Efficacy of sodium hypochlorite against multidrug-resistant Gram-negative bacteria

Longitudinal bacterial community dynamics and sodium hypochlorite intervention in a newly built university building

Urbanisation and building advancements have increased microbial growth in indoor environments, altering human interactions with these microorganisms. Restrooms and their sinks harbour diverse bacterial communities, that differ from those found in natural environments, that could have negative implications for human health. Over two and a half years, this study examined the diversity, temporal dynamics, and resilience of bacterial communities in restroom sink P-traps in a newly built university building. Structured into two phases, the first phase consisted of continuous monitoring of bacterial community dynamics for two years (n = 352), while the second phase involved an intervention with sodium hypochlorite (bleach) and subsequent sampling (n = 132). In the first phase, we show that sink communities converge, becoming more compositionally similar to other sinks within the building. Bacterial families such as Rhodocyclaceae and Flavobacteriaceae dominated across the sinks, and others such as Comamonadaceae, Moraxellaceae and Enterbacteriaceae were highly prevalent. When comparing bacterial structure and composition to other sinks located on the university campus, the mean bacterial dissimilarity decreased over time, indicating compositional similarity, particularly with the newer buildings on campus. The second phase demonstrated resilience by the bacterial sink communities. Following bleach treatments, a distinct increase in Acinetobacter was observed. However, by the fourth week after bleach invention, bacterial communities had re-established to levels observed prior to treatment. This study had the unique opportunity to sample a newly built building before occupancy and for the subsequent two and a half years. The findings provide crucial insights into the development and resilience of sink P-trap bacterial communities in restrooms, laying the groundwork for more targeted approaches to disinfection strategies.

N-Chlorotaurine Solutions as Agents for Infusion Detoxification Therapy: Preclinical Studies

N-chlorotaurine (NCT) is a broad-spectrum antimicrobial agent with outstanding tolerability, effective for topical and inhalation use. This paper presents the results of studies of single and repeated intravenous infusions of NCT to laboratory animals. The studies were conducted on female Wistar Han rats. The effect of NCT infusions on the general condition, behavioral reactions, main biochemical and hematological parameters, hemocoagulation system, cardiovascular system, and on the condition of the internal organs was studied. It was found that NCT infusions do not reveal deviations in the studied parameters that could indicate a toxic effect. The estimated LD50 is more than 80 mg/kg. In a subchronic experiment, a statistically significant decrease in cholesterol (by up to 11%), glucose (by up to 15%) and excess bases (up to four times) in the blood, and an increase in heart rate (by up to 31%) and frequency of defecations (by up to 35%), as well as pronounced antiplatelet effect, were found. In animals with simulated endotoxicosis, a decrease in the cytolysis and oxidative stress markers was observed. Such effects are caused by both chlorine-active compounds and taurine.The results obtained indicate broad prospects for the use of NCT solutions as an infusion detoxifying agent.

Screening of antimicrobial activity of Ilex paraguariensis St. Hil. leaf extracts against carbapenemase-producing bacteria

I. paraguariensis St. Hil. is a south American species of agronomic interest with studies supporting its medicinal properties. As the investigation of active ingredients with antimicrobial effect from medicinal plants is a suitable approach to the current antibacterial resistance problem, the aim of the present study was to determine the antibacterial activity of yerba mate ethanolic extracts against carbapenemase-producing gram-negative bacteria (reference strains and clinical isolates). Extracts showed antibacterial activity against Klebsiella pneumoniae ATCC® BAA-2342™ (KPC producing), Providencia rettgeri (NDM producing), Pseudomonas aeruginosa (MBL producing) and P. aeruginosa (VIM producing) at the concentrations tested. The Minimal-Inhibitory-Concentration and Minimal-Bactericidal-Concentration values ranged between 1 and 32 mg.ml-1 for the reference strains, and between 0.125 and 1 mg.ml-1 for the clinical isolates. The MBC/MIC index characterized the extracts as bactericidal. The combinations of commercial antibiotics and extracts showed a synergistic action on the reference strains studied. The lethal concentration 50 obtained using the Artemia salina toxicity assay were higher than 1 mg.ml-1 for all the extracts, indicating a low toxicity. The in vitro activity and low toxicity suggest that ethanolic I. paraguariensis leaf extracts constitute an outstanding source for new antibacterial compounds, and further studies should be carried out to understand their mechanism of action.

