1
|
Sanchis M, Inza I, Figueras MJ. Heterotrophic Plate Count Can Predict the Presence of Legionella spp. in Cooling Towers. Pathogens 2023; 12:466. [PMID: 36986388 PMCID: PMC10059076 DOI: 10.3390/pathogens12030466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 03/10/2023] [Accepted: 03/13/2023] [Indexed: 03/18/2023] Open
Abstract
Legionella pneumophila (Lp) colonizes aquatic environments and is a potential pathogen to humans, causing outbreaks of Legionnaire’s disease. It is mainly associated with contaminated cooling towers (CTs). Several regulations, including Spanish legislation (Sl), have introduced the analysis of heterotrophic plate count (HPC) bacteria and Legionella spp. (Lsp) in management plans to prevent and control Legionella outbreaks from CTs. The 2003 Sl for CTs (RD 865/2003) considered that concentrations of HPC bacteria ≤10,000 cfu/mL and of Lsp ≤100 cfu/L are safe; therefore, no action is required, whereas management actions should be implemented above these standards. We have investigated to what extent the proposed standard for HPC bacteria is useful to predict the presence of Lsp in cooling waters. For this, we analyzed Lsp and HPC concentrations, water temperature, and the levels of chlorine in 1376 water samples from 17 CTs. The results showed that in the 1138 water samples negative for Legionella spp. (LN), the HPC geometric mean was significantly lower (83 cfu/mL, p < 0.05) than in the positive Lsp. samples (135 cfu/mL). Of the 238 (17.3%) LP samples, 88.4% (210/238) were associated with values of HPC ≤10,000 cfu/mL and most of them showed HPC concentrations ≤100 (53.7%). In addition, a relatively low percentage of LP (28/238, 11.6%) samples were associated with HPC bacteria concentrations >10,000 cfu/mL, indicating that this standard does not predict the colonization risk for Legionella in the CTs studied. The present study has demonstrated that a threshold concentration ≤100 cfu/mL of HPC bacteria could better predict the higher concentration of Legionella in CTs, which will aid in preventing possible outbreaks.
Collapse
|
2
|
Dang Y, Zhang Q, Wang J, Wang Q, Han M, Niu Y, Li H, Li X. Assessment of microbiota diversity in dental unit waterline contamination. PeerJ 2022; 10:e12723. [PMID: 35036099 PMCID: PMC8743008 DOI: 10.7717/peerj.12723] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 12/10/2021] [Indexed: 01/07/2023] Open
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.
Collapse
Affiliation(s)
- Yun Dang
- Department of Nursing, School of Stomatology, Peking University, Beijing, China
| | - Qian Zhang
- Central Laboratory, School of Stomatology, Peking University, Beijing, China
| | - Jing Wang
- Department of Preventive Dentistry, School of Stomatology, Peking University, Beijing, China
| | - Qian Wang
- Department of Nursing, School of Stomatology, Peking University, Beijing, China
| | - Meng Han
- The Fourth Outpatient Department, School of Stomatology, Peking University, Beijing, China
| | - Yuting Niu
- Department of Pediatric Dentistry, School of Stomatology, Peking University, Beijing, China
| | - Hua Li
- Department of Nursing, School of Stomatology, Peking University, Beijing, China
| | - Xiue Li
- Department of Nursing, School of Stomatology, Peking University, Beijing, China
| |
Collapse
|
3
|
Hamilton KA, Kuppravalli A, Heida A, Joshi S, Haas CN, Verhougstraete M, Gerrity D. Legionnaires' disease in dental offices: Quantifying aerosol risks to dental workers and patients. J Occup Environ Hyg 2021; 18:378-393. [PMID: 34161202 DOI: 10.1080/15459624.2021.1939878] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Legionella pneumophila is an opportunistic bacterial respiratory pathogen that is one of the leading causes of drinking water outbreaks in the United States. Dental offices pose a potential risk for inhalation or aspiration of L. pneumophila due to the high surface area to volume ratio of dental unit water lines-a feature that is conducive to biofilm growth. This is coupled with the use of high-pressure water devices (e.g., ultrasonic scalers) that produce fine aerosols within the breathing zone. Prior research confirms that L. pneumophila occurs in dental unit water lines, but the associated human health risks have not been assessed. We aimed to: (1) synthesize the evidence for transmission and management of Legionnaires' disease in dental offices; (2) create a quantitative modeling framework for predicting associated L. pneumophila infection risk; and (3) highlight influential parameters and research gaps requiring further study. We reviewed outbreaks, management guidance, and exposure studies and used these data to parameterize a quantitative microbial risk assessment (QMRA) model for L. pneumophila in dental applications. Probabilities of infection for dental hygienists and patients were assessed on a per-exposure and annual basis. We