Hospital Water Systems Research Articles

Molecular Identification of Free-living Amoebae Isolated from Hospital Water Systems in Southwest Iran.

Free-living amoebae are opportunistic amoebae that usually live freely in various environmental conditions, including warm water and even in water supply network pipes and reservoirs connected to water. In addition to living freely, these protozoa are able to attack the host's body when they enter a human or animal body. Therefore, it is necessary to identify their presence in water resources. So, this study aimed to identify free-living amoebae isolated from water reservoirs of hospitals in southwest Iran. A total of 80 water samples were isolated from the hospitals of Ahvaz city, southwest Iran, and their physical and chemical parameters were measured. The samples were then put into non-food agar culture medium and stained using the Wright-Giemsa staining. Finally, the samples were identified by the PCR molecular method. The mean pH and turbidity values were 7.57 ± 0.03 and 3.31 ± 0.26 nephelometric turbidity unit (NTU), respectively. The mean residual chlorine and electrical conductivity were 0.91 ± 0.02 and 1122.39 ± 24.31, respectively. In addition, 9 (11.25%) and 3 (3.75%) samples were contaminated with Acanthamoeba spp. and Naegleria spp., respectively. However, no positive cases of Balamuthia spp. infection were observed. Moreover, two samples were co-infected with Acanthamoeba spp. and Naegleria spp. Due to the existence of free-living amoebae in water storage tanks at hospitals, it is necessary to prevent possible contamination with these amoebae and infectious agents by using new methods of disinfection and purification of water resources.

Isolation of nontuberculous mycobacteria species from different water sources: a study of six hospitals in Tehran, Iran

PurposeNontuberculous mycobacteria (NTM) are ubiquitous bacteria that are naturally resistant to disinfectants and antibiotics and can colonize systems for supplying drinking water. Therefore, this study aimed to evaluate the prevalence of NTM in the drinking water of six hospitals in Tehran, Iran.MethodsTotally, 198 water samples were collected. Each water sample was filtered via a membrane filter with a pore size of 0.45 µm and then decontaminated by 0.005% cetylpyridinium chloride. The membrane filters were incubated on two Lowenstein-Jensen media at 25 °C and 37 °C for 8 weeks. The positive cultures were identified with phenotypic tests, and then NTM species were detected according to the hsp65, rpoB, and 16S rDNA genes. Drug susceptibility testing (DST) was also carried out.ResultsOverall, 76 (40.4%) of the isolates were slowly growing mycobacteria (SGM) and 112 (59.6%) of the ones were rapidly growing mycobacteria (RGM). The most common NTM were Mycobacterium aurum, M. gordonae, M. phocaicum, M. mucogenicum, M. kansasii, M. simiae, M. gadium, M. lentiflavum, M. fortuitum, and M. porcinum. Among these 188 samples, NTM ranged from 1 to > 300 colony-forming unit (CFU) /500 mL, with a median of 182 CFU/500 mL. In the infectious department of all hospitals, the amount of CFU was higher than in other parts of the hospitals. The DST findings in this study indicated the diversity of resistance to different drugs. Among RGM, M. mucogenicum was the most susceptible isolate; however, M. fortuitum showed a different resistance pattern. Also, among SGM isolates, M. kansasii and M. simiae, the diversity of DST indicated.ConclusionsThe current study showed NTM strains could be an important component of hospital water supplies and a possible source of nosocomial infections according to the CFU reported in this study. The obtained findings also help clarify the dynamics of NTM variety and distribution in the water systems of hospitals in the research area.

Molecular screening and characterization of Legionella pneumophila associated free-living amoebae in domestic and hospital water systems