Increasing Risks to the Health of the Invertebrates-Balancing between Harm and Benefit

The article discusses the issue of extensive use of detergents and sanitizers in the time of new challenges associated with the COVID-19 (SARS-CoV-2) pandemic. These agents could pose threats to the existence of free-living invertebrates as essential components of the ecosystem. The biological effects of the mentioned classes of substances, their metabolites, and combined effects in the mixture have not been studied enough. The main challenges in trying to balance the threats and benefits of using such substances are the lack of knowledge of the biological effects of these products, the gaps in testing invertebrates' responses, and changes in environment-related regulations to minimize risks to animals and humans. Numerous studies in this field still leave research gaps, particularly concerning the combined toxicity of well-known and widely used disinfectants, surfactants, and heavy metals, posing potential future challenges. Additionally, the review identified the need for additional testing of invertebrates for their sensitivity to disinfectants and surfactants of different compositions, including improved (non-invasive) methods, studies for early life stages, and comparative studies of species resilience.

Evaluating disinfectant efficacy on mixed biofilms comprising Shiga toxigenic Escherichia coli, lactic acid bacteria, and spoilage microorganisms

This study aimed to investigate the impact of temperature and the presence of other microorganisms on the susceptibility of STEC to biocides. Mature biofilms were formed at both 10°C and 25°C. An inoculum of planktonic bacteria comprising 106 CFU/mL of spoilage bacteria and 103 CFU/mL of a single E. coli strain (O157, O111, O103, and O12) was used to form mixed biofilms. The following bacterial combinations were tested: T1: Carnobacterium piscicola + Lactobacillus bulgaricus + STEC, T2: Comamonas koreensis + Raoultella terrigena + STEC, and T3: Pseudomonas aeruginosa + C. koreensis + STEC. Tested biocides included quaternary ammonium compounds (Quats), sodium hypochlorite (Shypo), sodium hydroxide (SHyd), hydrogen peroxide (HyP), and BioDestroy®-organic peroxyacetic acid (PAA). Biocides were applied to 6-day-old biofilms. Minimum Bactericidal Concentrations (MBC) and Biofilm Eradication Concentrations (BEC) were determined. Planktonic cells and single-species biofilms exhibited greater susceptibility to sanitizers (p < 0.0001). Lactobacillus and Carnobacterium were more susceptible than the rest of the tested bacteria (p < 0.0001). Single species biofilms formed by E. coli O111, O121, O157, and O45 showed resistance (100%) to Shypo sanitizer (200 ppm) at 25°C. From the most effective to the least effective, sanitizer performance on single-species biofilms was PAA > Quats > HyP > SHyd > Shypo. In multi-species biofilms, spoilage bacteria within T1, T2, and T3 biofilms showed elevated resistance to SHyd (30%), followed by quats (23.25%), HyP (15.41%), SHypo (9.70%), and BioDestroy® (3.42%; p < 0.0001). Within T1, T2, and T3, the combined STEC strains exhibited superior survival to Quats (23.91%), followed by HyP (19.57%), SHypo (18.12%), SHyd (16.67%), and BioDestroy® (4.35%; p < 0.0001). O157:H7-R508 strains were less tolerant to Quats and Shypo when combined with T2 and T3 (p < 0.0001). O157:H7 and O103:H2 strains in mixed biofilms T1, T2, and T3 exhibited higher biocide resistance than the weak biofilm former, O145:H2 (p < 0.0001). The study shows that STEC within multi-species biofilms' are more tolerant to disinfectants.

Long-term exposure to food-grade disinfectants causes cross-resistance to antibiotics in Salmonella enterica serovar Typhimurium strains with different antibiograms and sequence types

BACKGROUND

Disinfectants are important in the food industry to prevent the transmission of pathogens. Excessive use of disinfectants may increase the probability of bacteria experiencing long-term exposure and consequently resistance and cross-resistance to antibiotics. This study aims to investigate the cross-resistance of multidrug-resistant, drug-resistant, and drug-susceptible isolates of Salmonella enterica serovar Typhimurium (S. Typhimurium) with different sequence types (STs) to a group of antibiotics after exposure to different food-grade disinfectants.

METHODS

A panel of 27 S. Typhimurium strains with different antibiograms and STs were exposed to increasing concentrations of five food-grade disinfectants, including hydrogen peroxide (H2O2), benzalkonium chloride (BAC), chlorine dioxide (ClO2), sodium hypochlorite (NaClO), and ethanol. Recovered evolved strains were analyzed using genomic tools and phenotypic tests. Genetic mutations were screened using breseq pipeline and changes in resistance to antibiotics and to the same disinfectant were determined. The relative fitness of evolved strains was also determined.

RESULTS

Following exposure to disinfectants, 22 out of 135 evolved strains increased their resistance to antibiotics from a group of 14 clinically important antibiotics. The results also showed that 9 out of 135 evolved strains had decreased resistance to some antibiotics. Genetic mutations were found in evolved strains. A total of 77.78% of ST34, 58.33% of ST19, and 66.67% of the other STs strains exhibited changes in antibiotic resistance. BAC was the disinfectant that induced the highest number of strains to cross-resistance to antibiotics. Besides, H2O2 induced the highest number of strains with decreased resistance to antibiotics.