also assessed the impact of varying ventilation rates and the use of personal protective equipment (PPE). Following an instrument purge (i.e., flush) and with a ventilation rate of 1.2 air changes per hour, the median per-exposure probability of infection for dental hygienists and patients exceeded a 1-in-10,000 infection risk benchmark. Per-exposure risks for workers during a purge and annual risks for workers wearing N95 masks did not exceed the benchmark. Increasing air change rates in the treatment room from 1.2 to 10 would achieve an ∼85% risk reduction, while utilization of N95 respirators would reduce risks by ∼95%. The concentration of L. pneumophila in dental unit water lines was a dominant parameter in the model and driver of risk. Future risk assessment efforts and refinement of microbiological control protocols would benefit from expanded occurrence datasets for L. pneumophila in dental applications.
Collapse
Affiliation(s)
- Kerry A Hamilton
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona
- The Biodesign Institute Center for Environmental Health Engineering, Arizona State University, Tempe, Arizona
| | - Aditya Kuppravalli
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona
- The Biodesign Institute Center for Environmental Health Engineering, Arizona State University, Tempe, Arizona
- BASIS Scottsdale High School, Scottsdale, Arizona
| | - Ashley Heida
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona
- The Biodesign Institute Center for Environmental Health Engineering, Arizona State University, Tempe, Arizona
| | - Sayalee Joshi
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona
- The Biodesign Institute Center for Environmental Health Engineering, Arizona State University, Tempe, Arizona
| | - Charles N Haas
- Department of Civil, Architectural, and Environmental Engineering, Drexel University, Philadelphia, Pennsylvania
| | - Marc Verhougstraete
- Mel and Enid Zuckerman College of Public Health, The University of Arizona, Tucson, Arizona
| | | |
Collapse
|
4
|
Otieno BO, Kihara EN, Mua BN. Infection Control Practices Among Private Practicing Dentists in Nairobi During the Pre-coronavirus Disease 2019 Period. Front Oral Health 2020; 1:587603. [PMID: 35047984 PMCID: PMC8757696 DOI: 10.3389/froh.2020.587603] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Accepted: 11/16/2020] [Indexed: 12/21/2022] Open
Abstract
Background: Cross-infection control is a dynamic field that requires frequent updates due to emerging diseases, advancement in technology, and scientific knowledge. Despite wide publication of guidelines, a laxity in compliance to the standard precautions for infection control by dental health-care personnel (DHCP) has been reported globally. Therefore, there is need to review previous shortcomings in order to adequately secure dental practices during the coronavirus disease 2019 (COVID-19) pandemic. The aim of the study was to determine knowledge and infection control practices by dentists in private practices. The study was done a few months before the first COVID-19 case was confirmed in Kenya. Materials and Methods: The study design was a descriptive cross-sectional study that was carried out in selected private dental clinics located in Nairobi. Data were collected using an interviewer-administered questionnaire. Convenience sampling method was utilized, while data were analyzed using SPSS 20.0.0.0. Results: A total of 71 private dentists participated in the study. Their mean age was 38 years with an age range of 27-55 years. Almost all (70, 98.6%) the dentists were able to define cross infection correctly. Majority (62, 87.3%) correctly differentiated between sterilization and disinfection, while 9 (12.7%) had difficulties. Most (68, 95.8%) of the respondents were aware of the standard precautions for cross-infection control. All participants used face masks and gloves. About half of them (38, 54%) practiced hand washing after removal of gloves and 31 (43.7%) before and after wearing of gloves, while 2 (2.8%) washed hands only before wearing gloves. Only 31 (42.3%) and 26 (36.6%) participants reported use of rubber dam isolation and impervious barrier, respectively. All the dentists reported disposal of sharps into especially labeled containers, while about half reported use of disposable suction traps and amalgam separators. Conclusion: The dentists had a good knowledge on various aspects of infection control measures that were studied. Use of basic personal protective equipment was widely practiced. There were irregularities in hand hygiene, use of rubber dam, surface barriers, and waste management. The work highlights that many dentists were unprepared to manage infectious risk during the COVID-19 outbreak, which justified the closure of the dental facilities. Development of strategies to promote adequate and safe practice is highly recommended.