Free-living amoebae are ubiquitous in the environment and cause both opportunistic and non-opportunistic infections in humans. Some genera of amoebae are natural reservoirs of opportunistic plumbing pathogens, such as Legionella pneumophila. In this study, the presence of free-living amoebae and Legionella was investigated in 140 water and biofilm samples collected from Australian domestic (n = 68) and hospital water systems (n = 72). Each sample was screened in parallel using molecular and culture-based methods. Direct quantitative polymerase chain reaction (qPCR) assays showed that 41% samples were positive for Legionella, 33% for L. pneumophila, 11% for Acanthamoeba, and 55% for Vermamoeba vermiformis gene markers. Only 7% of samples contained culturable L. pneumophila serogroup (sg)1, L. pneumophila sg2-14, and non-pneumophila Legionella. In total, 69% of samples were positive for free-living amoebae using any method. Standard culturing found that 41% of the samples were positive for amoeba (either Acanthamoeba, Allovahlkampfia, Stenamoeba, or V. vermiformis). V. vermiformis showed the highest overall frequency of occurrence. Acanthamoeba and V. vermiformis isolates demonstrated high thermotolerance and osmotolerance and strong broad spectrum bacteriogenic activity against Gram-negative and Gram-positive bacteria. Importantly, all Legionella positive samples were also positive for amoeba, and this co-occurrence was statistically significant (p < 0.05). According to qPCR and fluorescence in situ hybridization, V. vermiformis and Allovahlkampfia harboured intracellular L. pneumophila. To our knowledge, this is the first time Allovahlkampfia and Stenamoeba have been demonstrated as hosts of L. pneumophila in potable water. These results demonstrate the importance of amoebae in engineered water systems, both as a pathogen and as a reservoir of Legionella. The high frequency of gymnamoebae detected in this study from Australian engineered water systems identifies an issue of significant public health concern. Future water management protocols should incorporate treatments strategies to control amoebae to reduce the risk to end users.

Investigating the Origin of Mycobacterium chimaera Contamination in Heater-Cooler Units: Integrated Analysis with Fourier Transform Infrared Spectroscopy and Whole-Genome Sequencing.

Mycobacterium chimaera is ubiquitously spread in the environment, including factory and hospital water systems. Invasive cases of M. chimaera infection have been associated with aerosols produced by the use of heater-cooler units (HCU) during cardiac surgery. The aim of this study was to evaluate for the first time the performance of IR-Biotyper system on a large number of M. chimaera isolates collected from longitudinal environmental HCUs samples and water sources from hospitals located in three Italian provinces. In addition, IR-Biotyper results were compared with whole-genome sequencing (WGS) analysis, the reference method for molecular epidemiology, to investigate the origin of M. chimaera contamination of HCUs. From November 2018 to May 2021, 417 water samples from 52 HCUs (Stockert 3T, n = 41 and HCU40, n = 11) and 23 hospital taps (used to fill the HCU tanks) were concentrated, decontaminated, and cultured for M. chimaera. Positive cultures (n = 53) were purified by agar plate subcultures and analyzed by IR-Biotyper platform and Ion Torrent sequencing system. IR-Biotyper spectra results were analyzed using a statistical approach of dimensionality reduction by linear discriminant analysis (LDA), generating three separate clusters of M. chimaera, ascribable to each hospital. Furthermore, the only M. chimaera-positive sample from tap water clustered with the isolates from the HCUs of the same hospital, confirming that the plumbing system could represent the source of HCU contamination and, potentially, of patient infection. According to the genome-based phylogenies and following the classification proposed by van Ingen and collaborators in 2017, three distinct M. chimaera groups appear to have contaminated the HCU water systems: subgroups 1.1, 2.1, and branch 2. Most of the strains isolated from HCUs at the same hospital share a highly similar genetic profile. The nonrandom distribution obtained with WGS and IR-Biotyper leads to the hypothesis that M. chimaera subtypes circulating in the local plumbing colonize HCUs through the absolute filter, in addition with the current hypothesis that contamination occurs at the HCU production site. This opens the possibility that other medical equipment, such as endoscope reprocessing device or hemodialysis systems, could be contaminated by M. chimaera. IMPORTANCE Our manuscript focuses on interventions to reduce waterborne disease transmission, improve sanitation, and control infection. Sanitary water can be contaminated by nontuberculous Mycobacteria, including M. chimaera, a causative agent of invasive infections in immunocompromised patients. We found highly similar genetic and phenotypic profiles of M. chimaera isolated from heater-cooler units (HCU) used during surgery to thermo-regulate patients' body temperature, and from the same hospital tap water. These results lead to the hypothesis that M. chimaera subtypes circulating in the local plumbing colonize HCUs through the absolute filter, adding to the current hypothesis that contamination occurs at the HCU production site. In addition, this opens the possibility that other medical equipment using sanitized water, such as endoscope reprocessing devices or hemodialysis systems, could be contaminated by nontuberculous Mycobacteria, suggesting the need for environmental surveillance and associated control measures.

Mitigation of nontuberculous mycobacteria in hospital water: challenges for infection prevention.

