Water faucets as a source of Pseudomonas aeruginosa infection and colonization in neonatal and adult intensive care unit patients

Reservoirs of Nosocomial Pathogens in Intensive Care Units: A Systematic Review

Background

Nosocomial pathogens are known to exacerbate morbidity and mortality in contemporary critical healthcare. Hospital fomites, which include inanimate surfaces, have been identified as "breeding grounds" for pathogens that cause nosocomial infections. This systematic review aimed to deliver incisive insights on nosocomial pathogens in intensive care units (ICUs) and the role of fomites as potential reservoirs for their transmission.

Method

An extensive exploration of electronic databases, including PubMed and Scopus, from 1990 to 2023, was carried out between 25th and 29th May 2023, per standard PRISMA guidelines. Information were extracted from articles that reported on fomites in the ICU. Studies that did not quantitatively report the fomite contamination, and those that exclusively took samples from patients in the ICU were excluded from the analysis.

Results

About 40% of the total samples collected on fomites from all the studies yielded microbial growth, with species of Staphylococcus being the most predominant. Other prevalent microbes were Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Candida spp., Enterococcus sp., and Enterobacter sp. The neonatal intensive care unit (NICU) had the highest proportion of contaminated fomites. Among known fomites, the sphygmomanometer exhibited a 100% detection rate of nosocomial pathogens. This included E. aerogenes, Staphylococcus aureus, coagulase-negative Staphylococci (CoNS), E. coli, and K. pneumoniae. Multidrug-resistant (MDR) bacteria, such as methicillin-resistant S. aureus (MRSA), vancomycin-resistant Enterococci (VRE), extended-spectrum beta-lactamase (ESBL)-producing E. coli, and MDR Pseudomonas aeruginosa were commonly isolated on fomites in the ICUs.

Conclusion

Many fomites that are readily used in patient care in the ICU harbour nosocomial pathogens. The most common fomite appeared to be mobile phones, sphygmomanometers, and stethoscopes, with Staphylococcus being the most common contaminant. Consequently, the need for rigorous disinfection and sterilization protocols on fomites in the ICU cannot be overemphasized. Additionally, heightened awareness on the subject among health professionals is crucial to mitigating the risk and burden of nosocomial infections caused by drug-resistant bacteria.

Plasmid-Borne AFM Alleles in Pseudomonas aeruginosa Clinical Isolates from China

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a pathogen of global concern due to the fact that therapeutic drugs are limited. Metallo-β-lactamase (MBL)-producing P. aeruginosa has become a critical part of CRPA. Alcaligenes faecalis metallo-β-lactamase (AFM) is a newly identified subclass B1b MBL. In this study, 487 P. aeruginosa strains isolated from patients and the environment in an intensive care unit were screened for AFM alleles. Five AFM-producing strains were identified, including four AFM-2-producing strains (ST262) and one AFM-4-producing strain (ST671). AFM-2-producing strains were isolated from rectal and throat swabs, and AFM-4-producing strains were isolated from the water sink. The bla_AFM-2 carrying plasmids belonged to the IncP-2 type, while the bla_AFM-4 carrying plasmid pAR19438 was a pSTY-like megaplasmid. Plasmid pAR19438 was acquired bla_AFM-4 by the integration of the Tn1403-like transposon. All bla_AFM genes were embedded in an ISCR29-bla_AFM unit core module flanked by class 1 integrons. The core module of bla_AFM-2 was ISCR29-ΔgroL-bla_AFM-2-ble_MBL-ΔtrpF-ΔISCR, while the core module of bla_AFM-4 was ISCR29-ΔgroL-bla_AFM-2-ble_MBL-ΔtrpF-ISCR-msrB-msrA-yfcG-corA-ΔISCR. The flanking sequences of ISCR29-bla_AFM units also differed. The expression of AFM-2 and AFM-4 in DH5α and PAO1 illustrated the same effect for the evaluation of the MICs of β-lactams, except for aztreonam. Identification of AFM-4 underscores that the quick spread and emerging development of mutants of MBLs require continuous surveillance in P. aeruginosa. IMPORTANCE Acquiring metallo-β-lactamase genes is one of the important carbapenem resistance mechanisms of P. aeruginosa. Alcaligenes faecalis metallo-β-lactamase is a newly identified metallo-β-lactamase, the prevalence and genetic context of which need to be explored. In this study, we identified AFM-producing P. aeruginosa strains among clinical isolates and found a new mutant of AFM, AFM-4. The bla_AFM-4 carrying plasmid pAR19438 was a pSTY-like megaplasmid, unlike the plasmids encoding other bla_AFM alleles. The genetic context of bla_AFM-4 was also different. However, AFM-2 and AFM-4 had the same impacts on antibiotic susceptibility. The presence and transmission of AFM alleles in P. aeruginosa pose a challenge to clinical practice.

