Operational Factors Influencing Occurrence and Risk Exposure to Pseudomonas Aeruginosa and Legionella Pneumophila from Hospital Water Systems

RÉSUMÉ La qualité microbienne de l'eau potable peut être altérée dans la plomberie interne de grands bâtiments. Les bactéries opportunistes telles que Legionella pneumophila et Pseudomonas aeruginosa sont présentes et même amplifiées dans les systèmes internes de distribution d'eau et peuvent représenter un risque pour la santé aux points d’utilisation (robinets, pomme de douche, etc.). La formation du biofilm, la stagnation périodique, les rapports surface-volume élevés ainsi que des plages de températures variables sont des facteurs caractéristiques des réseaux de plomberie interne pouvant favoriser la croissance bactérienne. L. pneumophila est une bactérie souvent associée aux systèmes de distribution d'eau chaude. Dans les établissements de santé, plusieurs pays prônent une bonne gestion de la température de l’eau afin de prévenir la prolifération des légionelles dans les réseaux de distribution d’eau. P. aeruginosa est à l’origine de plusieurs épidémies en milieu hospitalier, souvent directement ou indirectement liées au système d'eau. P. aeruginosa est principalement détecté dans les échantillons d'eau froide au robinet et dans le biofilm de l’aérateur, du robinet ou du drain. Ces deux bactéries opportunistes peuvent demeurer dans le système d’eau pour de longues périodes et sont difficiles à éradiquer une fois la contamination établie.----------ABSTRACT Microbial quality of drinking water can be altered in the premise plumbing of large buildings. Opportunistic pathogens such as Legionella pneumophila and Pseudomonas aeruginosa are present and even amplified in the water distribution system of large buildings and represent a health risk at points-of-use (taps, shower head, etc). Biofilm formation, periodical stagnation, high surface-to-volume ratios, and favorable temperatures are characteristics of the premise plumbing system that can promote bacterial growth. Legionella pneumophila is frequently detected in hot water distribution systems and thermal control is a common measure implemented by healthcare facilities. Pseudomonas aeruginosa is a source of outbreaks, especially in intensive care units (ICU) and several of these outbreaks have been directly or indirectly linked to water systems. P. aeruginosa is primarily detected in cold water and faucet biofilm samples, specifically at the distal end of the water system. Both of these opportunistic pathogens can persist for prolonged periods of time once contamination is established

Géologie et géochimie des massifs ophiolitiques de Saga et Sangsang de la zone de suture du Yarlung Zangbo, Tibet

Les ophiolites de Saga et de Sangsang affleurent à l'ouest de la portion centrale de la ceinture ophiolitique de la Zone de Suture du Yarlung Zangbo (ZSYZ) au Tibet. Ces massifs semblent appartenir à un segment de zone de suprasubduction océanique tel que postulé pour les autres ophiolites de la portion Est de la ZSYZ. La chimie des roches mantelliques de ces deux massifs est toutefois très contrastée l'une de l'autre (fertile vs. réfractaire) et aussi lorsque comparée aux autres ophiolites de la ZSYZ, suggérant des histoires pétrogénétiques distinctes. Les relations de terrain et la géochimie indiquent que les ophiolites de Saga et de Sangsang ont été formées dans une configuration complexe arc - bassin arrière-arc où au moins deux plans de subduction intra-océaniques ont été actifs. Ces résultats permettent de mieux comprendre la morphologie de la zone de convergence avant les épisodes de collision qui ont mené à la configuration actuelle de la zone de suture

Tourmaline, scheelite, and magnetite compositions from orogenic gold deposits and glacial sediments of the Val-d’Or district (Québec, Canada) : applications to mineral exploration