The purpose of this review is to summarize recent literature on nontuberculous mycobacteria in water of healthcare systems. Despite improvement in identification techniques and emergence of infection prevention and control programs, nontuberculous mycobacteria remain present in hospital water systems, causing outbreaks and pseudo-outbreaks in healthcare settings. Waterborne outbreaks and pseudo-outbreaks of nontuberculous mycobacteria continue to affect hospitals. Improvements in methods of identification and investigation, including MALDI-TOF and whole genome sequencing with evaluation of single nucleotide polymorphisms, have been used successfully in outbreak and pseudo-outbreak investigations. Recent studies have shown control of outbreaks in immunocompromised patients through the use of sterile water for consumption, as well as control of pseudo-outbreaks by using sterile water for procedures. Construction activities have been implicated in outbreaks and pseudo-outbreaks of nontuberculous mycobacteria. Water management programs are now required by the Joint Commission, which will likely improve water risk mitigation. Improvement in detection and identification of nontuberculous mycobacteria has led to increasing recognition of waterborne outbreaks and pseudo-outbreaks. Water management programs are of vital importance in infection prevention.

Four-Year Environmental Surveillance Program of Legionella spp. in One of Palermo's Largest Hospitals.

Legionella is a ubiquitous bacterium that lives in freshwater environments and colonizes human-made water systems. Legionella pneumophila is the most virulent species, and risk factors for Legionnaires’ disease include increasing age, smoking, chronic diseases, and immunodeficiency. For this reason, it is very important to assess and monitor hospital water systems in order to prevent legionellosis. We have monitored a large hospital in Palermo for four years. To determine the presence of microorganisms, according to national guidelines, we used the culture method, which is considered the gold standard for Legionella detection. Sampling was divided into five macro-areas, and a total of 251 samples were collected during the period of investigation, 49% of which were Legionella spp.-positive and 51% were Legionella spp.-negative. Positive samples with L. pneumophila. sgr 2-15 were most frequent in the Underground (55.6%, p = 0.0184), Medicine (42.9%, p = 0.0184) and Other (63.2%, p = 0.002) areas; while positive samples for L. pneumophila sgr 1 were less frequent in the Underground (0.0%, p = 0.0184) and Surgery areas (4.5%, p = 0.033), and for Legionella anisa, were less frequent in the Medicine (4.1%, p = 0.021), Oncohematology (0.0%, p = 0.0282), and Other (0.0%, p = 0.016) areas. Finally, no significant differences were observed among the areas for each isolate considered. The surveillance carried out in these years demonstrates the importance of monitoring, which allows us to analyze the conditions of hospital facilities and, therefore, prevent Legionella spp. infections.

New immunomagnetic separation method to analyze risk factors for Legionella colonization in health care centres.

BackgroundIt’s pivotal to control the presence of legionella in sanitary structures. So, it’s important to determine the risk factors associated with Legionella colonization in health care centres. In recent years that is why new diagnostic techniques have been developed.ObjectiveTo evaluate risks factors for Legionella colonization using a novel and more sensitive Legionella positivity index.MethodsA total of 204 one-litre water samples (102 cold water samples and 102 hot water samples), were collected from 68 different sampling sites of the hospital water system and tested for Legionella spp. by two laboratories using culture, polymerase chain reaction and a method based on immunomagnetic separation (IMS). A Legionella positivity index was defined to evaluate Legionella colonization and associated risk factors in the 68 water samples sites. We performed bivariate analyses and then logistic regression analysis with adjustment of potentially confounding variables. We compared the performance of culture and IMS methods using this index as a new gold standard to determine if rapid IMS method is an acceptable alternative to the use of slower culture method.ResultsBased on the new Legionella positivity index, no statistically significant differences were found neither between laboratories nor between methods (culture, IMS). Positivity was significantly correlated with ambulatory health assistance (p = 0.05) and frequency of use of the terminal points. The logistic regression model revealed that chlorine (p = 0.009) and the frequency of use of the terminal points (p = 0.001) are predictors of Legionella colonization. Regarding this index, the IMS method proved more sensitive (69%) than culture method (65.4%) in hot water samples.SignificanceWe showed that the frequency of use of terminal points should be considered when examining environmental Legionella colonization, which can be better evaluated using the provided Legionella positivity index. This study has implications for the prevention of Legionnaires’ disease in hospital settings.