CONCLUSIONS

These findings provide a basis for understanding the effect of disinfectants on the antibiotic resistance of S. Typhimurium. This work highlights the link between long-term exposure to disinfectants and the evolution of resistance to antibiotics and provides evidence to promote the regulated use of disinfectants.

Energy efficient portable air cathode electrochlorinator for point-of-use disinfection of toilet wastewater

Active chlorine is the most widely used disinfectant for water disinfection as well as surface sterilization. Here, we report an air cathode electrochlorinator for point-of-use disinfection of toilet wastewater. The air cathode dominated by a four-electron pathway to reduce O₂ to OH^- was more suitable for chlorine synthesis than through a two-electron pathway to H₂O₂, which could reduce chlorine back to chloride ions. The minimum driving potential of the air cathode electrochlorinator was as low as 0.94 V, which made it possible to be directly powered by a piece of commercial mini photovoltaic solar panel without electronic converter. Under the cell voltage of 2 V, the Faraday current efficiency was 82.0 % and the electrical energy required to produce 1 kg active chlorine was estimated to be only 1.75 kWh. The normalized energy consumption to disinfect simulated toilet wastewater with a pathogen concentration of 10⁷ CFU/mL was estimated to be 7.2 W h/m³. Moreover, the material cost for fabrication of the electrochlorinator was estimated to be less than $ 0.62. These features guarantee the air cathode electrochlorinator of high potential for point-of-use disinfection of toilet wastewater.

Evaluation of the ability of commercial disinfectants to degrade free nucleic acid commonly targeted using molecular diagnostics

BACKGROUND

Polymerase chain reaction (PCR) is an essential tool for rapid detection of pathogens, but is susceptible to cross-contamination by residual nucleic acid, leading to false-positive results. Adequate surface decontamination would help prevent this, but most protocols target infectious microbes rather than free nucleic acid. The aim of this study was to evaluate the ability of commercial surface disinfectants to degrade different representative classes of nucleic acid.

METHODS

Commercial surface disinfectants with various active ingredients, as well as 10% chlorine bleach, were tested. Nucleic acid was dried on to stainless steel coupons and treated with disinfectant for 0-4 min prior to neutralization and quantification by quantitative reverse transcription PCR. The effective disinfectants were also evaluated in the presence of organic load.

RESULTS

Only dilute chlorine bleach and the hypochlorite-based commercial disinfectant significantly degraded any type of free nucleic acid. Hydrogen-peroxide- and quaternary-ammonium-based disinfectants gave <1 log reduction after 4 min for all targets. Results were time-dependent for each target, which underscores the importance of adequate contact time. Organic load appeared to have little impact on the efficacy of hypochlorite-based disinfectants for nucleic acid degradation.

CONCLUSIONS

This study demonstrates the importance of proper selection and application of disinfectant to remove residual nucleic acid when processing samples for molecular diagnostic testing.

Overuse of food-grade disinfectants threatens a global spread of antimicrobial-resistant bacteria

Food-grade disinfectants are extensively used for microbial decontamination of food processing equipment. In recent years, food-grade disinfectants have been increasingly used. However, the overuse of disinfectants causes another major issue, which is the emergence and spread of antimicrobial-resistant bacteria on a global scale. As the ongoing pandemic takes global attention, bacterial infections with antibiotic resistance are another ongoing pandemic that often goes unnoticed and will be the next real threat to humankind. Here, the effects of food-grade disinfectant overuse on the global emergence and spread of antimicrobial-resistant bacteria were reviewed. It was found that longtime exposure to the most common food-grade disinfectants promoted resistance to clinically important antibiotics in pathogenic bacteria, namely cross-resistance. Currently, the use of disinfectants is largely unregulated. The mechanisms of cross-resistance are regulated by intrinsic molecular mechanisms including efflux pumps, DNA repair system, modification of the molecular target, and metabolic adaptation. Cross-resistance can also be acquired by mobile genetic elements. Long-term exposure to disinfectants has an impact on the dissemination of antimicrobial resistance in soil, plants, animals, water, and human gut environments.

Infection control measures to stop the spread of sequence type 15 OXA-23-producing Acinetobacter baumannii in a Swedish Burn Center

OBJECTIVE

To describe the course of the outbreak and infection control measures to stop the spread of sequence type 15 OXA-23-producing Acinetobacter baumannii in the Burn Center of Uppsala University Hospital, between November 2014 and the end of April 2015.

METHODS

Compliance with hand hygiene, dress code, and cleaning routines were reviewed, the ward's environment was systematically investigated to identify potential environmental sources. Sampling routines for A. baumannii, from patients and environment, were established, and the epidemiological relationship was analysed for all carbapenem-resistant A. baumannii isolates using arbitrarily primed polymerase chain reaction (AP-PCR) and pulsed-field gel electrophoresis (PFGE).

