4 results
Implementation of a Low-Cost Method to Reduce Bacterial Load in Patient-Room Sink Drains
- Emilie Bédard, Marie-Ève Benoit, Thibault Bourdin, Dominique Charron, Gaëlle DeLisle, Stéphane Daraiche, Sophie Gravel, Etienne Robert, Philippe Constant, Eric Déziel, Caroline Quach, Michèle Prévost
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- Journal:
- Antimicrobial Stewardship & Healthcare Epidemiology / Volume 1 / Issue S1 / July 2021
- Published online by Cambridge University Press:
- 29 July 2021, pp. s21-s22
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Background: Sink drains can act as breeding grounds for multidrug-resistant (MDR) bacteria, leading to outbreaks. Drains provide a protected humid environment where nutrient-rich substances are available. Recent and growing installation of water and energy conservation devices have led to increased frequency of drain blockage due to biofilm accumulation. Ineffective drainage may lead to backflow and accumulation of water in the sink during use, increasing the risk of contaminated aerosols formation or direct contamination of surrounding material and equipment. Cleaning and disinfection procedures of sink drains need to be improved to prevent amplification and dispersion of MDR bacteria. The objective of this study was to investigate alternatives to reduce the biofilm and risk of contamination through aerosols. Methods: Sink drains from patient rooms were randomly selected in the neonatal intensive care unit of a 450-bed pediatric hospital. We tested 4 approaches: (1) new drain; (2) self-disinfecting heating-vibration drain; (3) chemical disinfection with 20 ppm chlorine for 30 minutes; and (4) thermal disinfection with > 90°C water for 30 minutes. A special device was used during disinfection to increase the disinfectant contact time with the biofilm. Treatments were conducted weekly, with prior sampling of drain water. Other drains were also sampled weekly, including a control drain with no intervention. Bacterial loads were evaluated using flow cytometry and heterotrophic plate counts. The drains were made of stainless steel, a heat-conductive material. Results: Preliminary results show that chlorine disinfection had a small impact (<1 log) on culturable bacteria at 48 hours after disinfection but not after a week or repeated weekly disinfection. Thermal disinfection using boiling water is promising, showing an important decrease of 4 log in culturable cells after 48 hours and a concentration still 100× lower 1 week after the disinfection. Repeated weekly thermal disinfection maintained lower culturable levels in the drain. No culturable cells were detected in water from the self-disinfecting drain 2 months after installation, whereas the new drain became fully colonized to concentrations similar to those of drains prior to interventions during the same period. Conclusions: Thermal disinfection of drains is a promising alternative to chlorine. This solution is interesting because it is nontoxic and easy to perform, requiring a small volume of hot water. The rapid recolonization of the new drain suggests that replacing contaminated drains is not a sustainable solution and would need to be paired with a thermal disinfection program to maintain low culturable cells.
Funding: No
Disclosures: None
Development of a New High-Throughput Multilocus Sequence Typing Method to Monitor Causative Agents of Nosocomial Infections
- Thibault Bourdin, Emilie Bedard, Marie-Ève Benoit, Michèle Prévost, Etienne Robert, Caroline Quach, Eric Déziel, Philippe Constant
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- Journal:
- Infection Control & Hospital Epidemiology / Volume 41 / Issue S1 / October 2020
- Published online by Cambridge University Press:
- 02 November 2020, p. s187
- Print publication:
- October 2020
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Background: Nosocomial infections cause 4%–56% mortality in newborns. Several epidemiological studies have shown that transmission of opportunistic pathogens from the sink to the patient, including Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Serratia marcescens are associated with nosocomial infections in neonatal intensive care units (NICUs). In this project, we aimed to develop fast, accurate, and high-throughput multilocus sequence typing assays (HiMLST-Illumina) to detect opportunistic pathogens to assess their distribution in the sink environment of NICUs and their transfer to patients. Methods: Genome sequences of P. aeruginosa (n = 45), S. maltophilia (n = 23) and S. marcescens (n = 34) strains were retrieved from public genome databases to build their pangenomes, using the open-source PGAdb-builder server. The core genome was identified for each opportunistic pathogen and was searched for genes displaying the highest polymorphism. The minimal number of loci to include in a HiMLST-Illumina assay was determined by comparing topology of phylogenetic trees of concatenated loci based on genome similarity, computed as the average nucleotide identity (ANI) score. The primers used for HiMLST-Illumina schemes were designed in silico on a conserved domain and were tested on reference strains of each species. Results: Bioinformatics analyses showed that 3–4 loci (<300 base pairs per locus) distinguished strains with the same performances than ANI scores. The assays were tested using opportunistic pathogen isolates and environmental DNA originating from NICU sinks. The HiMLST-Illumina analysis of environmental DNA revealed the presence of at least 1 of the 3 studied opportunistic pathogens in 50% of sampled drains (n = 20). In a previous sampling, P. aeruginosa was isolated on selective culture media before and 48 hours after disinfection of a sink drain with chlorine. S. marcescens was also isolated from another sink 2 weeks after disinfection. Identification of the isolates was confirmed by HiMLST-Illumina analyses and will be typed to compare with clinical isolates. Conclusions: Initial in silico tests predict a high discriminating power of the HiMLST-Illumina method, suggesting that it would be possible to quickly identify strains of interest in a large number of samples. The power of this method is also in the possibility for molecular typing without a need for cultivation. Preliminary results suggest that sinks are readily colonized by opportunistic pathogens. This HiMLST-Illumina scheme will be applied in a 2-year intensive survey of NICUs in 3 hospitals in Montreal to evaluate the performance of new sink designs in limiting bioaerosol production and transmission of opportunistic pathogens to patients.
