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Distribution of Nontuberculous Mycobacteria in Dental Unit Waterlines: A Potential Health Hazard in the Dental Office Publisher Pubmed



Vosooghi K1 ; Larypoor M2 ; Sakhaee F3 ; Ghazanfari Jajin M3 ; Moghaddam S3 ; Samieefar N4 ; Rahbari Keramat R5 ; Amiri Sabotki M6 ; Fateh A3, 7
Authors
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Authors Affiliations
  1. 1. Biology Department, Faculty of BioSciences, North Tehran Branch, Islamic Azad University, Tehran, Iran
  2. 2. Department of Biotechnology, Faculty of Biological Sciences, Tehran North Branch, Islamic Azad University, Tehran, Iran
  3. 3. Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran
  4. 4. Network of Interdisciplinarity in Neonates and Infants (NINI), Universal Scientific Education and Research Network (USERN), Tehran, Iran
  5. 5. School of Medicine, Tehran University of Medical Science, Tehran, Iran
  6. 6. Imam Khomeini Hospital Complex, Tehran University of Medical Science, Tehran, Iran
  7. 7. Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran

Source: Microbial Pathogenesis Published:2024


Abstract

Background: It is essential to control the microbiology of dental unit water lines (DUWs) to prevent the spread of nontuberculous mycobacteria (NTM) and associated oral diseases. Therefore, the objective of this study was to quantify the presence of NTM in the water of 112 DUWs from dental centers and 57 DUWs from individual dental offices in Tehran, Iran. Methods: A total of 169 water samples were collected from DUWs. After filtration through a 0.45 μm membrane, the samples were decontaminated with 0.005 % cetylpyridinium chloride and then cultured on two Lowenstein-Jensen media, incubated at 25 °C and 37 °C for 8 weeks. Positive cultures for mycobacteria were analyzed using phenotypic tests, and the NTM species were identified through 16S rDNA, rpoB, and hsp65 genes analysis. Drug resistance was also assessed. Results: Of the total isolates, 38 (34.5 %) were classified as slow-growing mycobacteria (SGM), while 72 (65.5 %) were categorized as rapid-growing mycobacteria (RGM). NTM isolates were identified using molecular tests, including M. chelonae, M. abscessus, M. lentiflavum, M. mucogenicum, M. fortuitum, M. kansasii, M. simiae, M. gordonae, M. conceptionense, M. phocaicum, M. porcinum, and M. aurum. The NTM counts ranged from 50 to >500 CFU/500 mL across these 188 samples, with a median of 350 CFU/500 mL. Additionally, we reported two cases of intraoral infection caused by M. abscessus and M. chelonae, where the source of infection was traced to NTM-contaminated DUWs. Conclusions: The study found that most DUWs contained water contaminated with NTM, posing a potential health risk to humans. This research underscores the necessity of stringent quality control and certification of DUW water, with particular emphasis on ensuring the absence of NTM. © 2024 Elsevier Ltd
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