High Incidence of Tuberculosis, Low Sensitivity of Current Diagnostic Scheme and Prolonged Culture Positivity in Four Colombian Prisons. A Cohort Study

Low Sensitivity of Current Diagnostic Scheme and Prolonged Culture Positivity in Four Colombian Prisons. A Cohort Study. PLoS ONE 8(11): e80592. doi:10.1371/journal.pone.0080592 High Incidence of Tuberculosis, Low Sensitivity of Current Diagnostic Scheme and Prolonged Culture Positivity in Four Colombian Prisons. A Cohort Study Zulma Vanessa Rueda 0 Lucelly Lpez 0 Lzaro A. Vlez 0 Diana Marn 0 Margarita Rosa Giraldo 0 Henry Pulido 0 Luis Carlos Orozco 0 Fernando Montes 0 Mara Patricia Arbelez 0 David W Dowdy, Johns Hopkins Bloomberg School of Public Health, United States of America 0 1 Grupo Investigador de Problemas en Enfermedades Infecciosas, Facultad de Medicina, Universidad de Antioquia, Medellin, Colombia, 2 Grupo de Epidemiologia, Facultad Nacional de Salud Publica, Universidad de Antioquia, Medellin, Colombia, 3 Escuela de Microbiologia, Universidad de Antioquia, Medellin, Colombia, 4 Seccion de Enfermedades Infecciosas, Departamento de Medicina Interna, Facultad de Medicina, Universidad de Antioquia , Medellin, Colombia, 5 Facultad Nacional de Salud Publica , Universidad de Antioquia, Medellin, Colombia, 6 Secretaria Seccional de Salud y Proteccion Social de Antioquia, Gobernacion de Antioquia , Medellin, Colombia, 7 Secretaria de Salud de Bello, Bello, Colombia, 8 Facultad de Enfermeria , Universidad Industrial de Santander , Bucaramanga, Santander, 9 Secretaria de Salud de Medellin, Alcaldia de Medellin, Medellin , Colombia Objective: To determine the incidence of pulmonary tuberculosis (TB) in inmates, factors associated with TB, and the time to sputum smear and culture conversion during TB treatment. Methods: Prospective cohort study. All prisoners with respiratory symptoms (RS) of any duration were evaluated. After participants signed consent forms, we collected three spontaneous sputum samples on consecutive days. We performed auramine-rhodamine staining, culturing with the thin-layer agar method, Lwestein-Jensen medium and MGIT, susceptibility testing for first-line drugs; and HIV testing. TB cases were followed, and the times to smear and culture conversion to negative were evaluated. Results: Of 9,507 prisoners held in four prisons between April/30/2010 and April/30/2012, among them 4,463 were screened, 1,305 were evaluated for TB because of the lower RS of any duration, and 72 were diagnosed with TB. The annual incidence was 505 cases/100,000 prisoners. Among TB cases, the median age was 30 years, 25% had <15 days of cough, 12.5% had a history of prior TB, and 40.3% had prior contact with a TB case. TB-HIV coinfection was diagnosed in three cases. History of prior TB, contact with a TB case, and being underweight were risk factors associated with TB. Overweight was a protective factor. Almost a quarter of TB cases were detected only by culture; three cases were isoniazid resistant, and two resistant to streptomycin. The median times to culture conversion was 59 days, and smear conversion was 33. Conclusions: The TB incidence in prisons is 20 times higher than in the general Colombian population. TB should be considered in inmates with lower RS of any duration. Our data demonstrate that patients receiving adequate antiTB treatment remain infectious for prolonged periods. These findings suggest that current recommendations regarding isolation of prisoners with TB should be reconsidered, and suggest the need for mycobacterial cultures during follow-up. - Funding: This research was fully funded by Colciencias (Administrative Department of Science, Technology and Innovation), a public agency from the Government of Colombia, http://www.colciencias.gov.co/; and Universidad de Antioquia (Grant No. 111549326144), www.udea.edu.co. Thanks to Estrategia de sostenibilidad CODI 2013-2014, from Universidad de Antioquia, who paid the publication fee. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist. The incidence of tuberculosis (TB) in prisons is estimated to range from 25.3 to 6799 cases per 100000 prisoners per year, and the risk for TB is greater in prisons than in the general population [median estimated annual incidence rate ratio for TB: 23.0 (IQR: 11.7 36.1)][1]. In addition, the high incidence in prisons has a significant impact on the TB incidence in the community (median estimated fraction of TB in the general population attributable to the exposure in prisons for TB: 8.5% and 6.3% in high- and middle/low-income countries, respectively)[1]. TB is suspected when a patient presents with persistent productive cough for more than two weeks, which may be accompanied by other respiratory and/or constitutional symptoms[2]. Most clinicians and national and international guidelines use this criterion for TB screening, and only individuals meeting this criterion proceed with further work up for TB. A study conducted in Cambodia, Thailand, and Vietnam, on patients with HIV infection showed that the presence of a cough for two weeks or more had a sensitivity of 33% for TB. When those authors used the presence of cough of any duration in the preceding 4 weeks, the sensitivity increased to 71%[3]. Given the low sensitivity of the current recommendations, these results suggest that broadening the criteria for testing will result in an increased number of TB cases detected in high-risk prisoner populations. Several risk factors reported in the literature (e.g., alcohol or drug users, or homelessness) may account for the high risk of TB in prisons, however, it is important to identify risk factors that can be used to stratify TB risk for screening purposes at the time of incarceration. In addition to identifying TB cases, in order to halt disease transmission, it is necessary to document when each TB case ceases to be infectious during treatment. This information can be used to guide health care providers in prisons on the optimal timing for discontinuation of respiratory isolation. The recommendations for discontinuation of isolation in prisons are as follow: 1) Treatment with a 4-drug regimen administered for at least 2 weeks by directly observed therapy (DOT); and 2) Clinical evidence of improvement in the condition of the inmate; and 3) Three consecutive negative sputum smears (obtained at least 8 hours apart, including one early morning specimen)[4]. Two factors must be taken into account before stopping isolation; the first is the time to sputum and culture conversion. One study reports that culture conversion from positive to negative in treated TB patients with fully susceptible disease is longer than was conventionally believed (median conversion time for culture: 38.5 days (95% CI, 33-43.5 days), 90th percentile: 93 days)[5]. The second factor is whether the indication to end respiratory isolation should be based on sputum culture-negativity or sputum smear-negativity. A study from The Netherla (...truncated)