Multidrug-resistant Pseudomonas aeruginosa outbreaks in two hospitals: association with contaminated hospital waste-water systems

Metagenomic profiling of hospital wastewater: A comprehensive national scale analysis of antimicrobial resistance genes and opportunistic pathogens

BACKGROUND

Healthcare settings are recognised as potential hotspots for the emergence and spread of antimicrobial resistance (AMR).

METHOD

Metagenomic sequencing was conducted on a national scale using wastewater from hospitals across Wales to screen for antimicrobial resistance genes (ARGs) and opportunistic pathogens.

RESULTS

The total abundance and diversity of ARGs varied significantly across the hospitals. Genes conferring resistance to aminoglycosides, beta-lactams, and Macrolide-Lincosamide-Streptogramin-class antibiotics were predominant, with distinct resistome patterns emerging spatially. OXA-type beta-lactamases were the dominant ARG types. Spatial variability was observed in the distribution of the "big five" carbapenemases (KPC, IMP, VIM, NDM, OXA-48-like) and mcr genes, as well as WHO-listed fungal priority pathogens and Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., and Escherichia coli (ESKAPEE) pathogens. Furthermore, antibiotic concentrations in the effluents often exceeded risk quotients, posing a substantial risk for AMR emergence.

CONCLUSIONS

Overall, the study highlights the effectiveness of combining wastewater-based epidemiology with metagenomics to gain critical insights into the distinct resistome and microbiome profiles in hospital settings. Tailored strategies are essential to mitigate the spread of antibiotics, clinically relevant ARGs and pathogens in these settings. This study underscores the necessity of implementing pre-treatment processes for hospital effluents before release into community sewers and environmental waters to curb the spread of these micro-pollutants.

Outbreak investigations of contact patients and the hospital environment after detection of carbapenemase-producing Pseudomonas aeruginosa on general hospital wards

BACKGROUND

Carbapenemase-producing Pseudomonas aeruginosa (CPPA) is known to cause outbreaks in healthcare settings. Outbreak investigations, including screening of contact patients and the environment, are key in infection prevention and control (IPC) management to contain them.

AIM

The aim of this study was to determine the yield of outbreak investigations performed after unexpected detections of CPPA in clinical or screening cultures of patients hospitalized on a general ward.

METHODS

In this retrospective cohort study, we included all adult patients newly detected with CPPA ('index patients') while hospitalized on a general ward from June 2011 to December 2021. We evaluated the outbreak investigations performed, i.e., screening of epidemiologically linked patients ('contact patients') and the environment. Isolates were analysed by whole-genome sequencing (WGS).

FINDINGS

Outbreak investigations of 34 of 38 (89.5%) index patients were evaluated, with screening of contact patients performed in 34 (100%) and the environment in 18 (52.9%). CPPA was detected in eight (44.4%) of the environmental screenings, and WGS confirmed relatedness to the index in four (22.2%). A total of 1707 of 1982 (86.1%) identified contact patients were screened, of which eight carried CPPA (0.5%). WGS confirmed transmission from index patient to contact patient in five of these (0.3%).

CONCLUSION

Environmental screening should be part of outbreak investigations for CPPA, as it identifies sources which enables timely installation of targeted IPC measures. Identification of index-to-contact patient transmission was rare in our setting, thus implying reconsideration of the definition of contact patients at high risk is needed.

Drain decontamination using in-situ-generated ozone

BACKGROUND

Sink drains can be a significant source of microbial contamination in healthcare settings due to aerosolization and splashback of pathogens caused by flowing water.

AIM

To demonstrate a method of ozone disinfection of drains using a novel generation process that suppresses pathogen growth in the drain sump, whether planktonic or dwelling in biofilms.

METHODS AND RESULTS

Highly biocidal ozone was generated in situ in the drain using the ambient air sealed between the water trap and a portable cold plasma device. Safety mechanisms in the device ensured that the operator was not exposed to ozone. Subsequent bacterial recovery illustrated an approximate bioburden reduction of 5 log10 for biofilms in the drain itself, and 6 log10 for biofilms located in the sink.

CONCLUSIONS

Plasma-generated ozone is a safe and effective method for controlling bioburden in periodically wetted, otherwise inaccessible pipework and drains.

SIGNIFICANCE AND IMPACT OF STUDY

The portable ozone disinfection system described has demonstrated potential for controlling the escape of pathogens from drains. Compared with conventional liquid-based disinfection techniques, the portable ozone disinfection system has the following advantages: (i) a gaseous biocide can reach all surfaces inside the treatment target, without any restriction from orientation or surface tension; (b) ozone is effective in reducing planktonic and biofilm bacterial counts; and (c) ozone is generated at the point of use from air, using minimal electrical power, requiring no chemical delivery or storage, and producing no toxic residues.

Exploring the occurrence of Pseudomonas aeruginosa and comprehensive whole genome analysis of the bcsir_p4_s20 strain from municipal wastewater in Chattogram

Various studies reported the existence of multidrug-resistant (MDR) Pseudomonas aeruginosa in environmental samples, including hospital wastewater, municipal wastewater, and surface water. In this study, we investigated the impact of untreated municipal wastewater transmitting antibiotic-resistant P. aeruginosa strains in wastewater networks of Chattogram City, Bangladesh, through antibiotic susceptibility profiles and whole-genome sequencing (WGS) of the MDR P. aeruginosa bcsir_p4_s20. Forty-two P. aeruginosa isolates were identified from eight locations using polymerase chain reaction (PCR), targeting the oprI and oprL genes, and antibiotic susceptibility was determined against 11 antibiotics by the disc diffusion method. Resistant isolates were identified at all locations, with the highest resistance frequency displayed towards meropenem, cefepime, and colistin. The WGS of bcsir_p4_s20 was performed using the NextSeq 2000 platform. Several bioinformatics tools, like FastQC, Trimmomatic, SPAdes, and Prokka, were used for quality evaluation, low-quality read and adapter filtration, de novo assembly, and functional annotation. Comprehensive Antibiotic Resistance Database (CARD), AMRFinderPlus, and virulence factor database (VFDB) were employed to determine resistance genes and virulence factors. The strain belongs to the O7 serogroup and sequence type ST357. The analysis identified antibiotic resistance genes (blaPDC-11, sul1, and others) that cause resistance through efflux pump and inactivation mechanisms, and virulent genes responsible for adherence (flagella, type IV pili), enzyme (phospholipase C), iron uptake (pyoverdine), secretion system (exoT, exoU), and toxin (toxA) secretion. Therefore, municipal wastewater is a potential reservoir for MDR P. aeruginosa, and establishing wastewater treatment plants (WWTPs) at the primary source points before discharging it to the wastewater network is suggested to mitigate the risk of outbreaks.

Large, protracted, multi-species and multi-clonal spread of VIM-type metallo-β-lactamase-producing Enterobacterales in an Italian hospital

BACKGROUND

Carbapenem-resistant Enterobacterales, particularly those producing carbapenemase (CPE), pose a major threat to human health, being listed among critical-priority resistant pathogens by the World Health Organization.

AIM

To report on a large nosocomial spread of CPE of different species producing Verona integron-encoded metallo-β-lactamase (VIM)-type carbapenemases, and on the infection prevention and control measures that were adopted to combat the spread.

