Transmission of metallo-β-lactamase-producing Pseudomonas aeruginosa in a nephrology-transplant intensive care unit with potential link to the environment

Investigation on the contaminate of hand washing activities on the surface of environmental objects in intensive care unit

To detect the contaminate of faucets in hospitals and the splash during hand washing, and to explore the reasonable layout of hand washing pools. Two faucets with roughly the same spatial layout in the ICU of a third-class first-class general hospital were selected, and the farthest splashing distance and specific splashing points were measured by color paper. Samples were detected by ATP detection technology and routine microbial detection method, and the contaminate of faucets was analyzed. After 72 h of daily hand-washing activities, the furthest distance to the splash point was about 100 cm around the faucet, and the place 40-110 cm around the faucet was contaminated seriously. The farthest distance that the splash point reached was about 80 cm around the faucet with the center of the circle, and the area 40-60 cm around the faucet was heavily contaminated. The distance from the water outlet of the long handle and the short handle faucet to the detection point had a high negative correlation (r = - 0.811, P < 0.001) and a moderate negative correlation (r =  - 0.475, P = 0.001) with the number of splash points, respectively. The qualified rates of ATP detection and microbial culture were 25% and 15%, respectively. Pseudomonas aeruginosa, Staphylococcus epidermidis, and other pathogenic bacteria were detected in the water outlet of the faucet and the surrounding environment. Safe hand hygiene facilities are one of the important guarantees of hand hygiene effect. Clean objects and objects related to patients should not be placed within 1 m range near the water outlet of faucet. Anti-splash baffle should be installed as much as possible when conditions permit to reduce the contaminate caused by splash during hand washing.

Disinfection of sink drains to reduce a source of three opportunistic pathogens, during Serratia marcescens clusters in a neonatal intensive care unit

OBJECTIVE

Evaluate the effects of five disinfection methods on bacterial concentrations in hospital sink drains, focusing on three opportunistic pathogens (OPs): Serratia marcescens, Pseudomonas aeruginosa and Stenotrophomonas maltophilia.

DESIGN

Over two years, three sampling campaigns were conducted in a neonatal intensive care unit (NICU). Samples from 19 sink drains were taken at three time points: before, during, and after disinfection. Bacterial concentration was measured using culture-based and flow cytometry methods. High-throughput short sequence typing was performed to identify the three OPs and assess S. marcescens persistence after disinfection at the genotypic level.

SETTING

This study was conducted in a pediatric hospitals NICU in Montréal, Canada, which is divided in an intensive and intermediate care side, with individual rooms equipped with a sink.

INTERVENTIONS

Five treatments were compared: self-disinfecting drains, chlorine disinfection, boiling water disinfection, hot tap water flushing, and steam disinfection.

RESULTS

This study highlights significant differences in the effectiveness of disinfection methods. Chlorine treatment proved ineffective in reducing bacterial concentration, including the three OPs. In contrast, all other drain interventions resulted in an immediate reduction in culturable bacteria (4-8 log) and intact cells (2-3 log). Thermal methods, particularly boiling water and steam treatments, exhibited superior effectiveness in reducing bacterial loads, including OPs. However, in drains with well-established bacterial biofilms, clonal strains of S. marcescens recolonized the drains after heat treatments.

CONCLUSIONS

Our study supports thermal disinfection (>80°C) for pathogen reduction in drains but highlights the need for additional trials and the implementation of specific measures to limit biofilm formation.

Difficult-to-treat (DTR) Pseudomonas aeruginosa harboring Verona-Integron metallo-β-lactamase (blaVIM): infection management and molecular analysis

