Isolation of non-tuberculous mycobacteria among tuberculosis patients during a 5-year period in Croatia

Here we evaluated the frequency and identified the main NTM species isolated among all bacteriologically confirmed tuberculosis (TB) patients in Croatia from 2007 to 2011. NTM species identification by molecular and phenotypic methods, as well as MIRU-VNTR genotyping, were performed according to previously described protocols. TB patients were divided into two groups ; co-isolation group encompassed those with NTM isolated in the period from two months prior up to nine months after M. tuberculosis isolation, while after-isolation group included patients with NTM isolated more than nine months after TB diagnosis. Among TB patients, 4.3% (n=140) had also NTM isolated from respiratory specimens, mostly M. gordonae, M. fortuitum and M. xenopi. The majority of patients (n=127) had only one NTM isolate, while 13 patients (9.3%) had two or more isolates of the same NTM species. One should take into account the possible significance of multiple NTM isolates in TB patients and evaluate each case individually.