Collapse
Affiliation(s)
- Benedict Odhiambo Otieno
- Department of Periodontology/Community and Preventive Dentistry, School of Dental Sciences, University of Nairobi, Nairobi, Kenya
| | - Eunice Njeri Kihara
- Department of Oral and Maxillofacial Surgery, Oral Pathology and Oral Medicine, School of Dental Sciences, University of Nairobi, Nairobi, Kenya
| | - Bernard Nzioka Mua
- Department of Periodontology/Community and Preventive Dentistry, School of Dental Sciences, University of Nairobi, Nairobi, Kenya
| |
Collapse
|
5
|
Munive-Degregori A, Mayta-Tovalino F, Gallo W, Luza S, Mauricio F, Ilizarbe S, Munive-Méndez A. Evaluation of Hydrogen Peroxide and Cetylpyridinium Chloride as Bacterial Decontaminants of Dental Unit Water Lines at a Private Peruvian Dental School. J Int Soc Prev Community Dent 2020; 10:731-735. [PMID: 33437706 PMCID: PMC7791582 DOI: 10.4103/jispcd.jispcd_265_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 06/27/2020] [Accepted: 07/09/2020] [Indexed: 12/03/2022] Open
Abstract
Aim: The aim of this study was to evaluate the hydrogen peroxide and cetylpyridinium chloride as bacterial decontaminants of dental unit water lines at a private Peruvian dental school. Materials and Methods: Water samples were obtained from 66 dental units of a University Dental Clinic before decontamination treatment and at days 3 and 7 thereafter. The biofilm treatments were applied equitably among the two treatment groups (n = 22) and one negative control (distilled water). The samples obtained on each collection day were taken to the biochemical laboratory in thermal boxes and then diluted, seeded, and incubated at 37°C for 24h to count colony forming units per milliliter (CFU/mL). Results: The samples to which hydrogen peroxide were applied had a mean of 1.53 × 105 CFU/mL before application, 0.04 × 105 CFU/mL at day 3, and 0.03 × 105 CFU/mL at day 7, whereas the samples undergoing cetylpyridinium chloride treatment had a mean of 1.74 × 105 CFU/mL before application, 615.38 CFU/mL on day 3, and 307.69 CFU/mL on day 7. Distilled water treatment showed a mean of 1.72 × 105 ± 0.39 × 105 CFU/mL at baseline, 1.51 × 105 ± 1.40 × 105 CFU/mL at day 3, and a mean of 1.74 × 105 ± 0.47 × 105 CFU/mL at day 7. Statistically significant differences were found among the three treatment groups at days 3 (P ≤ 0.001) and 7 (P ≤ 0.001) but not at baseline (P = 0.306). Conclusions: The antibacterial effect of cetylpyridinium chloride was significantly greater than that of hydrogen peroxide and distilled water, and can, therefore, be used for bacterial control in the water lines of dental units.
