Enhanced biomethane production from Scenedesmus sp. using polymer harvesting and expired COVID-19 disinfectant for pretreatment.

This study evaluates the repurposing of expired isopropanol (IPA) COVID-19 disinfectant (64% w/w) to pretreat algal biomass for enhancing methane (CH4) yield. The impact of harvesting methods (centrifugation and polymer flocculation) and microwave pretreatment on CH4 production from Scenedesmus sp. microalgal biomass were also investigated. Results show minimal impact of harvesting methods on the CH4 yield, with wet centrifuged and polymer-harvested biomass exhibiting comparable and low CH4 production at 66 and 74 L/kgvolatile solid, respectively. However, microalgae drying significantly increased CH4 yield compared to wet biomass, attributed to cell shrinkage and enhanced digestibility. Consequently, microwave and IPA pretreatment significantly enhanced CH4 production when applied to dried microalgae, yielding a 135% and 212% increase, respectively, compared to non-pretreated wet biomass. These findings underscore the advantage of using dried Scenedesmus sp. over wet biomass and highlight the synergistic effect of combining oven drying with IPA treatment to boost CH4 production whilst reducing COVID-19 waste.

Toxicity of fungal-derived volatile organic compounds against root-knot nematodes.

BACKGROUND: Root-knot nematodes (RKNs), including Meloidogyne species, are among the most destructive plant-parasites worldwide. Recent evidence suggests that entomopathogenic fungi (EPF) can antagonize RKNs. Such antagonistic effects are likely mediated by toxic metabolites, including volatile organic compounds (VOCs), produced by the fungi. However, how widespread these effects are across EPF species, and which VOCs mediate negative interactions between EPF and RKNs needs to be further elucidated. RESULTS: First, we evaluated the nematicidal effect of VOCs emitted by 46 EPF isolates against Meloidogyne incognita and found variable toxicity depending on the isolate. Second, we measured the nematicidal effect of highly toxic isolates, including species in the genus Talaromyces, Aspergillus, Clonostachys, and Purpureocillium and, third, we analyzed the nematicidal effect of major VOCs, including 2-methyl-1-propanol, 3-methyl-1-butanol, isopropyl alcohol and 2-methyl-3-pentanone. The mortality of M. incognita juveniles (J2s) was generally high (50%) either via airborne or in-solution contact with VOCs. Moreover, the tested VOCs significantly inhibited egg hatching, and repelled J2s away from the VOCs. CONCLUSION: This study not only provides insights into the ecological function of VOCs in the rhizosphere, but also provides new approaches for developing environmentally friendly control methods of RKNs in agroecosystems. © 2023 Society of Chemical Industry.

Highly Effective Salt-Activated Alcohol-Based Disinfectants with Enhanced Antimicrobial Activity.

Surfaces contaminated with pathogens raise concerns about the increased risk of disease transmission and infection. To clean biocontaminated surfaces, alcohol-based disinfectants have been predominantly used for disinfecting high-touch areas in diverse settings. However, due to its limited antimicrobial activities and concern over the emergence of alcohol-tolerant strains, much effort has been made to develop highly efficient disinfectant formulations. In this study, we hypothesize that the addition of a physical pathogen inactivation mechanism by salt recrystallization (besides the existing chemical inactivation mechanism by alcohol in such formulations) can improve inactivation efficiency by preventing the emergence of alcohol tolerance. To this end, we employed the drying-induced salt recrystallization process to implement the concept of highly efficient alcohol-based disinfectant formulations. To identify the individual and combined effects of isopropyl alcohol (IPA) and NaCl, time-dependent morphological/structural changes of various IPA solutions containing NaCl have been characterized by optical microscopy/X-ray diffraction analysis. Their antimicrobial activities have been tested on surfaces (glass slide, polystyrene Petri dish, and stainless steel) contaminated with Gram-positive/negative bacteria (methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella enterica subsp. enterica Typhimurium) and viruses (A/PR8/34 H1N1 influenza virus and HCoV-OC43 human coronavirus). We found that additional salt crystallization during the drying of the alcohol solution facilitated stronger biocidal effects than IPA-only formulations, regardless of the types of solid surfaces and pathogens, including alcohol-tolerant strains adapted from wild-type Escherichia coli MG1655. Our findings can be useful in developing highly effective disinfectant formulations by minimizing the use of toxic antimicrobial substances to improve public health and safety.

