Hospital Disinfection Research Articles

P-263. Sodium dichloroisocyanurate: A promising candidate for the disinfection of resilient drain biofilm

Abstract Background Biofilms are complex multicellular communities of microorganisms which can lead to a variety of human diseases and infections. Biofilms consist of microbes which are contained within a protective extra polymeric substance layer, resulting in increased resistance to disinfectants. From an economic perspective, it is estimated that potentially deadly biofilms, which cause 1.7 million hospital acquired infections (HAIs) each year in the US, can result in costs of $11.5 billion in treatment. Biofilms thrive in a variety of diverse environments, including hospital sinks and drains, which can pose a significant threat to patient safety. Sink drains maintain one of the highest burdens of antibiotic resistant bacteria amongst all other surfaces, with Pseudomonas aeruginosa consistently being the most prominent species found within ICU sink drains. Studies have shown that by completely removing sinks from patient rooms, there is a significant reduction in the colonisation of gram-negative bacteria, a leading cause of HAIs. Methods The aim of this study was to determine if three hospital-grade disinfectants were capable of killing biofilm, and as such, if they could be used as potential drain disinfectants. Disinfectants were comprised of Sodium Dichloroisocyanurate (NaDCC), Peracetic acid and bleach-based disinfectants. Pseudomonas aeruginosa biofilms were cultivated using the CDC biofilm reactor, a standardised method for determining biofilm efficacy within the United States. Results The NaDCC product was successful in completely killing the biofilm (using a one-minute contact time), resulting in a total 8.70 log reduction. Peracetic acid reduced biofilm by 3.82 logs, followed by bleach, which had the lowest reduction at 3.78 logs. Conclusion Drain disinfection is critical to ensure patient safety and reduce the instances of HAIs. This experiment can help in predicting the effectiveness of three hospital disinfectants for drain applications. NaDCC could provide a reliable solution for drain applications and subsequent patient safety. Disclosures Abbbie Martin, BsC, Kersia Ireland: Employee Tom O'Mahony, PhD, Kersia Ireland: Employee Natasha Doyle, PhD, Kersia Ireland: Employee

Variable sensitivity of clinical Candida auris strains to Biocides: implications for infection control in Healthcare Settings

PurposeCandida auris, a multidrug-resistant yeast, poses significant challenges in healthcare settings due to its ability to form biofilms and resistance to common disinfectants. Understanding its susceptibility to biocides used in hospital disinfection practices is crucial for infection control. We investigated the biocide sensitivity of eight clinical C. auris strains from different patients and one reference strain (CDC B11903) using the biocide activity tests.MethodsSpecies identification was confirmed through MALDI-TOF MS, while clade differentiation and phylogenetic classification were determined via whole-genome sequencing. Biofilm formation was assessed using the MTT assay. Antifungal susceptibilities were tested according to CLSI standards. The effectiveness of biocides, including chlorine, chlorhexidine, and benzalkonium chloride, was evaluated through broth microdilution following CLSI standards and quantitative suspension and carrier tests, following EN standards.ResultsAll clinical strains were identified as clade 1, and the reference strain as clade 4, with all exhibiting biofilm formation. Clade 1 strains showed resistance to fluconazole, with MIC values ranging from 8 to 32 µg/ml, while being susceptible to other antifungals. Broth microdilution MIC assays for biocides demonstrated that all strains exhibited resistance to benzalkonium chloride. Chlorine and chlorhexidine showed variable efficacy, dependent on concentration and environmental cleanliness. Alcohol-based hand sanitizers demonstrated effectiveness against C. auris from the first minute of application.ConclusionThe study highlights the variable susceptibility of C.auris to different biocides, underscoring the challenge in eradicating this pathogen from healthcare environments. Our findings advocate for the careful selection of disinfectants in hospital settings, emphasizing the need for high-concentration chlorine and chlorhexidine solutions to combat C. auris, even in especially clean environments.