Collapse
Affiliation(s)
| | - Frank Mayta-Tovalino
- Postgraduate Department, Faculty of Health Sciences, Universidad Científica del Sur, Lima, Peru.,Academic Department of Rehabilitative Stomatology, Faculty of Dentistry, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - Walter Gallo
- Academic Department of Rehabilitative Stomatology, Faculty of Dentistry, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - Silvia Luza
- Academic Department of Rehabilitative Stomatology, Faculty of Dentistry, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - Franco Mauricio
- Doctorate Department, Faculty of Dentistry, Universidad Nacional Federico Villarreal, Lima, Peru
| | - Saul Ilizarbe
- Academic Department of Rehabilitative Stomatology, Faculty of Dentistry, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - Arnaldo Munive-Méndez
- Academic Department, School of Dentistry, Universidad Peruana de Ciencias Aplicadas, Lima, Peru
| |
Collapse
|
6
|
Ditommaso S, Giacomuzzi M, Memoli G, Garlasco J, Zotti CM. Persistence of Legionella in Routinely Disinfected Heater-Cooler Units and Heater Units assessed by Propidium Monoazide qPCR. Pathogens 2020; 9:E978. [PMID: 33238543 DOI: 10.3390/pathogens9110978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/20/2020] [Accepted: 11/21/2020] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Evidence to date indicates that heater-cooler units (HCUs) and heater units (HUs) can generate potentially infectious aerosols containing a range of opportunistic pathogens such as Mycobacterium chimaera, other non-tuberculous mycobacterial (NTM) species, Pseudomonas aeruginosa and Legionella spp. Our purpose was to determine the extent of Legionella contamination and total viable count (TVC) in HCUs and HUs and to analyze the relationship by water system design of devices of two different brands (LivaNova vs. Maquet). METHODS Legionella spp. were detected and quantified by our optimized PMA-qPCR protocol; TVCs were assessed according to ISO protocol 6222. Analyses were performed in the first sampling round and after six months of surveillance. RESULTS Overall, Legionella spp. was detected in 65.7% of devices. In the second sampling round, Legionella positivity rates were significantly lower in water samples from the Maquet devices compared to the LivaNova ones (27.3% vs. 61.5%). LivaNova HCUs also yielded more Legionella, and aquatic bacteria counts than Maquet in both first and second-round samples. CONCLUSIONS We recommend that all surgical patients and staff exposed to aerosols from thermoregulatory devices should be followed up for Legionella infection and that microbiological surveillance on such devices should be conducted regularly as precautionary principle.
Collapse
|
7
|
Ditommaso S, Giacomuzzi M, Ricciardi E, Memoli G, Zotti CM. Colonization by Pseudomonas aeruginosa of dental unit waterlines and its relationship with other bacteria: suggestions for microbiological monitoring. J Water Health 2019; 17:532-539. [PMID: 31313992 DOI: 10.2166/wh.2019.240] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Pseudomonas aeruginosa is an environmental bacterium, ubiquitous in aquatic habitats and water distribution systems, including dental unit waterlines (DUWLs). We investigated the prevalence of P. aeruginosa in DUWLs from private dental settings. We also analyzed the relationship between P. aeruginosa contamination and the presence of Legionella spp. and total viable count (TVC) in order to suggest a simple and inexpensive protocol to test the quality of water from DUWLs. We detected and quantified P. aeruginosa both by culture and by a PMA (propidium monoazide)-qPCR method. Overall, we detected P. aeruginosa in 17 samples using the PMA-qPCR and in 11 samples using the culture. All culture-positive samples were positive with the PMA-qPCR too, with an agreement between the two methods of 93% and a Cohen's kappa coefficient of κ = 0.747 (good concordance). Comparing results with results of our previous study, we noted that (a) P. aeruginosa was isolated only from DUWLs with high TVC and (b) five out of six Legionella-positive samples were negative for Pseudomonas spp. Our final suggestion is that the cleanliness of DUWLs should be assessed by TVC because it is a good indicator of the presence of pathogens such as Legionella spp. and P. aeruginosa.