METHODS

Conventional culture and molecular methods were used for detection and identification of VIM-positive CPE (VIM-CPE) causing infections or colonizing patients or present in environmental specimens. Whole-genome sequencing analysis of selected isolates was performed to investigate clonal relatedness. Basic (active surveillance, contact precautions, close contact screening, cohorting of patients, surface cleaning, hand hygiene) and advanced (weekly point-prevalence surveys for rectal colonization, additional training of healthcare workers, extraordinary ward sanitization, extraordinary maintenance interventions, and environmental microbiological screening, single-use equipment, ward relocation) infection prevention and control (IPC) measures were implemented to combat the spread.

FINDINGS

Spread of VIM-CPE involving 151 patients (mostly colonizations) was documented in a single hospital ward from November 2021 to December 2023. The spread involved several different species of Enterobacterales, with clonal expansion documented in some cases. Implementation of basic and advanced IPC measures was temporarily successful at mitigating the spread, but multiple relapses were observed, suggesting the presence of an unidentified environmental reservoir.

CONCLUSION

VIM-CPE has the potential to cause large and complex nosocomial outbreaks in hospital environments, underscoring the challenges to their control by IPC practices.

Polymicrobial outbreak of carbapenemase producing Enterobacterales managed using universal admission and discharge screening and water-safe built environment

BACKGROUND

Carbapenemase-producing Enterobacterales (CPE) are antimicrobial resistant (AMR) bacteria which are increasing in incidence globally. Hospitals act as powerhouses for transmission of such bacteria with some regions experiencing prolonged outbreaks and high prevalence for several years. Current screening strategies are based on admission and risk-based screening only. Growing evidence supports hospital wastewater as playing a key role in transmission. We describe how changes to the CPE screening policy at Wexham Park Hospital (WPH) identified a hospital-based outbreak which, in turn, led to identification and mitigation of risks from the hospital wastewater system.

METHODS

Enhanced CPE patient screening (using a molecular methodology) was introduced to include admission and discharge screening of all patients admitted to the hospital over a 34-week period. The wastewater drainage infrastructure was surveyed, and likely interventions identified.

FINDINGS

The screening strategy detected a polymicrobial hospital-wide CPE outbreak involving different enzymes, predominantly New Delhi metallo-β-lactamase (NDM) and OXA-48 with the hospital wastewater system acting as the reservoir. During the 34-week period of enhanced screening, 1.2% of patients screened CPE positive, of which 14% of patients developed infection. Of the 65 CPE-positive patients detected, healthcare acquisition at WPH was likely in 47 (73%) patients. Mitigations to the risk from the hospital wastewater system combined with universal admission and discharge screening produced a long-standing reduction in transmission.

CONCLUSION

Universal admission and discharge screening along with introduction of water-safe concepts are effective in improving detection of CPE outbreaks and followed by a reduction of acquisition in healthcare settings where prevalence of such bacteria is increasing.

Clinical burden of community-associated infections caused by multidrug-resistant Pseudomonas aeruginosa: a propensity-matched longitudinal cohort study in Southern China

Background

Limited research has been conducted on the burden of community-associated infections caused by multidrug-resistant Pseudomonas aeruginosa (CA-MDRPa). We quantitatively modeled the incidence rate and clinical factors associated with CA-MDRPa among hospitalized patients in Southern China.

Methods

Data were obtained from the local nosocomial surveillance system. Poisson regression was applied to estimate annual incidence rate ratios (IRRs) from 2018 to 2021. After propensity-score 1:2 matching, multivariable conditional logistic regression was used to identify factors for CA-MDRPa upon admission and adverse clinical outcomes during hospitalization.

Results

278 patients were clinically and microbiologically diagnosed with CA-MDRPa and 647 with CA-non-MDRPa. CA-MDRPa rate exhibited a slight, non-significant, increase during the research period (IRR=1.03; 95% confidence interval [CI], 0.93-1.15). Neurological conditions, cardiovascular diseases, respiratory disorders, urinary tract infections, and use of cefoperazone/sulbactam prior to admission were identified as risk factors for CA-MDRPa upon admission. CA-MDRPa upon admission was associated with ESBL-producing P. aeruginosa acquisition during hospitalization (odds ratio [OR], 2.70; 95% CI, 1.53-4.77) and increased in-hospital mortality (OR, 2.24; 95% CI, 1.17-4.28).

Conclusions

The findings emphasize the importance of regular targeted screening for CA-MDRPa upon hospital admission and offer valuable insights for strengthening infection control and antimicrobial stewardship programs.

Is screening of patients for Pseudomonas aeruginosa groin/rectal carriage useful in identifying those at risk of bacteraemia in haematology and other high-risk clinical settings?

BACKGROUND

Pseudomonas aeruginosa is a leading cause of healthcare-associated infections in patients exposed to hospital waters. A rising incidence of P. aeruginosa bacteraemia at our tertiary teaching hospital prompted investigation.

AIM

Microbiological screening at patient admission to support early identification of acquisition.

METHODS

A 41-bed haematology ward (800-bed teaching-hospital, London) was surveyed between January 24th, 2020 and May 13th, 2020. Concurrent rectal and groin swabs were collected in duplicate upon admission weekly. Results were compared with historical shower, drain, and tap water contamination data.

FINDINGS

A total of 606 groin/rectal swabs were collected from 154 patients; 61 female and 93 male. Six out of 154 patients admitted (3.9%) were positive for P. aeruginosa. Two patients (1.3%; 95% confidence interval (CI): 0.16 to 4.6) were colonized at admission while four patients (2.6%; CI: 0.7 to 6.5) became colonized by 33 days (interquartile range: 13 to 54) of stay. Concurrent duplicate sampling yielded both positive and negative results in all colonized patient-cases. One patient subsequently developed P. aeruginosa bacteraemia. Shower water and corresponding drains from the four patient rooms where P. aeruginosa was acquired were heavily contaminated (>300 cfu/100 mL) with P. aeruginosa 265 days (median; range: 247-283) before patient admission.

CONCLUSION

Rectal/groin swab-screening at admission to hospital might be valuable for early detection of patient colonization but it is intrusive, resource-demanding, and yield may be low. In high-risk settings, enhanced environmental monitoring, decontamination of surfaces and drains, and point-of-use filter-barriers is recommended, especially if expected duration of stay exceeds 30 days.

Investigation of an outbreak of metallo-β-lactamase producing Pseudomonas aeruginosa linked to the water distribution system in a Hematopoietic Stem Cell Transplantation Unit

Introduction

Pseudomonas aeruginosa (PA) is an opportunistic pathogen. Metallo-β-lactamase producing PA (MBL-PA) poses a problematic issue given limited available treatments. In Argentina, it accounts for less than one percent of healthcare-associated infections.

Objectives

To describe an outbreak of verona integron-encoded metallo-β-lactamase (VIM) Pseudomonas aeruginosa in a Hematopoietic Stem Cell Transplantation Unit (HSCTU), and the strategies implemented to control it.

Materials and methods

Investigation of an outbreak by MBL-PA in an HSCTU in May 2023. Active case search, environmental sampling, identification and susceptibility pattern of strains, mitigation strategies. Case: patient admitted to the HSCTU with positive sample for MBL-PA after 48 hours of admission. Mitigation strategies: biweekly rectal swabbing, contact precautions, dedicated nursing staff, waterless patient care, and disinfection of bacterial reservoirs.