Pseudomonas aeruginosa harboring Verona Integron-encoded metallo-β-lactamase enzymes (VIM-CRPA) have been associated with infection outbreaks in several parts of the world. In the US, however, VIM-CRPA remain rare. Starting in December 2018, we identified a cluster of cases in our institution. Herein, we present our epidemiological investigation and strategies to control/manage these challenging infections. This study was conducted in a large academic healthcare system in Miami, FL, between December 2018 and January 2022. Patients were prospectively identified via rapid molecular diagnostics when cultures revealed carbapenem-resistant P. aeruginosa. Alerts were received in real time by the antimicrobial stewardship program and infection prevention teams. Upon alert recognition, a series of interventions were performed as a coordinated effort. A retrospective chart review was conducted to collect patient demographics, antimicrobial therapy, and clinical outcomes. Thirty-nine VIM-CRPA isolates led to infection in 21 patients. The majority were male (76.2%); the median age was 52 years. The majority were mechanically ventilated (n = 15/21; 71.4%); 47.6% (n = 10/21) received renal replacement therapy at the time of index culture. Respiratory (n = 20/39; 51.3%) or bloodstream (n = 13/39; 33.3%) were the most common sources. Most infections (n = 23/37; 62.2%) were treated with an aztreonam-avibactam regimen. Six patients (28.6%) expired within 30 days of index VIM-CRPA infection. Fourteen isolates were selected for whole genome sequencing. Most of them belonged to ST111 (12/14), and they all carried blaVIM-2 chromosomally. This report describes the clinical experience treating serious VIM-CRPA infections with either aztreonam-ceftazidime/avibactam or cefiderocol in combination with other agents. The importance of implementing infection prevention strategies to curb VIM-CRPA outbreaks is also demonstrated.

An intensive care unit outbreak with multi-drug-resistant Pseudomonas aeruginosa - spotlight on sinks

BACKGROUND

Pseudomonas aeruginosa and other Gram-negative bacteria have the ability to persist in moist environments in healthcare settings, but their spread from these areas can result in outbreaks of healthcare-associated infections.

METHODS

This study reports the investigation and containment of a multi-drug-resistant P. aeruginosa outbreak in three intensive care units of a Swiss university hospital. In total, 255 patients and 276 environmental samples were screened for the multi-drug-resistant P. aeruginosa outbreak strain. The environmental sampling and molecular characterization of patient and environmental strains, and control strategies implemented, including waterless patient care, are described.

RESULTS

Between March and November 2019, the outbreak affected 29 patients. Environmental sampling detected the outbreak strain in nine samples of sink siphons of three different intensive care units with a common water sewage system, and on one gastroscope. Three weeks after replacement of the sink siphons, the outbreak strain re-grew in siphon-derived samples and newly affected patients were identified. The outbreak ceased after removal of all sinks in the proximity of patients and in medication preparation areas, and minimization of tap water use. Multi-locus sequence typing indicated clonality (sequence type 316) in 28/29 patient isolates and all 10 environmental samples.

CONCLUSIONS

Sink removal combined with the introduction of waterless patient care terminated the multi-drug-resistant P. aeruginosa outbreak. Sinks in intensive care units may pose a risk for point source outbreaks with P. aeruginosa and other bacteria persisting in moist environments.

Genome-based typing reveals rare events of patient contamination with Pseudomonas aeruginosa from other patients and sink traps in a medical intensive care unit

AIM

We used genome-based typing data with the aim of identifying the routes of acquisition of Pseudomonas aeruginosa by patients hospitalized in a medical intensive care unit (MICU) over a long period in a non-epidemic context.

METHODS

This monocentric prospective study took place over 10 months in 2019 in a 15-bed MICU that applies standard precautions of hygiene. Lockable sink traps installed at all water points of use were bleach disinfected twice a week. We sampled all sink traps weekly to collect 404 P. aeruginosa environmental isolates and collected all P. aeruginosa isolates (N = 115) colonizing or infecting patients (N = 65). All isolates had their phenotypic resistance profile determined and their genome sequenced, from which we identified resistance determinants and assessed the population structure of the collection at the nucleotide level to identify events of P. aeruginosa transmission.

FINDINGS

All sink traps were positive for P. aeruginosa, each sink trap being colonized for several months by one or more clones. The combination of genomic and spatiotemporal data identified one potential event of P. aeruginosa transmission from a sink trap to a patient (1/65, 1.5%) and six events of patient cross-transmission, leading to the contamination of five patients (5/65, 7.7%). All transmitted isolates were fully susceptible to β-lactams and aminoglycosides.