Cupriavidus spp. and other waterborne organisms in healthcare water systems across the UK

Cupriavidus pauculus is a rare clinical pathogen, cases of which have been linked to contaminated hospital water systems. An outbreak of three cases of C.pauculus and other waterborne organisms was reported in a Glasgow hospital in 2018. To determine whether Cupriavidus spp. are present in hospital water systems elsewhere in Scotland and the UK, and to ascertain the optimal laboratory methodology for detection. This study also sought to establish where in the water system these organisms are detected, and whether a selective media could be developed for isolation. In addition, water samples were tested for the presence of other Gram-negative waterborne organisms. Water samples were received from 10 UK National Health Service hospitals and from various parts of the water system. Isolates were plated on to tryptone soya agar (TSA) and Pseudomonas isolation agar, and were further identified using matrix-assisted laser desorption ionization-time of flight mass spectrometry and 16S polymerase chain reaction. Cupriavidus spp. were detected in four of 10 hospitals tested, and all five isolates were from the periphery of the water system. All hospitals had evidence of other opportunistic premise plumbing pathogens. Cupriavidus spp. were identified using TSA, with some isolates growing on Pseudomonas isolation agar; as such, they may be detected inadvertently when testing water specifically for Pseudomonas aeruginosa. Isolation of Cupriavidus spp. was not unique to the Glasgow incident, and these bacteria are present in hospital water systems elsewhere in the UK. Water testing in response to clinical cases is recommended. Consideration should also be given to water testing following bacteraemias due to other rare and unusual water-borne pathogens.

From Copper Tolerance to Resistance in Pseudomonas aeruginosa towards Patho-Adaptation and Hospital Success.

The hospital environment constitutes a reservoir of opportunistic pathogens responsible for healthcare-associated infections (HCAI) such as Pseudomonas aeruginosa (Pa). Pa persistence within technological niches, the increasing emergence of epidemic high-risk clones in HCAI, the epidemiological link between plumbing strains and clinical strains, make it a major nosocomial pathogen. Therefore, understanding the mechanisms of Pa adaptation to hospital water systems would be useful in preventing HCAI. This review deciphers how copper resistance contributes to Pa adaptation and persistence in a hospital environment, especially within copper water systems, and ultimately to its success as a causative agent of HCAI. Numerous factors are involved in copper homeostasis in Pa, among which active efflux conferring copper tolerance, and copper-binding proteins regulating the copper compartmentalization between periplasm and cytoplasm. The functional harmony of copper homeostasis is regulated by several transcriptional regulators. The genomic island GI-7 appeared as especially responsible for the copper resistance in Pa. Mechanisms of copper and antibiotic cross-resistance and co-resistance are also identified, with potential co-regulation processes between them. Finally, copper resistance of Pa confers selective advantages in colonizing and persisting in hospital environments but also appears as an asset at the host/pathogen interface that helps in HCAI occurrence.

Is it time for water and drainage standards to be part of the accreditation process for haemato-oncology units?

Recent events in a Scottish new-build hospital have highlighted the risk to haemato-oncology and bone marrow transplant patients from contaminated water and drainage systems [1,2]. Haemato-oncology patients have a number of risk factors for infection that include: underlying haematological disease, chemotherapy, neutropenia, transplant procedures, steroids and the presence of Hickman lines. Exogenous organisms from hospital water systems that pose particular risk to haemato-oncology patients are Legionella spp., Gram-negative opportunistic pathogens, environmental mycobacteria and fungi.

The impact of two commonly used neutralizing agents in water sampling bottles on legionella and pseudomonas bacteria recovery