Results

In May 2023 two cases were identified. A retrospective search determined an additional case. One (10%) of the environmental samples was positive for VIM type MBL-PA in the drain of the hand hygiene station in the nurse's office. Strains were susceptible to colistin and fosfomycin and intermediate to aztreonam. Incidence density (ID) of colonization and infection by MBL-PA in the HSCTU were .68/1,000 patient-days (pd) and 0, respectively, in the second semester of 2022. In the first semester of 2023, ID rose to 2.93/1,000 pd for colonization and .73/1,000 pd for infection.Mitigation strategies aimed at reducing exposure of immunocompromised hosts to water. No new cases have been identified since.

Conclusions

We report an MBL-PA outbreak probably linked to the water distribution system in an HSCTU, and mitigation strategies put in place.

Evaluating the Efficacy of Actinidia deliciosa (Kiwi Fruit) Extract in Inhibiting Pseudomonas aeruginosa Biofilm Formation: An In Vitro Study With Therapeutic Implications

Background Gram-negative Pseudomonas aeruginosa is a common bacteria that is well-known for its capacity to build biofilms, which are organized cell communities encased in a self-produced polymeric matrix. Treating infections becomes more challenging due to biofilms' capacity to provide immunity and resistance to antibiotics. The search for novel anti-biofilm agents has gained significant momentum, and the diverse range of bioactive compounds found in natural products offers a promising avenue. Rich in vitamins, antioxidants, and various phytochemicals, Actinidia deliciosa (kiwi fruit) has demonstrated potential as an antibacterial agent. Aim of the study This study aims to assess the efficacy of A. deliciosa extract in inhibiting biofilm formation by P. aeruginosa in vitro, providing valuable insights into its potential as a natural therapeutic agent for preventing recurrent bacterial infections. Materials and methodology The antibacterial and antibiofilm properties of A. deliciosa (kiwi fruit) methanolic extract were assessed in this study against P. aeruginosa (PAO1). The fruit was gathered, examined by a botanist for authenticity, and then cold macerated in methanol to create an extract. A two-fold broth dilution procedure was used to calculate the minimum inhibitory concentration (MIC), and agar well-diffusion was used to evaluate the antimicrobial activity. Pyocyanin pigment quantification was carried out after the extract was applied, and the antibiofilm impact was evaluated using a crystal violet assay. GraphPad Prism (GraphPad Software, San Diego, CA) was used for statistical analysis. Results Based on our findings, A. deliciosa was shown to have significant antibacterial and antibiofilm properties against P. aeruginosa (PAO1). At 5 mg/mL, the methanolic extract of A. deliciosa exhibited antibacterial activity with an 8 mm zone of inhibition and suppressed PAO1 growth. At 2.5 mg/mL and 1.25 mg/mL doses, PAO1 significantly decreased the production of biofilms by 60% and 29%, respectively. In addition, pyocyanin pigment synthesis was decreased by 30% and 9.25%, respectively, at sub-MIC doses of 2.5 mg/mL and 1.25 mg/mL. When evaluated at 2.5 mg/mL, the extract did not, however, appreciably affect bacterial growth. Conclusion This study enhances the understanding of antibiotic resistance, alternative treatments, and pathogenic microbes. The in vitro findings suggest that A. deliciosa fruit extract may inhibit pyocyanin production in PAO1. Further research with different formulations is recommended to explore its anti-biofilm properties and potential pharmacological applications.

Gut microbiome diversity and biogeography for Chinese bumblebee Bombus pyrosoma

Gut microbiota of the bumblebee is critical as it modulates the health and fitness of the host. However, the mechanisms underlying the formation and maintenance of the diversity of bumblebee gut bacteria over a long period of evolution have yet to be elucidated. In particular, the gut bacterial diversity and community assembly processes of Bombus pyrosoma across the Chinese border remain unclear. In this study, we systematically carried out unprecedented sampling of 513 workers of the species Bombus pyrosoma across the Chinese landscape and used full-length 16S rRNA gene sequencing to examine their gut microbiota diversity and biogeography. The gut microbiota composition and community structure of Bombus pyrosoma from different geographical locations were diverse. On the whole, the gut bacteria Gilliamella and Snodgrassella are dominant in bumblebees, but opportunistic pathogens Serratia and Pseudomonas are dominant in some sampling sites such as Hb15, Gs1, Gs45, Qhs15, and Ssx35. All or part of environmental factors such as latitude, annual mean temperature, elevation, human footprint, population density, and annual precipitation can affect the alpha diversity and community structure of gut bacteria. Further analysis showed that the assembly and shift of bumblebee gut bacterial communities under geographical variation were mainly driven by the stochastic drift of the neutral process rather than by variable selection of niche differentiation. In conclusion, our unprecedented sampling uncovers bumblebee gut microbiome diversity and shifts over evolutionary time.

IMPORTANCE

The microbiotas associated with organisms facilitates host health and fitness, and the homeostasis status of gut microbiota also reflects the habitat security faced by the host. In addition, managing gut microbiota is important to improve bumblebee health by understanding the ecological process of the gut microbiome. Thus, we first carried out an runprecedented sampling of 513 workers of the species Bombus pyrosoma across the Chinese landscape and used full-length 16S rRNA gene sequencing to uncover their gut microbiota diversity and biogeography. Our study provides new insights into the understanding of gut microbiome diversity and shifts for Chinese Bumblebee over evolutionary time.

Controlling of foodborne pathogen biofilms on stainless steel by bacteriophages: A systematic review and meta-analysis

This study investigates the potential of using bacteriophages to control foodborne pathogen biofilms on stainless steel surfaces in the food industry. Biofilm-forming bacteria can attach to stainless steel surfaces, rendering them difficult to eradicate even after a thorough cleaning and sanitizing procedures. Bacteriophages have been proposed as a possible solution, as they can penetrate biofilms and destroy bacterial cells within, reducing the number of viable bacteria and preventing the growth and spread of biofilms. This systematic review and meta-analysis evaluates the potential of bacteriophages against different biofilm-forming foodborne bacteria, including Cronobacter sakazakii, Escherichia coli, Staphylococcus aureus, Pseudomonas fluorescens, Pseudomonas aeruginosa and Listeria monocytogenes. Bacteriophage treatment generally causes a significant average reduction of 38 % in biofilm formation of foodborne pathogens on stainless steel. Subgroup analyses revealed that phages are more efficient in long-duration treatment. Also, applying a cocktail of phages is 1.26-fold more effective than applying individual phages. Phages at concentrations exceeding 107 PFU/ml are significantly more efficacious in eradicating bacteria within a biofilm. The antibacterial phage activity decreases substantially by 3.54-fold when applied at 4 °C compared to temperatures above 25 °C. This analysis suggests that bacteriophages can be a promising solution for controlling biofilms in the food industry.

Genomic Differences Associated with Resistance and Virulence in Pseudomonas aeruginosa Isolates from Clinical and Environmental Sites

Pseudomonas aeruginosa is a pathogen that causes healthcare-associated infections (HAIs) worldwide. It is unclear whether P. aeruginosa isolated from the natural environment has the same pathogenicity and antimicrobial resistance potential as clinical strains. In this study, virulence- and resistance-associated genes were compared in 14 genomic sequences of clinical and environmental isolates of P. aeruginosa using the VFDB, PATRIC, and CARD databases. All isolates were found to share 62% of virulence genes related to adhesion, motility, secretion systems, and quorum sensing and 72.9% of resistance genes related to efflux pumps and membrane permeability. Our results indicate that both types of isolates possess conserved genetic information associated with virulence and resistance mechanisms regardless of the source. However, none of the environmental isolates were associated with high-risk clones (HRCs). These clones (ST235 and ST111) were found only in clinical isolates, which have an impact on human medical epidemiology due to their ability to spread and persist, indicating a correlation between the clinical environment and increased virulence. The genomic variation and antibiotic susceptibility of environmental isolates of P. aeruginosa suggest potential biotechnological applications if obtained from sources that are under surveillance and investigation to limit the emergence and spread of antibiotic resistant strains.

