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. 2011;6(10):e26276.
doi: 10.1371/journal.pone.0026276. Epub 2011 Oct 27.

High prevalence of primary multidrug resistant tuberculosis in persons with no known risk factors

Larissa Otero  1 , Fiorella Krapp, Cristina Tomatis, Carlos Zamudio, Francine Matthys, Eduardo Gotuzzo, Patrick Van der Stuyft, Carlos Seas
Affiliations

High prevalence of primary multidrug resistant tuberculosis in persons with no known risk factors

Larissa Otero et al. PLoS One. 2011.

Abstract

Introduction: 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.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Patient enrolment and drug resistance results.
Legend: DST = Drug susceptibility test; Drug resistant = any drug resistance, including MDR; MDR = multidrug resistant.
Figure 2
Figure 2. DST patterns in patients with no reported risk factors for MDR-TB: rates and confidence intervals.
Legend: Mono resistant: resistance to a single drug out of the four tested; Poly resistant: resistance to at least two drugs not involving the combination of isoniazid and rifampicin; Only MDR: resistance to isoniazid and rifampicin only; MDR plus: resistance to isoniazid, rifampicin and another drug.
See this image and copyright information in PMC

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