Impact on S. aureus and E. coli Membranes of Treatment with Chlorhexidine and Alcohol Solutions: Insights from Molecular Simulations and Nuclear Magnetic Resonance.

Membranes form the first line of defence of bacteria against potentially harmful molecules in the surrounding environment. Understanding the protective properties of these membranes represents an important step towards development of targeted anti-bacterial agents such as sanitizers. Use of propanol, isopropanol and chlorhexidine can significantly decrease the threat imposed by bacteria in the face of growing anti-bacterial resistance via mechanisms that include membrane disruption. Here we have employed molecular dynamics simulations and nuclear magnetic resonance to explore the impact of chlorhexidine and alcohol on the S. aureus cell membrane, as well as the E. coli inner and outer membranes. We identify how sanitizer components partition into these bacterial membranes, and show that chlorhexidine is instrumental in this process.

Inactivation of Lactobacillus Bacteriophages by Dual Chemical Treatments.

Phage contamination is one of the significant problems in the food fermentation industry, which eventually causes economic losses to the industry. Here, we investigated the viability of Lactobacillus plantarum phage P1 and P2 using various biocides treatments (ethanol, isopropanol, sodium hypochlorite and peracetic acid). Results indicated that phage P1 and P2 could be completely inactivated by treatment with 75% ethanol for 5 min, followed by 400 ppm of sodium hypochlorite treatment for 5 min. Phage P2 could be completely inactivated in the reverse sequence, while 800 ppm of sodium hypochlorite was required to achieve a similar effect for phage P1. Moreover, 100% isopropanol could increase the inactivating effect of 75% ethanol. This study may provide basic information on using multiple antimicrobials for phage control in laboratories and food plants.

A mixed-methods evaluation on the efficacy and perceptions of needleless connector disinfectants.

OBJECTIVE: Optimizing needleless connector hub disinfection practice is a key strategy in central-line-associated bloodstream infection (CLABSI) prevention. In this mixed-methods evaluation, 3 products with varying scrub times were tested for experimental disinfection followed by a qualitative nursing assessment of each. METHODS: Needleless connectors were inoculated with varying concentrations of Staphylococcus epidermidis, Pseudomonas aeruginosa, and Staphylococcus aureus followed by disinfection with a 70% isopropyl alcohol (IPA) wipe (a 15-second scrub time and a 15-second dry time), a 70% IPA cap (a 10-second scrub time and a 5-second dry time), or a 3.15% chlorhexidine gluconate with 70% IPA (CHG/IPA) wipe (a 5-second scrub time and a 5-second dry time). Cultures of needleless connectors were obtained after disinfection to quantify bacterial reduction. This was followed by surveying a convenience sample of nursing staff with intensive care unit assignments at an academic tertiary hospital on use of each product. RESULTS: All products reduced overall bacterial burden when compared to sterile water controls, however the IPA and CHG/IPA wipes were superior to the IPA caps when product efficacy was compared. Nursing staff noted improved compliance with CHG/IPA wipes compared with the IPA wipes and the IPA caps, with many preferring the lesser scrub and dry times required for disinfection. CONCLUSION: Achieving adequate bacterial disinfection of needleless connectors while maximizing healthcare staff compliance with scrub and dry times may be best achieved with a combination CHG/IPA wipe.

Alcohol flush does not aid in endoscope channel drying but may serve as an adjunctive microbiocidal measure: A new take on an old assumption.