Characterization of biofilm formation and multi-drug resistance among Pseudomonas aeruginosa isolated from hospital wastewater in Dhaka, Bangladesh

Hospital wastewater has been identified as a hotspot for the emergence and transmission of multidrug-resistant (MDR) pathogens that present a serious threat to public health. Therefore, we investigated the current status of antibiotic resistance as well as the phenotypic and genotypic basis of biofilm formation in Pseudomonas aeruginosa from hospital wastewater in Dhaka, Bangladesh. The disc diffusion method and the crystal violet assay were performed to characterize antimicrobial resistance and biofilm formation, respectively. Biofilm and integron-associated genes were amplified by the polymerase chain reaction. Isolates exhibited varying degrees of resistance to different antibiotics, in which >80% of isolates showed sensitivity to meropenem, amikacin, and gentamicin. The results indicated that 93.82% of isolates were MDR and 71 out of 76 MDR isolates showed biofilm formation activities. We observed the high prevalence of biofilm-related genes, in which algD+pelF+pslD+ (82.7%) was found to be the prevalent biofilm genotypic pattern. Sixteen isolates (19.75%) possessed class 1 integron (int1) genes. However, statistical analysis revealed no significant association between biofilm formation and multidrug resistance (χ2 = 0.35, P = 0.55). Taken together, hospital wastewater in Dhaka city may act as a reservoir for MDR and biofilm-forming P. aeruginosa, and therefore, the adequate treatment of wastewater is recommended to reduce the occurrence of outbreaks.

Sink-traps are a major source for carbapenemase-producing Enterobacteriaceae transmission

OBJECTIVE

We studied the extent of carbapenemase-producing Enterobacteriaceae (CPE) sink contamination and transmission to patients in a nonoutbreak setting.

METHODS

During 2017-2019, 592 patient-room sinks were sampled in 34 departments. Patient weekly rectal swab CPE surveillance was universally performed. Repeated sink sampling was conducted in 9 departments. Isolates from patients and sinks were characterized using pulsed-field gel electrophoresis (PFGE), and pairs of high resemblance were sequenced by Oxford Nanopore and Illumina. Hybrid assembly was used to fully assemble plasmids, which are shared between paired isolates.

RESULTS

In total, 144 (24%) of 592 CPE-contaminated sinks were detected in 25 of 34 departments. Repeated sampling (n = 7,123) revealed that 52%-100% were contaminated at least once during the sampling period. Persistent contamination for >1 year by a dominant strain was common. During the study period, 318 patients acquired CPE. The most common species were Klebsiella pneumoniae, Escherichia coli, and Enterobacter spp. In 127 (40%) patients, a contaminated sink was the suspected source of CPE acquisition. For 20 cases with an identical sink-patient strain, temporal relation suggested sink-to-patient transmission. Hybrid assembly of specific sink-patient isolates revealed that shared plasmids were structurally identical, and SNP differences between shared pairs, along with signatures for potential recombination events, suggests recent sharing of the plasmids.

CONCLUSIONS

CPE-contaminated sinks are an important source of transmission to patients. Although traditionally person-to-person transmission has been considered the main route of CPE transmission, these data suggest a change in paradigm that may influence strategies of preventing CPE dissemination.

Multidrug-Resistant Bacteria Contaminating Plumbing Components and Sanitary Installations of Hospital Restrooms

Antimicrobial resistance (AMR) poses several issues concerning the management of hospital-acquired infections, leading to increasing morbidity and mortality rates and higher costs of care. Multidrug-resistant (MDR) bacteria can spread in the healthcare setting by different ways. The most important are direct contact transmission occurring when an individual comes into physical contact with an infected or colonized patient (which can involve healthcare workers, patients, or visitors) and indirect contact transmission occurring when a person touches contaminated objects or surfaces in the hospital environment. Furthermore, in recent years, toilets in hospital settings have been increasingly recognised as a hidden source of MDR bacteria. Different sites in restrooms, from toilets and hoppers to drains and siphons, can become contaminated with MDR bacteria that can persist there for long time periods. Therefore, shared toilets may play an important role in the transmission of nosocomial infections since they could represent a reservoir for MDR bacteria. Such pathogens can be further disseminated by bioaerosol and/or droplets potentially produced during toilet use or flushing and be transmitted by inhalation and contact with contaminated fomites. In this review, we summarize available evidence regarding the molecular features of MDR bacteria contaminating toilets of healthcare environments, with a particular focus on plumbing components and sanitary installation. The presence of bacteria with specific molecular traits in different toilet sites should be considered when adopting effective managing and containing interventions against nosocomial infections potentially due to environmental contamination. Finally, here we provide an overview of traditional and new approaches to reduce the spreading of such infections.

Premise Plumbing Pipe Materials and In-Building Disinfectants Shape the Potential for Proliferation of Pathogens and Antibiotic Resistance Genes

In-building disinfectants are commonly applied to control the growth of pathogens in plumbing, particularly in facilities such as hospitals that house vulnerable populations. However, their application has not been well optimized, especially with respect to interactive effects with pipe materials and potential unintended effects, such as enrichment of antibiotic resistance genes (ARGs) across the microbial community. Here, we used triplicate convectively mixed pipe reactors consisting of three pipe materials (PVC, copper, and iron) for replicated simulation of the distal reaches of premise plumbing and evaluated the effects of incrementally increased doses of chlorine, chloramine, chlorine dioxide, and copper-silver disinfectants. We used shotgun metagenomic sequencing to characterize the resulting succession of the corresponding microbiomes over the course of 37 weeks. We found that both disinfectants and pipe material affected ARG and microbial community taxonomic composition both independently and interactively. Water quality and total bacterial numbers were not found to be predictive of pathogenic species markers. One result of particular concern was the tendency of disinfectants, especially monochloramine, to enrich ARGs. Metagenome assembly indicated that many ARGs were enriched specifically among the pathogenic species. Functional gene analysis was indicative of a response of the microbes to oxidative stress, which is known to co/cross-select for antibiotic resistance. These findings emphasize the need for a holistic evaluation of pathogen control strategies for plumbing.

Influence of pipe materials on in-building disinfection of P. aeruginosa and A. baumannii in simulated hot water plumbing

A framework is needed to account for interactive effects of plumbing materials and disinfectants on opportunistic pathogens (OPs) in building water systems. Here we evaluated free chlorine, monochloramine, chlorine dioxide, and copper-silver ionization (CSI) for controlling Pseudomonas aeruginosa and Acinetobacter baumannii as two representative OPs that colonize hot water plumbing, in tests using polyvinylchloride (PVC), copper-PVC, and iron-PVC convectively-mixed pipe reactors (CMPRs). Pipe materials vulnerable to corrosion (i.e., iron and copper) altered the pH, dissolved oxygen, and disinfectant levels in a manner that influenced growth trends of the two OPs and total bacteria. P. aeruginosa grew well in PVC CMPRs, poorly in iron-PVC CMPRs, and was best controlled by CSI disinfection, whereas A. baumannii showed the opposite trend for pipe material and was better controlled by chlorine and chlorine dioxide. Various scenarios were identified in which pipe material and disinfectant can interact to either hinder or accelerate growth of OPs, illustrating the difficulties of controlling OPs in portions of plumbing systems experiencing warm, stagnant water.

