title: [Growth of rifampin-dependent Mycobacterium tuberculosis in conditions without rifampin].
abstract: OBJECTIVE
  To study the growth of rifampin-dependent Mycobacterium tuberculosis in conditions without rifampin.
  
  
  METHODS
  A typical rifampin-dependent strain was identified and a single colony growing in the optimal concentration of rifampin was selected and inoculated (10(-4) mg/ml) to L-J and 12B liquid media, cultured at 37 degrees C. The bacterial growth and characteristics were studied.
  
  
  RESULTS
  In the L-J medium containing rifampin, bacterial growth was observed in two weeks, but in the medium without rifampin tiny colonies were not observed until three weeks. In the 12B media with and without rifampin, bacterial growth was evident on day 9 and day 13 respectively. Thick and larger colonies and cauliflower-like growth were observed in media containing rifampin, but smaller colonies and fried egg-like growth were observed in media without rifampin. Microscopic study showed thick and heavily stained bacteria in media containing rifampin, but small and lightly stained bacteria in media without rifampin. Transmission electron microscopy demonstrated that bacteria growing in the presence of rifampin had complete cell walls, but those growing in the absence of rifampin had abnormal cell walls.
  
  
  CONCLUSIONS
  Rifampin-dependent Mycobacterium tuberculosis may be changed into bacterial L-forms in media without rifampin.
authors.affiliation: Chongqing Pulmonology Hospital, Chongqing 400020, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhong
authors.forename: Yiwei
authors.initials: Y
authors.lastname: Wang
authors.forename: Chuanlong
authors.initials: C
authors.lastname: Sun
authors.forename: Huiguo
authors.initials: H
authors.lastname: Yin
authors.forename: Anrong
authors.initials: A
authors.lastname: Wang
authors.forename: Ming
authors.initials: M
authors.lastname: Zhong
authors.forename: Leshan
authors.initials: L
authors.lastname: Lou
mesh_terms: D000904:Antibiotics, Antitubercular / Q000494:pharmacology*; D008854:Microscopy, Electron; D009169:Mycobacterium tuberculosis / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development*; D012293:Rifampin / Q000494:pharmacology*
chemical_list: D000904:Antibiotics, Antitubercular; D012293:Rifampin