BACKGROUND: Alcohol is perceived to aid flexible endoscope channel drying, however we previously showed alcohol increased the time required to dry some channels with forced air versus water alone. Yet, alcohol may prevent microorganism outgrowth during storage. Drying endoscope channels has been shown to prevent outgrowth, but it is unknown if incomplete drying (<10 µL remaining) provides similar protection. METHODS: Endoscope channel test articles were used to determine the efficacy of 70%-30% alcohol flush for prevention of Pseudomonas aeruginosa outgrowth and drying efficiency. For non-alcohol flushed channels, the impact of forced air drying on outgrowth of P. aeruginosa was determined. RESULTS: Alcohol flush (70%-30%) prevented outgrowth with little to no recovery of P. aeruginosa during ambient storage. 70% alcohol increased channel drying time by 1.5 or 3-fold compared to 50% alcohol or water, respectively. Forced air drying of non-alcohol flushed channels greatly reduced the initial contamination level and prevented outgrowth. Incomplete drying of contaminated channels was akin to no application of forced air. Applying forced air for more time than necessary to remove residual liquid did not completely eliminate the low level recovery of P. aeruginosa. CONCLUSIONS: Flushing with reduced concentrations of alcohol may provide a strategy to prevent microbial outgrowth while reducing drying time.

Disinfection of needleless connectors to reduce Staphylococcus aureus bacterial load.

HIGHLIGHTS: Compare effectiveness of chemical disinfectants in reducing S. aureus. Five disinfectants reduced the bacterial load, especially chlorhexidine solutions. Focus on Brazilian clinical practice of needleless connector disinfection. PURPOSE: This study aimed to gain further knowledge about the comparative effectiveness of chemical disinfectants in reducing the bacterial load of NCs inoculated with S. aureus. METHODS: Disinfection of needleless connectors was undertaken in vitro against S. aureus comparing 70% isopropyl alcohol (IPA), 70% ethanol, 0.5% and 2% chlorhexidine in 70% IPA applied with gauze, and 70% IPA single-use cap (Site-Scrub®). RESULTS: All disinfectants reduced the bacterial load (P<0.001), especially the chlorhexidine solutions. Mechanical friction should follow guidelines. CONCLUSION: This study found that all tested disinfectants effectively reduced the bacterial load and more clinical studies must be developed with a focus on the Brazilian clinical practice of needleless connector disinfection.

Comparison of chlorhexidine and alcohol-based antisepsis on the paralumbar fossa in cattle.

OBJECTIVE: To determine skin reaction, post-treatment reduction (immediate effect), and 1 hour post-treatment reduction (sustained effect) of aerobic bacterial colony forming units (CFU) following three antiseptic protocols in cattle. STUDY DESIGN: Prospective, randomized experimental study. ANIMALS: Eighteen cows. METHODS: Three sites in each paralumbar fossa were clipped and randomly assigned to one of three treatment groups: 5 minute 4% chlorhexidine gluconate scrub (CHG); 90 second 80% ethanol scrub (ET); 90 second 70% isopropyl alcohol scrub (IPA). All sites were monitored at all sampling time points and at 24 hours following treatment for adverse skin reaction. Samples were collected pre-, immediately post-, and 1 hour post-treatment and plated in duplicate. Bacterial counts were shifted to eliminate zeroes, log10 transformed, and averaged. ANOVA was used to compare differences in mean reduction in log10 CFU/ml between groups. RESULTS: Reduction in log10CFU/ml was more pronounced immediately after application of IPA (p = .001) and ET (p = .001) than CHG. This reduction was better sustained after preparation with CHG than ET (p = .005) but not IPA. Immediate and sustained reductions in bacterial loads did not differ after application of IPA or ET. No adverse skin reactions were noted. CONCLUSIONS: Skin preparation with alcohol-based antiseptics was well tolerated and improved immediate bacterial reduction compared to CHG. This reduction was better sustained 1 hour after application of CHG than ET, but no difference was detected between CHG and IPA. CLINICAL RELEVANCE: Lack of adverse skin reaction and performance provide evidence to support skin preparation with alcohol-based antiseptics in cattle.

Antimicrobial persistence of two alcoholic preoperative skin preparation solutions.