CONCLUSIONS

Genome-based typing revealed the contamination of patients by P. aeruginosa originating from sink traps to be infrequent (1.5%) in an MICU with sink trap-bleaching measures, and that only 7.7% of the patients acquired P. aeruginosa originating from another patient.

Routes of transmission of VIM-positive Pseudomonas aeruginosa in the adult intensive care unit-analysis of 9 years of surveillance at a university hospital using a mathematical model

Background

Hospital outbreaks of multidrug resistant Pseudomonas aeruginosa are often caused by Pseudomonas aeruginosa clones which produce metallo-β-lactamases, such as Verona Integron-encoded Metallo-β-lactamase (VIM). Although different sources have been identified, the exact transmission routes often remain unknown. However, quantifying the role of different transmission routes of VIM-PA is important for tailoring infection prevention and control measures. The aim of this study is to quantify the relative importance of different transmission routes by applying a mathematical transmission model using admission and discharge dates as well as surveillance culture data of patients.

Methods

We analyzed VIM-PA surveillance data collected between 2010 and 2018 of two intensive-care unit (ICU) wards for adult patients of the Erasmus University Medical Center Rotterdam using a mathematical transmission model. We distinguished two transmission routes: direct cross-transmission and a persistent environmental route. Based on admission, discharge dates, and surveillance cultures, we estimated the proportion of transmissions assigned to each of the routes.

Results

Our study shows that only 13.7% (95% CI 1.4%, 29%) of the transmissions that occurred in these two ICU wards were likely caused by cross-transmission, leaving the vast majority of transmissions (86.3%, 95% CI 71%, 98.6%) due to persistent environmental contamination.

Conclusions

Our results emphasize that persistent contamination of the environment may be an important driver of nosocomial transmissions of VIM-PA in ICUs. To minimize the transmission risk from the environment, potential reservoirs should be regularly and thoroughly cleaned and disinfected, or redesigned.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-022-01095-x.

Evaluation of Multidrug-Resistant P. aeruginosa in Healthcare Facility Water Systems

According to the WHO, P. aeruginosa is one of the antibiotic-resistant bacteria that represent the biggest threat to public health. The aim of the study was to establish the prevalence of antibiotic-resistant P. aeruginosa in the water systems of various healthcare facilities over the course of nine years. A total of 4500 tap water system samples were taken from seventeen healthcare facilities. The culture method was used to detect P. aeruginosa, and the isolates were then tested for antibiotic resistance using the standardised disc diffusion method. Eleven antibiotics from five different classes were tested. P. aeruginosa was found to have contaminated 2.07% (no. 93) of the water samples. The majority of positive samples came from the dental units (30.11%) and the ward kitchens (23.66%). Considering the total isolates, 56.99% (no. 3) were resistant to at least one of the antibiotics tested. A total of 71.43% of P. aeruginosa isolated from water emerging from dental unit handpieces was antibiotic-resistant, with 45% of it resistant to ≥3 classes of antibiotics. Out of the total isolates, 19.35% showed resistance to carbapenems. It would be advisable to systematically screen tap water for opportunistic micro-organisms such as P. aeruginosa, as many countries already do, including this in the Water Safety Plan.

Preventing infections caused by carbapenemase-producing bacteria in the intensive care unit - Think about the sink

OBJECTIVE

Outbreaks caused by carbapenemase-producing bacteria (CPB) are challenging to manage in critical care settings and can be protracted due to inadvertent and ubiquitous ecological niches within the built unit environment, such as handwashing sinks. We discuss evidence from a narrative review on transmission pathways and interventions for critical care practitioners.

METHODS

A literature review was undertaken using Pubmed, CINAHL and Embase and included outbreaks of CPB, and equivalent bacteria in critical care units, between 1998 and May 2020. Intervention studies targeting elements of sinks that were employed in response to outbreaks in critical care units were included (n = 30).

