Tuberculosis and the risk of infection with other intracellular bacteria: a population-based study

SUMMARY Persons who develop tuberculosis (TB) may have subtle immune defects that could predispose to other intracellular bacterial infections (ICBIs). We obtained data on TB and five ICBIs (Chlamydia trachomatis, Salmonella spp., Shigella spp., Yersinia spp., Listeria monocytogenes) reported to the Tennessee Department of Health, USA, 2000-2011. Incidence rate ratios (IRRs) comparing ICBIs in persons who developed TB and ICBIs in the Tennessee population, adjusted for age, sex, race and ethnicity were estimated. IRRs were not significantly elevated for all ICBIs combined [IRR 0.87, 95% confidence interval (CI) 0.71-1.06]. C. trachomatis rate was lowest in the year post-TB diagnosis (IRR 0.17, 95% CI 0.04-0.70). More Salmonella infections occurred in extrapulmonary TB compared to pulmonary TB patients (IRR 14.3, 95% CI 1.67-122); however, this appeared to be related to HIV co-infection. TB was not associated with an increased risk of other ICBIs. In fact, fewer C. trachomatis infections occurred after recent TB diagnosis. Reasons for this association, including reduced exposure, protection conferred by anti-TB drugs or macrophage activation by Mycobacterium tuberculosis infection warrant further investigation.