Funding: None
Disclosures: None
Post-Outbreak Investigation of Pseudomonas aeruginosa Faucet Contamination by Quantitative Polymerase Chain Reaction and Environmental Factors Affecting Positivity
- Emilie Bédard, Céline Laferrière, Dominique Charron, Cindy Lalancette, Christian Renaud, Nadia Desmarais, Eric Déziel, Michèle Prévost
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- Journal:
- Infection Control & Hospital Epidemiology / Volume 36 / Issue 11 / November 2015
- Published online by Cambridge University Press:
- 20 July 2015, pp. 1337-1343
- Print publication:
- November 2015
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OBJECTIVE
To perform a post-outbreak prospective study of the Pseudomonas aeruginosa contamination at the faucets (water, aerator and drain) by culture and quantitative polymerase chain reaction (qPCR) and to assess environmental factors influencing occurrence
SETTINGA 450-bed pediatric university hospital in Montreal, Canada
METHODSWater, aerator swab, and drain swab samples were collected from faucets and analyzed by culture and qPCR for the post-outbreak investigation. Water microbial and physicochemical parameters were measured, and a detailed characterization of the sink environmental and design parameters was performed.
RESULTSThe outbreak genotyping investigation identified drains and aerators as the source of infection. The implementation of corrective measures was effective, but post-outbreak sampling using qPCR revealed 50% positivity for P. aeruginosa remaining in the water compared with 7% by culture. P. aeruginosa was recovered in the water, the aerator, and the drain in 21% of sinks. Drain alignment vs the faucet and water microbial quality were significant factors associated with water positivity, whereas P. aeruginosa load in the water was an average of 2 log higher for faucets with a positive aerator.
CONCLUSIONSP. aeruginosa contamination in various components of sink environments was still detected several years after the resolution of an outbreak in a pediatric university hospital. Although contamination is often not detectable in water samples by culture, P. aeruginosa is present and can recover its culturability under favorable conditions. The importance of having clear maintenance protocols for water systems, including the drainage components, is highlighted.
Infect. Control Hosp. Epidemiol. 2015;36(11):1283–1291
8 - Phase variation and antigenic variation
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- By Richard Villemur, INRS-Institut, Eric Déziel, INRS-Institut
- Edited by Peter Mullany, University College London
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- Book:
- The Dynamic Bacterial Genome
- Published online:
- 06 August 2009
- Print publication:
- 26 September 2005, pp 277-322
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Summary
Bacteria owe their ability to thrive in diverse and ever-changing conditions to their extraordinary faculty of adaptation. They have developed many strategies to adjust to new environments. These mechanisms include random modifications within their genome, such as point mutation, duplication, deletion, insertion, and acquisition of new DNA (e.g., lateral gene transfer). These multiple events generate a heterogeneous microbial population containing numerous novel phenotypes. Whenever the environment changes, a subpopulation more apt to survive in these new conditions emerges, thus allowing bacteria to thrive, for example, by acquiring resistance to antibiotics. However, as the intensity, duration, and nature of stress are extremely variable, the optimal response to new environmental conditions may be unpredictable. The means by which bacteria either respond to stress, such as exposure to toxic/inhibitory compounds or starvation, or avoid detection by the host's immune system are crucial for their survival. The spontaneous mutation rate is usually insufficient for allowing an efficient adaptation to these changes. However, certain bacterial populations contain hypermutator strains exhibiting highly increased rates of spontaneous mutations, therefore promoting adaptation to changing environments (Taddei et al., 1997). Nevertheless, this benefit may disappear once adaptation is achieved because the evolved genotype may have accumulated irreversible mutations that are detrimental in other conditions (Giraud et al., 2001a, 2001b).
Alternatively, bacteria have developed adaptation strategies based on DNA rearrangement events restricted to specific genomic regions. These defined loci allow bacteria to generate an array of phenotypic variants, whereas minimizing detrimental effects of random mutations on fitness.