Who are at risk for tuberculosis recurrence?

Abstract

Multi-drug resistance (MDR) is much higher among recurrent tuberculosis cases than among new cases in Latvia and globally.

Aim: To find out the risk factors for TB reinfection (RI) and reactivation (RA).

Design and methods: Retrospective case control study. Non-probability convenience sampling of retreatment cases (RC) according to WHO definitions of 54 available M.tuberculosis (MT) cultures for current and previous TB episodes from years 1999 to 2007. Drug sensitivity test and genotyping in both episodes, data extraction. Cases (RI) - 43 TB RC with genotipically different MT in both episodes, suggesting reinfection with different strain. Controls (RA) 11 TB RC with genotipically identical MT in both episodes, suggesting reactivation.

Results: 31 RI cases (72%) in previous TB episode was treated in hospitals till the year 2002 (OR 4.52, p<0.05), but most part of RA controls 7 (62%) from 2003 to 2007. 30 from RI cases (70%) were drug-susceptable (OR 6.15 p<0.05) with more earlier (80 days) sputum smear conversion to negative in comparison with controls (141 days), but prolonged hospital treatment (229 and 154 days accordingly). RI cases in 77% becomes reinfected with MDR MT strains, predominantly (70%) Beijing and LAM9 genotype. Controls in 45% were MDR, with acquisition of drug resistance and prevalence of Beijing and LAM9 genotype in 73%.

Conclusion: Non-MDR TB patients were at risk for reinfection with MDR MT strains during prolonged hospitalization in conditions of poor infection control. To decrease risk of TB transmission in hospitals; strong infection control measures and ambulatory treatment should be enforced. As a risk factor for TB relapse drug resistant MT in the previous episode is suspected.