FINDINGS

We found control measures included sink removal, use of physical barriers or design modification to protect patients from sinks, engineering controls to mitigate bacterial dispersal and administrative controls. A multi-disciplinary approach involving practitioners from critical care, infection prevention and control, engineering and other staff, should be involved in ongoing measures and in outbreak control activities. Ascertaining the optimal method to end CPB outbreaks in critical care is challenging due to the lack of prospective studies available. However, the literature suggests that sinks can and do serve as reservoirs of CPB near critically ill patients, and should be considered hazardous, especially when sub-optimally designed or used.

A prospective multicentre surveillance study to investigate the risk associated with contaminated sinks in the intensive care unit

OBJECTIVES

The aim was to assess the incidence of sink contamination by multidrug-resistant (MDR) Pseudomonas aeruginosa and Enterobacteriaceae, risk factors for sink contamination and splashing, and their association with clinical infections in the intensive care setting.

METHODS

A prospective French multicentre study (1 January to 30 May 2020) including in each intensive care unit (ICU) a point-prevalence study of sink contamination, a questionnaire of risk factors for sink contamination (sink use, disinfection procedure) and splashing (visible plashes, distance and barrier between sink and bed), and a 3-month prospective infection survey.

RESULTS

Seventy-three ICUs participated in the study. In total, 50.9% (606/1191) of the sinks were contaminated by MDR bacteria: 41.0% (110/268) of the sinks used only for handwashing, 55.3% (510/923) of those used for waste disposal, 23.0% (62/269) of sinks daily bleached, 59.1% (126/213) of those daily exposed to quaternary ammonium compounds (QACs) and 62.0% (285/460) of those untreated; 459 sinks (38.5%) showed visible splashes and 30.5% (363/1191) were close to the bed (<2 m) with no barrier around the sink. MDR-associated bloodstream infection incidence rates ≥0.70/1000 patient days were associated with ICUs meeting three or four of these conditions, i.e. a sink contamination rate ≥51%, prevalence of sinks with visible splashes ≥14%, prevalence of sinks close to the patient's bed ≥21% and no daily bleach disinfection (6/30 (20.0%) of the ICUs with none, one or two factors vs. 14/28 (50.0%) of the ICUs with three or four factors; p 0.016).

DISCUSSION

Our data showed frequent and multifactorial infectious risks associated with contaminated sinks in ICUs.

Prevalence of β-lactamase genes, class 1 integrons, major virulence factors and clonal relationships of multidrug-resistant Pseudomonas aeruginosa isolated from hospitalized patients in southeast of Iran

Objective(s):

Pseudomonas aeruginosa is one of the most important nosocomial pathogens causing a high rate of mortality among hospitalized patients. Herein, we report the prevalence of antibiotic resistance genes, class 1 integrons, major virulence genes and clonal relationship among multidrug- resistant (MDR) P. aeruginosa, isolated from four referral hospitals in the southeast of Iran.

Materials and Methods:

In this study, 208 isolates of P. aeruginosa were collected from four referral hospitals in southeast of Iran. Disk diffusion method was used to determine susceptibility to 13 antibacterial agents. AmpC was detected by phenotypic method and β-lactamase genes, virulence genes and class 1 integrons were detected by PCR. Clonal relationship of the isolates was determined by RAPD-PCR.

Results:

All the isolates were susceptible to polymyxin-B and colistin. Overall, 40.4% of the isolates were MDR, among which resistance to third generation cephalosporins, aminoglycosides, and carbapenems was 47.5%, 32.3% and 40%, respectively. None of the isolates was positive for bla_NDM-1 genes, while 84.5% and 4.8% were positive for the bla_IMP-1 and bla_VIM, metallo-β-lactamase genes, respectively. Incidence of class 1 integrons was 95% and AmpC was detected in 33% of the isolates. Prevalence of exoA, exoS, exoU, pilB and nan1 were 98.8%, 44%, 26%, 8.3% and 33.3%, respectively. RAPD profiles identified four large clusters consisting of 77 isolates, and two small clusters and three singletons.

Conclusion: :

The rate of MDR P. aeruginosa isolates was high in different hospitals in this region. High genetic similarity among MDR isolates suggests cross-acquisition of infection in the region.