A New Convenient Method to Assess Antibiotic Resistance and Antimicrobial Efficacy against Pathogenic Clostridioides difficile Biofilms.

Clostridioides difficile is a widely distributed anaerobic pathogen. C. difficile infection is a serious problem in healthcare. Its biofilms have been found to exhibit biocorrosivity, albeit very little, but sufficient for it to correlate with biofilm growth/health. This work demonstrated the use of a disposable electrochemical biofilm test kit using two solid-state electrodes (a 304 stainless steel working electrode, and a graphite counter electrode, which also served as the reference electrode) in a 10 mL serum vial. It was found that the C. difficile 630∆erm Adp-4 mutant had a minimum inhibitory concentration (MIC) for vancomycin twice that of the 630∆erm wild type strain in biofilm prevention (2 ppm vs. 1 ppm by mass) on 304 stainless steel. Glutaraldehyde, a commonly used hospital disinfectant, was found ineffective at 2% (w/w) for the prevention of C. difficile 630∆erm wild type biofilm formation, while tetrakis(hydroxymethyl)phosphonium sulfate (THPS) disinfectant was very effective at 100 ppm for both biofilm prevention and biofilm killing. These antimicrobial efficacy data were consistent with sessile cell count and biofilm imaging results. Furthermore, the test kit provided additional transient biocide treatment information. It showed that vancomycin killed C. difficile 630∆erm wild type biofilms in 2 d, while THPS only required minutes.

Research on the management effect and tangible and intangible results of PDCA management cycle method in the quality of hospital disinfection supply center.

Research on the management effect and tangible and intangible results of PDCA management cycle method in the quality of hospital disinfection supply center.

Diagnosing OSA and Insomnia at Home Based Only on an Actigraphy Total Sleep Time and RIP Belts an Algorithm "Nox Body Sleep™".

The COVID-19 pandemic has influenced clinical sleep protocols with stricter hospital disinfection requirements. Facing these new rules, we tested if a new artificial intelligence (AI) algorithm: The Nox BodySleep™ (NBS) developed without airflow signals for the analysis of sleep might assess pertinently sleep in patients with Obstructive Sleep Apnea (OSA) and chronic insomnia (CI) as a control group, compared to polysomnography (PSG) manual scoring. NBS is a recurrent neural network model that estimates Wake, NREM, and REM states, given features extracted from activity and respiratory inductance plethysmography (RIP) belt signals (Nox A1 PSG). Sleep states from 139 PSG studies (CI N = 72; OSA N = 67) were analyzed by NBS and compared to manually scored PSG using positive percentage agreement, negative percentage agreement, and overall agreement metrics. Similarly, we compared common sleep parameters and OSA severity using sleep states estimated by NBS for each recording and compared to manual scoring using Bland-Altman analysis and intra-class correlation coefficient. For 127,170 sleep epochs, an overall agreement of 83% was reached for Wake, NREM and REM states (92% for REM states in CI patients) between NBS and manually scored PSG. Overall agreement for estimating OSA severity was 100% for moderate-severe OSA and 91% for minimal OSA. The absolute errors of the apnea-hypopnea index (AHI) and total sleep time (TST) were significantly lower for the NBS compared to no scoring of sleep. The intra-class correlation was higher for AHI and significantly higher for TST using the NBS compared to no scoring of sleep. NBS gives sleep states, parameters and AHI with a good positive and negative percentage agreement, compared with manually scored PSG.

Hospital Acquired Infection Revisited: Route of Transmission

Aims: to revisited hospital route of infection transmission in patients under medical care with its related problems and re-focus on some important MDR nosocomial infection agents route of transmission to vulnerable patients. Discussion: Accidental infections acquired in hospitals or hospital acquired infection (HAI) is a global major health condition, and become a major obstacle in the present day era of hospitalization. Increased risk of morbidity with mortality, lengthened hospitalization, massive prescription of antibiotics, and socio-economically become a definite financial burden. Disinfection and sterilization in hospitals is of increasing concern. Besides that, the abuse of antibiotics has led to the prompt wide spread of multidrug-resistant drugs (MDR) microorganisms which is characterized by the ability to quickly adapt to an environment that previously does not support its growth commonly and able to initiate serious life-threatening HAI. The need to understand route of transmission and its associated obstacles will help combating MDR microorganisms. Conclusion: The Global emergence of MDR microorganisms with its difficult route of infections has created a major obstacle to combat the bacterial pathogens, and need serious attention from all stakeholders, throughout the world.