BACKGROUND: Normal skin flora and suboptimal skin antisepsis are the primary drivers of healthcare-associated infections (HAIs). Antimicrobial persistence of preoperative skin preparation is necessary to limit microorganisms on the skin and help minimize their entry into an incision or device-insertion site after application. AIM: To assess the antimicrobial persistence of two preoperative skin preparation solutions. METHODS: A randomized, single-centre, partially blinded, clinical study was conducted in 103 healthy volunteers to evaluate the persistent antimicrobial properties of BD ChloraPrep™ (2% w/v chlorhexidine gluconate [CHG] + 70% v/v isopropyl alcohol [IPA]) and BD PurPrep™ (8.3% w/w povidone-iodine [PVPI] + 72.5% w/w IPA) skin preparations out to 7 days and 96 h, respectively, on abdomen and groin testing sites. An additional 32 healthy volunteers participated in a neutralization procedure to ensure that the study recovery solution was non-toxic to microorganisms, and a spore-recovery procedure to demonstrate that microorganisms could be successfully recovered from the PVP-I+IPA film-forming product. FINDINGS: Both CHG+IPA and PVP-I+IPA produced a mean bacterial log10 reduction >2 and >3 on the abdomen and groin, respectively, 10 min after application. CHG+IPA maintained antimicrobial persistence out to 7 days post application, whereas PVP-I+IPA maintained antimicrobial persistence out to 96 h post application, the longest time-point selected for this product. CONCLUSION: CHG+IPA and PVP-I+IPA were both found to be effective, persistent antiseptic skin preparations. Overall, skin irritation was uncommon, and only one adverse event occurred following product application, which was not considered product-related but was considered procedure-related.

Prevalence of the fimbrial operon mrkABCD, mrkA expression, biofilm formation and effect of biocides on biofilm formation in carbapenemase-producing Klebsiella pneumoniae isolates belonging or not belonging to high-risk clones.

BACKGROUND: The role of mrkA adhesin expression, biofilm production, biofilm viability and biocides in the biofilm of carbapenemase-producing Klebsiella pneumoniae isolates was investigated. METHODS: Seventeen isolates representing different sequence types and carbapenemases were investigated. mrkA expression was determined by real-time reverse transcription polymerase chain reaction. Biofilm production (25°C and 37°C, with and without humidity) was determined by the crystal violet assay. The effect of isopropanol, povidone-iodine, sodium hypochlorite, chlorhexidine digluconate, benzalkonium chloride, ethanol and triclosan on biofilm was determined. The effect of povidone-iodine on biofilm biomass and thickness was also determined by confocal laser scanning microscopy. RESULTS: mrkA expression ranged from 28.2 to 1.3 [high or intermediate level; 64% of high-risk (HR) clones] and from 21.5 to 1.3 (50% of non-HR clones). At 25°C, biofilm formation was observed in 41% of isolates (absence of humidity) and 35% of isolates (presence of humidity), whereas at 37°C, biofilm formation was observed in 76% of isolates with and without humidity. At 25°C, biofilm producers were more frequently observed in HR clones (45% with humidity and 55% without humidity) than non-HR clones (17% with and without humidity). Biofilm viability from day 21 was higher at 25°C than 37°C. The greatest decrease in biofilm formation was observed with povidone-iodine (29% decrease), which also decreased biofilm thickness. CONCLUSIONS: Biofilm formation in carbapenemase-producing K. pneumoniae is related to mrkA expression. Biofilm formation is affected by temperature (37°C>25°C), whereas humidity has little effect. Biofilm viability is affected by temperature (25°C>37°C). At 25°C, HR clones are more frequently biofilm producers than non-HR clones. Povidone-iodine can decrease biofilm production and biofilm thickness.

Effects of Solvents, Emulsions, Cosolvents, and Complexions on Ex Vivo Mouse Myometrial Contractility.