Microbiological monitoring may be indicated by the local risk assessment of hospital water systems. When water sampling is carried out, it is imperative that the activity of any residual biocide is completely neutralized. Sodium thiosulphate pentahydrate (Na₂S₂O₃·5H₂O) is commonly used to neutralize oxidizing biocides in water samples for microbiological testing. Ethylenediaminetetraacetic acid dihydrate (Na2EDTA.2H2O) is recommended to neutralize silver-copper ionization treated water samples. However, there are inconsistencies in the recommended effective concentration. Furthermore, sampling bottles dosed with Na2EDTA.2H2O are not commercially available. To investigate the efficacy of Na2EDTA.2H2O as a neutralizing agent compared with sodium thiosulphate (Na₂S₂O₃·5H₂O) on water samples treated with silver and copper ions and to assess the biocidal activity in water samples. An interlaboratory investigation was carried out using simulated water samples spiked with Legionella pneumophila or Pseudomonas aeruginosa with and without silver and copper ions. Bacterial recovery was determined in sterile sampling bottles dosed with either 50 mg/L Na2EDTA.2H2O or 180 mg/L Na₂S₂O₃·5H₂O as the chemical biocide neutralizing agent. Na₂S₂O₃·5H₂O effectively complexed both silver and copper ions and inhibited biocidal activity. The 50 mg/L of Na2EDTA.2H2O continued to demonstrate significant biocidal activity in the spiked samples. This study demonstrated that Na2EDTA.2H2O is not an efficacious neutralizing agent on water samples treated with silver and copper ions. Sample bottles dosed with 180 mg/L Na₂S₂O₃·5H₂O were more effective in neutralizing silver and copper ions generated in water that had been treated by silver-copper ionization systems.

Investigation of the presence of Legionella pneumophila in water samples from Erzurum and surrounding provinces in Turkey.

Legionnaires' disease, which is a waterborne disease leading to pneumonia that can result in death, is one of the major health issues today. The study aims to carry out a three-year retrospective review of routine Legionella follow-up analyses in various samples taken mostly from hospitals in the province of Erzurum and nearby provinces, and to discover a the frequency of isolation of the agent and serogroups from each kind of media. The study included a total of 2,025 water samples taken from hospitals, hotels, Turkish baths and shopping malls in Erzurum,and 13 nearby cities between 2016 and 2018. Samples were filtered by 0.45 μm-diameter membrane filter paper in the Public Health Laboratory of Erzurum and examined for L. pneumophila using culture method, according to the criteria set out in ISO 11731-2. The presence of L. pneumophila was found in 65 of the 2,025 water samples taken in hospitals, and in none of 40 samples taken in hotels, Turkish baths and shopping malls. L. pneumophila serogroup 2-14 was detected in 46 (70.8%) of 65 samples found positive, whereas L. pneumophila serogroup 1 was detected in 18 (27.7%). Furthermore, both the L. pneumophila serogroup 2-14 and L. pneumophila serogroup 1 were detected simultaneously in one example (1.5%). The first three samples indicate that the highest positivity rates were in hot water taps (11.6%), hot water tanks (6.1%) and shower heads (4.8%). The Prevalence rat of L. pneumophila was found to be quite low compared to other studies conducted in the western regions of Turkey. Legionella positivity was found to be higher in the hot water systems of hospitals and related points, compared to the other sample points.

Surveillance of hospital water systems to help predict the risk of nosocomial legionellosis-Consider other factors.

Surveillance of hospital water systems to help predict the risk of nosocomial legionellosis-Consider other factors.

Improved detection of non-tuberculous mycobacteria in hospital water samples

Non-tuberculous mycobacteria (NTM) are opportunistic pathogens commonly colonizing hospital water systems, and may be responsible for healthcare-associated infections (HAI). Investigation of HAI and outbreaks caused by NTM necessitates water analyses. However, NTM are slow-growing bacteria within the mesophilic community present in water, and are difficult to detect. Prior to culture on specific media, their recovery usually requires decontamination and concentration steps. We assessed the effectiveness of filtration as regards the recovery of 7 NTM species in hospital water samples. We also compared the use of cetylpyridinium chloride (CPC) at different concentrations and Sodium Hydroxide (NaOH) 4% in decontamination of water samples with mesophilic bacteria. Our laboratory protocol showed that membrane filtration was suitable for concentration and recovery of NTM from water. Sample decontamination with CPC was more NTM-preservative than NaOH. A combination of CPC at 0.005% and filtration allowed detection of NTM at low concentrations, ranging from 3 to 98 CFU/100mL according to the NTM species.

Investigation of two cases of Mycobacterium chelonae infection in haemato-oncology patients using whole-genome sequencing and a potential link to the hospital water supply

Haemato-oncology patients are at increased risk of infection from atypical mycobacteria such as Mycobacterium chelonae which are commonly found in both domestic and hospital water systems. To describe the investigation and control measures following two patient cases of M.chelonae and positive water samples in the study hospital. Water testing was undertaken from outlets, storage tanks and mains supply. Whole-genome sequencing (WGS) was used to compare patient and positive water samples. The subsequent infection control measures implemented are described. The WGS results showed two main populations of M.chelonae within the group of sampled isolates. The results showed that the patient strains were unrelated to each other, but that the isolate from one patient was closely related to environmental samples from water outlets, supporting nosocomial acquisition. WGS was used to investigate two patient cases of M.chelonae and positive water samples from a hospital water supply. Relevant control measures and the potential for chemical dosing of water systems to enhance proliferation of atypical mycobacteria are discussed.