Effect of ozone gas on cultures of Candida albicans and Aspergillus fumigatus: evaluation of two ozonation devices.

Candida albicans and Aspergillus fumigatus are two important agents of Healthcare-associated infections. This study aimed to evaluate the antifungal activity of ozone (O3) gas produced by two commercial devices against cultures of these two species. Sterile plastic plates were inoculated with C. albicans and A. fumigatus and placed on a countertop at three distances (30 cm, 1 m, and 2 m) and three positions in relation to the wall (near, middle, and away), considering the source of O3. Plates were exposed to O3 for one hour and incubated. After incubation, the counting of colony-forming units was performed. As a control, an inoculated plate was incubated, without being exposed to O3. Tests were carried out with two different devices (namely, Mod.I and Mod.II), with the air conditioner on and off, in triplicate. Both devices showed antifungal activity. Mod. I presented better results, due to a higher flow rate. The best activity was on plates at 30 cm, middle position. Contrarily, on plates at 2m, near the wall, the inhibition activity was lower. The best results were obtained with the air conditioner off. Candida albicans was more sensitive to O3 than A. fumigatus. This method of decontamination by O3 gas shows potential due to its fast and easy execution. The establishment of new protocols for hygiene and hospital disinfection using this approach should be considered, which may reduce environmental contamination by fungi and, consequently, the burden of fungal infections.

The survival of multi-drug resistant bacteria on raw Douglas fir material

In today’s age of ecological transition, the use of materials such as renewable wood in construction is particularly relevant, but also a challenge in the healthcare sector where the hygiene dimension also comes into play. In this study we have investigated the survival of multi-resistant bacteria commonly responsible for healthcare-associated infections (HAIs) (ESBL-positive Klebsiella pneumoniae and glycopeptide-resistant Enterococcus faecalis) on two different types of wood (Douglas fir : Pseudotsuga menziesii and Maritime Pine : Pinus pinaster) compared to other materials (smooth: stainless steel and rough: pumice stone) and the effect of a disinfection protocol on the bacterial survival on Pseudotsuga menziesii. Approximately 108 bacteria were inoculated on each material and bacterial survival was observed over several days (D0, D1, D2, D3, D6, D7 and D15). Each analysis was performed in triplicate for each time and material. The results show an important reduction of the bacterial inoculum for Klebsiella pneumoniae and Enterococcus faecalis on Douglas fir, in contrast with the results obtained on maritime pine, stainless steel and pumice stone. No bacterial survival was detected on Douglas fir after application of a hospital disinfection protocol. These different results show that wood may have a place in the future of healthcare construction. Further studies would be interesting to better understand the different properties of wood.

Effectiveness of hydrogen peroxide wipes for surface disinfection in healthcare facilities.

The correct method of surface disinfection in hospitals is an essential tool in the fight against the spread of healthcare-associated infections caused by multi-resistant microorganisms. Currently, there are many disinfectants on the market that can be used against different microorganisms. However, the effectiveness of different active molecules is controversial in the literature. The aim of this study was to evaluate the effectiveness of wipes based on hydrogen peroxide (1.0 %) and highly specific plant-based surfactants, contained in H2O2TM (Hi-speed H2O2TM) products, against some hospital-associated microorganisms. The effectiveness of the wipes was tested against nosocomial and control strains of methicillin-resistant Staphylococcus aureus, carbapenem-resistant Pseudomonas aeruginosa, Klebsiella pneumoniae carbapenemase, Aspergillus fumigatus and Candida parapsilosis. Specifically, in vitro activity was assessed using three different techniques: stainless steel surface testing, surface diffusion testing and well diffusion test. The three different methods tested confirm the wipes' good effectiveness against the most common multi-resistant bacteria and against fungi. These data show that the tested wipes could be a valid adjunct to the disinfection process and could assist in the prevention of healthcare-associated infections.

