EPIDEMIOLOGICAL AND CLINICAL ASPECTS OF PULMONARY MYCOBACTERIOSIS IN SISAK-MOSLAVINA COUNTY

Abstract

Summary. While tuberculosis incidence and the number of Mycobacterium tuberculosis isolates have been decreasing in the Republic of Croatia, the number of nontuberculous mycobacteria isolates has been on the increase. Determination of clinical significance of the isolated NTM strains is a complex and demanding process which comprises a simultaneous analysis of clinical, microbiological and radiological findings as well as their correlation with the complete diagnostic criteria following the guidelines of the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA). Regional differences in the distribution of NTM strains and their clinical relevance relativize the generality of conclusions about their clinical presentation. Since in Croatia there are still no data on bacteriological distribution and NTM strains prevalence as well as the incidence of pulmonary mycobacteriosis in certain regions, in this, as far as we know, first regional study, the commonest strains of NTM have been analysed. The strains were isolated from samples taken from the respiratory tract in 48 patients in Sisak – Moslavina county (SMC) in the period from 1 st January 2007 to 31 st December 2017 and their clinical significance estimated following the complete diagnostic criteria of ATS/IDSA. Bacteriological identification of NTM in a region has a great clinical and diagnostic significance since it helps choose treatment options and is an important tool to a clinician in making a decision on antibiotic treatment, checking the treatment effectiveness and estimating the relapse. According to microbiological criteria, 21 patients (40.4%) had isolates which predicted a possible pulmonary mycobacteriosis. By applying the complete diagnostic criteria following the guidelines of ATS/IDSA, a probable disease was established in 12 patients (57.1%), out of whom five were treated (23.8%), while the others were checked radiologically and bacteriologically without an antibiotic therapy. Following the complete criteria, the mean annual incidence of the possible pulmonary mycobacteriosis in S – M county is 0.69 cases in 100,000 inhabitants, and of confirmed ones 0.29 cases. Out of seven isolating episodes M. kansasii , the genuine pulmonary mycobacteriosis was established in three patients (43%), out of three episodes M. xenopi in one patient (33%), and the only one episode of M. avium isolation caused a clinically significant disease (100%). Regional differences in the distribution and relevance of NTM strains point to the significance of ecological factors of the environment in the incidence and clinical manifestations of pulmonary mycobacteriosis, so they ought to be more systematically researched and studied.