Collapse
Affiliation(s)
- Savina Ditommaso
- Department of Public Health and Pediatrics, University of Turin, Piazza Polonia 94, 10126 Turin, Italy E-mail:
| | - Monica Giacomuzzi
- Department of Public Health and Pediatrics, University of Turin, Piazza Polonia 94, 10126 Turin, Italy E-mail:
| | - Elisa Ricciardi
- Department of Public Health and Pediatrics, University of Turin, Piazza Polonia 94, 10126 Turin, Italy E-mail:
| | - Gabriele Memoli
- Department of Public Health and Pediatrics, University of Turin, Piazza Polonia 94, 10126 Turin, Italy E-mail:
| | - Carla M Zotti
- Department of Public Health and Pediatrics, University of Turin, Piazza Polonia 94, 10126 Turin, Italy E-mail:
| |
Collapse
|
8
|
Lizzadro J, Mazzotta M, Girolamini L, Dormi A, Pellati T, Cristino S. Comparison between Two Types of Dental Unit Waterlines: How Evaluation of Microbiological Contamination Can Support Risk Containment. Int J Environ Res Public Health 2019; 16:E328. [PMID: 30682855 PMCID: PMC6388184 DOI: 10.3390/ijerph16030328] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/16/2019] [Accepted: 01/18/2019] [Indexed: 01/16/2023]
Abstract
Infection risk management in a dental unit waterline (DUWL) involves healthcare personnel and patients and is related to routine exposure to water and aerosols that may contain bacterial species. To improve water safety plans, maintenance, and sanitation procedures, analyses of heterotrophic plate counts (HPCs) at 36 °C, and two other microorganisms frequently associated with biofilms, Pseudomonas aeruginosa and Legionella spp., were performed in order to evaluate differences in microbiological contamination between two types of DUWLs: Type A, provided by a water tank, and Type B, directly connected to municipal water. The data showed that the water supply and water safety plan differentially influenced microbiological contamination: Type A DUWLs were more contaminated than Type B DUWLs for all microbiological parameters tested, with significant changes in the percentage of positive samples and contamination levels that were beyond the limits of standard guidelines. The results obtained show how the storage tank, the absence of anti-retraction valves, and the disinfection procedures performed are the main critical points of Type A DUWLs, which confirms that dental unit management (maintenance/sanitization) is often missed or not correctly applied by stakeholders, with an underestimation of the real risk of infection for patients and operators.
Collapse
Affiliation(s)
- Jessica Lizzadro
- Department of Biological, Geological, and Environmental Sciences, BiGeA, University of Bologna, via San Giacomo 12, 40126 Bologna, Italy.
| | - Marta Mazzotta
- Department of Biological, Geological, and Environmental Sciences, BiGeA, University of Bologna, via San Giacomo 12, 40126 Bologna, Italy.
| | - Luna Girolamini
- Department of Biological, Geological, and Environmental Sciences, BiGeA, University of Bologna, via San Giacomo 12, 40126 Bologna, Italy.
| | - Ada Dormi
- Department of Medical and Surgical Science, DIMEC, University of Bologna, via San Giacomo 12, 40126 Bologna, Italy.
| | - Tiziana Pellati
- GVM Care & Research, via Emaldi 10, 48124 Lugo di Ravenna, Italy.
| | - Sandra Cristino
- Department of Biological, Geological, and Environmental Sciences, BiGeA, University of Bologna, via San Giacomo 12, 40126 Bologna, Italy.
| |
Collapse
|
9
|
Bonetta S, Pignata C, Bonetta S, Meucci L, Giacosa D, Marino E, Gorrasi I, Gilli G, Carraro E. Effectiveness of a neutral electrolysed oxidising water (NEOW) device in reducing Legionella pneumophila in a water distribution system: A comparison between culture, qPCR and PMA-qPCR detection methods. Chemosphere 2018; 210:550-556. [PMID: 30029147 DOI: 10.1016/j.chemosphere.2018.07.053] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 07/09/2018] [Accepted: 07/10/2018] [Indexed: 05/22/2023]
Abstract
Disinfection of hot water systems is critical for reducing Legionnaires' disease in high-risk buildings. The use of neutral electrolysed oxidising water (NEOW) is a promising method for the control of microorganisms in hot water systems. However, full-scale evaluations of the efficacy of NEOW devices to control Legionella pneumophila are currently lacking. The aim of this study was to assess the effectiveness of a NEOW device in reducing L. pneumophila in a hotel water network. Water samples (n = 67) were collected from different sites of a hotel distribution system before and after the installation of the NEOW device at the 1st, 4th, 8th and 12th week. Detection of L. pneumophila was performed comparing culture, qPCR and PMA-qPCR methods. Total bacterial counts (22 °C and 37 °C), Pseudomonas spp. and physico-chemical parameters were also monitored. The NEOW treatment resulted in a reduction of the amount of L. pneumophila positive samples (-32%) and of the number of heavily contaminated points (>104 CFU/L and >103 CFU/L) (-100% and -96%, respectively). Treatment maintained L. pneumophila at low levels (<102 CFU/L), which do not require specific intervention measures. The effectiveness of the disinfection system was also confirmed by PMA-qPCR (p < 0.001). The use of PMA resulted in a signal decrease in almost all samples upon the disinfection treatment. The NEOW disinfection device appears to be a promising approach to reduce the colonisation of hot water systems by L. pneumophila; however, further investigations are needed to ascertain its efficiency over longer time periods.