Local outbreak of extended-spectrum β-lactamase SHV2a-producing Pseudomonas aeruginosa reveals the emergence of a new specific sub-lineage of the international ST235 high-risk clone

BACKGROUND

Pseudomonas aeruginosa is a major bacterial pathogen responsible for hospital-acquired infections. Although its epidemiology is considered as non-clonal, certain international high-risk multidrug-resistant clones have been recognized.

AIM

From the first report of an intra-hospital outbreak due to an SHV2a-producing P. aeruginosa strain, to describe the emergence of a new ST235-specific lineage harbouring this rare extended-spectrum β-lactamase (ESBL).

METHODS

Between May and October 2018, four patients hospitalized in the cardiovascular intensive care unit of a French teaching hospital were infected by a multidrug-resistant P. aeruginosa isolate. Serotype and antimicrobial susceptibility were tested; multi-locus sequence type (MLST), core genome MLST, and resistome were determined through whole genome sequencing. A phylogenetic analysis based on single nucleotide polymorphism was performed using available ST235 genomes.

FINDINGS

The four strains were susceptible to colistin, ciprofloxacin, ceftazidime-avibactam, and ceftolozane-tazobactam. bla_SHV2a was identified in each genome of this ST235-O11 serotype cluster that showed an identical cgMLST profile (0-2 out of 4162 different alleles). The phylogenic analysis of 162 ST235 genomes showed that only four other strains harboured a bla_SHV2a, originating from France and USA, clustering together although being different from the outbreak strains.

CONCLUSIONS

Among the ST235 P. aeruginosa strains, a sub-lineage sharing a common genetic background and harbouring the bla_SHV2a ESBL seems to emerge from different locations, yielding secondary local outbreaks.

Diversity and metallo-β-lactamase-producing genes in Pseudomonas aeruginosa strains isolated from filters of household water treatment systems

The microbiological quality of drinking water has long been a critical element in public health. Considering the high clinical relevance of Pseudomonas aeruginosa, we examined the filters of household water treatment systems for its presence and characteristics to determine the systems' efficiency in eliminating the bacteria. In total, filters of 50 household water treatment systems were examined. Microbiological and molecular methods were used for the detection and confirmation of P. aeruginosa isolates. Random Amplification of Polymorphic DNA-polymerase chain reaction (RAPD-PCR) was performed to detect similarities and differences among P. aeruginosa isolates. Combined disk (CD) method and double disk synergy test (DDST) were performed to detect metallo-beta-lactamase (MBL)-producing P. aeruginosa isolates. Finally, PCR was performed to detect MBL genes in MBL-producing strains. From the 50 analyzed systems, 76 colonies of P. aeruginosa were identified. In some systems, isolated bacteria from different filters harbored similar genetic profiles, indicating that these isolates may be able to pass through the filter and reach higher filters of the system. Phenotypic tests revealed 7 (9.2%) MBL-producing strains. Two isolates were positive for bla_VIM-1, whereas one isolate was positive for bla_NDM and bla_IMP-1. The wide distribution of resistant phenotypes and genetic plasticity of these bacteria in household water treatment systems indicate that resistance mechanisms circulate among P. aeruginosa isolates in the environment of the filtration systems. The presence of MBL-producing genes in these systems and P. aeruginosa as a potential reservoir of these resistance genes can be a major concern for public health.

Droplet- Rather than Aerosol-Mediated Dispersion Is the Primary Mechanism of Bacterial Transmission from Contaminated Hand-Washing Sink Traps

An alarming rise in hospital outbreaks implicating hand-washing sinks has led to widespread acknowledgment that sinks are a major reservoir of antibiotic-resistant pathogens in patient care areas. An earlier study using green fluorescent protein (GFP)-expressing Escherichia coli (GFP-E. coli) as a model organism demonstrated dispersal from drain biofilms in contaminated sinks. The present study further characterizes the dispersal of microorganisms from contaminated sinks. Replicate hand-washing sinks were inoculated with GFP-E. coli, and dispersion was measured using qualitative (settle plates) and quantitative (air sampling) methods. Dispersal caused by faucet water was captured with settle plates and air sampling methods when bacteria were present on the drain. In contrast, no dispersal was captured without or in between faucet events, amending an earlier theory that bacteria aerosolize from the P-trap and disperse. Numbers of dispersed GFP-E. coli cells diminished substantially within 30 minutes after faucet usage, suggesting that the organisms were associated with larger droplet-sized particles that are not suspended in the air for long periods.IMPORTANCE Among the possible environmental reservoirs in a patient care environment, sink drains are increasingly recognized as a potential reservoir to hospitalized patients of multidrug-resistant health care-associated pathogens. With increasing antimicrobial resistance limiting therapeutic options for patients, a better understanding of how pathogens disseminate from sink drains is urgently needed. Once this knowledge gap has decreased, interventions can be engineered to decrease or eliminate transmission from hospital sink drains to patients. The current study further defines the mechanisms of transmission for bacteria that colonize sink drains.