Methods for SARS-CoV-2 hospital disinfection, in vitro observations

IntroductionEscalation of chemical disinfection during the COVID-19 pandemic raised occupational hazard concerns. Alternative and potentially safer methods such as ultraviolet-C (UVC) irradiation and ozone are desirable, notwithstanding the lack of standardized criteria for their use in the healthcare environment. AimCompare the virucidal activity of 70% ethanol, sodium dichloroisocyanurate (NaDCC), chlorhexidine, ozonated water, UVC-222 nm, UVC-254 nm against three SARS-CoV-2 variants of concern cultured in vitro. MethodsInactivation of three SARS‐CoV‐2 variants (alpha, beta, gamma) by the following chemical methods was tested: ethanol 70%, NaDCC (100 ppm, 500 ppm, 1000 ppm), chlorhexidine (2%, 1% and 0.5%), ozonated water 7 ppm. For irradiation, a je2Care 222nm UVC Lamp was compared to a Sylvania G15 UV254 nm lamp on SARS-CoV-2 variants. ResultsViral inactivation by >3 log was achieved with ethanol, NaDCC and chlorhexidine. The minor virucidal effect of ozonated water was <1 log. Virus treatment with UVC-254 nm reduced viral activity by 1-5 logs with higher inactivation after exposure for 3 minutes compared to 6 seconds. For all three variants, under equivalent conditions, exposure to UVC-222 nm did not achieve time-dependent inactivation as was observed with treatment with UVC-254 nm. ConclusionThe virucidal activity on replication-competent SARS-CoV-2 by conventional chemical methods, including chlorhexidine at concentrations as low as 0.5%, was not matched by UVC irradiation, and to an even lesser extent by ozonated water treatment.

Design, construction and robust validation of a germicidal device based on UV irradiation: a necessity for hospital disinfection in the COVID-19 era

Pandemic by SARS-CoV-2 has revealed the importance of disinfection methods due to pathogens of medical importance being detectable and infective after several hours on contaminated surfaces, including medical devices. The aim of this work was to design, construction, and validation of a UVC light irradiation system in the short wavelength region (200 to 320 nm). We studied the effective of the system through in vitro disinfection to eliminate pathogens such as SARS-CoV-2, ESKAPE bacteria and fungi in biofilm and planktonic forms. Doses of 0.25 J/cm2 (10 s of exposure to UVC light), 100% death of ESKAPE bacteria and fungi in planktonic form was observed. Through biofilm formation induction assays of these microorganisms showed resistance to treatment with UV light; however, their viability was not detected after 20 s of exposure (via confocal microscopy). For SARS-CoV-2, 100% reduction was reached after 120 s of exposure. This evidence shows the need to employ emerging methods of disinfection of surfaces and medical devices since these are potential vehicles for transmitting pathogens. The advantages of using UV light as an emergent disinfection method in the era of COVID-19 are discussed.

Biocidal Verification Program for Healthcare Facilities: Evaluation of the Efficacy and Microbial Tolerance of Disinfectants

