Isolation of Nontuberculous Mycobacteria Existing in Isfahan (Iran) Hospital Water Supplies by Phenotypic Method

Nontuberculous mycobacteria are of crucial importance in medicine due to their undisputable impact on human health. Among ecosystem factors, hospital water plays a major role as the inhabitant of mycobacteria and medium for transmission of opportunistic pathogens to a human. In addition, there is increasing evidence showing the correlation of mycobacteria in hospital water and nosocomial infection. Therefore, the aim of the current study was to assess the frequency of mycobacteria in hospital water and identify them according to Runyon classification.

A total of 85 water samples were collected from hospital water resources in Isfahan, Iran. They were transferred to the research laboratory and subjected to filtration and decontamination. They were then subcultured to Lowenstein Jensen media and incubated at various temperatures and inspected weekly for the appearance of Mycobacterium-like colonies. A set of phenotypic tests were finally applied to identify the isolates based on Runyon classification.

Out of 85 water samples, 76 were collected from tap waters and showers used in patient departments and the rest were collected from surface and underground water used in hospitals. Of 40 mycobacteria isolated, 15, 11, and 14 belonged to Runyon's groups of I, II and IV, respectively.

The results of the current study showed that a noticeable rate of water resources in hospitals in Isfahan are contaminated with mycobacteria. This can be considered as a potential hazardous source of infection for patients with immunocompromised immune systems such as the elderly, children, and patients with immunodeficiency conditions.