Discordance among Belief, Practice, and the Literature in Infection Prevention in the NICU

This study evaluates practices of infection control in the NICU as compared with the available literature. We aimed to assess providers’ awareness of their institutional policies, how strongly they believed in those policies, the correlation between institution size and policies adopted, years of experience and belief in a policy’s efficacy, and methods employed in the existing literature. An IRB-approved survey was distributed to members of the AAP Neonatal Section. A systematic review of the literature provided the domains of the survey questions. Data was analyzed as appropriate. A total of 364 providers responded. While larger NICUs were more likely to have policies, their providers are less likely to know them. When a policy is in place and it is known, providers believe in the effectiveness of that policy suggesting consensus or, at its worst, groupthink. Ultimately, practice across the US is non-uniform and policies are not always consistent with best available literature. The strength of available literature is adequate enough to provide grade B recommendations in many aspects of infection prevention. A more standardized approach to infection prevention in the NICU would be beneficial and is needed.

Considerations for large building water quality after extended stagnation

The unprecedented number of building closures related to the coronavirus disease (COVID-19) pandemic is concerning because water stagnation will occur in many buildings that do not have water management plans in place. Stagnant water can have chemical and microbiological contaminants that pose potential health risks to occupants. Health officials, building owners, utilities, and other entities are rapidly developing guidance to address this issue, but the scope, applicability, and details included in the guidance vary widely. To provide a primer of large building water system preventative and remedial strategies, peer-reviewed, government, industry, and nonprofit literature relevant to water stagnation and decontamination practices for plumbing was synthesized. Preventative practices to help avoid the need for recommissioning (e.g., routine flushing) and specific actions, challenges, and limitations associated with recommissioning were identified and characterized. Considerations for worker and occupant safety were also indicated. The intended audience of this work includes organizations developing guidance.

Considerations for Large Building Water Quality after Extended Stagnation

The unprecedented number of building closures related to the coronavirus disease (COVID‐19) pandemic is concerning because water stagnation will occur in many buildings that do not have water management plans in place. Stagnant water can have chemical and microbiological contaminants that pose potential health risks to occupants. Health officials, building owners, utilities, and other entities are rapidly developing guidance to address this issue, but the scope, applicability, and details included in the guidance vary widely. To provide a primer of large building water system preventative and remedial strategies, peer‐reviewed, government, industry, and nonprofit literature relevant to water stagnation and decontamination practices for plumbing was synthesized. Preventative practices to help avoid the need for recommissioning (e.g., routine flushing) and specific actions, challenges, and limitations associated with recommissioning were identified and characterized. Considerations for worker and occupant safety were also indicated. The intended audience of this work includes organizations developing guidance.

Faucet aerators as a reservoir for Carbapenem-resistant Acinetobacter baumannii: a healthcare-associated infection outbreak in a neurosurgical intensive care unit

Background

On January 7, 2019, we observed an outbreak of healthcare-associated infection (HAI) caused by Carbapenem-resistant Acinetobacter baumannii (CRAB) in the neurosurgical intensive care unit (NSICU). A follow-up epidemiological investigation was conducted, and an emergency response was initiated. We aimed to study the clonal transmission of CRAB and its possible source.

Methods

A matched case-control (1:2) study was performed to identify the possible predisposing factors. A multifaceted intervention was implemented to control the outbreak. We collected environmental samples from patients' rooms and living area of the staff. CRAB isolates were tested for genetic relatedness by Pulsed-Field Gel Electrophoresis (PFGE).

Results

Environmental sampling showed that a faucet aerator was contaminated with A. baumannii. Molecular typing revealed the only outbreak strain, which was isolated from tracheal aspirate cultures of the first case of community-acquired infection and 3 cases of HAI. In environmental samples, the outbreak strain was found only in the faucet aerator of the dining room. This CRAB outbreak was discovered in time, and further progress of this outbreak was prevented through a pre-set emergency response procedure.