RESULTS

A total of 54 patients were treated at the burn intensive care unit during the studied, approximately five months period, and an OXA-23-producing A. baumannii was isolated from nine patients (9/54, 17%), whereof two died (2/9, 22.2%). All isolates shared identical PFGE-genotype patterns and belonged to sequence type 15; AP-PCR was eligible for prompt epidemiological investigations.

CONCLUSIONS

Higher awareness and increased compliance with hand hygiene and dress code as well as intensified cleaning protocols of the environment and equipment were successfully established and likely to have led to stop the spread of sequence type 15 OXA-23-producing Acinetobacter baumannii.

Improving intestinal absorption and antibacterial effect of florfenicol via nanocrystallisation technology

To study the effects of nanocrystallisation technology on the intestinal absorption properties and antibacterial activity of florfenicol (FF). The florfenicol nanocrystals (FF-NC) were prepared by wet grinding and spray drying. Additionally, changes in particle size, charge, morphology, and dissolution of FF-NC in the long-term stability were monitored by laser particle sizer, TEM, SEM, paddle method, and the structure of FF-NC powder was characterised by nuclear magnetic resonance (NMR) test. The antibacterial activity, intestinal absorption and intestinal histocompatibility of FF-NC were investigated by the stiletto, mini broth dilution susceptibility test, in situ single-pass intestinal perfusion (SPIP) and haematoxylin-eosin (H-E) staining. After 12 months of storage, the particle size and zeta potential of FF-NC were 280.43 ± 8.21 nm and -19.64 ± 3.45 mV, and the electron microscopy results showed that FF-NC were nearly circular with no adhesion between particles. In addition, the drug loading, encapsulation efficiency, and dissolution of FF-NC did not change significantly during storage. The inhibition zone of FF-NC against Escherichia coli and Staphylococcus aureus was 21.37 ± 1.70 mm and 25.17 ± 2.47 mm, respectively. Compared with the FF, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of FF-NC are reduced, and the absorption rate constant (K_a) and efficient permeability coefficient (P_eff) of FF-NC in the three intestinal segments were increased by 1.28, 0.25, and 9.10 times and 0.59, 0.17, and 6.0 times, respectively. The results of tissue sections showed that FF-NC had little damage to the small intestinal. Nanocrystallisation technology is an effective method to increase the intestinal absorption and antibacterial activity of FF.

Sodium Hypochlorite and Diode Laser in Non-Surgical Treatment of Periodontitis: Clinical and Bacteriological Study with Real Time Polymerase Chain Reaction (PCR)

Increasing the disinfection during non-surgical treatment of periodontitis is primordial. This study assesses the effectiveness of sodium hypochlorite and a 980 nm diode laser in non-surgical treatment of periodontitis. Thirty sites of localized periodontitis with a probing pocket depth (PPD) of ≥ 6 mm were included. Fifteen underwent scaling root planing (SRP group) and 15 underwent SRP + 0.5% NaOCl and a 980 nm diode laser (study group). A biological molecular test and real time polymerase chain reaction (RT-PCR) were performed before (T0) and after intervention (T1). Total bacterial count and counts of Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, Prevotella intermedia, Peptostreptococcus micros, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, Eubacterium nodatum, Capnocytophaga gingivalis were assessed. Plaque index (PI), bleeding on probing (BOP), gingival recession (GR), PPD and clinical attachment loss (CAL) were evaluated at T0, and 3 and 6 months after. Study group showed a statistically significant reduction of TBC (5.66 × 10⁸ CFU/mL) compared to SRP (6.2 × 10⁹ CFU/mL). Both groups showed a statistically significant reduction of Treponema denticola, Tannerella forsythia, Prevotella intermedia, Peptostrep. (micromonas) micros and Fusobacterium nucleatum; however, a significant reduction of Eubacterium nodatum and Capnocytophaga gingivalis was observed in the study group. At T6, both groups had a statistically significant reduction of PI, BOP, GR, PD and CAL. The study group showed more GR compared to SRP and a significant reduction of PD (4.03 mm ± 0.49) compared to SRP (5.28 mm ± 0.67). This study reveals that NaOCl and a diode laser are effective as an adjunctive to the non-surgical treatment of periodontitis.

Suggestions on Relieving Physical Anxiety of Medical Workers and Improving Physical and Mental Health Under the COVID-19 Epidemic-A Case Study of Meizhou City

The study examined the effects of swimming pools on healthcare professionals' willingness to engage in recreational activities, physical anxiety, and physical and mental well-being in the context of COVID-19. The research adopted the mixed research method, used SPSS 26.0 statistical software to test the reliability of the questionnaire, and then collected 840 valid questionnaires; first analyzed the data with basic statistics, t-test, ANOVA, and PPMCC test methods, and then used the interview method to collect expert opinions. A multi-check approach assembled all data and discussions. The study found that the use of personnel dynamic tracking systems or measures, combined with sodium hypochlorite and repeated filtration to stabilize water quality, could maintain the confidence of most medical workers in the swimming pool sports environment for epidemic prevention and avoid violations. The government could formulate safety prevention and control mechanisms in traffic and establish appropriate traffic routes. Next, formulated a prescription for swimming or other physical activity mechanisms for men aged 31-50 and redesigned measures for medical staff over 51 years old to have tense head issues and physical fatigue, promote blood circulation and improve sleep quality. This will promote the purpose of relieving stress and regulating the physical and mental health of medical staff after engaging in swimming.

