title: High prevalence of primary multidrug resistant tuberculosis in persons with no known risk factors.
abstract: BACKGROUND
  In high multidrug resistant (MDR) tuberculosis (TB) prevalence areas, drug susceptibility testing (DST) at diagnosis is recommended for patients with risk factors for MDR. However, this approach might miss a substantial proportion of MDR-TB in the general population. We studied primary MDR in patients considered to be at low risk of MDR-TB in Lima, Peru.
  
  
  METHODS
  We enrolled new sputum smear-positive TB patients who did not report any MDR-TB risk factor: known exposure to a TB patient whose treatment failed or who died or who was known to have MDR-TB; immunosuppressive co-morbidities, ex prison inmates; prison and health care workers; and alcohol or drug abuse. A structured questionnaire was applied to all enrolled participants to confirm the absence of these factors and thus minimize underreporting. Sputum from all participants was cultured on Löwenstein-Jensen media and DST for first line drugs was performed using the 7H10 agar method.
  
  
  RESULTS
  Of 875 participants with complete data, 23.2% (203) had risk factors for MDR-TB elicited after enrolment. Among the group with no reported risk factors who had a positive culture, we found a 6.3% (95%CI 4.4-8.3) (37/584) rate of MDR-TB. In this group no epidemiological characteristics were associated with MDR-TB. Thus, in this group, multidrug resistance occurred in patients with no identifiable risk factors.
  
  
  CONCLUSIONS
  We found a high rate of primary MDR-TB in a general population with no identifiable risk factors for MDR-TB. This suggests that in a high endemic area targeting patients for MDR-TB based on the presence of risk factors is an insufficient intervention.
authors: Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru. larissaotero@gmail.com
authors: Larissa
authors: L
authors: Otero
authors: Fiorella
authors: F
authors: Krapp
authors: Cristina
authors: C
authors: Tomatis
authors: Carlos
authors: C
authors: Zamudio
authors: Francine
authors: F
authors: Matthys
authors: Eduardo
authors: E
authors: Gotuzzo
authors: Patrick
authors: P
authors: Van der Stuyft
authors: Carlos
authors: C
authors: Seas
mesh_terms: D019353:Endemic Diseases; D006801:Humans; D008403:Mass Screening / Q000379:methods; D010568:Peru / Q000453:epidemiology; D015995:Prevalence; D012307:Risk Factors; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis / Q000453:epidemiology*