Conclusions

The faucet aerator acted as a reservoir for bacteria in the outbreak, and contamination of the faucet aerator might have occurred from splashes originating from handwashing by the healthcare workers (HCWs). In high-risk areas, such as NSICU, the faucet aerators should not be used during an outbreak or they should be regularly cleaned and disinfected. The start-up criteria for the emergency response played a key role in controlling the CRAB outbreak, and its settings should be discussed more widely.

Effects of a disinfection device on colonization of sink drains and patients during a prolonged outbreak of multidrug-resistant Pseudomonas aeruginosa in an intensive care unit

BACKGROUND

Sink drains in intensive care units (ICUs) are frequently colonized with bacteria such as Pseudomonas aeruginosa.

AIM

To study the influence of installing disinfecting devices on sink drains on colonization of sinks and patients in an ICU during a prolonged outbreak of multidrug-resistant P. aeruginosa.

METHODS

From 2010, there was a clonal outbreak of multidrug-resistant P. aeruginosa (MDR-PA). In April 2013, in ICU subunit A, the siphons draining these sinks were replaced by devices applying heat and electromechanical vibration to disinfect the draining fluid. In the other units, siphons were replaced by new polyvinyl chloride plastic siphons (control). In February 2016 the disinfecting devices were also placed at ICU subunit B.

FINDINGS

Baseline colonization rate of sinks was 51% in ICU A and 46% in ICU B. In ICU A colonization decreased to 5% (P < 0.001) after the intervention whereas it was 62% in ICU B (control). After installing the disinfection devices in ICU B, colonization rate was 8.0 and 2.4% in ICU A and B, respectively (both P < 0.001 compared with baseline). Colonization in ICU patients decreased from 8.3 to 0 per 1000 admitted patients (P < 0.001) and from 2.7 to 0.5 per 1000 admitted patients (P = 0.1) in ICU A and B respectively.

CONCLUSION

Colonization with MDR-PA in sink drains in an ICU was effectively managed by installing disinfection devices to the siphons of sinks. Colonization of patients was also significantly reduced, suggesting that sink drains can be a source of clinical outbreaks with P. aeruginosa and that disinfecting devices may help to interrupt these outbreaks.

Strategies for the Preservation, Restoration and Modulation of the Human Milk Microbiota. Implications for Human Milk Banks and Neonatal Intensive Care Units

Studies carried in the last years have revealed that human milk contains a site-specific microbiota and constitutes a source of potentially beneficial bacteria to the infant gut. Once in the infant gut, these bacteria contribute to the assembly of a physiological gut microbiota and may play several functions, contributing to infant metabolism, protection against infections, immunomodulation or neuromodulation. Many preterm neonates are fed with pasteurized donor’s human milk (DHM) or formula and, therefore, are devoid of contact with human milk microbes. As a consequence, new strategies are required to allow the exposition of a higher number of preterm infants to the human milk microbiota early in life. The first strategy would be to promote and to increase the use of own mother’s milk (OMM) in Neonatal Intensive Care Units (NICUs). Even small quantities of OMM can be very valuable since they would be added to DHM in order to microbiologically “customize” it. When OMM is not available, a better screening of donor women, including routine cytomegalovirus (CMV) screening of milk, may help to avoid the pasteurization of the milk provided by, at least, a relevant proportion of donors. Finally, when pasteurized DHM or formula are the only feeding option, their supplementation with probiotic bacteria isolated from human milk, such as lactic acid bacteria or bifidobacteria, may be an alternative to try to restore a human milk-like microbiota before feeding the babies. In the future, the design of human milk bacterial consortia (minimal human milk microbiotas), including well characterized strains representative of a healthy human milk microbiota, may be an attractive strategy to provide a complex mix of strains specifically tailored to this target population.

High-Temperature Short-Time Pasteurization System for Donor Milk in a Human Milk Bank Setting