Biocides as Biomedicines against Foodborne Pathogenic Bacteria

Biocides are currently considered the first line of defense against foodborne pathogens in hospitals or food processing facilities due to the versatility and efficiency of their chemical active ingredients. Understanding the biological mechanisms responsible for their increased efficiency, especially when used against foodborne pathogens on contaminated surfaces and materials, represents an essential first step in the implementation of efficient strategies for disinfection as choosing an unsuitable product can lead to antibiocide resistance or antibiotic–biocide cross-resistance. This review describes these biological mechanisms for the most common foodborne pathogens and focuses mainly on the antipathogen effect, highlighting the latest developments based on in vitro and in vivo studies. We focus on biocides with inhibitory effects against foodborne bacteria (e.g., Escherichia spp., Klebsiella spp., Staphylococcus spp., Listeria spp., Campylobacter spp.), aiming to understand their biological mechanisms of action by looking at the most recent scientific evidence in the field.

Effect of colistin sulfate in the health status and bacteriological gut flora in store pigs with nonspecific gastroenteritis

Piglets with the nonspecific gastroenteritis received Colistin 12000000 with drinking water for 5 days is the doses 0.6 g/100 kg in Group 1 and 0.8 g/100 kg in Group 2. This provided the complete therapeutic efficacy (the clinical recovery) on Day 4 in both treatment groups. The dynamics of the erythrocytes and leukocytes suggested the recovery of the morphofunctional homeostasis after the disease in both treatment groups. After the treatment with the Colistin 12000000, the prevalence of the Streptococcus gallolyticus reduced by 8.3% in the Group 1. Klebsiella pneumoniae prevalence reduced by 33.3%. In Group 2, the prevalence of Streptococcus gallolyticus reduced by 41.7% after the 5-day therapy and was 25.0% at the end of the study. Klebsiella pneumoniae prevalence reduced twice, and it was ultimately observed in 16.7% of cases. Other bacteria presented in the washings at the baseline in both groups were no more observed at the end of the treatment. The symbiotic flora was found in both groups at the end of the experiment in a sufficient number. Thus, the efficient dose of the test drug was 0.6 g/100 kg provided the desirable clinical effect comparable to the higher dosing regimen. The drug well tolerated, with no side effects or adverse events reported throughout the study.

Acute inhalation toxicity of aerosolized electrochemically generated solution of sodium hypochlorite

OBJECTIVE

The objective was to determine the inhalation toxicity of the electrochemically generated sodium hypochlorite solution after its single administration to laboratory animals in the form of a highly dispersed aerosol.

MATERIALS AND METHODS

The study has been conducted according to the OECD Test Guideline №403 'Acute Inhalation Toxicity.' Laboratory animals were exposed to inhalation of an aerosol containing 1.7 ± 0.13 mg/m³ of active chlorine. The hematological and biochemical parameters of the blood of experimental animals have been determined, as well as specific parameters: the activity of cathepsins B and L, catalase, and α1-antitrypsin. Histological study of the lungs of animals has been carried out.

RESULTS

During inhalation and 14 days after it, no death of the animals was observed; the behavior, appearance, and weight gain did not differ from the control group. There were no significant deviations in hematological parameters, except the decrease in the level of platelets. The biochemical study showed slight changes in the activity of alkaline phosphatase and aspartate aminotransferase on the 1st day after inhalation; these parameters returned to normal within 14 days of observation. Specific biochemical parameters did not show the development of oxidative stress. No specific histological pathologies of lung tissue have been found.

CONCLUSIONS

Thus, the studied electrochemically generated sodium hypochlorite solution under single inhalation exposure in aerosol form practically does not cause a toxic effect. The data obtained allow classifying such solution to the 4th (or even 5th - after additional studies) class of toxicity in accordance with Globally Harmonized System of Classification and Labeling of Chemicals.

