Nutrient agar with sodium chloride supplementation for presumptive detection of Moraxella catarrhalis in clinical specimens.

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 ß-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.

[The clinical usefulness of a newly rapid diagnosis kit, detection of respiratory syncytial virus].

ImmunoCard STAT! RSV (Meridian Bioscience, Inc, USA) is a rapid immunoassay method newly developed for detection of respiratory syncytial virus (RSV) by immunochromatography. We carried out an evaluation of the ImmunoCard STAT! RSV. One hundred fifty-nine nasal wash samples and nasopharyngeal aspirates from patients were used to evaluate three different kits, which are ImmunoCard STAT! RSV, RSV testpack (Abbott JAPAN) and Directigen EZ RSV (Nippon Becton, Dickinson and Company) . One hundred twenty-eight samples showed equivalent results. When nested reversed transcription-PCR (nested RT-PCR) results for 31 samples showing discrepancies among three kits, 10 samples were positive, and 21 samples were negative by nested RT-PCR. Compared to Nested RT-PCR results, ImmunoCard STAT! RSV showed a sensitivity of 90.5% (19/21) and a specificity of 80.0% (8/10), as well as RSV testpack showed a sensitivity of 10.0% (2/21) and a specificity of 100% (10/10), Directigen EZ RSV showed 95.2% (20/21) and 0.0% (0/ 10), respectively. Furthermore, the detection limits were also evaluated by using ACTT No. VR1540 for RSV A-2 strain, and ACTT No. VR1401 for Wash strain. The detection limit of ImmunoCard STAT! RSV was 5.15 x 10(6) TCID50/mL in subgroup A strain and was 7.58 x 10(5) TCID50/mL in subgroup B strain. This result was similar to RSV testpack, and was better than the detection limit of Directigen EZ RSV. It is concluded that ImmunoCard STAT! RSV is useful in detecting RSV in a clinical setting with equivalent performance to conventional other detecting kits.