Donor milk is the best alternative for the feeding of preterm newborns when mother's own milk is unavailable. For safety reasons, it is usually pasteurized by the Holder method (62.5°C for 30 min). Holder pasteurization results in a microbiological safe product but impairs the activity of many biologically active compounds such as immunoglobulins, enzymes, cytokines, growth factors, hormones or oxidative stress markers. High-temperature short-time (HTST) pasteurization has been proposed as an alternative for a better preservation of some of the biological components of human milk although, at present, there is no equipment available to perform this treatment under the current conditions of a human milk bank. In this work, the specific needs of a human milk bank setting were considered to design an HTST equipment for the continuous and adaptable (time-temperature combination) processing of donor milk. Microbiological quality, activity of indicator enzymes and indices for thermal damage of milk were evaluated before and after HTST treatment of 14 batches of donor milk using different temperature and time combinations and compared to the results obtained after Holder pasteurization. The HTST system has accurate and simple operation, allows the pasteurization of variable amounts of donor milk and reduces processing time and labor force. HTST processing at 72°C for, at least, 10 s efficiently destroyed all vegetative forms of microorganisms present initially in raw donor milk although sporulated Bacillus sp. survived this treatment. Alkaline phosphatase was completely destroyed after HTST processing at 72 and 75°C, but γ-glutamil transpeptidase showed higher thermoresistance. Furosine concentrations in HTST-treated donor milk were lower than after Holder pasteurization and lactulose content for HTST-treated donor milk was below the detection limit of analytical method (10 mg/L). In conclusion, processing of donor milk at 72°C for at least 10 s in this HTST system allows to achieve the microbiological safety objectives established in the milk bank while having a lower impact regarding the heat damage of the milk.

Molecular epidemiology, resistance, and virulence properties of Pseudomonas aeruginosa cross-colonization clonal isolates in the non-outbreak setting

Pseudomonas aeruginosa is the predominant opportunistic pathogen leading to nosocomial infection and outbreak in hospitals. Hospitalized patients may be infected with this bacterium through close contact with contaminated environmental media. However, the molecular epidemiology, resistance, and virulence properties of Pseudomonas aeruginosa cross-colonization isolates has received limited attention in the non-outbreak setting. This study aims to investigate the epidemiological relationship of clinical and environmental P. aeruginosa isolates and to characterize the resistance and virulence properties of clonal clusters and sporadic strains in a non-outbreak setting. A total of 436 patients were screened for P. aeruginosa during hospitalization, and environmental samples were taken from their immediate ward media, including faucets, doorknobs, bedrails, pillows, quilts, and mattresses. As a result, 100 P. aeruginosa isolates were obtained, including 74 clinical strains and 26 environmental strains. By using Pulsed-Field Gel Electrophoresis, the fingerprint displayed 20 distinct clusters and 44 sporadic strains. According to identical genotypes, there were clear P. aeruginosa cross-colonization processes from the ward media to inpatients, indicating faucets, bedrails, and pillows as the main propagation media that had been contaminated by clonal isolates previously detected in other patients. In addition, there were P. aeruginosa transmission processes between inpatients that were unexplained for lack of epidemiological evidence. As compared to sporadic strains of P. aeruginosa, clonal clusters are more capable of producing high-level biofilm, developing multi-drug resistance and inducing high-degree cytotoxicity. Among P. aeruginosa clonal clusters, there was a strong positive correlation between antibiotic resistance and biofilm production. We conclude that constant cross-colonization of P. aeruginosa clonal isolates will pose a long-term serious threat in terms of nosocomial outbreaks. Thus, strict disinfection and sterilization procedures should be implemented for ward media, and P. aeruginosa in environments and patients should be closely monitored, especially those strains with strong resistance and virulence.

A prospective survey of Pseudomonas aeruginosa colonization and infection in the intensive care unit

Background

Pseudomonas aeruginosa (PA) surveillance may improve empiric antimicrobial therapy, since colonizing strains frequently cause infections. This colonization may be ‘endogenous’ or ‘exogenous’, and the source determines infection control measures. We prospectively investigated the sources of PA, the clinical impact of PA colonization upon admission and the dynamics of colonization at different body sites throughout the intensive care unit stay.

Methods

Intensive care patients were screened on admission and weekly from the pharynx, endotracheal aspirate, rectum and urine. Molecular typing was performed using Enterobacterial Repetitive Intergenic Consensus Polymerase Chain reaction (ERIC-PCR).

Results

Between November 2014 and January 2015, 34 patients were included. Thirteen (38%) were colonized on admission, and were at a higher risk for PA-related clinical infection (Hazard Ratio = 14.6, p = 0.0002). Strains were often patient-specific, site-specific and site-persistent. Sixteen out of 17 (94%) clinical isolates were identical to strains found concurrently or previously on screening cultures from the same patient, and none were unique. Ventilator associated pneumonia-related strains were identical to endotracheal aspirates and pharynx screening (87–75% of cases). No clinical case was found among patients with repeated negative screening.

Conclusion

PA origin in this non-outbreak setting was mainly ‘endogenous’ and PA-strains were generally patient- and site-specific, especially in the gastrointestinal tract. While prediction of ventilator associated pneumonia-related PA-strain by screening was fair, the negative predictive value of screening was very high.