A Flexible Chemosensor Based on Colorimetric and Fluorescent Dual Modes for Rapid and Sensitive Detection of Hypochlorite Anion

A flexible chemosensor has been developed based on colorimetric and fluorescent dual modes using tetraphenylethylene-centered tetraaniline (TPE4A) for rapid and sensitive detection of hypochlorite anion. The fluorescent probe TPE4A exhibits a unique aggregation-induced emission (AIE) character which is proved by a blue shift of the fluorescent peak from 544 to 474 nm with the water equivalents increasing. With the addition of hypochlorite in solution, the absorbance of the probe changes and the responding fluorescence color can be observed to change from light green to purple. The detection limit of hypochlorite is 1.80 × 10-4 M in solution, and the visual detection limit is 1.27 µg/cm2 with the naked eye for the flexible paper-based chemosensor. The proposed flexible chemosensors show a good selectivity and sensitivity which has great potential for effective detection of hypochlorite anions without any spectroscopic instrumentation.

Potential application of novel technology developed for instant decontamination of personal protective equipment before the doffing step

The use of personal protective equipment (PPE) has been considered the most effective way to avoid the contamination of healthcare workers by different microorganisms, including SARS-CoV-2. A spray disinfection technology (chamber) was developed, and its efficacy in instant decontamination of previously contaminated surfaces was evaluated in two exposure times. Seven test microorganisms were prepared and inoculated on the surface of seven types of PPE (respirator mask, face shield, shoe, glove, cap, safety glasses and lab coat). The tests were performed on previously contaminated PPE using a manikin with a motion device for exposure to the chamber with biocidal agent (sodium hypochlorite) for 10 and 30s. In 96.93% of the experimental conditions analyzed, the percentage reduction was >99% (the number of viable cells found on the surface ranged from 4.3x106 to <10 CFU/mL). The samples of E. faecalis collected from the glove showed the lowest percentages reduction, with 86.000 and 86.500% for exposure times of 10 and 30 s, respectively. The log10 reduction values varied between 0.85 log10 (E. faecalis at 30 s in glove surface) and 9.69 log10 (E. coli at 10 and 30 s in lab coat surface). In general, E. coli, S. aureus, C. freundii, P. mirabilis, C. albicans and C. parapsilosis showed susceptibility to the biocidal agent under the tested conditions, with >99% reduction after 10 and 30s, while E. faecalis and P. aeruginosa showed a lower susceptibility. The 30s exposure time was more effective for the inactivation of the tested microorganisms. The results show that the spray disinfection technology has the potential for instant decontamination of PPE, which can contribute to an additional barrier for infection control of healthcare workers in the hospital environment.

Multimodal intervention to reduce acquisition of carbapenem-non-susceptible Gram-negative bacteria in intensive care units in the National Referral Hospital of Indonesia: An interrupted time series study

PURPOSE

To evaluate a low-cost multimodal intervention on the acquisition of carbapenem-non-susceptible Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa by patients in low-resource intensive care units.

MATERIALS AND METHODS

We performed a quasi-experimental study in a referral hospital in Jakarta, Indonesia: pre-intervention phase 1 (2013-2014), intervention phase 2 (2014-2015) and post-intervention phase 3 (2015-2016). The intervention was hand hygiene promotion and environmental cleaning and disinfection combined with patient disinfection and cohorting. The primary outcome was acquisition of resistant bacteria per 100 patient-days at risk, which was assessed by active microbiological surveillance and analysed with a multilevel Poisson segmented regression model.

RESULTS

In phase 1 (387 patients), the acquisition rate was 4.3/100 days for carbapenem-non-susceptible A. baumannii versus 1.1/100 days for both K. pneumoniae and P. aeruginosa. There was a significant step change from phase 1 to phase 3 (361 patients) in the acquisition of carbapenem-non-susceptible strains, the incidence rate ratio (IRR) was 0.343 (99%CI: 0.164-0.717). This significant change was mainly due to reduced acquisitions of resistant A. baumannii (IRR 0.4, 99%CI: 0.181-1.061). Negative confounding was observed.

CONCLUSION

A multimodal intervention to prevent acquisition of resistant pathogens is feasible and may be effective in ICUs in lower-middle income countries.

COVID-19 into Chemical Science Perspective: Chemical Preventive Measures and Drug Development

COVID-19 facts and literature are discussed into chemical science intuition highlighting the direct role of chemistry to the ongoing global pandemic by covering structural identification of the virus, chemical preventive measures and development of drugs. We reviewed the four most promising repurposed drugs which are presently being investigated in mass clinical trials on COVID-19 infected persons and synthetic routes of these drugs with their recent advancement. Chemical preventive measures such as soap water, hand sanitizer and disinfectant are the only available options in the arsenal to fight against COVID-19, till an effective medicine or vaccine will be made available. As such the present review will focus on the mode of action of the major chemical preventives.

Excessive use of disinfectants against COVID-19 posing a potential threat to living beings

•

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan city of China in late December 2019.

•

The rapid spread of the COVID-19 across the communities shock the entire population, because of no existing therapies.

•

Health professionals recommended frequent washing of hands with soap and alcohol-based sanitizers, but these disinfectants has worst effects on human health.