A great need exists to develop tocolytic and uterotonic drugs that combat poor, labor-related maternal and fetal outcomes. A widely utilized method to assess novel compounds for their tocolytic and uterotonic efficacy is the isometric organ bath contractility assay. Unfortunately, water-insoluble compounds can be difficult to test using the physiological, buffer-based, organ bath assay. Common methods for overcoming solubility issues include solvent variation, cosolvency, surfactant or complexion use, and emulsification. However, these options for drug delivery or formulation can impact tissue function. Therefore, the goal of this study was to evaluate the ability of common solvents, surfactants, cosolvents, and emulsions to adequately solubilize compounds in the organ bath assay without affecting mouse myometrial contractility. We found that acetone, acetonitrile, and ethanol had the least effect, while dimethylacetamide, ethyl acetate, and isopropanol displayed the greatest inhibition of myometrial contractility based on area under the contractile curve analyses. The minimum concentration of surfactants, cosolvents, and human serum albumin required to solubilize nifedipine, a current tocolytic drug, resulted in extensive bubbling in the organ bath assay, precluding their use. Finally, we report that an oil-in-water base emulsion containing no drug has no statistical effect beyond the control (water), while the drug emulsion yielded the same potency and efficacy as the freely solubilized drug.

Antimicrobial performance of two preoperative skin preparation solutions containing iodine and isopropyl alcohol.

BACKGROUND: Healthcare-associated infections (HAIs) are a persistent clinical challenge caused primarily by bacteria on the skin. Proper utilization of optimized antiseptic skin preparation solutions helps reduce the prevalence and impact of HAIs by decreasing patient skin microorganisms preoperatively. The purpose of this study was to evaluate the efficacy of 2 antimicrobial solutions containing iodine and isopropyl alcohol (IPA): Povidone iodine (PVP-I) with IPA (ie, PVP-I+IPA, PurPrep) and Iodine Povacrylex+IPA (DuraPrep). METHODS: The antimicrobial activity of the test solutions was evaluated in vitro by determinations of minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) against 1105 diverse microbial isolates and a time-kill assay to evaluate efficacy against 120 strains of Gram-positive and Gram-negative bacteria and yeasts. Peel tests were performed between skin samples treated with test solutions and representative drape/dressing materials to determine effects of test solutions on the biomechanical adhesion properties. Finally, an Institutional Review Board (IRB)-approved, randomized, controlled, single-center, partially blinded in vivo study was performed to assess the immediate and persistent antimicrobial activity of the test solutions on the abdomen and groin. RESULTS: Both PVP-I+IPA and Iodine Povacrylex+IPA solutions demonstrated broad-spectrum antimicrobial activity with MIC and MBC at less than 1% of the full-strength concentration of each product against a wide variety of microorganisms. In the time-kill tests, both solutions were able to successfully reduce all microbial populations by 99.99% (ie, 4 log10) at the contact times of 30 seconds, 2 minutes and 10 minutes. The 2 solutions showed relatively similar adhesion results when tested with 3 representative operating room materials. Both PVP-I+IPA and Iodine Povacrylex+IPA met the expected Food and Drug Administration (FDA) efficacy requirements at 10 minutes and 6 hours post-treatment for both anatomic sites (ie, groin, and abdomen) in the clinical study, with no safety issues or adverse events. CONCLUSIONS: Analysis of the in vitro antimicrobial activity, biomechanical adhesive strength, and in vivo efficacy of PVP-I+IPA demonstrated similar results compared to Iodine Povacrylex+IPA. Both products were efficacious at reducing or eliminating a wide range of clinically-relevant microorganisms in lab-based and clinical settings, supporting their use as antiseptic skin preparation solutions to reduce bacteria on the skin that can cause infection.

Viral Inactivation with Emphasis on SARS-CoV-2 Using Physical and Chemical Disinfectants.

