title: Nutrient agar with sodium chloride supplementation for presumptive detection of Moraxella catarrhalis in clinical specimens.
abstract: We previously reported that Nissui nutrient agar (N medium) promoted the growth of Moraxella catarrhalis but not commensal Neisseria spp. In the present study, we examined which constituent of N medium was responsible for the selective growth of M. catarrhalis using 209 M. catarrhalis and 100 commensal Neisseria spp. clinical strains. We found that peptone, but not meat extract or agar of N medium, had growth-promoting or growth-inhibiting ability with respect to M. catarrhalis and commensal Neisseria spp. Thus, we investigated the amino acid content of N peptone and found it had higher concentrations of amino acids than other commercial peptone products. On varying the sodium chloride concentration of reconstituted N medium, we noted that the concentration was an important factor in bacterial growth differences. Varying the sodium chloride concentration of other commercial nutrient agars achieved similar results to those for N medium. This is, to our knowledge, the first study observing that sodium chloride concentration is responsible for difference in growth between the two organisms. We also successfully isolated colonies of M. catarrhalis from respiratory specimens on N medium, whereas the growth of commensal Neisseria spp. was inhibited, and by adding bovine hematin and β-NAD we were able to isolate Haemophilus influenzae colonies as efficiently as with a chocolate agar. In conclusion, nutrient agar can be used as a medium for the preferential isolation of M. catarrhalis from upper respiratory tract specimens.
authors.affiliation: Department of Microbiology and Immunology, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-Ku, Tokyo 113-8510, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nishiyama
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Saito
authors.forename: Toshio
authors.initials: T
authors.lastname: Chida
authors.forename: Kazumitsu
authors.initials: K
authors.lastname: Sano
authors.forename: Tatsuyuki
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Noboru
authors.initials: N
authors.lastname: Okamura
mesh_terms: D000362:Agar; D000818:Animals; D002417:Cattle; D003470:Culture Media / Q000737:chemistry*; D006193:Haemophilus influenzae / Q000187:drug effects / Q000254:growth & development; D006427:Hemin / Q000378:metabolism; D006801:Humans; D001936:Moraxella catarrhalis / Q000145:classification / Q000187:drug effects / Q000254:growth & development* / Q000302:isolation & purification*; D045828:Moraxellaceae Infections / Q000175:diagnosis / Q000382:microbiology*; D009343:Neisseria / Q000187:drug effects / Q000254:growth & development; D012137:Respiratory System; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D003470:Culture Media; D012965:Sodium Chloride; D006427:Hemin; D000362:Agar