Tourmaline, scheelite, and magnetite from orogenic gold deposits (n = 22) and glacial sediments (n = 5) of the Val-d'Or mining district (Québec, Canada) were investigated by Electron Probe Micro-Analyzer (EPMA) and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) in order to determine their chemical signature and to assess their potential as indicator minerals for gold exploration. Three types of tourmaline are recognized. Type I tourmaline from deposits hosted in felsic and intermediate-composition calc-alkaline rocks has low contents of V, Cr, Mn, Fe, Co, Ni, Zn, and Sn and a high content of Mg compared to Type II tourmaline from deposits hosted in mafic tholeiitic rocks. Type III tourmaline from deposits located at the contact between mafic metavolcanic and metasedimentary rocks shows a chemistry similar to Type I tourmaline with slightly higher Li, Mn, and Pb contents. Tourmaline from orogenic gold deposits is characterized by lower contents of Zn, Cu, Sn, and Pb compared to data from tourmaline associated with Cu-Zn, Pb-Zn-Cu, and Sn mineralization. Till tourmaline carries the chemical signature of that from orogenic gold deposits with a majority having the signature of Type I tourmaline. Orogenic gold deposits scheelite from the Val-d'Or district hosted in calc-alkaline intrusions of intermediate composition displays high Na, REE, and Y contents compared to scheelite from sediment- and mafic-hosted gold deposits. Till scheelite carries the chemical signature of that from orogenic gold deposits. Although rare in orogenic gold deposits of the Val-d'Or district, hydrothermal magnetite in the gold veins is characterized by higher Cr, Zn, Mn, K, Ca, Ti, and Al than magmatic magnetite found in dioritic and gabbroic host rocks. Magnetite associated with gold mineralization forms fine, disseminated grains, suggesting that the coarse-grained magnetite recovered in till does not originate from the gold veins. Till tourmaline and scheelite carry the signature of the orogenic gold deposits and can thus be used for exploration in overburden sediments

Pseudomonas aeruginosa in premise plumbing of large buildings

Pseudomonas aeruginosa is an opportunistic bacterial pathogen that is widely occurring in the environment and is recognized for its capacity to form or join biofilms. The present review consolidates current knowledge on P.aeruginosa ecology and its implication in healthcare facilities premise plumbing. The adaptability of P.aeruginosa and its capacity to integrate the biofilm from the faucet and the drain highlight the role premise plumbing devices can play in promoting growth and persistence. A meta-analysis of P.aeruginosa prevalence in faucets (manual and electronic) and drains reveals the large variation in device positivity reported and suggest the high variability in the sampling approach and context as the main reason for this variation. The effects of the operating conditions that prevail within water distribution systems (disinfection, temperature, and hydraulic regime) on the persistence of P.aeruginosa are summarized. As a result from the review, recommendations for proactive control measures of water contamination by P.aeruginosa are presented. A better understanding of the ecology of P.aeruginosa and key influencing factors in premise plumbing are essential to identify culprit areas and implement effective control measures

Recommandations pratiques pour l’élaboration d’un circuit d’exercices en communauté visant le maintien de l’autonomie des personnes âgées vivant à domicile

Travail d’intégration présenté en vue de l’obtention du grade de maîtrise en physiothérapieIntroduction/problématique : Au Québec, 96% des personnes âgées (PÂs) de plus de 65 ans vivent à domicile. Parmi celles-ci, 57% présentent des incapacités légères à modérées en lien avec la mobilité. Pour promouvoir leur santé et maintien à domicile, les PÂs doivent demeurer actives. Plusieurs programmes en communauté sont offerts pour améliorer ou maintenir leur santé physique. Toutefois, peu de projets prennent en considération les aspects autant cognitifs que physiques ainsi que le processus d’implantation d’un programme d’exercices en communauté. Objectif : Établir des recommandations pratiques pour un programme complet d’entraînement en communauté pour les PÂs autonomes. Méthodologie : Effectuer une revue narrative de la littérature sur l’implantation des circuits d’exercices en communauté et l’entraînement physique et cognitif. Résultats : Pour élaborer un circuit d’exercices visant les PÂs autonomes, il est recommandé d’impliquer la communauté dans son développement et de privilégier un entraînement multimodal incluant des composantes cardiovasculaires, musculaires, d’équilibre et de flexibilité. Ces exercices doivent viser le maintien de l’autonomie et des fonctions cognitives. Conclusion : Un circuit en communauté est pertinent pour augmenter le niveau d’activité physique des PÂs. Les différentes dimensions abordées dans cette revue narrative de la littérature devront être considérées lors de sa création, son implantation et son suivi

Comparison of aerosol spectrometers: Accounting for evaporation and sampling losses

