[Distribution of nontuberculous mycobacteria isolated from clinical specimens and identified with DNA sequence analysis]

Abstract

The aims of the study were to perform the identification of nontuberculous mycobacteria (NTM) isolated from different clinical specimens in the Mycobacteriology Laboratory of Celal Bayar University, Manisa (located at Aegean region of Turkey), by DNA sequence analysis, and to discuss the epidemiological aspects of the data obtained. Out of 5122 clinical specimens sent to the laboratory with the initial diagnosis of tuberculosis in the period April 2007 to July 2011, M.tuberculosis complex and NTM were identified in 225 (4.39%) and 126 (2.46%) samples, respectively. DNA sequence analysis by targeting hsp65 and 16S rDNA gene regions was performed on 101 of the NTM strains in Mycobacteriology Laboratory of Ege University, Izmir. DNA sequence analysis data was evaluated using RIDOM and GenBLAST data bases. NTM strains were identified as 40 M.porcinum (39.60%), 36 M.lentiflavum (35.65%), six M.abscessus (5.64%), five M.peregrinum (4.95%), four M.gordonae (3.96%), three M.fortuitum (2.97%), two M.chelonae (1.98%), and one for each M.alvei (0.99%), M.scrofulaceum (0.99%), M.kansasii (0.99%) species. Two strains which were both 95-98% compatible with other mycobacteria in the data bases could not be identified with certainty. Seventy-two (94.73%) strains of M.lentiflavum and M.porcinum, which were the most frequent (75.24%) species in the study, were isolated from bronchoalveolar lavage (BAL) specimens. The remaining 99 strains examined could not be proven as the cause of the disease due to absence of patients' clinical data, whereas two M.abscessus strains isolated from the sputum were considered as the cause of the disease according to the ATS/IDSA criteria. The isolation rate of NTM in 2010 was found significantly higher (5.33%) than previous years. Review of the 2010 data showed that all strains of M.porcinum and M.lentiflavum, which were the most frequently identified strains were isolated from BAL specimens. This situation is in line with the start of using of an automatic bronchoscope washing machine in our hospital in the same year. In conclusion, NTM were isolated in 2.46% of the clinical specimens of the patients with the initial diagnosis of tuberculosis and these strains belonged to 10 different NTM species. The two NTM species most frequently isolated in our study were M.lentiflavum and M.porcinum which are known for their potential to cause human infections and antibiotic resistance. As these strains were mostly isolated in BAL specimens, it is concluded that automatic bronchoscope washing machines and water delivery system in the hospitals should be examined in terms of contamination by NTM. The isolated NTM strains could not be distinguished as the cause of the disease or a contaminant, which is the limiting factor in this study. However, knowing that the environmental mycobacteria can cause hospital infections, the data obtained in this study can contribute to epidemiology of NTM infections in Turkey.