Laboratory cross-contamination of Mycobacterium tuberculosis in Northwest of Iran

IntroductionGold standard method for Mycobacterium tuberculosis identification is microbial culture, but this method can cause cross-contaminations. In the present study we aimed to investigate possible cross-contaminations in two main tuberculosis laboratories in Northwest of Iran.MethodsOne hundred and fifty-six isolates from two central tuberculosis laboratories were investigated by IS6110-RFLP and VNTR-ETR methods.Results53 isolates were clustered in 18 clusters. 15 isolates were smear negative and single culture positive among which four isolates were suspected to be contaminated and in two isolates (1.28%) contaminations were confirmed.ConclusionWith this confirmation clustered isolates reduced from 53 isolates to 49 isolates and recent transmission rate of tuberculosis reduced to 21.2%. This study showed genotyping smear negative and single culture positive isolates can prevent unnecessary treatments and for this purpose VNTR-ETR is a suitable method.