In vitro and in silico evaluation of the serrapeptase effect on biofilm and amyloids of Pseudomonas aeruginosa

Pseudomonas aeruginosa is an emerging threat for hospitalized and cystic fibrosis patients. Biofilm, a microbial community embedded in extracellular polymeric substance, fortifies bacteria against the immune system. In biofilms, the expression of functional amyloids is linked with highly aggregative, multi-resistant strains, and chronic infections. Serrapeptase (SPT), a protease possessing similar or superior anti-microbial properties with many antibiotics, presents anti-amyloid potential. However, studies on the employment of SPT against Pseudomonas biofilms and Fap amyloid, or the possible mechanisms of action are scarce. Here, SPT inhibited biofilm formation of P. aeruginosa ATCC 27853 on both plastic and glass surfaces, with an IC50 of 11.26 µg/mL and 0.27 µg/mL, respectively. The inhibitory effect of SPT on biofilm was also verified with optical microscopy of crystal violet-stained biofilms and with confocal microscopy. Additionally, SPT caused a dose-dependent decrease of bacterial viability (IC50 of 3.07 µg/mL) as demonstrated by MTT assay. Reduction of bacterial functional amyloids was also demonstrated, employing both fluorescence microscopy with thioflavin T and photometrical determination of Congo-red-positive compounds. Both viability and functional amyloids correlated significantly with biofilm inhibition. Finally, in silico molecular docking studies provided a mechanistic insight into the interaction of SPT with FapC or FapD, proving that both peptides are possible targets of SPT. These results offer new insights into the biofilm formation of P. aeruginosa and potentiate the involvement of SPT in the prevention and eradication of Pseudomonas biofilms. KEY POINTS: • Serrapeptase inhibits biofilm formation of P. aeruginosa on plastic and glass. • Biofilm inhibition correlated with reduced viability and functional amyloid levels. • In silico studies indicated that serrapeptase may target FapC and FapD peptides.

Large-scale characterization of hospital wastewater system microbiomes and clinical isolates from infected patients: profiling of multi-drug-resistant microbial species

BACKGROUND

Hospital-acquired infections (HAIs) and infectious agents exhibiting antimicrobial resistance (AMR) are challenges globally. Environmental patient-facing wastewater apparatus including handwashing sinks, showers and toilets are increasingly identified as sources of infectious agents and AMR genes.

AIM

To provide large-scale metagenomics analysis of wastewater systems in a large teaching hospital in the Republic of Ireland experiencing multi-drug-resistant HAI outbreaks.

METHODS

Wastewater pipe sections (N=20) were removed immediately prior to refurbishment of a medical ward where HAIs had been endemic. These comprised toilet U-bends, and sink and shower drains. Following DNA extraction, each pipe section underwent metagenomic analysis.

FINDINGS

Diverse taxonomic and resistome profiles were observed, with members of phyla Proteobacteria and Actinobacteria dominating (38.23 ± 5.68% and 15.78 ± 3.53%, respectively). Genomes of five clinical isolates were analysed. These AMR bacterial isolates were from patients >48 h post-admission to the ward. Genomic analysis determined that the isolates bore a high number of antimicrobial resistance genes (ARGs).

CONCLUSION

Comparison of resistome profiles of isolates and wastewater metagenomes revealed high degrees of similarity, with many identical ARGs shared, suggesting probable acquisition post-admission. The highest numbers of ARGs observed were those encoding resistance to clinically significant and commonly used antibiotic classes. Average nucleotide identity analysis confirmed the presence of highly similar or identical genomes in clinical isolates and wastewater pipes. These unique large-scale analyses reinforce the need for regular cleaning and decontamination of patient-facing hospital wastewater pipes and effective infection control policies to prevent transmission of nosocomial infection and emergence of AMR within potential wastewater reservoirs.

Waterborne infections in haemato-oncology units - a narrative review

Bone marrow transplant and haemato-oncology patients are at risk of healthcare associated infections due to waterborne pathogens. We undertook a narrative review of waterborne outbreaks in haemato-oncology patients from 2000-2022. Databases searched included Pubmed, DARE and CDSR and were undertaken by two authors. We analysed the organisms implicated, sources identified and infection prevention and control strategies implemented. The most commonly implicated pathogens were Pseudomonas aeruginosa, non-tuberculous mycobacteria and Legionella pneumophila. Bloodstream infection was the most common clinical presentation. The majority of incidents employed multimodal strategies to achieve control, addressing both the water source and routes of transmission. This review highlights the risk to haemato-oncology patients from waterborne pathogens and discusses future preventative strategies and the requirement for new UK guidance for haemato-oncology units.

Genetic and environmental determinants of surface adaptations in Pseudomonas aeruginosa

Pseudomonas aeruginosa is a well-studied Gram-negative opportunistic bacterium that thrives in markedly varied environments. It is a nutritionally versatile microbe that can colonize a host as well as exist in the environment. Unicellular, planktonic cells of P. aeruginosa can come together to perform a coordinated swarming movement or turn into a sessile, surface-adhered population called biofilm. These collective behaviours produce strikingly different outcomes. While swarming motility rapidly disseminates the bacterial population, biofilm collectively protects the population from environmental stresses such as heat, drought, toxic chemicals, grazing by predators, and attack by host immune cells and antibiotics. The ubiquitous nature of P. aeruginosa is likely to be supported by the timely transition between planktonic, swarming and biofilm lifestyles. The social behaviours of this bacteria viz biofilm and swarm modes are controlled by signals from quorum-sensing networks, LasI-LasR, RhlI-RhlR and PQS-MvfR, and several other sensory kinases and response regulators. A combination of environmental and genetic cues regulates the transition of the P. aeruginosa population to specific states. The current review is aimed at discussing key factors that promote physiologically distinct transitioning of the P. aeruginosa population.

Environmental Contamination and Persistence of Clostridioides difficile in Hospital Wastewater Systems

