title: Prevalence, Risk Factors, and Treatment Outcomes of Isoniazid- and Rifampicin-Mono-Resistant Pulmonary Tuberculosis in Lima, Peru.
abstract: BACKGROUND
  Isoniazid and rifampicin are the two most efficacious first-line agents for tuberculosis (TB) treatment. We assessed the prevalence of isoniazid and rifampicin mono-resistance, associated risk factors, and the association of mono-resistance on treatment outcomes.
  
  
  METHODS
  A prospective, observational cohort study enrolled adults with a first episode of smear-positive pulmonary TB from 34 health facilities in a northern district of Lima, Peru, from March 2010 through December 2011. Participants were interviewed and a sputum sample was cultured on Löwenstein-Jensen (LJ) media. Drug susceptibility testing was performed using the proportion method. Medication regimens were documented for each patient. Our primary outcomes were treatment outcome at the end of treatment. The secondary outcome included recurrent episodes among cured patients within two years after completion of the treatment.
  
  
  RESULTS
  Of 1292 patients enrolled, 1039 (80%) were culture-positive. From this subpopulation, isoniazid mono-resistance was present in 85 (8%) patients and rifampicin mono-resistance was present in 24 (2%) patients. In the multivariate logistic regression model, isoniazid mono-resistance was associated with illicit drug use (adjusted odds ratio (aOR) = 2.10; 95% confidence interval (CI): 1.1-4.1), and rifampicin mono-resistance was associated with HIV infection (aOR = 9.43; 95%CI: 1.9-47.8). Isoniazid mono-resistant patients had a higher risk of poor treatment outcomes including treatment failure (2/85, 2%, p-value<0.01) and death (4/85, 5%, p<0.02). Rifampicin mono-resistant patients had a higher risk of death (2/24, 8%, p<0.01).
  
  
  CONCLUSIONS
  A high prevalence of isoniazid and rifampicin mono-resistance was found among TB patients in our low HIV burden setting which were similar to regions with high HIV burden. Patients with isoniazid and rifampicin mono-resistance had an increased risk of poor treatment outcomes.
authors.affiliation: Vanderbilt University School of Medicine, Nashville, TN, United States of America.
authors.forename: Leonela
authors.initials: L
authors.lastname: Villegas
authors.affiliation: Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: Larissa
authors.initials: L
authors.lastname: Otero
authors.affiliation: Vanderbilt University School of Medicine, Nashville, TN, United States of America.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Sterling
authors.affiliation: Vanderbilt University School of Medicine, Nashville, TN, United States of America.
authors.forename: Moises A
authors.initials: MA
authors.lastname: Huaman
authors.affiliation: Unit of General Epidemiology and Disease Control, Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium.|Department of Public Health, Faculty of Medicine, Ghent University, Ghent, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Van der Stuyft
authors.affiliation: Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Gotuzzo
authors.affiliation: Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: Carlos
authors.initials: C
authors.lastname: Seas
mesh_terms: D000328:Adult; D000995:Antitubercular Agents / Q000627:therapeutic use*; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D007538:Isoniazid / Q000627:therapeutic use*; D008297:Male; D010568:Peru / Q000453:epidemiology; D015995:Prevalence; D012293:Rifampin / Q000627:therapeutic use*; D012307:Risk Factors; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy* / Q000453:epidemiology*
chemical_list: D000995:Antitubercular Agents; D007538:Isoniazid; D012293:Rifampin