BACKGROUND: Recently, an outbreak of a novel human coronavirus SARS-CoV-2 has become a world health concern leading to severe respiratory tract infections in humans. Virus transmission occurs through person-to-person contact, respiratory droplets, and contaminated hands or surfaces. Accordingly, we aim at reviewing the literature on all information available about the persistence of coronaviruses, including human and animal coronaviruses, on inanimate surfaces and inactivation strategies with biocides employed for chemical and physical disinfection. METHOD: A comprehensive search was systematically conducted in main databases from 1998 to 2020 to identify various viral disinfectants associated with HCoV and methods for control and prevention of this newly emerged virus. RESULTS: The analysis of 62 studies shows that human coronaviruses such as severe acute respiratory syndrome (SARS) coronavirus, Middle East respiratory syndrome (MERS) coronavirus or endemic human coronaviruses (HCoV), canine coronavirus (CCV), transmissible gastroenteritis virus (TGEV), and mouse hepatitis virus (MHV) can be efficiently inactivated by physical and chemical disinfectants at different concentrations (70, 80, 85, and 95%) of 2-propanol (70 and 80%) in less than or equal to 60 s and 0.5% hydrogen peroxide or 0.1% sodium hypochlorite within 1 minute. Additionally, glutaraldehyde (0.5-2%), formaldehyde (0.7-1%), and povidone-iodine (0.1-0.75%) could readily inactivate coronaviruses. Moreover, dry heat at 56°C, ultraviolet light dose of 0.2 to 140 J/cm2, and gamma irradiation could effectively inactivate coronavirus. The WHO recommends the use of 0.1% sodium hypochlorite solution or an ethanol-based disinfectant with an ethanol concentration between 62% and 71%. CONCLUSION: The results of the present study can help researchers, policymakers, health decision makers, and people perceive and take the correct measures to control and prevent further transmission of COVID-19. Prevention and decontamination will be the main ways to stop the ongoing outbreak of COVID-19.

Disinfectant effectiveness against SARS-CoV-2 and influenza viruses present on human skin: model-based evaluation.

OBJECTIVES: Disinfection effectiveness against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on human skin remains unclear because of the hazards of viral exposure. An evaluation model, which has been previously generated using human skin obtained from forensic autopsy samples, accurately mimics in vivo skin conditions for evaluating the effectiveness of disinfection against the virus. Using this model, we evaluated disinfection effectiveness against viruses on human skin. METHODS: Ethanol (EA), isopropanol (IPA), chlorhexidine gluconate (CHG) and benzalkonium chloride (BAC) were used as target disinfectants. First, disinfectant effectiveness against SARS-CoV-2 and influenza A virus (IAV) was evaluated in vitro. Disinfectant effectiveness against SARS-CoV-2 and IAV on human skin was then evaluated by titrating viruses present on the skin after applying each disinfectant on the skin for 5-60 seconds. RESULTS: Both, SARS-CoV-2 and IAV on human skin were completely inactivated within 5 seconds by 40%-80% EA and 70% IPA (log reduction values (LRVs) were >4). However, SARS-CoV-2 and IAV were barely inactivated by 20% EA (LRVs were <1). In vitro evaluation showed that, compared with EA and IPA, CHG and BAC were significantly inferior in terms of disinfection effectiveness. Conversely, the disinfection effectiveness of CHG and BAC against SARS-CoV-2 was higher on human skin than in vitro, and increased with increases in their concentration and reaction time (LRVs of 0.2% CHG/0.05% BAC were >2, and LRVs of 1.0% CHG/0.2% BAC were >2.5). CONCLUSIONS: Proper hand hygiene practices using alcohol-based disinfectants such as EA/IPA effectively inactivate SARS-CoV-2 and IAV on human skin.

Activation of short-chain ketones and isopropanol in sulfate-reducing bacteria.