Clostridioides difficile produces an environmentally resistant dormant spore morphotype that infected patients shed to the hospital environment. C. difficile spores persist in clinical reservoirs that are not targeted by hospital routine cleaning protocols. Transmissions and infections from these reservoirs present a hazard to patient safety. This study aimed to assess the impact of patients acutely suffering from C. difficile-associated diarrhea (CDAD) on C. difficile environmental contamination to identify potential reservoirs. Twenty-three hospital rooms accommodating CDAD inpatients with corresponding soiled workrooms of 14 different wards were studied in a German maximum-care hospital. Additionally, four rooms that never accommodated CDAD patients were examined as negative controls. Stagnant water and biofilms from sinks, toilets, and washer disinfector (WD) traps as well as swabs from cleaned bedpans and high-touch surfaces (HTSs) were sampled. For detection, a culture method was used with selective medium. A latex agglutination assay and a Tox A/B enzyme-linked immunosorbent assay were performed with suspect colonies. Stagnant water and biofilms in hospital traps (29%), WDs (34%), and HTSs (37%) were found to be reservoirs for large amounts of C. difficile during the stay of CDAD inpatients that decreased but could persist 13 ± 6 days after their discharge (13%, 14%, and 9.5%, respectively). Control rooms showed none or only slight contamination restricted to WDs. A short-term cleaning strategy was implemented that reduced C. difficile in stagnant water almost entirely. IMPORTANCE Wastewater pipes are microbial ecosystems. The potential risk of infection emanating from the wastewater for individuals is often neglected, since it is perceived to remain in the pipes. However, sewage systems start with siphons and are thus naturally connected to the outside world. Wastewater pathogens do not only flow unidirectionally to wastewater treatment plants but also retrogradely, e.g., through splashing water from siphons to the hospital environment. This study focused on the pathogen C. difficile, which can cause severe and sometimes fatal diarrheas. This study shows how patients suffering from such diarrheas contaminate the hospital environment with C. difficile and that contamination persists in siphon habitats after patient discharge. This might pose a health risk for hospitalized patients afterward. Since this pathogen's spore morphotype is very environmentally resistant and difficult to disinfect, we show a cleaning measure that can almost entirely eliminate C. difficile from siphons.

Containment of a Verona Integron-Encoded Metallo-Beta-Lactamase-Producing Pseudomonas aeruginosa Outbreak Associated With an Acute Care Hospital Sink-Tennessee, 2018-2020

Background

Contaminated healthcare facility wastewater plumbing is recognized as a source of carbapenemase-producing organism transmission. In August 2019, the Tennessee Department of Health (TDH) identified a patient colonized with Verona integron-encoded metallo-beta-lactamase-producing carbapenem-resistant Pseudomonas aeruginosa (VIM-CRPA). A record review revealed that 33% (4 of 12) of all reported patients in Tennessee with VIM had history of prior admission to acute care hospital (ACH) A intensive care unit (ICU) Room X, prompting further investigation.

Methods

A case was defined as polymerase chain reaction detection of bla_VIM in a patient with prior admission to ACH A from November 2017 to November 2020. The TDH performed point prevalence surveys, discharge screening, onsite observations, and environmental testing at ACH A. The VIM-CRPA isolates underwent whole-genome sequencing (WGS).

Results

In a screening of 44% (n = 11) of 25 patients admitted to Room X between January and June 2020, we identified 36% (n = 4) colonized with VIM-CRPA, resulting in 8 cases associated with Room X from March 2018 to June 2020. No additional cases were identified in 2 point-prevalence surveys of the ACH A ICU. Samples from the bathroom and handwashing sink drains in Room X grew VIM-CRPA; all available case and environmental isolates were found to be ST253 harboring bla_VIM-1 and to be closely related by WGS. Transmission ended after implementation of intensive water management and infection control interventions.

Conclusions

A single ICU room's contaminated drains were associated with 8 VIM-CRPA cases over a 2-year period. This outbreak highlights the need to include wastewater plumbing in hospital water management plans to mitigate the risk of transmission of antibiotic-resistant organisms to patients.

The First Swedish Outbreak with VIM-2-Producing Pseudomonas aeruginosa, Occurring between 2006 and 2007, Was Probably Due to Contaminated Hospital Sinks

Multidrug-resistant Pseudomonas aeruginosa is an increasing clinical problem worldwide. The aim of this study was to describe the first outbreak of a Verona integron-borne metallo-ß-lactamase (VIM)-2-producing P. aeruginosa strain in Sweden and its expansion in the region. A cluster of multidrug-resistant P. aeruginosa appeared at two neighbouring hospitals in 2006. The isolates were characterized by PCR, pulsed-field gel electrophoresis (PFGE), and whole-genome sequencing. Patient charts, laboratory records, and hygiene routines were reviewed, and patients, staff, and the environment were screened. The investigation revealed a clonal outbreak of a VIM-2-producing P. aeruginosa strain belonging to the high-risk clonal complex 111, susceptible only to gentamicin and colistin. No direct contact between patients could be established, but most of them had stayed in certain rooms/wards weeks to months apart. Cultures from two sinks yielded growth of the same strain. The outbreak ended when control measures against the sinks were taken, but new cases occurred in a tertiary care hospital in the region. In conclusion, when facing prolonged outbreaks with this bacterium, sinks and other water sources in the hospital environment should be considered. By implementing proactive control measures to limit the bacterial load in sinks, the waterborne transmission of P. aeruginosa may be reduced.

Adsorption of BSA Protein in Aqueous Medium Using Vegetable Tannin Resin from Acacia mearnsii (Mimosa) and Modified Lignocellulosic Fibers from the Bark of Eucalyptus citriodora

Proteins are abundant biomolecules found in human cells, as well as pathogenic bacteria and viruses. Some of them become pollutants when released into water. Adsorption is an advantageous method for separating proteins in aqueous media since proteins are already immobilized on solid surfaces. Adsorbents with surfaces rich in tannins are efficient due to their affinity for strong interactions with the various amino acids that make up proteins. This work aimed to develop an adsorbent for protein adsorption in aqueous medium using lignocellulosic materials modified from eucalyptus bark and vegetable tannins. A more efficient resin was prepared containing 10% eucalyptus bark fibers and 90% tannin mimosa by condensation with formaldehyde, and it was characterized by UV-Vis, FTIR-ATR spectroscopy and determinations of degree of swelling, bulk and bulk density and specific mass. For UV-Vis spectroscopy the percentage of condensed and hydrolysable tannins in the extracts of fibers of the dry husks of Eucalyptus Citriodora was estimated and it was also determined your soluble solids. The study of bovine serum albumin (BSA) adsorption was carried out in batch with quantification by UV-Vis spectroscopy. The most efficient prepared resin obtained 71.6 ± 2.78% removal in a solution of 260 mg L-1 of BSA working in a better pH range of the aqueous solution of BSA in its isoelectric point, ~ 5, 32 ± 0.02, under these conditions, the synthesized resin can reach a maximum BSA adsorption capacity of ~ 26.7 ± 0.29 mg g-1 in 7 min. The new synthesized resin presents good prospects for adsorption of proteins or species that in their structure have higher percentages of amino functional groups or amino acids with aliphatic, acidic and/or basic hydrophilic characteristics.

Graphical Abstract

Aspects and problems associated with the water services to be considered in intensive care units

Background

Water is a product taken for granted and assumed to be a safe commodity in intensive care units (ICU). Biofilm readily becomes established in complex water services presenting a risk to vulnerable patients. Harboured within biofilms are opportunistic pathogens which can be transmitted via hand contact, splashing, aerosol and indirect contact through medical equipment. Evidence linking the role of water services in transmission of infection to patients in ICUs has increased in recent years.

Aims

This research based commentary set out to identify current problems with water and wastewater systems in ICU settings.

Methods

Databases and open source information was used to obtain data on current water and wastewater-related issues in ICU settings. This and the authors experiences have been used to describe current challenges.

Findings

the authors found a number of problems with water systems in ICU to which there has not been a cohesive response in terms of guidance to support users and designers. The resultant void permits new projects to proceed with suboptimal and designs which place patients and staff at risk.

Discussion

Hand hygiene stations are frequently misused or close enough to patients such that splashing poses a transmission risk. The wastewater system (drain) also presents a risk, from where Gram-negative antibiotic resistant organisms may be dispersed resulting in untreatable patient infections. The water and wastewater system provide a superhighway for the movement of pathogenic microorganisms and these risks need to be addressed if we are to safeguard vulnerable users in ICU.