Context: The disinfection of healthcare facilities is of utmost importance to prevent the spread of infectious diseases. In this regard, biocidal activity testing is used to evaluate the efficacy of disinfectants in hospitals. Aim: Establishing a disinfectant efficacy test aimed at combating infections and cross-contamination. Settings and Design: The experiment was carried out in two treatment groups for each of the four microorganisms on ten surface coupons, with a viability control group determined as the baseline inoculum. Methods and Materials: The study used two disinfectants—hydroxyethane (ethylene hydrate) and 2-hydroxypropane (sec-propyl alcohol)—to evaluate their efficacy in reducing bacterial contamination on inanimate surfaces. Statistical analysis used: The data obtained was analyzed using Minitab software, which involved a normal probability plot, a homogeneity of variances test, and a test for equal variances. The statistical significance level was set at α = 0.05. Results: The normal probability plot of microorganism-disinfectant groups with a 95% confidence interval showed improvement in normalization after the logarithmic transformation of datasets. The homogeneity of variances test did not reveal any statistically significant differences between the groups, and all the comparison intervals overlapped for the logarithmically transformed datasets in contrast to the raw datasets. The bacterial reduction after exposure to disinfectants for five minutes compared with the control group in the surface challenge biocidal test expressed as absolute and logarithmic reduction showed a significant reduction in bacterial growth, with Burkholderia cepacia showing greater persistence on the examined sample of the surfaces. Conclusions: The current study showed that the effect of the microorganism tolerance contributed to the variation in responses rather than the disinfectant or the surface types, suggesting the risk of resistant bacteria on the contaminated surface in the dissemination of infections. Thus, monitoring and routine disinfection validation programs for the control of microbial burden in healthcare are crucial for infection and contamination mitigation

Molecularly imprinted 2D photonic crystal hydrogel sensor for sodium dichloroisocyanurate.

Sodium dichloroisocyanurate (SDIC) is an efficient, safe and convenient halogen disinfectant that is widely used for hospital, tableware and swimming pool disinfection. In order to ensure its effective use and safety, especially in clinical settings, effective identification methods are necessary. The effective chlorine content is one of the quality standards for chlorine-containing disinfectants, but its complex experimental operation as well as poor specificity and portability limit its application. In contrast, testing based on molecularly imprinted photonic crystal sensors provides excellent performance. Therefore, it is of great significance to establish a new and simple SDIC recognition method. We prepared a novel molecularly imprinted two-dimensional (2D) photonic crystal hydrogel (MIPH) for sensitive and label-free recognition of SDIC. The response performance of the resultant MIPH sensor was determined by monitoring particle spacing changes in the polystyrene (PS) 2D photonic crystals embedded in the hydrogel. Particle spacing changes were recorded by measuring changes in the diameter of the Debye diffraction ring of the MIPH sensor. As the concentration of SDIC in solution increased from 1 × 10-2 to 1.0 mmol L-1, the diameter of the Debye diffraction ring increased by 6 mm, and the corresponding photonic crystal particle spacing decreased by 56 nm. The particle spacing changes in the MIPH sensor showed a linear relationship with the SDIC concentration in the range of 1 × 10-2-1.0 mmol L-1, and the limit of detection (S/N = 3) was found to be 3 × 10-3 mmol L-1. The constructed hydrogel sensor was successfully used to detect SDIC in sodium dichloroisocyanurate disinfectant powder, demonstrating recoveries of 96-100% and RSD of 7.2-7.6%. Our molecularly imprinted SDIC photonic crystal hydrogel provides a universal strategy for designing sensors for other clinical disinfectants.

Staphylococcus epidermidis joint isolates: Whole-genome sequencing demonstrates evidence of hospital transmission and common antimicrobial resistance.

We investigated genetic, epidemiologic, and environmental factors contributing to positive Staphylococcus epidermidis joint cultures. Retrospective cohort study with whole-genome sequencing (WGS). We identified S. epidermidis isolates from hip or knee cultures in patients with 1 or more prior corresponding intra-articular procedure at our hospital. WGS and single-nucleotide polymorphism-based clonality analyses were performed, including species identification, in silico multilocus sequence typing (MLST), phylogenomic analysis, and genotypic assessment of the prevalence of specific antibiotic resistance and virulence genes. Epidemiologic review was performed to compare cluster and noncluster cases. In total, 60 phenotypically distinct S. epidermidis isolates were identified. After removal of duplicates and impure samples, 48 isolates were used for the phylogenomic analysis, and 45 (93.7%) isolates were included in the clonality analysis. Notably, 5 S. epidermidis strains (10.4%) showed phenotypic susceptibility to oxacillin yet harbored mecA, and 3 (6.2%) strains showed phenotypic resistance despite not having mecA. Smr was found in all isolates, and mupA positivity was not observed. We also identified 6 clonal clusters from the clonality analysis, which accounted for 14 (31.1%) of the 45 S. epidermidis isolates. Our epidemiologic investigation revealed ties to common aspirations or operative procedures, although no specific common source was identified. Most S. epidermidis isolates from clinical joint samples are diverse in origin, but we identified an important subset of 31.1% that belonged to subclinical healthcare-associated clusters. Clusters appeared to resolve spontaneously over time, suggesting the benefit of routine hospital infection control and disinfection practices.

