title: Multiple infection with resistant and sensitive M. tuberculosis strains during treatment of pulmonary tuberculosis patients.
abstract: OBJECTIVE
  To identify multiple infection events during anti-tuberculosis treatment in a cohort of pulmonary tuberculosis (PTB) patients in a local hospital in Callao, Peru.
  
  
  METHODS
  We evaluated 10 patients with smear-positive PTB who had two or more different isolates available during DOTS treatment. We determined drug susceptibility to rifampicin, isoniazid, ethambutol and streptomycin, and performed molecular sub-typing by restriction fragment length polymorphism (RFLP) and PCR.
  
  
  RESULTS
  Drug susceptibility patterns changed from sensitive to resistant in the first and subsequent isolate of three of 10 patients. This change coincided with a dramatic alteration of their DNA fingerprint profile. We ruled out the possibility of cross-contamination or potential labelling errors.
  
  
  CONCLUSIONS
  We found multiple infections with sensitive and resistant strains of Mycobacterium tuberculosis throughout the same treatment scheme in three patients with PTB. Further studies are needed to determine the frequency of exogenous re-infection and simultaneous/ mixed infection and their impact on TB control in Peru.
authors.affiliation: The Working Group on Tuberculosis, National Institute of Health, Lima, Peru. gbaldevi@jhsph.edu
authors.forename: G C
authors.initials: GC
authors.lastname: Baldeviano-Vidalón
authors.forename: N
authors.initials: N
authors.lastname: Quispe-Torres
authors.forename: C
authors.initials: C
authors.lastname: Bonilla-Asalde
authors.forename: D
authors.initials: D
authors.lastname: Gastiaburú-Rodriguez
authors.forename: J E
authors.initials: JE
authors.lastname: Pro-Cuba
authors.forename: F
authors.initials: F
authors.lastname: Llanos-Zavalaga
mesh_terms: D000293:Adolescent; D000328:Adult; D000995:Antitubercular Agents / Q000008:administration & dosage*; D003430:Cross-Sectional Studies; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D004351:Drug Resistance / Q000235:genetics; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000235:genetics*; D010568:Peru / Q000453:epidemiology; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D018088:Tuberculosis, Multidrug-Resistant / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology*
chemical_list: D000995:Antitubercular Agents; D004269:DNA, Bacterial