domingo, 28 de octubre de 2012

HIV Infection and Geographically Bound Transmission of Drug-Resistant Tuberculosis, Argentina - - Emerging Infectious Disease journal - CDC

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HIV Infection and Geographically Bound Transmission of Drug-Resistant Tuberculosis, Argentina - - Emerging Infectious Disease journal - CDC

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Volume 18, Number 11–November 2012


HIV Infection and Geographically Bound Transmission of Drug-Resistant Tuberculosis, Argentina

Viviana RitaccoComments to Author , Beatriz López, Marta Ambroggi, Domingo Palmero, Bernardo Salvadores, Elida Gravina, Eduardo Mazzeo, Susana Imaz, Lucía Barrera, and National TB Laboratory Network
Author affiliations: Instituto Nacional de Enfermedades Infecciosas ANLIS “Dr. Carlos G. Malbrán,” Buenos Aires, Argentina (V. Ritacco, B. López, E. Mazzeo, L. Barrera); Hospital “Dr. F.J. Muñiz,” Buenos Aires (M. Ambroggi, D. Palmero); Programa Provincial de Tuberculosis, Santa Fe, Argentina (B. Salvadores); Hospital Zonal General Agudos “Dr. Diego Paroissien,” La Matanza, Argentina (E. Gravina); and Instituto Nacional de Enfermedades Respiratorias “Dr. Emilio Coni” ANLIS “Dr Carlos G Malbran,” Santa Fe (S. Imaz)
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During 2003–2009, the National Tuberculosis (TB) Laboratory Network in Argentina gave 830 patients a new diagnosis of multidrug-resistant (MDR) TB and 53 a diagnosis of extensively drug- resistant (XDR) TB. HIV co-infection was involved in nearly one third of these cases. Strain genotyping showed that 7 major clusters gathered 56% of patients within restricted geographic areas. The 3 largest clusters corresponded to epidemic MDR TB strains that have been undergoing transmission for >10 years. The indigenous M strain accounted for 29% and 40% of MDR and XDR TB cases, respectively. Drug-resistant TB trends in Argentina are driven by spread of a few strains in hotspots where the rate of HIV infection is high. To curb transmission, the national TB program is focusing stringent interventions in these areas by strengthening infection control in large hospitals and prisons, expediting drug resistance detection, and streamlining information-sharing systems between HIV and TB programs.
During the early 1990s, HIV-associated multidrug-resistant tuberculosis (MDR TB) emerged in Argentina (1). In Buenos Aires, the country’s most heavily populated city, certain multidrug-resistant Mycobacterium tuberculosis strains spread quickly among patients with AIDS (2,3). Specifically, the so-called M strain caused a major MDR TB outbreak at the Hospital Muñiz, a referral treatment center for infectious diseases (4). HIV-infected patients repeatedly seeking assistance at different health centers introduced the M strain into hospitals in nearby districts, where secondary transmission occurred (5). This strain was later responsible for the emergence of MDR TB in HIV-negative patients who had not previously undergone TB treatment (6). In 2002, the M strain was isolated from 2 patients with extensively drug-resistant TB (XDR TB). Two other MDR TB outbreak strains, Ra and Rb, emerged in Rosario, the third largest city in Argentina, simultaneously with the M strain (7).
MDR TB emergence highlighted the need for a MDR/XDR TB surveillance system focused on incidence and transmission. In 2003, the National TB Laboratory Network launched a systematic registry of all incident MDR/XDR TB cases diagnosed throughout the country. The registry includes a genotype database for all MDR/XDR TB patients going back to the initial outbreaks and population studies. We present the findings of a 7-year follow-up study of MDR and XDR TB in Argentina, with emphasis on potential transmission events involving strains responsible for previous outbreaks.

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