•

Precautionary measures should be ensured to protect ourselves and the community from the possible risk associated with disinfectants.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan city of China in late December 2019 and identified as a novel coronavirus disease 2019 (COVID-19). On January 30, the World Health Organization (WHO) declared the coronavirus outbreak a global public health emergency. The rapid spread of the pathogen across the communities shock the entire population. As no existing therapy were available during the pandemic. Health professionals recommended frequent washing of hands with soap and alcohol-based sanitizers. Disinfectants were extensively sprayed to minimize the possibility of getting COVID-19. Despite the potential benefits of these germicidal agents against COVID-19. Alcohol-based hand sanitizers lead to dry skin, infection, and alcohol poisoning. Children are considered more prone to alcohol poisoning and other major health concern. Precautionary measures should be ensured to protect the community from the possible risk associated with disinfectants.

Inactivation of Multi-Drug Resistant Non-Typhoidal Salmonella and Wild-Type Escherichia coli STEC Using Organic Acids: A Potential Alternative to the Food Industry

Salmonella and Escherichia coli are the main bacterial species involved in food outbreaks worldwide. Recent reports showed that chemical sanitizers commonly used to control these pathogens could induce antibiotic resistance. Therefore, this study aimed to describe the efficiency of chemical sanitizers and organic acids when inactivating wild and clinical strains of Salmonella and E. coli, targeting a 4-log reduction. To achieve this goal, three methods were applied. (i) Disk-diffusion challenge for organic acids. (ii) Determination of MIC for two acids (acetic and lactic), as well as two sanitizers (quaternary compound and sodium hypochlorite). (iii) The development of inactivation models from the previously defined concentrations. In disk-diffusion, the results indicated that wild strains have higher resistance potential when compared to clinical strains. Regarding the models, quaternary ammonium and lactic acid showed a linear pattern of inactivation, while sodium hypochlorite had a linear pattern with tail dispersion, and acetic acid has Weibull dispersion to E. coli. The concentration to 4-log reduction differed from Salmonella and E. coli in acetic acid and sodium hypochlorite. The use of organic acids is an alternative method for antimicrobial control. Our study indicates the levels of organic acids and sanitizers to be used in the inactivation of emerging foodborne pathogens.

Antimicrobial Properties of Nonantibiotic Agents for Effective Treatment of Localized Wound Infections: A Minireview

Wounds present serious health problems in humans and animals. Importantly, if left untreated, wounds invariably lead to long-term morbidity. The inappropriate use and costs of antibiotics place significant challenges globally and affect the health budgets of many countries. Though some antibiotics are administered systemically, treatment of localized infections, in particular, chronic wound infections, does not need such therapy-this would minimize development of antibiotic resistance. Of these measures, nanoparticles of silver, ZnO, and gold seem to give promising results against common wound pathogens while having few limitations. Chemical components of essential oils, which are extracted from different plants, have been shown to act against common wound pathogens. Plant extracts have shown different mechanisms in biofilm elimination. Chlorhexidine and chlorine derivatives act as wound antiseptics. Attempts with biological agents such as maggots have also been shown to provide anti-infective as well as mechanical removal of wound debris. Honey, including those obtained from bees, has a wide coverage against wound pathogens. Glycerin and hypertonic saline are anti-infective through the concentration-dependent killing of pathogens. Hyperbaric oxygen acts against many wound pathogens, in particular anaerobes. This review is focused on nonantibiotic attempts for the cure of localized infections, in particular, chronic wounds with common wound pathogens.

Borderline resistance to oxacillin in Staphylococcus aureus after treatment with sub-lethal sodium hypochlorite concentrations

Surface disinfectants are regularly used in prophylactic and infection control measures. Concern has been raised whether residues of sub-inhibitory disinfectant concentrations may constitute a selective pressure and could contribute to the development of strains which are tolerant and/or resistant to biocides including antibiotics. The current study investigated whether Staphylococcus (S.) aureus ATCC® 29213™ and ATCC® 6538™ would change their growth characteristics and antimicrobial susceptibility profiles after prolonged treatment with sub-inhibitory concentrations of sodium hypochlorite (NaOCl). NaOCl is a fast-acting disinfectant with a broad-spectrum activity, inexpensive and widely used in healthcare and the food production industry. Minimum inhibitory concentration (MIC) for NaOCl was determined by broth macrodilution according to the guidelines for disinfectant efficacy testing provided by the German Veterinary Medical Society. Serial passages after 24 h and 72 h, respectively, in defined sub-inhibitory concentrations of NaOCl resulted in a number of phenotypic variants. Two of these variants, derived from S. aureus ATCC® 29213™, showed elevated MICs of oxacillin and were considered as in vitro-generated borderline oxacillin-resistant S. aureus (BORSA). Transmission electron microscopy revealed a significantly thickened cell wall in these isolates, a phenomenon that has also been described for Listeria monocytogenes after low-level exposure to NaOCl. Whole genome sequencing revealed an early stop codon in the gene coding for the GdpP protein and thereby abolishing the function of this gene. GdpP represents a phosphodiesterase that regulates gene expression, and loss of function of the GdpP protein has been described in association with borderline oxacillin resistance. Our findings suggest that a mutation in the GdpP protein gene and morphological changes of the cell wall were induced by repeated exposure to sub-lethal NaOCl concentrations, and most likely accounted for a BORSA phenotype in two variants derived from S. aureus ATCC® 29213™.

