Assessment of microbiota diversity in dental unit waterline contamination

Yun Dang; Qian Zhang; Jing Wang; Qian Wang; Meng Han; Yuting Niu; Hua Li; Xiue Li

doi:10.7717/peerj.12723

Assessment of microbiota diversity in dental unit waterline contamination

PeerJ. 2022 Jan 6:10:e12723. doi: 10.7717/peerj.12723. eCollection 2022.

Authors

Yun Dang^#¹, Qian Zhang^#², Jing Wang³, Qian Wang¹, Meng Han⁴, Yuting Niu⁵, Hua Li¹, Xiue Li¹

Affiliations

¹ Department of Nursing, School of Stomatology, Peking University, Beijing, China.
² Central Laboratory, School of Stomatology, Peking University, Beijing, China.
³ Department of Preventive Dentistry, School of Stomatology, Peking University, Beijing, China.
⁴ The Fourth Outpatient Department, School of Stomatology, Peking University, Beijing, China.
⁵ Department of Pediatric Dentistry, School of Stomatology, Peking University, Beijing, China.

^# Contributed equally.

Abstract

Background: Dental unit waterlines (DUWLs) provide water for handpieces, air/water syringes, and mouth-rinse water outlets. DUWL contamination can negatively affect the operating environment and public health. Therefore, it is important to elucidate the bacterial concentrations and microbial composition in the DUWLs from different dental specialties.

Methods: We collected 350 5-mL dental water samples (from high-speed handpieces, air/water syringes, and mouth-rinse water outlets) from 60 dental chair units (DCUs) at a dental hospital to determine the bacterial concentrations by culture methods. Meanwhile, to investigate the diversity and community structure of microbe in the DUWLs, 17 high-quality DNA from 60 250-mL air/water syringe water samples, which were collected from the same 60 DCUs, were analyzed using 16S rDNA high-throughput sequencing.

Results: The median bacterial concentration was 166 (31.5, 672.5) CFU/mL and the range was 0-3,816,000 CFU/mL. Only 42.6% of the water samples had bacterial concentrations below 100 CFU/mL. The Kruskal-Wallis H-test revealed that the water samples from three dental specialties had significantly different bacterial concentrations (H = 27.441, P < 0.01). High-throughput sequencing results showed significant differences in bacterial community structure between periodontics and the other two dental specialties. In the samples from three dental specialties, 508 OTUs were detected, with 160, 182 and 176 OTUs unique to the periodontics, endodontics and prosthodontics specialties, respectively. Linear discriminant analysis (LDA) effect size (LEfSe) suggested that Hydrocarboniphaga, Zoogloea, Aquabacterium, and Hydrogenophaga were enriched in the periodontics specialty; Acinetobacter, Geothrix, and Desulfovibrio were enriched in the prosthodontics specialty; and Alistipes, Clostridium XIVa, and Serratia were enriched in the endodontics specialty. Seven potentially human-pathogenic genera (Pseudomonas, Acinetobacter, Sphingomonas, Ochrobactrum, Rhizobium, Brevundimonas, and Methylobacterium) with relative abundance exceeding 1% were also detected in the DUWLs.

Conclusions: The bacterial concentrations and microbial composition were influenced by different dental specialties, so a validated disinfection protocol should be used to control DUWL contamination in different dental specialties.

Keywords: Dental unit waterlines; High-throughput sequencing; Microbiota; Water quality.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Bacteria / genetics
Biofilms
Disinfection / methods
Equipment Contamination*
Humans
Microbiota* / genetics

Associated data

figshare/10.6084/m9.figshare.16543935

Grants and funding

This research was supported by grants from the Peking University School of Stomatology (PKUSS20170112) and the Chinese Medical Association Publishing House (CMAPH-NRG2019008). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.