Scavenging of reactive oxygen species effectively reduces Pseudomonas aeruginosa biofilms through disrupting policing

Biofilm formation is likely to contribute greatly to antibiotic resistance in bacteria and therefore the efficient removal of bacterial biofilms needs addressing urgently. Here, we reported that the supplement of non-inhibitory concentration of N-acetyl-L-cysteine (NAC), a common reactive oxygen species (ROS) scavenger, can significantly reduce the biomass of mature Pseudomonas aeruginosa biofilms (corroborated by crystal violet assay and laser scanning confocal microscopy). 1 mM NAC increased the cheater (ΔlasR mutant) frequency to 89.4 ± 1.5% in the evolved PAO1 after the 15-day treatment. Scavenging of ROS by NAC induced the collapse of P. aeruginosa biofilms, but it did not alter quorum sensing-regulated genes expression (e.g., hcnC and cioAB) and hydrogen cyanide production. The replenishment of public good protease contributed to the recovery of biofilm biomass, indicating the role of disrupting policing in biofilm inhibition. Furthermore, 7 typical ROS scavengers (e.g., superoxide dismutase, catalase and peroxidase, etc.) also effectively inhibited mature P. aeruginosa biofilms. This study demonstrates that scavenging of ROS can promote the selective control of P. aeruginosa biofilms through policing disruption as a targeted biofilm control strategy in complex water environments.

A protracted outbreak of difficult-to-treat resistant Pseudomonas aeruginosa in a haematology unit: a matched case-control study demonstrating increased risk with use of fluoroquinolone

BACKGROUND

Between September 2016 and November 2020, 17 cases of difficult-to-treat resistant Pseudomonas aeruginosa (DTR-PA) were reported in haematology patients at a tertiary referral hospital in the North of England.

AIM

A retrospective case-control study was conducted to investigate the association between DTR-PA infection and clinical interventions, patient movement, antimicrobial use and comorbidities.

METHODS

Cases were patients colonized or infected with the outbreak strain of DTR-PA who had been admitted to hospital prior to their positive specimen. Exposures were extracted from medical records, and cases were compared with controls using conditional logistic regression. Environmental and microbiological investigations were also conducted.

FINDINGS

Seventeen cases and 51 controls were included. The final model included age [>65 years, adjusted OR (aOR) 6.85, P=0.232], sex (aOR 0.60, P=0.688), admission under the transplant team (aOR 14.27, P=0.43) and use of ciprofloxacin (aOR 102.13, P=0.030). Investigations did not indicate case-to-case transmission or a point source, although a common environmental source was highly likely.

CONCLUSION

This study found that the use of fluoroquinolones is an independent risk factor for DTR-PA in haematology patients. Antimicrobial stewardship and review of fluoroquinolone prophylaxis should be considered as part of PA outbreak investigations in addition to standard infection control interventions.

Better Outcome of Off-Label High-Dose Ceftazidime in Hemato-Oncological Patients with Infections Caused by Extensively Drug-Resistant Pseudomonas Aeruginosa

Background

P. aeruginosa sepsis in immunocompromised patients is a serious complication of cancer treatment, especially in the case of an Extensively Drug Resistant (XDR) pathogen. The aim of the study is to evaluate the efficacy of high-dose ceftazidime in the treatment of XDR P. aeruginosa infection and to compare it with the conventionally treated cohort in hemato-oncological patients.

Methods

We identified 27 patients with XDR P. aeruginosa infection during the 2008-2018 period, 16 patients served as a conventionally treated cohort with an antipseudomonal beta-lactam antibiotic in standard dose (cohort A), and 11 patients were treated with high-dose ceftazidime (cohort B). Most of the patients were neutropenic and under active treatment for their cancer in both cohorts.

Results

Mortality and related mortality were statistically significantly better for cohort B than cohort A; it was 18.2% and 9.1% for cohort B and 68.8% and 68.8% for cohort A, respectively. More patients in cohort A needed mechanical ventilation and renal replacement therapy, 75% and 50% for cohort A and 27.3% and 9.9% for cohort B, respectively. It corresponded well with the worst sequential organ failure score (SOFA) in cohort A compared to cohort B, 16 versus 7, respectively. Reversible neurotoxicity was seen only in two patients in cohort B.

Conclusion

Ceftazidime in high doses is a very potent antibiotic (ATB) for treating XDR P. aeruginosa infections in neutropenic cancer with acceptable toxicity.

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.

Transmission of COVID-19 and other infectious diseases in public washrooms: A systematic review

BACKGROUND

The risk of infectious disease transmission in public washrooms causes concern particularly in the context of the COVID-19 pandemic. This systematic review aims to assess the risk of transmission of viral or bacterial infections through inhalation, surface contact, and faecal-oral routes in public washrooms in healthcare and non-healthcare environments.

METHODS

We systematically reviewed environmental sampling, laboratory, and epidemiological studies on viral and bacterial infection transmission in washrooms using PubMed and Scopus. The review focused on indoor, publicly accessible washrooms.

RESULTS

Thirty-eight studies from 13 countries were identified, including 14 studies carried out in healthcare settings, 10 in laboratories or experimental chambers, and 14 studies in restaurants, workplaces, commercial and academic environments. Thirty-three studies involved surface sampling, 15 air sampling, 8 water sampling, and 5 studies were risk assessments or outbreak investigations. Infectious disease transmission was studied in relation with: (a) toilets with flushing mechanisms; (b) hand drying systems; and (c) water taps, sinks and drains. A wide range of enteric, skin and soil bacteria and enteric and respiratory viruses were identified in public washrooms, potentially posing a risk of infection transmission. Studies on COVID-19 transmission only examined washroom contamination in healthcare settings.

CONCLUSION

Open-lid toilet flushing, ineffective handwashing or hand drying, substandard or infrequent surface cleaning, blocked drains, and uncovered rubbish bins can result in widespread bacterial and/or viral contamination in washrooms. However, only a few cases of infectious diseases mostly related to faecal-oral transmission originating from washrooms in restaurants were reported. Although there is a risk of microbial aerosolisation from toilet flushing and the use of hand drying systems, we found no evidence of airborne transmission of enteric or respiratory pathogens, including COVID-19, in public washrooms. Appropriate hand hygiene, surface cleaning and disinfection, and washroom maintenance and ventilation are likely to minimise the risk of infectious disease transmission.

Drains and the periphery of the water system - what do you do when the guidance is outdated?

The periphery of the water system (defined as the last 2 m of pipework from an outlet and ensuing devices including drainage), is the juncture of multiple inherent risks: the necessity to use materials with higher risk of biofilm formation, difficulty in maintaining safe water temperatures, a human interface with drainage systems, poor design, poor layout and use by staff. Add to this risk a large new healthcare facility capital build programme in England, outdated guidance and bacteria emanating from drainage systems containing highly mobile genetic elements (threatening the end of the antibiotic era), and the scene is set for the perfect storm.

There is an urgent need for the re-evaluation of the periphery of the water system and drainage systems. Consequently, in this article we examine the requirement and placement of hand wash stations (HWSs), design of showers, kitchens and the dirty utility with respect to water services. Lastly, we discuss the provision of safe water to high-risk patient groups. The purpose of this article is to stimulate debate and provide infection control and design teams with support in deviating from the outdated existing guidance and to challenge conventional thinking until new advice is forthcoming.