Pseudomonas aeruginosa bacteremia among liver transplant recipients

Pseudomonas aeruginosa bacteremia remains as a life-threatening complication after liver transplantation (LT) and is intractable because of the high rate of drug resistance to commonly used antibiotics. To better understand the characteristics of this postoperative complication, PubMed and Embase searches as well as reference mining was done for relevant literature from the start of the databases through August 2018. Among LT recipients, the incidence of P. aeruginosa bacteremia ranged from 0.5% to 14.4% and mortality rates were up to 40%. Approximately 35% of all episodes of bloodstream infections (BSIs) were P. aeruginosa bacteremia, of which 47% were multidrug resistant and 63% were extensively drug resistant. Several factors are known to affect the mortality of LT recipients with P. aeruginosa bacteremia, including hypotension, mechanical ventilation, and increasing severity of illness. In LT recipients with P. aeruginosa bacteremia, alteration in DNA gyrase A genes and overexpression of proteins involved in efflux systems, namely the expression of KPC-2-type carbapenemase, NDM-1, and VIM-2-type MBL, contribute to the high resistance of P. aeruginosa to a wide variety of antibiotics. Because of complicated mechanisms of drug resistance, P. aeruginosa causes high morbidity and mortality in bacteremic LT patients. Consequently, early detection and treatment with adequate early targeted coverage for P. aeruginosa BSI are of paramount importance in the early posttransplantation period to obtain a better prognosis for LT patients.

Sink-Related Outbreaks and Mitigation Strategies in Healthcare Facilities

PURPOSE OF REVIEW

In this review, we summarize recent outbreaks attributed to hospital sinks and examine design features and behaviors that contributed to these outbreaks. The effectiveness of various risk mitigation strategies is presented. Finally, we examine investigational strategies targeted at reducing the risk of sink-related infections.

RECENT FINDINGS

Outbreaks of hospital sink-related infections involve a diverse spectrum of microorganisms. They can be attributed to defects in sink design and hospital wastewater systems that promote the formation and dispersion of biofilm, as well as healthcare practitioner and patient behaviors. Risk mitigation strategies are often bundled; while they may reduce clinical cases, sink colonization may persist. Novel approaches targeting biofilms show promise but require more investigation. Emphasis should be placed on optimizing best practices in sink design and placement to prevent infections. Hospitals should consider developing a rational surveillance and prevention strategy based on the current design and state of their sinks.

Tap out: reducing waterborne Pseudomonas aeruginosa transmission in an intensive care unit

BACKGROUND

Pseudomonas aeruginosa is a ubiquitous and important opportunistic pathogen in immunocompromised or critically ill patients. Nosocomial P. aeruginosa outbreaks have been associated with hospital water sources.

AIM

To describe engineering interventions to minimize contamination of water outlets and the subsequent clinical impact.

METHODS

New tap outlets were fitted at selected outlets across the intensive care unit (ICU). Laboratory testing demonstrated that, following artificial contamination with P. aeruginosa, these taps could be effectively decontaminated using a thermal washer-disinfector. Water samples were collected weekly from new outlets on the ICU over an eight-month period and tested for the enumeration of P. aeruginosa via membrane filtration. Surveillance of P. aeruginosa from clinical specimens was routinely undertaken.

