title: [Fluctuation in the ratio between drug-resistant and -susceptible M. tuberculosis bacilli which were isolated from patients with prolonged anti-tuberculosis treatment].
abstract: OBJECTIVE
  In this study, we examined the fluctuation in the ratio between strains of tuberculosis bacilli resistant and susceptible to the anti-tuberculosis drugs.
  
  
  METHODS
  We selected the cases in which the bacilli acquired drug resistance during the therapy and the cases in which drug resistance was fluctuating during prolonged anti-tuberculosis treatment. We selected the isolates throughout the medication period, and the selected isolates were separated into respective single colonies. Then we measured the minimal inhibitory concentration (MIC) for each colony by microdilution test for M. tuberculosis complex, BrothMIC MTB-1 (Kyokuto Pharmaceutical Inc., Tokyo).
  
  
  RESULTS
  Five patients were eligible for analysis because their medical histories were clearly recorded and drug resistance changed during the course. The MIC of 19 isolates, 202 colonies were measured. Isolates with coexisting drug-resistant and -susceptible colonies were detected in 2 patients. From these results, we considered that the fluctuation in the ratio between drug-resistant and -susceptible bacilli changes with the progression of anti-tuberculosis medication.
  
  
  CONCLUSIONS
  We showed in this article that the drug-resistant bacilli increased rapidly when the strains acquired the drug resistance during medication, and when the administration of particular anti-tuberculosis drug was stopped, the susceptible bacilli seemed to increase gradually. However, the strain immediately became fully drug-resistant when the particular antibacterial drug was readministered.
authors.affiliation: Osaka Medical Center for Respiratory and Allergic Diseases, 3-7-1, Habikino, Habikino-shi, Osaka 583-8588, Japan. ano@zeus.eonet.ne.jp
authors.forename: Hiromi
authors.initials: H
authors.lastname: Ano
authors.forename: Tomoshige
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Hiroko
authors.initials: H
authors.lastname: Yoshida
authors.forename: Chieko
authors.initials: C
authors.lastname: Ishida
authors.forename: Nobuko
authors.initials: N
authors.lastname: Tanigawa
authors.forename: Kunimitsu
authors.initials: K
authors.lastname: Kawahara
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Toba
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Takashima
authors.forename: Izuo
authors.initials: I
authors.lastname: Tsuyuguchi
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D014376:Tuberculosis / Q000188:drug therapy
chemical_list: D000995:Antitubercular Agents