Investigation and control of an outbreak due to a contaminated hospital water system, identified following a rare case of Cupriavidus pauculus bacteraemia

Cupriavidus pauculus is rare cause of clinical infection. We describe an outbreak of C.pauculus and other Gram-negative bacteraemias in a paediatric haemato-oncology unit secondary to a contaminated water supply and drainage system. To describe the investigation and control measures implemented for a waterborne infection outbreak in a new build hospital. Extensive water testing from various points within the water system was undertaken. Taps, showerheads and components including flow straighteners underwent microbiological analysis. Drains were also swabbed. Surveillance for Gram-negative infections was established on the unit. Water testing revealed widespread contamination of the water and drainage system. Outlets were also heavily contaminated, including flow straighteners. Drains were found to have underlying structural abnormalities. Water testing enabled us to detect high-risk components within the water system such as the expansion vessels and outlets and the results assisted with hypotheses generation. Review of commissioning data and risk assessments revealed extensive risks present within the water system prior to and after hospital opening. Careful design, adequate control measures and maintenance are essential for hospital water systems in order to prevent infections due to waterborne organisms. We discuss what can be learned from this incident with a view to future prevention.

Cytotoxicity, Intracellular Replication, and Contact-Dependent Pore Formation of Genotyped Environmental Legionella pneumophila Isolates from Hospital Water Systems in the West Bank, Palestine.

Legionella pneumophila is the causative agent of Legionnaires’ disease. Due to the hot climate and intermittent water supply, the West Bank, Palestine, can be considered a high-risk area for this often fatal atypical pneumonia. L. pneumophila occurs in biofilms of natural and man-made freshwater environments, where it infects and replicates intracellularly within protozoa. To correlate the genetic diversity of the bacteria in the environment with their virulence properties for protozoan and mammalian host cells, 60 genotyped isolates from hospital water systems in the West Bank were analyzed. The L. pneumophila isolates were previously genotyped by high resolution Multi Locus Variable Number of Tandem Repeat Analysis (MLVA-8(12)) and sorted according to their relationship in clonal complexes (VACC). Strains of relevant genotypes and VACCs were compared according to their capacity to infect Acanthamoeba castellanii and THP-1 macrophages, and to mediate pore-forming cytotoxicity in sheep red blood cells (sRBCs). Based on a previous detailed analysis of the biogeographic distribution and abundance of the MLVA-8(12)-genotypes, the focus of the study was on the most abundant L. pneumophila- genotypes Gt4(17), Gt6 (18) and Gt10(93) and the four relevant clonal complexes [VACC1, VACC2, VACC5 and VACC11]. The highly abundant genotypes Gt4(17) and Gt6(18) are affiliated with VACC1 and sequence type (ST)1 (comprising L. pneumophila str. Paris), and displayed seroroup (Sg)1. Isolates of these two genotypes exhibited significantly higher virulence potentials compared to other genotypes and clonal complexes in the West Bank. Endemic for the West Bank was the clonal complex VACC11 (affiliated with ST461) represented by three relevant genotypes that all displayed Sg6. These genotypes unique for the West Bank showed a lower infectivity and cytotoxicity compared to all other clonal complexes and their affiliated genotypes. Interestingly, the L. pneumophila serotypes ST1 and ST461 were previously identified by in situ-sequence based typing (SBT) as main causative agents of Legionnaires’ disease (LD) in the West Bank at a comparable level. Overall, this study demonstrates the site-specific regional diversity of L. pneumophila genotypes in the West Bank and suggests that a combination of MLVA, cellular infection assays and hierarchical agglomerative cluster analysis allows an improved genotype-based risk assessment.

