department of Pediatrics, University Hospital Olomouc, I. P. Pavlova 6, Olomouc, Czech Republic.
authors.forename: Frantisek
authors.initials: F
authors.lastname: Kopriva
authors.affiliation: Department of Respiratory Medicine, University Hospital Olomouc, I. P. Pavlova 6, Olomouc, Czech Republic.
authors.forename: Vitezslav
authors.initials: V
authors.lastname: Kolek
mesh_terms: D000362:Agar; D001431:Bacteriological Techniques / Q000379:methods*; D003470:Culture Media / Q000737:chemistry*; D006801:Humans; D013290:Streptococcal Infections / Q000175:diagnosis*; D034364:Streptococcus milleri Group / Q000302:isolation & purification*
chemical_list: D003470:Culture Media; D000362:Agar