Collapse
Affiliation(s)
- Sara Bonetta
- Department of Public Health and Pediatrics, University of Torino, Piazza Polonia 94, 10126, Torino, Italy.
| | - Cristina Pignata
- Department of Public Health and Pediatrics, University of Torino, Piazza Polonia 94, 10126, Torino, Italy
| | - Silvia Bonetta
- Department of Public Health and Pediatrics, University of Torino, Piazza Polonia 94, 10126, Torino, Italy
| | - Lorenza Meucci
- Società Metropolitana Acque Torino S.P.A, C.so XI Febbraio 14, 10152, Torino, Italy
| | - Donatella Giacosa
- Società Metropolitana Acque Torino S.P.A, C.so XI Febbraio 14, 10152, Torino, Italy
| | - Elena Marino
- Società Metropolitana Acque Torino S.P.A, C.so XI Febbraio 14, 10152, Torino, Italy
| | - Ilaria Gorrasi
- Department of Public Health and Pediatrics, University of Torino, Piazza Polonia 94, 10126, Torino, Italy
| | - Giorgio Gilli
- Department of Public Health and Pediatrics, University of Torino, Piazza Polonia 94, 10126, Torino, Italy
| | - Elisabetta Carraro
- Department of Public Health and Pediatrics, University of Torino, Piazza Polonia 94, 10126, Torino, Italy
| |
Collapse
|
10
|
Ditommaso S, Giacomuzzi M, Ricciardi E, Garbuio R, Zotti CM. The role of chemical products at low doses in preventing the proliferation of bacteria in dental unit waterlines: the ICX ® experience. J Water Health 2018; 16:150-158. [PMID: 29424728 DOI: 10.2166/wh.2017.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In this study we evaluated (1) the efficacy of a protocol that combines hydrogen peroxide (shock treatment) and ICX® tablets (continuous treatment) for the control of microbial contamination in dental unit water lines, and (2) the in vitro antimicrobial activity of ICX® tablets on collection and wild strains isolated from dental chair output waters. To assess the treatment effectiveness, the microbial load in the output water samples of three dental chairs were investigated: one control chair received only shock treatment. In vitro bactericidal activity was tested against Staphylococcus aureus and Pseudomonas aeruginosa. Data obtained from samples collected from chairs treated with ICX® and shock treatment and data from the control chair did not differ significantly on the basis of microbial load. In the in vitro study, the product was unable to kill Gram-negative bacteria. These results show that the continuous introduction of ICX® was not effective in maintaining low counts of the heterotrophic bacteria in the output water of dental devices, and shock treatment may be needed more frequently than monthly.
