Minimizing microbial contamination risk simultaneously from multiple hospital washbasins by automated cleaning and disinfection of U-bends with electrochemically activated solutions

Efficacy of Oxy-Ionic Solutions With Varying pH Levels Against Streptococcus mutans In Vitro

Background Chlorhexidine (CHX) is a widely used antimicrobial agent known for its ability to inhibit cariogenic bacteria, reduce plaque formation, neutralize acidity, and promote remineralization. However, the effectiveness of oxy-ionic solutions at different pH levels as an alternative antimicrobial treatment requires further exploration. This study aims to compare the antimicrobial effects of oxy-ionic solutions at various pH levels with those of CHX and fluoride. Methodology This study employed disc diffusion tests to measure the inhibition zone diameters of each solution and broth dilution assays to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Results The oxy-ionic solutions exhibited varying degrees of antimicrobial effectiveness depending on their pH levels. The solution at pH 5 demonstrated the best antimicrobial performance among the oxy-ionic solutions, with inhibition zones comparable to those of CHX. The MIC and MBC values indicated that oxy-ionic solutions in mildly acidic environments generally resulted in better antimicrobial activity. Conclusions The study concludes that while CHX remains highly effective against cariogenic bacteria, oxy-ionic solutions, particularly at pH 5, offer a promising alternative. The antimicrobial efficacy of oxy-ionic solutions is influenced by their pH levels. Further research is recommended to explore the long-term effects and clinical applications of oxy-ionic solutions in maintaining oral health and preventing disease.

Immersion of debrided diabetic foot ulcer (DFU) tissue in electrochemically generated pH neutral hypochlorous acid significantly reduces the microbial bioburden: whole-genome sequencing of Staphylococcus aureus, the most prevalent species recovered

BACKGROUND

Diabetic foot ulcer infections (DFUIs) are the leading cause of lower limb amputations, mediated predominantly by Staphylococcus aureus. pH neutral electrochemically-generated hypochlorous acid (anolyte) is a non-toxic, microbiocidal agent with significant potential for wound disinfection.

AIMS

To investigate both the effectiveness of anolyte for microbial bioburden reduction in debrided ulcer tissues and the population of resident S. aureus.

METHODS

Fifty-one debrided tissues from 30 people with type II diabetes were aliquoted by wet weight and immersed in 1 or 10 ml volumes of anolyte (200 parts per million) or saline for three min. Microbial loads recovered were determined in colony forming units/g (CFU/g) of tissue following aerobic, anaerobic and staphylococcal-selective culture. Bacterial species were identified and 50 S. aureus isolates from 30 tissues underwent whole-genome sequencing (WGS).

FINDINGS

The ulcers were predominantly superficial, lacking signs of infection (39/51, 76.5%). Of the 42/51 saline-treated tissues yielding ≥10⁵ CFU/g, a microbial threshold reported to impede wound-healing, only 4/42 (9.5%) were clinically-diagnosed DFUIs. Microbial loads from anolyte-treated tissues were significantly lower than saline-treated tissues using 1 ml (1065-fold, 2.0 log) and 10 ml (8216-fold, 2.1 log) immersion volumes (p<0.0005). Staphylococcus aureus was the predominant species recovered (44/51, 86.3%) and 50 isolates underwent WGS. All were meticillin-susceptible and comprised 12 sequence types (STs), predominantly ST1, ST5 and ST15. Whole-genome multilocus sequence typing identified three clusters of closely related isolates from 10 patients indicating inter-patient transmission.

CONCLUSIONS

Short immersions of debrided ulcer tissue in anolyte significantly reduced microbial bioburden: a potential novel DFUI treatment.

Prevalence, genetic diversity, antibiotic resistance and biofilm formation of Acinetobacter baumannii isolated from urban environments

AIM

Acinetobacter baumannii is a well-known nosocomial pathogen that has been isolated from different clinical sources. This pathogen also causes community-acquired infections, with mortality rates as high as 64%. The exact natural habitat of this bacterium is still unknown. In this study, we investigated the prevalence of A. baumannii in diverse soil and high-touch surface samples collected from a university campus, malls, parks, hypermarkets and produce markets, roundabout playground slides, and bank ATMs.

METHODS AND RESULTS

All obtained isolates were characterized for their antibiotic susceptibility, biofilm formation capacities, and were typed by multi-locus sequence analysis. A total of 63 A. baumannii isolates were recovered, along with 46 A. pittii and 8 A. nosocomialis isolates. Sequence typing revealed that 25 A. baumannii isolates are novel strains. Toilets and sink washing basins were the most contaminated surfaces, accounting for almost 50% of the recovered isolates. A number of A. baumannii (n=10), A. pittii (n=19) and A. nosocomialis (n=5) isolates were recovered from handles of shopping carts and baskets. The majority of isolates were strong biofilm formers and 4 exhibited a multi-drug resistant (MDR) phenotype.

