Isolation of nontuberculous mycobacteria from in-use waters of burns and haemodialysis hospital units

Ehsan Aryan,1,* Azra haghani-nasimi,2 Mohammad derakhshan,3 Davoud mansouri ,4 Zahra meshkat,5 Masoud yousefi,6

1. Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences
2. Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences
3. Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences
4. Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences
5. Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences
6. Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences

Abstract

Introduction

Nontuberculous mycobacteria (ntm) are widely present in water sources and they are accounted a major threat for immunocompromised patients. burn and haemodialysis (hd) patients are weekly exposed to a large amount of water in hospitals. to study the possible presence of ntm in waters used in burns and hd units, four university hospitals were investigated in mashhad, northeast iran.

Methods

Ninety six water samples including 35 and 61 samples were collected from burns and hd units, respectively. one liter of each sample was concentrated through filtration by a 0.45-µm nitrocellulose membrane filter after removing chlorine and non-mycobacterial contamination from water respectively by 3% sodium thiosulfate and 0.005% cetylpyridinium chloride. the sediment of each sample was inoculated on both lowenstein-jensen medium and 7h11 middlebrook agar and incubated at 25, 37, and 42°c, and examined twice a week for 8 weeks. acid-fast colonies were subjected to dna extraction followed by rpob-pcr restriction enzyme analysis (pra) using mspi and haeiii.

Results

Efficacy of the concentration method was determined as 10 cfu/l using different sterile water samples spiked with different known numbers of mycobacterium smegmatis mc2155 strain. a total of 19 ntm species (19.8%) including m. chelonae (36.8%), m. simiae (15.8%), m. fortuitum type ii, m. austroafricanum, m. gordonae type i (10.5% each), and m. gordonae type iv (5.3%) were isolated and identified from hospital waters. moreover, two isolates could not be definitely identified by rpob-pra.

Conclusion

About 63% of ntm isolates of this study are clinically significant in humans; therefore in-use waters should effectively be disinfected in critical hospital units.

Keywords

Nontuberculous mycobacteria (ntm), rflp, haemodialysis, burn icu