Species diversity and molecular characterization of nontuberculous mycobacteria in hospital water system of a developing country, Iran

Background: Hospital environment is of crucial importance in cross-transmission of opportunistic pathogens to the patients. Nontuberculous mycobacteria have the remarkable capability to withstand the adverse condition of hospital environments and pose a potential threat to the health of patients. The current study aimed to assess the frequency and diversity of mycobacteria in hospital water of a developing country using a combination of conventional and molecular methods.

Methods: A total of 148 hospital water samples collected from 38 hospitals were analyzed for the presence of mycobacteria using standard protocols for isolation and characterization of the isolates. The conventional tests were used for preliminary identification and Runyon's classification, the PCR amplification of hsp65 gene and sequence analysis of 16S rRNA were applied for the genus and species identification.

Results: A total of 71 [48%] isolates including 30 rapidly growing and 41 slowly growing mycobacteria were recovered. The three most prevalent species were M. lentiflavum, 28.2%, M. paragordonae, 21.1%, and M. fredriksbergense, 9.8%, followed by M. simiae and M. novocastrense, 7%, M. canariasense and M. cookii like, 5.6%, M. setense, 4.2%, M. fortuitum and M. gordonae, 2.8%, and the single isolates of M. austroafricanum, M. massiliense, M. obuense, and M. phocaicum like.

Conclusion: The results of our study show that the hospital water resources, drinking or non-drinking can be the reservoir of a diverse range of mycobacteria. This reaffirms the fact that these organisms due to intrinsic resistance to common antiseptic and disinfectant solutions persist in hospitals and create a threat to the patient's health and in particular to those that suffer from weakness of immunity.