National surveillance pilot study unveils a multicenter, clonal outbreak of VIM-2-producing Pseudomonas aeruginosa ST111 in the Netherlands between 2015 and 2017

Verona Integron-encoded Metallo-beta-lactamase (VIM) is the most frequently-encountered carbapenemase in the healthcare-related pathogen Pseudomonas aeruginosa. In the Netherlands, a low-endemic country for antibiotic-resistant bacteria, no national surveillance data on the prevalence of carbapenemase-producing P. aeruginosa (CPPA) was available. Therefore, in 2016, a national surveillance pilot study was initiated to investigate the occurrence, molecular epidemiology, genetic characterization, and resistomes of CPPA among P. aeruginosa isolates submitted by medical microbiology laboratories (MMLs) throughout the country. From 1221 isolates included in the study, 124 (10%) produced carbapenemase (CIM-positive); of these, the majority (95, 77%) were positive for the bla_VIM gene using PCR. Sequencing was performed on 112 CIM-positive and 56 CIM-negative isolates (n = 168), and genetic clustering revealed that 75/168 (45%) isolates were highly similar. This genetic cluster, designated Group 1, comprised isolates that belonged to high-risk sequence type ST111/serotype O12, had similar resistomes, and all but two carried the bla_VIM-2 allele on an identical class 1 integron. Additionally, Group 1 isolates originated from around the country (i.e. seven provinces) and from multiple MMLs. In conclusion, the Netherlands had experienced a nationwide, inter-institutional, clonal outbreak of VIM-2-producing P. aeruginosa for at least three years, which this pilot study was crucial in identifying. A structured, national surveillance program is strongly advised to monitor the spread of Group 1 CPPA, to identify emerging clones/carbapenemase genes, and to detect transmission in and especially between hospitals in order to control current and future outbreaks.

Migration of Escherichia coli and Klebsiella pneumoniae Carbapenemase (KPC)-Producing Enterobacter cloacae through Wastewater Pipework and Establishment in Hospital Sink Waste Traps in a Laboratory Model System

Sink waste traps and drains are a reservoir for multi-drug resistant Gram-negative bacteria in the hospital environment. It has been suggested that these bacteria can migrate through hospital plumbing. Hospital waste traps were installed in a laboratory model system where sinks were connected through a common wastewater pipe. Enterobacterales populations were monitored using selective culture, MALDI-TOF identification and antibiotic resistance profiling before and after a wastewater backflow event. When transfer between sinks was suspected, isolates were compared using whole-genome sequencing. Immediately after the wastewater backflow, two KPC-producing Enterobacter cloacae were recovered from a waste trap in which Carbapenemase-producing Enterobacterales (CPE) had not been detected previously. The isolates belonged to ST501 and ST31 and were genetically indistinguishable to those colonising sinks elsewhere in the system. Following inter-sink transfer, KPC-producing E. cloacae ST501 successfully integrated into the microbiome of the recipient sink and was detected in the waste trap water at least five months after the backflow event. Seven weeks and three months after the backflow, other inter-sink transfers involving Escherichia coli ST5295 and KPC-producing E. cloacae ST501 were also observed.

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.

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

BACKGROUND

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.

AIM

To describe the investigation and control measures implemented for a waterborne infection outbreak in a new build hospital.

METHODS

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.

FINDINGS

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.

CONCLUSION

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.

Prevalence of Antibiotic-Resistant Bacteria ESKAPE among Healthy People Estimated by Monitoring of Municipal Wastewater

There is increasing attention toward factors that potentially contribute to antibiotic resistance (AR), as well as an interest in exploring the emergence and occurrence of antibiotic resistance bacteria (ARB). We monitored six ARBs that cause hospital outbreaks in wastewater influent to highlight the presence of these ARBs in the general population. We analyzed wastewater samples from a municipal wastewater treatment plant (MWWTP) and hospital wastewater (HW) for six species of ARB: Carbapenem-resistant Enterobacteria (CARBA), extended-spectrum β-lactamase producing Enterobacteria (ESBL), multidrug-resistant Acinetobacter (MDRA), multidrug-resistant Pseudomonas aeruginosa (MDRP), methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococci (VRE). We registered a high percentage of ARBs in MWWTP samples (>66%) for all ARBs except for MDRP, indicating a high prevalence in the population. Percentages in HW samples were low (<78%), and no VRE was detected throughout the study. CARBA and ESBL were detected in all wastewater samples, whereas MDRA and MRSA had a high abundance. This result demonstrated the functionality of using raw wastewater at MWWTP to monitor the presence and extent of ARB in healthy populations. This kind of surveillance will contribute to strengthening the efforts toward reducing ARBs through the detection of ARBs to which the general population is exposed.

Nosocomial Infections: Pathogenicity, Resistance and Novel Antimicrobials

Background. The fight against the spread of infectious diseases creates the problem of resistance to pathogens and the most resistant of them – the propagators of nosocomial infections – are formed in hospitals because of a number of reasons. The solution of the problem lies in different areas, but the search of new effective means for the treatment of such diseases remains relevant right today. The shortest way to do this is to find the "pain points" of the pathogens themselves, i.e. the factors of their pathogenicity and resistance to which the action of novel antiseptics should be directed. Objective. We aimed to analyse and evaluate the main factors of pathogenicity and resistance of pathogens of nosocomial infections to determine modern approaches to the development of novel antimicrobials. Methods. Search and systematization of new scientific data and results concerning pathogenic factors of microbial pathogens that can be used as targets for the action of drugs. Results. Over the last 10–20 years, due to the development of new research methods in biology, it has become possible to clarify the features and additional conditions for the detection of pathogenic factors of nosocomial infections. Additional mechanisms of manifestation of resistance, adhesiveness, invasiveness, transmission of signs, secretion of toxins by pathogens are shownthat determines the general increase of their resistance to the action of currently used means. The general idea of ​​creating antiseptics that will not increase the resistance of pathogens can now be implemented by using substances with multidirectional or indirect mechanisms of action that minimally affect the metabolism of the cell and significantly reduce its resistance and pathogenicity. Conclusions. Factors of pathogenicity of propagators of nosocomial infections and mechanisms of their implementation can be considered as the main targets for the action of novel antiseptics that will inhibit the spread of pathogens without increasing their resistance. The promising substances for such drugs, among other things, are bacteriophages and their modifications, enzybiotics, immunobiotics, autoinducer inhibitors, quorum sensing-system inhibitors, b-lactamase inhibitors and others. Some of these substances in combination with the new generation of antibiotics significantly enhance their effectiveness and together they are able to overcome the resistance of even multidrug-resistant pathogens.

A splash-reducing clinical handwash basin reduces droplet-mediated dispersal from a sink contaminated with Gram-negative bacteria in a laboratory model system

Infection prevention strategies need to be identified and evaluated to reduce the risk associated with contaminated hospital sinks. This study used settle plates to compare the dispersal of Gram-negative bacteria from a conventional, rear-draining clinical handwash basin (CHWB) and a 'splash-reducing' CHWB with and/or without impaired drainage. Two scenarios were assessed: dispersal from a contaminated basin and dispersal from a contaminated drain. The associated tap was operated for 1 min and, for all contamination scenarios, the 'splash-reducing' CHWB had significantly lower odds of spreading contamination than the conventional CHWB.