The physiological and toxicological effects of antibiotics on an interspecies insect model

Silkworm (Bombyx mori L.) has a clear genetic background, parts of which are highly homologous to certain genes related to human hereditary diseases. Thus, the species presents an excellent interspecies model for drug screening and microbe-host interaction studies. Chloramphenicol (CAM) and vancomycin (VCM) are antibiotics commonly used to treat specific bacterial infections in medical care, animal husbandry, and agriculture. However, inappropriate dosages and prolonged therapy increase their risk of toxicity. In this work, we investigated the physiological and toxicological responses of silkworm to combined oral administration of CAM and VCM. Results showed that antibiotics promote the feeding behavior of silkworm and significantly reduce (P < 0.05) intestinal cultivable bacterial counts. Moreover, antibiotics decreased the antioxidant enzyme activities of superoxide dismutase, catalase, glutathione S-transferase, and thioredoxin reductase and caused oxidative damage to the silkworm intestine; the degree of damage was confirmed by histopathology analysis. The gene expression levels of antimicrobial peptides (attacin, lysozyme, and cecropins) were also perturbed by antibiotics. After antibiotic exposure, 16S rRNA metagenomic sequencing revealed increases in the relative abundance of Sphingobium, Burkholderia, Barnesiella, Bacteroides, Bradyrhizobium, Acinetobacter, Phenylobacterium, Plesiomonas, Escherichia/Shigella, and unclassified bacteria, as well as a reduction of Enterococcus. The metabolic and functional profiles of intestinal microbiota, particularly metabolic processes, such as energy, cofactors and vitamins, lipid, amino acid, and carbohydrate metabolisms, changed after antibiotic exposure. In conclusion, our findings reveal that antibiotics exert substantial effects on silkworm. The present study may promote the applications of silkworm as an interspecies model in the medical and pharmaceutical fields.

Influence of surface copper content on Stenotrophomonas maltophilia biofilm control using chlorine and mechanical stress

This work aimed to evaluate the action of materials with different copper content (0, 57, 96 and 100%) on biofilm formation and control by chlorination and mechanical stress. Stenotrophomonas maltophilia isolated from drinking water was used as a model microorganism and biofilms were developed in a rotating cylinder reactor using realism-based shear stress conditions. Biofilms were characterized phenotypically and exposed to three control strategies: 10 mg l^-1 of free chlorine for 10 min, an increased shear stress (a fluid velocity of 1.5 m s^-1 for 30s), and a combination of both treatments. These shock treatments were not effective in biofilm control. The benefits from the use of copper surfaces was found essentially in reducing the numbers of non-damaged cells. Copper materials demonstrated better performance in biofilm prevention than chlorine. In general, copper alloys may have a positive public health impact by reducing the number of non-damaged cells in the water delivered after chlorine exposure.

Evaluation of disinfectant efficacy against multidrug-resistant bacteria: A comprehensive analysis of different methods

BACKGROUND

Multidrug-resistant gram-negative bacteria (MDR-GNB) constitute a threat to health care worldwide. Disinfectants are used to prevent and control the spread of MDR-GNB in a hospital setting but their efficacy might be impaired by bacterial mechanisms that may act on both antimicrobials and disinfectants. Determination of minimum inhibitory concentrations is mainly used to determine bacterial susceptibility against disinfectants, but practical tests on surfaces might be more suitable to predict in-use conditions. Our objective was to compare and evaluate 4 different methods widely used to assess surface disinfectant efficacy.

METHODS

The efficacy of benzalkonium chloride (BAC), peracetic acid (PAA), and ethanol (ETH) against multidrug-resistant Acinetobacter, Pseudomonas, and Klebsiella strains was assessed by minimum inhibitory concentration determinations, quantitative suspension tests, qualitative suspension tests, and carrier tests. Test results were compared to ascertain the most appropriate method.

RESULTS

ETH, PAA, and BAC were highly effective against MDR-GNB, but we observed marked differences in efficacious concentrations (up to 100-fold) as a function of the test method applied. Minimum inhibitory concentration determination was not reliable for evaluating susceptibility or resistance to BAC.

CONCLUSIONS

Surface tests should be used to determine bacterial susceptibility against disinfectants. Moreover, suitable guidelines are needed that allow for the standardization and comparison of bactericidal values obtained by different investigators.