Effect of selected disinfectants on biofilm-forming clinical isolates of Staphylococcus aureus in Lagos State, Nigeria

Background and Aims: Staphylococcus aureus is one of the most important pathogens of public health concern and a leading cause of nosocomial infections. In this study, we evaluated the effect of routinely used disinfectants in hospitals for surface decontamination on biofilm-forming S. aureus. Materials and Methods: forty-eight S. aureus isolates were phenotypically evaluated for biofilm formation using the Tissue Culture Plate (TCP) technique. Effect of disinfectants (Dettol®, Izal®, Jik® and Savlon®) on biofilm was tested and time-kill kinetics evaluated. PCR was used to confirm the identity of S. aureus using species-specific primers. Results: biofilm formation assay revealed that 15 (31.2%) of the isolates formed biofilm with 7 (14.5%) and 8 (16.6%) considered as strong and moderate biofilm formers, respectively. Biofilm formation was time-dependent (p&lt;0.0001). Jik® was significantly effective (p&lt;0.0001) as it disrupted biofilm formed in all 15 (100%) isolates, followed by Izal® 13 (86.6%), Savlon® 11 (73.3%) and Dettol® 9 (60%). Time-kill kinetics of the four disinfectants revealed Dettol®, Jik® and Savlon® achieved total (100%), (7 log10) lethality against isolates within 1 h contact time while Izal® attained complete lethality at 6 h contact time. Conclusions: of the four disinfectants evaluated Jik®, a chlorine- based formulation, was more effective in destroying biofilmforming S. aureus. The need to use effective disinfectants in sanitization is imperative to facilitate the control and prevention of hospital and community-acquired infections.

713. Prevalence of Microbicide Resistance Genes in Clinical Isolates of Acinetobacter baumannii

Abstract Background The persistence of Acinetobacter on different surfaces and the continuous exposure of bacteria to disinfectants such as quaternary ammonium compounds (QACs) in the healthcare environment have led to microbicide tolerance. Acinetobacter baumannii have also rapidly acquired carbapenem resistance. Here we determined the prevalence of microbicide resistance genes in carbapenem susceptible and resistant clinical isolates of Acinetobacter. Methods All clinical isolates were collected from two separate hospitals in Detroit between 2017-2021. Following DNA isolation using Qiagen kit, Nextera Flex kit was used for library preparation of Acinetobacter clinical isolates. Whole genome sequencing (WGS) was performed via Illumina NextSeq 550 using the prepared DNA library. The FASTQ files from the sequencing run were then subjected to bioinformatic analysis with Bionumerics software v7.6. ResFinder was used for determination of presence or absence of QAC resistant genes and results were tabulated by Carbapenem-Resistant Acinetobacter baumannii (CRAb) or Carbapenem-Susceptible Acinetobacter baumannii (CSAb) with or without the QAC resistant genes. Results Out of the 139 Acinetobacter patient isolates, 70/139 (50.4%) were CRAb containing carbapenemase blaOXA-23 and 69/139 (49.6%) belonged to CSAb (Table 1). Figure 1. shows the prevalence of antimicrobial resistance (AMR) genes in CRAb and CSAb isolates with qacE genes. For CRAb isolates, 56% had qacE genes while 39% of CSAb had qacE genes. About 42% of CRAb isolates were multi-drug resistant (MDR), indicating a prevalence of qacE genes among the MDR isolates. Table 2 shows the presence of qacE genes by sequence type (ST). In the ST2 (Pasteur) and ST406 (Pasteur) strains, qacE gene was mainly present. Interestingly, most of the Acinetobacter isolates that belong to ST2 (ST195 and ST281, Oxford) are CRAb with qacE gene.Figure 1:Different AMR genes and qacE in both CRAb and CSAb isolates Conclusion Clinical isolates in our study had an even distribution of both CRAb and CSAb. The presence of qacE gene was more prevalent in the CRAb isolates compared to the CSAb isolates. While different STs harbored the qacE gene, the prevalence of qacE gene was highest in ST2 among all isolates. Future studies are needed to determine the reduced susceptibility to other commonly used hospital disinfectants. Disclosures Keith S. Kaye, MD, MPH, Abbvie: Advisor/Consultant|Abbvie: Honoraria|Entasis: Advisor/Consultant|Entasis: Honoraria|GSK: Advisor/Consultant|GSK: Honoraria|Merck: Advisor/Consultant|Merck: Honoraria|Shionogi: Advisor/Consultant|Shionogi: Honoraria|VenatoRx: Advisor/Consultant|VenatoRx: Honoraria