CONCLUSIONS

Our study is the first to highlight community restrooms and shopping carts as potential reservoirs for pathogenic Acinetobacter species. Further studies are required to identify the reasons associated with the occurrence of A. baumannii inside restrooms. Proper disinfection of community environmental surfaces and spreading awareness about the importance of hand hygiene may prevent the dissemination of pathogenic bacteria within the community.

SIGNIFICANCE AND IMPACT OF STUDY

Serious gaps remain in our knowledge of how A. baumannii spreads to cause disease. This study will advance our understanding of how this pathogen spreads between healthcare and community environments. In addition, our findings will help healthcare decision makers implement better measures to control and limit further transmission of A. baumannii.

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.

Sewer biofilm microbiome and antibiotic resistance genes as function of pipe material, source of microbes, and disinfection: field and laboratory studies

Wastewater systems are recognized pathways for the spread of antibiotic resistant bacteria, but relatively little is known about the microbial ecology of the sewer environment. Sewer biofilm colonization by antibiotic resistance gene (ARG) carrying bacteria may impact interpretations of sewage epidemiology data, water quality during sewer overflows, and hazard to utility workers. The objectives of this research were to evaluate the (1) microbiome of real and simulated sewer biofilms and their potential to accumulate ARGs and (2) susceptibility of simulated sewer biofilms to bleach disinfection. First, biofilm samples were collected from sewer municipal systems. Next, an annular biofilm reactor was used to simulate the sewer environment while controlling the pipe material (concrete vs. PVC). The reactor was operated either as fed semi-batch with sewer sediment and synthetic wastewater (Sed-SB) or fed with a continuous flow of raw sewage (WW-CF). The abundance of ARGs, human fecal marker HF183, and 16S rRNA gene copies in these biofilm samples was measured with qPCR. Amplicon sequencing was performed to compare the prokaryotic diversity between samples. Finally, the susceptibility of reactor biofilm to a 4.6% bleach disnfection protocol was evaluated using viability qPCR and amplicon sequencing. Field and WW-CF biofilms contained the most ARG copies and the microbial community compositions varied between the different biofilm samples (field, Sed-SB, and WW-CF). Pipe material did not affect the abundance of ARGs in the reactor samples. However, log removal following bleach treatment suggested that the biofilm grown on PVC surface was primarily dislodged from the surface by the bleach treatment whereas more bacteria were lysed within the biofilm that remained on the concrete surface. Viable bacteria carrying ARGs were observed following 10 minutes of treatment. This study showed that sewer biofilms can accumulate bacteria carrying ARGs and that while bleach can reduce sewer biofilm density, the protocol tested here will not completely remove the biofilms.

Whole-genome sequencing identifies highly related Pseudomonas aeruginosa strains in multiple washbasin U-bends at several locations in one hospital: evidence for trafficking of potential pathogens via wastewater pipes

BACKGROUND

Hand washbasin U-bends have increasingly been associated with nosocomial outbreaks by Gram-negative bacteria, including Pseudomonas aeruginosa which is virtually ubiquitous in U-bends. Wastewater networks servicing U-bends are potential highways for trafficking pathogenic bacteria.

AIM

To use P. aeruginosa to investigate trafficking of bacteria between hospital washbasin U-bends.

METHODS

Twenty-five washbasin U-bends in five locations in Dublin Dental University Hospital (DDUH) were investigated for trafficking of P. aeruginosa: 10 in Clinic 2 (C2), 10 in the Accident & Emergency Department (A&E) and five in three other locations. In addition, washbasin tap samples (N=80) and mains and tap water samples (N=72) were cultured for P. aeruginosa. Selected P. aeruginosa isolates recovered over 29 months underwent whole-genome sequencing, and relatedness was interpreted using whole-genome multi-locus sequence typing and pairwise single nucleotide polymorphism (SNP) analysis.

FINDINGS

P. aeruginosa was recovered from all U-bends but not from taps or water. Eighty-three U-bend isolates yielded 10 sequence types (STs), with ST560 and ST179 from A&E, C2 and two other locations predominating (70%). ST560 was also recovered from a common downstream pipe. Isolates within ST560 and ST179 were highly related regardless of source. ST560 was divided into Cluster I (N=25) and Cluster II (N=2) with average allelic differences and SNPs of three and zero, and two and five, respectively. The 31 ST179 isolates exhibited an average allelic difference and SNPs of three and 12, respectively.

CONCLUSION

Highly related P. aeruginosa strains were identified in multiple U-bends in several DDUH locations, indicating trafficking via the wastewater network.

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

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

A novel sink drain cover prevents dispersal of microorganisms from contaminated sink drains

In hospital sinks, a novel plastic drain cover was effective in preventing dispersal of gram-negative bacilli and fluorescent gel associated with splattering of flowing water. Our findings suggest that the sink drain covers could provide a simple means to reduce dissemination of pathogens from contaminated sinks.