FINDINGS

Prior to the interventions, water sampling on ICU indicated that 30% of the outlets were positive for P. aeruginosa at any one time, and whole genome sequencing data suggested at least 30% transmission from water to patient. Since their installation, weekly sampling of the new tap outlets has been negative for P. aeruginosa, and the number of P. aeruginosa clinical isolates has fallen by 50%.

CONCLUSION

Installation and maintenance of tap outlets free of P. aeruginosa can substantially reduce the number of P. aeruginosa clinical isolates in an ICU.

Nosocomial Infections with IMP-19-Producing Pseudomonas aeruginosa Linked to Contaminated Sinks, France

We isolated IMP-19–producing Pseudomonas aeruginosa from 7 patients with nosocomial infections linked to contaminated sinks in France. We showed that bla_IMP-19 was located on various class 1 integrons among 8 species of gram-negative bacilli detected in sinks: P. aeruginosa, Achromobacter xylosoxidans, A. aegrifaciens, P. putida, Stenotrophomonas maltophilia, P. mendocina, Comamonas testosteroni, and Sphingomonas sp.

The Hospital Water Environment as a Reservoir for Carbapenem-Resistant Organisms Causing Hospital-Acquired Infections-A Systematic Review of the Literature

Over the last 20 years there have been 32 reports of carbapenem-resistant organisms in the hospital water environment, with half of these occurring since 2010. The majority of these reports have described associated clinical outbreaks in the intensive care setting, affecting the critically ill and the immunocompromised. Drains, sinks, and faucets were most frequently colonized, and Pseudomonas aeruginosa the predominant organism. Imipenemase (IMP), Klebsiella pneumoniae carbapenemase (KPC), and Verona integron-encoded metallo-β-lactamase (VIM) were the most common carbapenemases found. Molecular typing was performed in almost all studies, with pulse field gel electrophoresis being most commonly used. Seventy-two percent of studies reported controlling outbreaks, of which just more than one-third eliminated the organism from the water environment. A combination of interventions seems to be most successful, including reinforcement of general infection control measures, alongside chemical disinfection. The most appropriate disinfection method remains unclear, however, and it is likely that replacement of colonized water reservoirs may be required for long-term clearance.

Engineering waterborne Pseudomonas aeruginosa out of a critical care unit

OBJECTIVE

To describe engineering and holistic interventions on water outlets contaminated with Pseudomonas aeruginosa and the observed impact on clinical P. aeruginosa patient isolates in a large Intensive Care Unit (ICU).

DESIGN

Descriptive study.

SETTING

Queen Elizabeth Hospital Birmingham (QEHB), part of University Hospitals Birmingham (UHB) NHS Foundation Trust is a tertiary referral teaching hospital in Birmingham, UK and provides clinical services to nearly 1 million patients every year.

METHODS

Breakpoint models were used to detect any significant changes in the cumulative yearly rates of clinical P. aeruginosa patient isolates from August 2013-December 2016 across QEHB.

RESULTS

Water sampling undertaken on the ICU indicated 30% of the outlets were positive for P. aeruginosa at any one time. Molecular typing of patient and water isolates via Pulsed Field Gel Electrophoresis suggested there was a 30% transmission rate of P. aeruginosa from the water to patients on the ICU. From, February 2014, QEHB implemented engineering interventions, consisting of new tap outlets and PALL point-of-use filters; as well as holistic measures, from February 2016 including a revised tap cleaning method and appropriate disposal of patient waste water. Breakpoint models indicated the engineering and holistic interventions resulted in a significant (p<0.001) 50% reduction in the number of P. aeruginosa clinical patient isolates over a year.

CONCLUSION

Here we demonstrate that the role of waterborne transmission of P. aeruginosa in an ICU cannot be overlooked. We suggest both holistic and environmental factors are important in reducing transmission.

