Dental Unit Waterlines in Quito and Caracas Contaminated with Nontuberculous Mycobacteria: A Potential Health Risk in Dental Practice

Abstract

Three cases of severe odontogenic infections due to nontuberculous mycobacteria (NTM) in Venezuela that were directly associated with dental procedures and the finding of dental unit waterlines (DUWLs) in dental offices that were colonized with mycobacteria species was the reason for assessing the water quality of DUWLs in dental offices in two capital cities in South America, namely, Quito and Caracas. The main water supplies and the water from 143 DUWLs in both cities were sampled and especially checked for contamination with NTM. To measure the overall bacteriological quality of the water also the presence of heterotrophic bacteria, coliform bacteria, and Pseudomonas was determined. Results showed that respectively 3% and 56% of the DUWLs in Quito and Caracas yielded NTM species (up to 1000 colony-forming units (CFU)/mL). Furthermore, high and unacceptable total viable counts of heterotrophic bacteria and/or coliform bacteria and Pseudomonas were detected in 73% of the samples. We conclude that, in both cities, the water in the majority of DUWLs was contaminated with NTM and other potential pathogens, presenting a risk to human health. The detection of NTM in DUWL water with acceptable heterotrophic bacteria counts shows the need to include NTM in water quality testing. Mycobacteria are more resistant to disinfection procedures than other types of vegetative bacteria, and most testing protocols for DUWLs do not assess mycobacteria and thus do not guarantee risk-free water.

Invasive Mycobacterium abscessus Outbreak at a Pediatric Dental Clinic

“…Proper maintenance of dental facility water lines is critical to prevent overgrowth of microorganisms such as MAB. These organisms display tolerance to commonly used disinfectants and have been identified in the plumbing of health care facilities and dental office water distribution systems [ 14 , 15 ]. Culturing of the water system yielded elevated heterotrophic plate counts and multiple mycobacterial species, which differed from clinical species identified.…”

Odontogenic cutaneous sinus tracts due to infection with nontuberculous mycobacteria: a report of three cases

“…The extent of this problem has been studied in a recent publication from our laboratory. This study was conducted to evaluate water quality in DUWLs in Caracas, Venezuela and Quito, Ecuador, and high levels of NTM were found in most of the units [15]. The identified species included M. fortuitum, M. chelonae, M. abscessus, M. brisbanense, and M. peregrinum.…”

Chlorine-based DUWL disinfectant leads to a different microbial composition of water derived biofilms compared to H2O2-based chemical disinfectants in vitro

“…Furthermore, a chlorine-based DUWL disinfectant proved to be successful in reducing the number of aerobic bacterial counts in effluent water ( O’Donnell et al, 2009 ). Mycobacterium has been previously isolated from DUWL and can be retrieved from aerosol samples ( O’Donnell et al, 2011 ; Walker et al, 2004 ; Castellano Realpe et al, 2020 ). The presence of this species is of a public health interest since it can cause infections in immunocompromised patients ( Koh, 2017 ).…”