Improved detection of non-tuberculous mycobacteria in hospital water samples

Nontuberculous mycobacteria (NTM) are opportunistic pathogens commonly colonizing hospital watersystems, and may be responsible for healthcare-associated infections (HAI). Investigation of HAI and outbreaks caused by NTM necessitates water analyses. However, NTM are slow-growing bacteria within themesophilic community present in water, and are difficult to detect. Prior to culture on specific media, their recovery usually requires decontamination and concentration steps. We assessed the effectivenessof filtration as regards the recovery of 7 NTM species in hospital water samples. We also compared theuse of cetylpyridinium chloride (CPC) at different concentrations and Sodium Hydroxide (NaOH) 4% indecontamination of water samples with mesophilic bacteria. Our laboratory protocol showed that membrane filtration was suitable for concentration and recovery of NTM from water. Sample decontaminationwith CPC was more NTM-preservative than NaOH. A combination of CPC at 0.005% and filtration alloweddetection of NTM at low concentrations, ranging from 3 to 98 CFU/100 mL according to the NTM species.