Collapse
Affiliation(s)
- Savina Ditommaso
- Department of Public Health and Pediatrics, University of Turin, Piazza Polonia 94, 10126 Turin, Italy E-mail:
| | - Monica Giacomuzzi
- Department of Public Health and Pediatrics, University of Turin, Piazza Polonia 94, 10126 Turin, Italy E-mail:
| | - Elisa Ricciardi
- Department of Public Health and Pediatrics, University of Turin, Piazza Polonia 94, 10126 Turin, Italy E-mail:
| | - Roberto Garbuio
- Freelance Dentist, Piazza Campidoglio 2, 10036 Settimo Torinese, Italy
| | - Carla M Zotti
- Department of Public Health and Pediatrics, University of Turin, Piazza Polonia 94, 10126 Turin, Italy E-mail:
| |
Collapse
|
11
|
Bonetta S, Pignata C, Bonetta S, Meucci L, Giacosa D, Marino E, Gilli G, Carraro E. Viability of Legionella pneumophila in Water Samples: A Comparison of Propidium Monoazide (PMA) Treatment on Membrane Filters and in Liquid. Int J Environ Res Public Health 2017; 14:ijerph14050467. [PMID: 28448459 PMCID: PMC5451918 DOI: 10.3390/ijerph14050467] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 04/18/2017] [Accepted: 04/20/2017] [Indexed: 11/16/2022]
Abstract
Legionella pneumophila is a ubiquitous microorganism widely distributed in aquatic environments and can cause Legionellosis in humans. A promising approach to detect viable cells in water samples involves the use of quantitative polymerase chain reaction (qPCR) in combination with photoactivatable DNA intercalator propidium monoazide (PMA). However, the PMA efficiency could be different depending on the experimental conditions used. The aim of this study was to compare two PMA exposure protocols: (A) directly on the membrane filter or (B) in liquid after filter washing. The overall PMA-induced qPCR means reductions in heat-killed L. pneumophila cells were 2.42 and 1.91 log units for exposure protocols A and B, respectively. A comparison between the results obtained reveals that filter exposure allows a higher PMA-qPCR signal reduction to be reached, mainly at low concentrations (p < 0.05). This confirms the potential use of this method to quantify L. pneumophila in water with low contamination.
Collapse
Affiliation(s)
- Sara Bonetta
- Department of Public Health and Pediatrics, University of Torino, P.zza Polonia 94, 10126 Torino, Italy.
| | - Cristina Pignata
- Department of Public Health and Pediatrics, University of Torino, P.zza Polonia 94, 10126 Torino, Italy.
| | - Silvia Bonetta
- Department of Public Health and Pediatrics, University of Torino, P.zza Polonia 94, 10126 Torino, Italy.
| | - Lorenza Meucci
- Società Metropolitana Acque Torino S.p.A., C.so XI Febbraio, 14, 10152 Torino, Italy.
| | - Donatella Giacosa
- Società Metropolitana Acque Torino S.p.A., C.so XI Febbraio, 14, 10152 Torino, Italy.
| | - Elena Marino
- Società Metropolitana Acque Torino S.p.A., C.so XI Febbraio, 14, 10152 Torino, Italy.
| | - Giorgio Gilli
- Department of Public Health and Pediatrics, University of Torino, P.zza Polonia 94, 10126 Torino, Italy.
| | - Elisabetta Carraro
- Department of Public Health and Pediatrics, University of Torino, P.zza Polonia 94, 10126 Torino, Italy.
| |
Collapse
|
12
|
Kevorkyan A, Tomova I, Raycheva R, Stoeva V, Stoilova Y, Lalabonova H, Kondeva V. Legionella pneumophila antibodies in serum samples from medical and dental personnel: a seroepidemiological survey. BIOTECHNOL BIOTEC EQ 2017. [DOI: 10.1080/13102818.2017.1290549] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Affiliation(s)
- A. Kevorkyan
- Department of Epidemiology and Disaster Medicine, Medical University Plovdiv, Plovdiv, Bulgaria
| | - I. Tomova
- National Reference Laboratory High Medical Risk Infections, National Center of Infectious and Parasitic Diseases (NCIPD), Sofia, Bugaria
| | - R. Raycheva
- Department of Social Medicine and Public Health, Medical University Plovdiv, Plovdiv, Bulgaria
| | - V. Stoeva
- Department of Epidemiology and Disaster Medicine, Medical University Plovdiv, Plovdiv, Bulgaria
| | - Y. Stoilova
- Department of Epidemiology and Disaster Medicine, Medical University Plovdiv, Plovdiv, Bulgaria
| | - H. Lalabonova
- Department of Maxillofacial Surgery, Medical University Plovdiv, Plovdiv, Bulgaria
| | - V. Kondeva
- Department of Pediatric Dentistry, Medical University Plovdiv, Plovdiv, Bulgaria
| |
Collapse
|
13
|
Lal S, Pearce M, Achilles-Day UEM, Day JG, Morton LHG, Crean SJ, Singhrao SK. Developing an ecologically relevant heterogeneous biofilm model for dental-unit waterlines. Biofouling 2017; 33:75-87. [PMID: 27928939 DOI: 10.1080/08927014.2016.1260710] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 11/03/2016] [Indexed: 06/06/2023]
Abstract
This study monitored the biodiversity of microbes cultured from a heterogeneous biofilm which had formed on the lumen of a section of dental waterline tubing over a period of 910 days. By day 2 bacterial counts on the outlet-water showed that contamination of the system had occurred. After 14 days, a biofilm comparable to that of clinical waterlines, consisting of bacteria, fungi and amoebae had formed. This showed that the proprietary silver coating applied to the luminal surface of the commercial waterline tubing failed to prevent biofilm formation. Molecular barcoding of isolated culturable microorganisms showed some degree of the diversity of taxa in the biofilm, including the opportunistic pathogen Legionella pneumophila. Whilst the system used for isolation and identification of contaminating microorganisms may underestimate the diversity of organisms in the biofilm, their similarity to those found in the clinical environment makes this a promising test-bed for future biocide testing.
