title: Exogenous reinfection with multidrug-resistant Mycobacterium tuberculosis in patients with advanced HIV infection.
abstract: BACKGROUND
  In the United States there have been recent outbreaks of multidrug-resistant tuberculosis. These outbreaks have primarily involved persons infected with the human immunodeficiency virus (HIV).
  
  
  METHODS
  We collected clinical information on 17 patients seen at a New York City hospital who had repeatedly positive cultures for Mycobacterium tuberculosis. Analysis of restriction-fragment--length polymorphisms (RFLPs) was performed on serial isolates of M. tuberculosis obtained from these patients.
  
  
  RESULTS
  Six patients had isolates that remained drug-susceptible, and the RFLP patterns of these isolates did not change over time. Eleven patients had isolates that became resistant to antimicrobial agents. The RFLP patterns of the isolates from six of these patients remained essentially unchanged (two strains showed one additional band) despite the development of drug resistance. In five other patients, however, the RFLP patterns of the isolates changed dramatically at the time that drug resistance was detected. The change in the RFLP pattern of the isolate from one patient appeared to be the result of contamination during processing in the laboratory. In the remaining four patients, all of whom had advanced HIV disease, the clinical and microbiologic evidence was consistent with the presence of active tuberculosis caused by a new strain of M. tuberculosis.
  
  
  CONCLUSIONS
  Resistance to antituberculous drugs can develop not only in the strain that caused the initial disease, but also as a result of reinfection with a new strain of M. tuberculosis that is drug-resistant. Exogenous reinfection with multidrug-resistant M. tuberculosis can occur either during therapy for the original infection or after therapy has been completed.
authors.affiliation: Department of Medicine, Stanford University, Calif.
authors.forename: P M
authors.initials: PM
authors.lastname: Small
authors.forename: R W
authors.initials: RW
authors.lastname: Shafer
authors.forename: P C
authors.initials: PC
authors.lastname: Hopewell
authors.forename: S P
authors.initials: SP
authors.lastname: Singh
authors.forename: M J
authors.initials: MJ
authors.lastname: Murphy
authors.forename: E
authors.initials: E
authors.lastname: Desmond
authors.forename: M F
authors.initials: MF
authors.lastname: Sierra
authors.forename: G K
authors.initials: GK
authors.lastname: Schoolnik
mesh_terms: D017088:AIDS-Related Opportunistic Infections; D000328:Adult; D000995:Antitubercular Agents / Q000494:pharmacology* / Q000627:therapeutic use; D004269:DNA, Bacterial / Q000032:analysis; D004352:Drug Resistance, Microbial; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D012150:Polymorphism, Restriction Fragment Length; D012008:Recurrence; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy / Q000382:microbiology*
chemical_list: D000995:Antitubercular Agents; D004269:DNA, Bacterial