Evaluation of a novel surface-coating formulation with time-extended antimicrobial activity for healthcare environment disinfection

BackgroundThe importance of environmental contamination in the transmission of pathogens among hospitalized patients is universally recognized, and disinfection of surfaces is a widely accepted modality for reducing healthcare-associated infections. Nevertheless, hospital disinfection is still suboptimal. In this study, we evaluated the sustained effects of the novel formulation OxiLast™ which extends the antimicrobial effects of chlorine-based disinfectants.MethodsIn an experimental lab phase, PVC surfaces were coated with OxiLast™ and then inoculated with representative Gram-positive and Gram-negative pathogenic bacteria. Cells were recovered at different contact times (5, 15, 30 min) to assess the reduction in bacterial counts compared to uncoated surfaces and also subject to various challenges to assess robustness. A similar methodology was then applied in an unoccupied hospital room to evaluate the sustained effect of OxiLast™ on high-touch surfaces.ResultsOxiLast™ demonstrated notable activity against the range of bacterial strains tested with ≥ 4 log10 reduction in bacterial counts observed for up to seven days following one surface application, for various strains and contact times. Similar results were observed following challenges such as simulated abrasion of coated surfaces, organic contamination or successive inoculations. The results were confirmed in a simulated patient care environment.ConclusionsThe addition of OxiLast™ to common chlorine-based disinfectants has shown a substantial and sustained reduction in bacterial pathogen counts for up to 7 days following one application. The consistent results in the laboratory and hospital are promising and should be tested in a real-life clinical scenario.

Inactivation of dried cells and biofilms of Listeria monocytogenes by exposure to blue light at different wavelengths and the influence of surface materials.