Collapse
Affiliation(s)
- Sham Lal
- a Oral & Dental Sciences Research Group , College of Clinical and Biomedical Sciences, University of Central Lancashire , Preston , UK
- b Department of Microbiology , Shah Abdul Latif University , Khairpur , Pakistan
| | - Mark Pearce
- a Oral & Dental Sciences Research Group , College of Clinical and Biomedical Sciences, University of Central Lancashire , Preston , UK
| | | | - John G Day
- d Culture Collection of Algae and Protozoa , The Scottish Association for Marine Science (SAMS) , Oban , UK
| | - L H Glyn Morton
- a Oral & Dental Sciences Research Group , College of Clinical and Biomedical Sciences, University of Central Lancashire , Preston , UK
| | - St John Crean
- a Oral & Dental Sciences Research Group , College of Clinical and Biomedical Sciences, University of Central Lancashire , Preston , UK
| | - Sim K Singhrao
- a Oral & Dental Sciences Research Group , College of Clinical and Biomedical Sciences, University of Central Lancashire , Preston , UK
| |
Collapse
|
14
|
Ditommaso S, Giacomuzzi M, Ricciardi E, Zotti CM. Efficacy of a Low Dose of Hydrogen Peroxide (Peroxy Ag⁺) for Continuous Treatment of Dental Unit Water Lines: Challenge Test with Legionella pneumophila Serogroup 1 in a Simulated Dental Unit Waterline. Int J Environ Res Public Health 2016; 13:E745. [PMID: 27455299 PMCID: PMC4962286 DOI: 10.3390/ijerph13070745] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 07/11/2016] [Accepted: 07/19/2016] [Indexed: 11/29/2022]
Abstract
This study was designed to examine the in vitro bactericidal activity of hydrogen peroxide against Legionella. We tested hydrogen peroxide (Peroxy Ag⁺) at 600 ppm to evaluate Legionella survival in a simulated dental treatment water system equipped with Water Hygienization Equipment (W.H.E.) device that was artificially contaminated. When Legionella pneumophila serogroup (sg) 1 was exposed to Peroxy Ag⁺ for 60 min we obtained a two decimal log reduction. High antimicrobial efficacy was obtained with extended periods of exposure: four decimal log reduction at 75 min and five decimal log reduction at 15 h of exposure. Involving a simulation device (Peroxy Ag⁺ is flushed into the simulation dental unit waterlines (DUWL)) we obtained an average reduction of 85% of Legionella load. The product is effective in reducing the number of Legionella cells after 75 min of contact time (99.997%) in the simulator device under test conditions. The Peroxy Ag⁺ treatment is safe for continuous use in the dental water supply system (i.e., it is safe for patient contact), so it could be used as a preventive option, and it may be useful in long-term treatments, alone or coupled with a daily or periodic shock treatment.
Collapse
Affiliation(s)
- Savina Ditommaso
- Department of Public Health and Pediatrics, University of Turin, Turin 10126, Italy.
| | - Monica Giacomuzzi
- Department of Public Health and Pediatrics, University of Turin, Turin 10126, Italy.
| | - Elisa Ricciardi
- Department of Public Health and Pediatrics, University of Turin, Turin 10126, Italy.
| | - Carla M Zotti
- Department of Public Health and Pediatrics, University of Turin, Turin 10126, Italy.
| |
Collapse
|