BACKGROUND: Degradation of acetone by aerobic and nitrate-reducing bacteria can proceed via carboxylation to acetoacetate and subsequent thiolytic cleavage to two acetyl residues. A different strategy was identified in the sulfate-reducing bacterium Desulfococcus biacutus that involves formylation of acetone to 2-hydroxyisobutyryl-CoA. RESULTS: Utilization of short-chain ketones (acetone, butanone, 2-pentanone and 3-pentanone) and isopropanol by the sulfate reducer Desulfosarcina cetonica was investigated by differential proteome analyses and enzyme assays. Two-dimensional protein gel electrophoresis indicated that D. cetonica during growth with acetone expresses enzymes homologous to those described for Desulfococcus biacutus: a thiamine diphosphate (TDP)-requiring enzyme, two subunits of a B12-dependent mutase, and a NAD+-dependent dehydrogenase. Total proteomics of cell-free extracts confirmed these results and identified several additional ketone-inducible proteins. Acetone is activated, most likely mediated by the TDP-dependent enzyme, to a branched-chain CoA-ester, 2-hydroxyisobutyryl-CoA. This compound is linearized to 3-hydroxybutyryl-CoA by a coenzyme B12-dependent mutase followed by oxidation to acetoacetyl-CoA by a dehydrogenase. Proteomic analysis of isopropanol- and butanone-grown cells revealed the expression of a set of enzymes identical to that expressed during growth with acetone. Enzyme assays with cell-free extract of isopropanol- and butanone-grown cells support a B12-dependent isomerization. After growth with 2-pentanone or 3-pentanone, similar protein patterns were observed in cell-free extracts as those found after growth with acetone. CONCLUSIONS: According to these results, butanone and isopropanol, as well as the two pentanone isomers, are degraded by the same enzymes that are used also in acetone degradation. Our results indicate that the degradation of several short-chain ketones appears to be initiated by TDP-dependent formylation in sulfate-reducing bacteria.

Comparison of the effect of isopropyl alcohol and chlorhexidine solution rinses on body temperature of female cats undergoing sterilization surgery.

OBJECTIVES: Isopropyl alcohol 70% as a rinse agent for chlorhexidine scrub has been shown to decrease body temperature more quickly than chlorhexidine solution in mice prepared aseptically prior to surgery. For this reason, some high-quality, high-volume (HQHV) surgical sterilization clinics use chlorhexidine solution rather than alcohol. We sought to determine if temperature upon entry to recovery, heat loss per kg and rate of temperature decline during surgery were different between cats rinsed with chlorhexidine solution vs 70% isopropyl alcohol following surgical scrub, and if there were significant predictors of recovery temperature. METHODS: Female cats admitted for surgery to trap-neuter-return (TNR) clinics at a veterinary college were assigned chlorhexidine solution or alcohol rinse agents via block randomization. Veterinary students and veterinarians performed spay surgeries using HQHV techniques. In recovery, heat support and reversal agents were available for cats with a low body temperature or that were slow to recover. Baseline values, outcome variables and duration of each stage (preparation, surgery, recovery) were assessed using Wilcoxon rank-sum and t-tests. Recovery temperature was evaluated using random effects multiple linear regression. RESULTS: The recovery temperature, heat loss per kg, heat loss per min, need for reversal and need for heat support in recovery were not significantly different between rinse groups. Weight <2.3 kg, body condition score <4, duration of surgery and postinduction temperature were predictors of recovery temperature. The rate of heat loss in the first 30 mins of surgery was slightly lower for cats in the alcohol rinse group and the recovery duration was shorter for cats weighing less <2.3 kg in the alcohol rinse group. CONCLUSIONS AND RELEVANCE: There were no clinically meaningful differences in body temperature between chlorhexidine and alcohol rinses. Both chlorhexidine solution and isopropyl alcohol 70% are appropriate rinse agents for aseptic preparation of feline spay surgeries.

Tolerance to disinfectants (chlorhexidine and isopropanol) and its association with antibiotic resistance in clinically-related Klebsiella pneumoniae isolates.