ABSTRACT: Measuring aerosol size distribution with precision is critical to understand the transmission of pathogens causing respiratory illnesses and to identify risk mitigation strategies. It is however a challenging task as the size of pathogen-carrying particles evolves over time due to evaporation. Although measurement techniques well established in the field of aerosol science are often used to characterize bioaerosols, their performance is seldom assessed with respect to evaporation and deposition in sampling lines. Four instruments providing aerosol size distribution were compared using oil and water-based particles. They each rely on different measurement principles: phase doppler anemometry, light scattering, electrical mobility and aerodynamic impaction. Size distributions of oil-based particles showed consistency across different measurement instruments, but significant discrepancies arose for water-based particles undergoing evaporation. These larger differences result from both evaporation and particle deposition in transit between the sampling point and the measurement inside the instrument. Phase doppler anemometry was best suited for precise size distribution measurement, as it eliminates the need for a sampling line, thereby preventing particle loss or evaporation during transit. With this instrument as a reference, empirical correction factors for evaporation and deposition were derived from dimensionless numbers and experimental data, enabling quantitative assessment of bioaerosol size distribution using different instruments. To obtain the size distribution at the source of the aerosol generation, complete drying of a salt solution was performed. Using the complete drying technique and accounting for losses, sampling instruments can reliably provide this critical information and allow for thorough risk assessment in the context of airborne transmission

Hospital drains as reservoirs of Pseudomonas aeruginosa: Multiple-locus variable-number of tandem repeats analysis genotypes recovered from faucets, sink surfaces and patients

Identifying environmental sources of Pseudomonas aeruginosa (Pa) related to hospital-acquired infections represents a key challenge for public health. Biofilms in water systems offer protection and favorable growth conditions, and are prime reservoirs of microorganisms. A comparative genotyping survey assessing the relationship between Pa strains recovered in hospital sink biofilm and isolated in clinical specimens was conducted. Environmental strains from drain, faucet and sink-surface biofilm were recovered by a culture method after an incubation time ranging from 48 to 240 h. The genotyping of 38 environmental and 32 clinical isolates was performed using a multiple-locus variable-number of tandem repeats analysis (MLVA). More than one-third of Pa isolates were only cultivable following >/=48 h of incubation, and were predominantly from faucet and sink-surface biofilms. In total, 41/70 strains were grouped within eight genotypes (A to H). Genotype B grouped a clinical and an environmental strain isolated in the same ward, 5 months apart, suggesting this genotype could thrive in both contexts. Genotype E grouped environmental isolates that were highly prevalent throughout the hospital and that required a longer incubation time. The results from the multi-hospital follow-up study support the drain as an important reservoir of Pa dissemination to faucets, sink surfaces and patients. Optimizing the recovery of environmental strains will strengthen epidemiological investigations, facilitate pathway identification, and assist in identifying and controlling the reservoirs potentially associated to hospital-acquired infections

High-throughput short sequence typing schemes for pseudomonas aeruginosa and stenotrophomonas maltophilia pure culture and environmental DNA

ABSTRACT: Molecular typing techniques are utilized to determine genetic similarities between bacterial isolates. However, the use of environmental DNA profiling to assess epidemiologic links between patients and their environment has not been fully explored. This work reports the development and validation of two high-throughput short sequence typing (HiSST) schemes targeting the opportunistic pathogens Pseudomonas aeruginosa and Stenotrophomonas maltophilia, along with a modified SM2I selective medium for the specific isolation of S. maltophilia. These HiSST schemes are based on four discriminative loci for each species and demonstrate high discriminating power, comparable to pairwise whole-genome comparisons. Each scheme includes species-specific PCR primers for precise differentiation from closely related taxa, without the need for upstream culture-dependent methods. For example, the primers targeting the bvgS locus make it possible to distinguish P. aeruginosa from the very closely related Pseudomonas paraeruginosa sp. nov. The selected loci included in the schemes are adapted to massive parallel amplicon sequencing technology. An R-based script implemented in the DADA2 pipeline was assembled to facilitate HiSST analyses for efficient and accurate genotyping of P. aeruginosa and S. maltophilia. We demonstrate the performance of both schemes through in silico validations, assessments against reference culture collections, and a case study involving environmental samples

Combination of heat shock and enhanced thermal regime to control the growth of a persistent Legionella pneumophila strain

Following nosocomial cases of Legionella pneumophila, the investigation of a hot water system revealed that 81.5% of sampled taps were positive for L. pneumophila, despite the presence of protective levels of copper in the water. A significant reduction of L. pneumophila counts was observed by culture after heat shock disinfection. The following corrective measures were implemented to control L. pneumophila: increasing the hot water temperature (55 to 60 degrees C), flushing taps weekly with hot water, removing excess lengths of piping and maintaining a water temperature of 55 degrees C throughout the system. A gradual reduction in L. pneumophila counts was observed using the culture method and qPCR in the 18 months after implementation of the corrective measures. However, low level contamination was retained in areas with hydraulic deficiencies, highlighting the importance of maintaining a good thermal regime at all points within the system to control the population of L. pneumophila