[Evaluation of cycloserine in the treatment of infections caused by nontuberculous mycobacteria viewed from in vitro experiments].
Evaluation of cycloserine as a drug in the treatment of infections caused by nontuberculous mycobacteria was made from in-vitro studies, in which Mycobacterium tuberculosis strains were used as the standard of the evaluation. The susceptibility testing to cycloserine was made using Ogawa egg medium. Bacterial suspensions, 10 mg wet weight/ml, prepared from 10 day-old cultures (M. tuberculosis, 14 day-old cultures) growing on Ogawa egg medium were used as the source of inoculation. A 0.02 ml-sample of the suspensions was inoculated onto Ogawa egg medium containing cycloserine or containing no drug, and the media inoculated were incubated at 37 degrees C. The minimal inhibitory concentration (MIC) was determined after incubation for 14 days (M. tuberculosis, for 21 days). The MIC was determined as the lowest concentration of the drug, on which the growth of test strains was completely inhibited. However, residual growth was sometimes observed. This was regarded as growth inhibition, because control medium containing no drug showed always abundant, membraneous growth. The results are shown in Fig.. The growth of M. tuberculosis strains was inhibited by the concentrations of 6.25 to 25 micrograms/ml. However, considering our previous observations on the relationship between the cycloserine resistance and the drug efficacy (reference 1), we regarded the MIC 12.5 micrograms/ml as critical concentration for presumable clinical efficacy. The ratios of strains of various mycobacterial species showing the MICs lower than the critical concentration are shown in Table. As seen in this table, clinical efficacy of cycloserine was expected in the treatment of infections caused by Mycobacterium kansasii, M. malmoense, M. simiae, M. scrofulaceum and M. marinum.(ABSTRACT TRUNCATED AT 250 WORDS)
Tsukamura
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D003523:Cycloserine / Q000008:administration & dosage / Q000494:pharmacology*; D004353:Drug Evaluation, Preclinical; D008826:Microbial Sensitivity Tests; D009161:Mycobacterium / Q000187:drug effects*; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000254:growth & development; D009170:Nontuberculous Mycobacteria / Q000187:drug effects* / Q000254:growth & development
D003523:Cycloserine