Disinfectants play an essential role in controlling the dissemination of bacteria in health care settings, but it may also contribute to the selection of antibiotic resistance bacteria. This study looked at Klebsiella pneumoniae isolates collected from three hospitals in Lima, Peru, in order to evaluate: their susceptibility to chlorhexidine [CHG] and isopropanol [ISP]), and their association with antimicrobial susceptibility. We analyzed 59 K. pneumoniae isolates and assessed their CHG and ISP susceptibility by minimum inhibitory concentrations (MICs). Additionally, we performed a regression analysis to assess the association between disinfectant tolerance and antibiotic resistance (measured by the disc diffusion method), colistin resistance (by microdilution), carbapenemases presence (by polymerase chain reaction [PCR]), and clonal relationships (by pulsed-field gel electrophoresis [PFGE]). Eleven K. pneumoniae strains were isolated from fomites, and 48 strains from clinical samples. The MIC range of these isolates was 8-128 µg/ml for CHG and 16-256 mg/ml for ISP. We found that resistance to trimethoprim/sulfamethoxazole (TMP/SMX) was the main factor associated with CHG log2 MIC (ß = 0.65; 95%CI: 0.03, 1.27; R2 = 0.07). In the case of ISP, the log2(MIC) was associated with the institution of origin, showing lower ISP log2(MIC) in fomites compared to clinical samples(ß = -0.77; 95%CI: -1.54, -0.01; R2 = 0.08). Resistance to CHG and ISP among K. pneumoniae isolates found in Peruvian hospitals seems to be elevated and highly variable. Further studies are needed to confirm our results and implement actionable interventions if necessary.

Ethanol and isopropanol inactivation of human coronavirus on hard surfaces.

BACKGROUND: The coronavirus disease 2019 pandemic has greatly increased the frequency of disinfecting surfaces in public places, causing a strain on the ability to obtain disinfectant solutions. An alternative is to use plain alcohols (EtOH and IPA) or sodium hypochlorite (SH). AIM: To determine the efficacy of various concentrations of EtOH, IPA and SH on a human coronavirus (HCoV) dried on to surfaces using short contact times. METHODS: High concentrations of infectious HCoV were dried on to porcelain and ceramic tiles, then treated with various concentrations of the alcohols for contact times of 15 s, 30 s and 1 min. Three concentrations of SH were also tested. Reductions in titres were measured using the tissue culture infectious dose 50 assay. FINDINGS: Concentrations of EtOH and IPA from 62% to 80% were very efficient at inactivating high concentrations of HCoV dried on to tile surfaces, even with a 15-s contact time. Concentrations of 95% dehydrated the virus, allowing infectious virus to survive. The dilutions of SH recommended by the Centers for Disease Control and Prevention (1/10 and 1/50) were efficient at inactivating high concentrations of HCoV dried on to tile surfaces, whereas a 1/100 dilution had substantially lower activity. CONCLUSIONS: Multiple concentrations of EtOH, IPA and SH efficiently inactivated infectious HCoV on hard surfaces, typical of those found in public places. Often no remaining infectious HCoV could be detected.

COVID-19 global pandemic planning: Performance and electret charge of N95 respirators after recommended decontamination methods.

Shortages of N95 respirators for use by medical personnel have driven consideration of novel conservation strategies, including decontamination for reuse and extended use. Decontamination methods listed as promising by the Centers for Disease Control and Prevention (CDC) (vaporous hydrogen peroxide (VHP), wet heat, ultraviolet irradiation (UVI)) and several methods considered for low resource environments (bleach, isopropyl alcohol and detergent/soap) were studied for two commonly used surgical N95 respirators (3M™ 1860 and 1870+ Aura™). Although N95 filtration performance depends on the electrostatically charged electret filtration layer, the impact of decontamination on this layer is largely unexplored. As such, respirator performance following decontamination was assessed based on the fit, filtration efficiency, and pressure drop, along with the relationship between (1) surface charge of the electret layer, and (2) elastic properties of the straps. Decontamination with VHP, wet heat, UVI, and bleach did not degrade fit and filtration performance or electret charge. Isopropyl alcohol and soap significantly degraded fit, filtration performance, and electret charge. Pressure drop across the respirators was unchanged. Modest degradation of N95 strap elasticity was observed in mechanical fatigue testing, a model for repeated donnings and doffings. CDC recommended decontamination methods including VHP, wet heat, and UV light did not degrade N95 respirator fit or filtration performance in these tests. Extended use of N95 respirators may degrade strap elasticity, but a loss of face seal integrity should be apparent during user seal checks. NIOSH recommends performing user seal checks after every donning to detect loss of appropriate fit. Decontamination methods which degrade electret charge such as alcohols or detergents should not be used on N95 respirators. The loss of N95 performance due to electret degradation would not be apparent to a respirator user or evident during a negative pressure user seal check.