Spread from the Sink to the Patient: In Situ Study Using Green Fluorescent Protein (GFP)-Expressing Escherichia coli To Model Bacterial Dispersion from Hand-Washing Sink-Trap Reservoirs

There have been an increasing number of reports implicating Gammaproteobacteria as often carrying genes of drug resistance from colonized sink traps to vulnerable hospitalized patients. However, the mechanism of transmission from the wastewater of the sink P-trap to patients remains poorly understood. Herein we report the use of a designated hand-washing sink lab gallery to model dispersion of green fluorescent protein (GFP)-expressing Escherichia coli from sink wastewater to the surrounding environment. We found no dispersion of GFP-expressing E. coli directly from the P-trap to the sink basin or surrounding countertop with coincident water flow from a faucet. However, when the GFP-expressing E. coli cells were allowed to mature in the P-trap under conditions similar to those in a hospital environment, a GFP-expressing E. coli-containing putative biofilm extended upward over 7 days to reach the strainer. This subsequently resulted in droplet dispersion to the surrounding areas (<30 in.) during faucet operation. We also demonstrated that P-trap colonization could occur by retrograde transmission along a common pipe. We postulate that the organisms mobilize up to the strainer from the P-trap, resulting in droplet dispersion rather than dispersion directly from the P-trap. This work helps to further define the mode of transmission of bacteria from a P-trap reservoir to a vulnerable hospitalized patient.

IMPORTANCE Many recent reports demonstrate that sink drain pipes become colonized with highly consequential multidrug-resistant bacteria, which then results in hospital-acquired infections. However, the mechanism of dispersal of bacteria from the sink to patients has not been fully elucidated. Through establishment of a unique sink gallery, this work found that a staged mode of transmission involving biofilm growth from the lower pipe to the sink strainer and subsequent splatter to the bowl and surrounding area occurs rather than splatter directly from the water in the lower pipe. We have also demonstrated that bacterial transmission can occur via connections in wastewater plumbing to neighboring sinks. This work helps to more clearly define the mechanism and risk of transmission from a wastewater source to hospitalized patients in a world with increasingly antibiotic-resistant bacteria that can thrive in wastewater environments and cause infections in vulnerable patients.

Assessment of terminal cleaning in pediatric isolation rooms: Options for low-resource settings

BACKGROUND

Few studies have evaluated terminal cleaning in low-resource settings.

METHODS

Adequacy of pediatric isolation room terminal cleaning was evaluated using quantitative bacterial surface cultures, ATP bioluminescence assays, and fluorescent high-touch surface markers at Tygerberg Children's Hospital in South Africa (August 1, 2014-October 31, 2015). Cleaning adequacy was assessed by comparing pre- and postcleaning measurements. Influence of verbal feedback was determined by comparing cleaners' first and subsequent cleaning episodes. Cleaning methods were compared for cost, time, and feasibility.

RESULTS

Adequacy of terminal cleaning was evaluated in 25 isolation rooms after hospitalization for pulmonary tuberculosis (n = 13), respiratory (n = 5) and enteric viruses (n = 5), pertussis (n = 1), and methicillin-resistant Staphylococcus aureus (n = 1). Mean aerobic colony counts and mean ATP relative light units declined between pre- and postcleaning evaluations (39 ± 41 to 15 ± 30 [P < .001] and 72 ± 40 to 23 ± 11 [P < .001]). Fluorescent marker removal was initially poor, but improved significantly at subsequent cleaning episodes (17 out of 78 [22%] to 121 out of 198 [61%]; P < .001); mean aerobic colony counts and ATP values also declined significantly following feedback. Cost, time, and resources required for ATP and surface cultures far exceeded that required for fluorescent markers.

CONCLUSIONS

Adequacy of isolation room cleaning improved following feedback to cleaning staff. Fluorescent markers are an inexpensive option for cleaning evaluation and training in low-resource settings.

Continued transmission of Pseudomonas aeruginosa from a wash hand basin tap in a critical care unit

Pseudomonas aeruginosa is an important nosocomial pathogen, colonizing hospital water supplies including taps and sinks. We report a cluster of P. aeruginosa acquisitions during a period of five months from tap water to patients occupying the same burns single room in a critical care unit. Pseudomonas aeruginosa cultured from clinical isolates from four different patients was indistinguishable from water strains by pulsed-field gel electrophoresis. Water outlets in critical care may be a source of P. aeruginosa despite following the national guidance, and updated guidance and improved control measures are needed to reduce the risks of transmission to patients.