Mycobacterial contamination in tap and shower waters in Thailand.

This article focuses on the quantification of nontuberculous Mycobacterium spp. (NTM), opportunistic premise plumbing pathogens (OPPPs), in tap, point-of-use (POU)-treated, and shower waters in Bangkok, Thailand, using quantitative PCR (qPCR). The study found relatively high NTM numbers in non-stagnant tap (mean ~1.3 × 10³ copies/mL) and shower waters (mean ~2.4 × 10³ copies/mL), with stagnation increasing counts by up to 1.0 log, reaching a maximum of 2.0 × 10⁴ copies/mL in stagnant tap water. POU-treated waters showed lower but variable NTM levels, with one sample near the detection limit and others comparable to tap water, suggesting current POU treatments may not consistently reduce NTM. Compared internationally, the NTM levels in Bangkok waters were higher than most reported studies, highlighting the need for effective POU disinfection strategies and providing data to inform quantitative microbial risk assessments (QMRA) where NTM infection poses a health concern.