CHARACTERIZATION OF THE PROPORTION OF CLUSTERED TUBERCULOSIS CASES IN GUATEMALA, CA: INSIGHTS FROM A MOLECULAR EPIDEMIOLOGY STUDY, 2010-2014

Abstract

ABSTRACTBackgroundThere is little information about the proportion of clustering of tuberculosis cases from low-income settings, which can represent ongoing transmission events. We investigated for the first time the proportion of clustered tuberculosis cases based on genotypic matching in Guatemala City, Guatemala between 2010 and 2014 and potential risk factors associated with these clustered cases in HIV-infected subjects. Moreover, the genetic diversity of M. tuberculosis isolates in this country is presented.Design and methodsThis study was a retrospective observational study conducted on Mycobacterium tuberculosis isolates from HIV-infected and non-HIV infected tuberculosis cases that submitted samples to a referral tuberculosis laboratory in Guatemala City, Guatemala from 2010-2014. Genotyping results were compared with the international spoligotyping database, SITVIT2 and classified accordingly. We generated a spoligoforest using the MERCAT program. We categorized spoligotype patterns as clustered or non-clustered depending of their genotype and estimated the proportion of clustering and the recent transmission index (RTIn-1). We analyzed the crude association between demographic, clinical and behavioral variables and clustering in the HIV-population.ResultsFrom 2010 to 2014, a total of 479 patients were confirmed as tuberculosis cases by culture at the study site. Spoligotype patterns were available from 391 patients (82%), nine of them with two isolates included in the study. We detected 71 spoligotype patterns and overall, the most frequent spoligotyping families were LAM (39%), followed by T (22%), Haarlem (14%), X (13%), Unknown (6%) and Beijing (3%), representing 97% of the isolates. Out of the 400 isolates, 365 (91%) were grouped in 36 clusters (range: 2-92). The recent transmission index (RTIn-1) was 82%. Pulmonary tuberculosis was strongly associated with clustering in the 113 HIV-infected group with available data (OR=4.3, 95% CI 1.0-17.7).ConclusionThere might be high levels of ongoing transmission of M. tuberculosis in Guatemala City, Guatemala as indicated by clustering in a convenience sample. Among HIV-infected patients, clustering was more likely in pulmonary disease.