Mycobacterial contamination in tap and shower waters in Thailand

Abstract

Waterborne disease is increasingly becoming associated with opportunistic premise plumbing pathogens (OPPPs), which can resist residual chlorination, regrow throughout drinking water distribution systems, and colonize premise plumbing. Nontuberculous mycobacteria (NTM) in- clude clinically important species and e x ert a high burden on healthcare systems. We briefly report a qPCR-based surv e y of My cobacterium spp. numbers in tap, POU-treated, and shower waters from Bangkok, Thailand. Non-stagnant tap waters and non-stagnant sho w er w aters had mean numbers of 1.3 ×103 and 2.4 ×103 copies/mL, respectively. Water stagnation resulted in mean numbers higher by up to 1.0 log. The lo w est number, 25 copies/mL, was obtained from a POU-treated sample, while the highest number, 2.0 ×104 copies/mL, came from a stagnant tap. Comparing with international data, mean numbers in this study were greater than those in nine out of 11 (82%) comparable studies, and the maximum numbers in this study were also high. Our samples of B angk ok w aters e xhibited relativ ely high My cobacterium spp. numbers, suggesting the need for appropriate POU treatment systems where NTM infection is a health concern. This survey data can be used to set inactiv ation perf ormance targets in PO U w ater disinfection sy stem design and ma y also lead to quantitativ e microbial risk assessment (QMRA) studies. Significance and impact of the study: Nont uberculous m y cobacteria, which ubiquitously coloniz e drinking w ater distribution sy stems and premise plumbing , are import ant waterborne pathogens causing infection through aerosol inhalation. Ho w e v er, their occurrence is not w ell characteriz ed, especially in de v eloping countries. This study reports Mycobacterium spp. numbers via qPCR in tap and shower waters in Bangkok, Thailand, including a comparison with interna- tional surv e y s. Our samples of B angk ok w aters e xhibited relativ ely high numbers of My cobacterium spp., suggesting the need for appropriate PO U treatment sy stems where NTM infection is a health concern. T he data can help set inactiv ation perf ormance targets in PO U disinfection systems and may also lead to quantitative microbial risk assessment studies.