Hospital-acquired Legionella pneumonia outbreak at an academic medical center: Lessons learned

BackgroundAn outbreak of Legionella pneumonia occurred at a university hospital using copper-silver ionization for potable water disinfection. We present the epidemiological and laboratory investigation of the outbreak, and associated case-control study. MethodsCases were defined by syndrome compatible with Legionella pneumonia with laboratory-confirmed Legionella infection. The water circuit and disinfection system were assessed, and water samples collected for Legionella culture. Whole genome multi-locus sequence typing (wgMLST) was used to compare the genetic similarity of patient and environmental isolates. A case-control study was conducted to identify risk factors for Legionella pneumonia. ResultsWe identified 13 cases of hospital-acquired Legionella. wgMLST revealed >99.9% shared allele content among strains isolated from clinical and water samples. Smoking (P= .008), steroid use (P= .007), and documented shower during hospitalization (P= .03) were risk factors for Legionella pneumonia on multivariable analysis. Environmental assessment identified modifications to the hospital water system had occurred in the month preceding the outbreak. Multiple mitigation efforts and application of point of use water filters stopped the outbreak. ConclusionsPotable water system Legionella colonization occurs despite existing copper-silver ionization systems, particularly after structural disruptions. Multidisciplinary collaboration and direct monitoring for Legionella are important for outbreak prevention. Showering is a modifiable risk factor for nosocomial Legionella pneumonia. Shower restriction and point-of-use filters merit consideration during an outbreak.

Pseudomonas aeruginosa infection in augmented care: the molecular ecology and transmission dynamics in four large UK hospitals

Pseudomonas aeruginosa is a common opportunistic pathogen and molecular typing in outbreaks has linked patient acquisition to contaminated hospital water systems. To elucidate the role of P.aeruginosa transmission rates in non-outbreak augmented care settings in the UK. Over a 16-week period, all water outlets in augmented care units of four hospitals were sampled for P.aeruginosa and clinical isolates were collected. Outlet and clinical P.aeruginosa isolates underwent whole-genome sequencing (WGS), which with epidemiological data identified acquisition from water as definite (level 1), probable (level 2), possible (level 3), and no evidence (level 4). Outlets were positive in each hospital on all three occasions: W (16%), X (2.5%), Y (0.9%) and Z (2%); and there were 51 persistently positive outlets in total. WGS identified likely transmission (at levels 1, 2 and 3) from outlets to patients in three hospitals for P.aeruginosa positive patients: W (63%), X (54.5%) and Z (26%). According to the criteria (intimate epidemiological link and no phylogenetic distance), approximately 5% of patients in the study 'definitely' acquired their P.aeruginosa from their water outlets in the intensive care unit. This study found extensive evidence of transmission from the outlet to the patients particularly in the newest hospital (W), which had the highest rate of positive outlets. The overall findings suggest that water outlets are the most likely source of P.aeruginosa nosocomial infections in some settings, and that widespread introduction of control measures would have a substantial impact on infections.

A dominant strain of Elizabethkingia anophelis emerged from a hospital water system to cause a three-year outbreak in a respiratory care center

Elizabethkingia species are ubiquitous bacteria but uncommonly cause human infection. An outbreak of Elizabethkingia anophelis bacteraemia was observed in a respiratory care center of a tertiary hospital in Taiwan from 2015 to 2018. Clinical and environmental isolates were collected for the outbreak investigation. Pulsed-field gel electrophoresis (PFGE) and complete-genome sequencing were conducted to elucidate the mechanism of transmission. The three-year outbreak involved 26 patients with E.anophelis bacteraemia and the incidence significantly increased during the outbreak period compared with that observed from 2010 to 2014 (P<0.05). All 26 clinical isolates during the outbreak period belonged to a cluster by PFGE analysis. In contrast, the PFGE pattern was heterogeneous among comparative historical strains. Hospital tap water was highly contaminated by Elizabethkingia species (18/34, 52.9%); among that, five E.anophelis belonged to the outbreak cluster (5/18, 27.8%). As for the inanimate surface survey, 3.4% sites (4/117) revealed positive growth of E.anophelis including two from feeding tubes/bags and two from sputum suction regulators. All four isolates belonged to the outbreak clone. The outbreak strain had no apparent relationship to currently known E.anophelis strains worldwide through complete-genome sequencing analysis. Specific infection control strategies aimed at water source control and environmental disinfection were implemented subsequently and the outbreak ended in mid-2018. A specific E.anophelis strain was identified from a three-year outbreak. The elucidation of the mechanism of dominance and intra-hospital transmission is crucial for development of corresponsive infection control policies and outbreak control.