Antimicrobial blue light (aBL) in the 400-470 nm wavelength range has been reported to kill multiple bacteria. This study assessed its potential for mitigating an important foodborne pathogen, Listeria monocytogenes (Lm), focusing on surface decontamination. Three wavelengths were tested, with gallic acid as a photosensitizing agent (Ps), against dried cells obtained from bacterial suspensions, and biofilms on stainless-steel (SS) coupons. Following aBL exposure, standard microbiological analysis of inoculated coupons was conducted to measure viability. Statistical analysis of variance was performed. Confocal laser scanning microscopy was used to observe the biofilm structures. Within 16 h of exposure at 405 nm, viable Lm dried cells and biofilms were reduced by approx. 3 log CFU/cm2 with doses of 2,672 J/cm2. Application of Ps resulted in an additional 1 log CFU/cm2 at 668 J/cm2, but its effect was not consistent. The highest dose (960 J/cm2) at 420 nm reduced viable counts on the biofilms by 1.9 log CFU/cm2. At 460 nm, after 800 J/cm2, biofilm counts were reduced by 1.6 log CFU/cm2. The effect of material composition on Lm viability was also investigated. Irradiation at 405 nm (668 J/cm2) of cells dried on polystyrene resulted in one of the largest viability reductions (4.0 log CFU/cm2), followed by high-density polyethylene (3.5 log CFU/cm2). Increasing the dose to 4,008 J/cm2 from 405 nm (24 h), improved its efficacy only on SS and polyvinyl chloride. Biofilm micrographs displayed a decrease in biofilm biomass due to the removal of biofilm portions from the surface and a shift from live to dead cells suggesting damage to biofilm cell membranes. These results suggest that aBL is a potential intervention to treat Lm contamination on typical material surfaces used in food production. IMPORTANCE Current cleaning and sanitation programs are often not capable of controlling pathogen biofilms on equipment surfaces, which transmit the bacteria to ready-to-eat foods. The presence of native plant microbiota and organic matter can protect pathogenic bacteria by reducing the efficacy of sanitizers as well as promoting biofilm formation. Post-operation washing and sanitizing of produce contact surfaces might not be adequate in eliminating the presence of pathogens and commensal bacteria. The use of a dynamic and harmless light technology during downtime and close of operation could serve as a useful tool in preventing biofilm formation and persistence. Antimicrobial blue light (aBL) technology has been explored for hospital disinfection with very promising results, but its application to control foodborne pathogens remains relatively limited. The use of aBL could be a complementary strategy to inactivate surfaces in restaurant or supermarket deli settings.

Modelling hospital disinfectant against multi-drug-resistant dry surface biofilms grown under artificial human sweat

Dry surface biofilms (DSB) have been found abundantly across hospital surfaces within intensive care units and may explain how nosocomial pathogens can remain virulent and persist on surfaces for extended periods. Testing standards governing the performance of disinfectant products employ planktonic models under routine growth conditions, which are known to be less tolerant than their biofilm counterpart. To evaluate biofilm models cultured under artificial human sweat (AHS), a source of nutrient expected on touch surfaces, to assess the antimicrobial performance of common cleaning agents, including a quaternary ammonium, hydrogen peroxide and active chlorine. 5 single-species biofilms, using pathogenic bacteria such as Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis, were generated on stainless steel substrates using a sedimentation protocol under both AHS and nutrient rich conditions for a direct comparison of phenotypic tolerance. The biofilm models were grown over 5 days followed by desiccation cycles, before being submerged into the disinfectant solutions for up to 25 minutes. Epifluorescence (EF) microscopy using LIVE/DEAD™ stain was used to visualise microcolony viability. The results revealed biofilms cultured under AHS exhibited a greater antimicrobial tolerance and reduced speed of kill for all cleaning agents compared with the routine media; an average reduction of 72.4% vs 96.9%, respectively. EF microscopy revealed traces of viable bacteria across all coupons after disinfection indicating a potential opportunity for regrowth and recontamination. The notable difference in biocidal performance between the two growth conditions highlights potential pitfalls within current antimicrobial test standards, and the importance of accurate representation of the microbial challenge.

Fatal exposure to quaternary ammonium disinfectant in 2 dogs

To describe the clinical course and necropsy findings of 2 dogs after exposure to quaternary ammonium disinfectants. Two dogs were treated after accidental exposure to quaternary ammonium disinfectants in kennel settings. Both dogs developed ulcerative upper gastrointestinal lesions, severe pulmonary disease, and skin lesions. In the second case, the skin lesions were severe and became necrotizing. Both patients were ultimately euthanized due to severity of illness and lack of response to therapy. Quaternary ammonium compounds are commonly used as disinfectants in veterinary hospitals and boarding facilities. This is the first report detailing presentation, clinical picture, case management, and necropsy findings in dogs exposed to these chemicals. Awareness of the severity of these poisonings and the potential for fatal outcome is imperative.