Genotyping of human Mycobacterium kansasii isolates from Poland

Mycobacterium kansasii is a slow-growing nontuberculous mycobacterium (NTM) which causes pulmonary diseases. It is one of the most frequent NTM pathogens isolated from clinical samples. The heterogeneity within the M. kansasii species may have important pathogenic and clinical implications. Of the 7 currently recognized M. kansasii genotypes, types I and II are most prevalent and have been associated with human disease. The aim of the study was to investigate the distribution of M. kansasii genotypes among Polish patients suspected of having NTM pulmonary disease. A total of 225 isolates recovered from 122 patients were analyzed. All isolates were collected at the Medical University of Warsaw over a 15-year period (2000-2015) and identified as M. kansasii by High-Pressure Liquid Chromatography (HPLC) analysis or the GenoType Mycobacterium AS/CM assay. The cases were analyzed based on microbiological, clinical and radiological criteria published by the ATS. Genomic DNA was extracted and PCR-Restriction Fragment Length Polymorphism (RFLP) method was used for genotyping of M. kansasii strains for hsp65 , rpoB and tuf genes. Based on PCR-RFLP analysis 224 M. kansasii strains were identified as genotype I and 1 was categorized as genotype II. 110 strains were isolated from patients who met all ATS criteria of NTM disease, 26 from patients meeting at least 2 criteria, and 57 from patients who had no obvious clinical and radiological symptoms. This study demonstrated that M. kansasii clinical isolates from Poland are almost exclusively of subtype I. The high detection rate of M. kansasii subtype I in clinical samples may suggest that this genotype has a particular ability for colonization and/or infection of the human host.