Study on the In Vitro Activity of Five Disinfectants against Nosocomial Bacteria

An enhanced, statistically repeatable method for screening antimicrobial formulations in laundry applications, an adaptation of BSI EN 17658

There is an increasing need for reliable methods to measure the reduction of microorganisms during the domestic laundering process. An enhanced throughput (ETP) methodology, an adaptation of the European standard BS EN 17658:2022, was developed as a screening tool for evaluating experimental laundry formulations with improved capacity and efficiency. The modifications include the replacement of a lab-scale tumbling device with a more compact and affordable instrument along with additional procedural modifications to simplify the test procedure without compromising the critical parameters such as mechanical action, bioburden, liquor ratio and soil. The ETP method was utilized to replicate the rinse cycle test from an international ring trial, where the participating laboratories assessed the efficacy of 0.04% Dodecyl dimethylammonium chloride (DDAC) as a benchmark standard. In addition, an experimental formulation was evaluated according to ETP and the full EN standard against the five required microorganisms including Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Enterococcus hirae and Candida albicans. Overall, the average log reduction values obtained with both the benchmark and experimental formulation did not differ between the two methods. Furthermore, based on the benchmark data, the ETP method consistently showed lower variability within a lab than the EN method, as evaluated in the ring trial. The advantages and weaknesses of ETP as a research screening tool are also discussed in this work.

Evaluation of the Antibacterial Activity of Acetic Acid in Comparison With Three Disinfectants Against Bacteria Isolated From Hospital High-Touch Surfaces

Acetic acid, a readily available and less toxic alternative to conventional disinfectants, is widely used for cleaning in household settings. This study evaluates the antibacterial efficacy of acetic acid against bacteria isolated from hospital high-touch surfaces, comparing its performance to commonly used disinfectants, including phenol, sodium hypochlorite, and didecyldimethylammonium chloride (DDAC). A total of 120 samples were collected from high-touch surfaces in specialized patient areas. The antibacterial activity of acetic acid, phenol, sodium hypochlorite, and DDAC was assessed using the standard broth microdilution method against the isolated bacterial strains. From the 120 samples, 140 bacterial isolates were obtained. Acetic acid demonstrated strong antibacterial activity, with mean minimum inhibitory concentrations (MICs) ranging from 0.05 ± 0.00 to 0.25 ± 0.06 μL/mL, effectively inhibiting coagulase-negative Staphylococcus (CONS), Klebsiella pneumoniae, Proteus vulgaris, Enterococcus species, and Serratia marcescens. Its performance surpassed phenol and DDAC against these strains. Phenol exhibited higher MICs (0.50 ± 0.00 to 0.83 ± 0.10 μL/mL), indicating lower efficacy, while DDAC (0.06 ± 0.00 to 0.17 ± 0.04 μL/mL) and sodium hypochlorite (0.06 ± 0.00 to 0.10 ± 0.00 μL/mL) demonstrated comparable antibacterial effects. Phenol and sodium hypochlorite were found nonsignificant, while DDAC is highly effective at a concentration of 8.5%. Hospital surfaces were found to be contaminated with diverse bacterial strains. Acetic acid demonstrated significant antibacterial efficacy against both gram-positive and gram-negative bacteria, with MICs ranging from 0.05 ± 0.00 to 0.25 ± 0.06 μL/mL, suggesting its potential as an effective, economical, and less toxic alternative to conventional disinfectants.

Emerging biofilm formation and disinfectant susceptibility of ESBL-producing Klebsiella pneumoniae

Klebsiella pneumoniae is an opportunistic pathogen responsible for various infections in humans and animals. It is known for its resistance to multiple antibiotics, particularly through the production of Extended-Spectrum Beta-Lactamases (ESBLs), and its ability to form biofilms that further complicate treatment. This study aimed to isolate and identify K. pneumoniae from animal and environmental samples and assess commercial disinfectants' effectiveness against K. pneumoniae isolates exhibiting ESBL-mediated resistance and biofilm-forming ability in poultry and equine farms in Giza Governorate, Egypt. A total of 320 samples, including nasal swabs from equine (n = 60) and broiler chickens (n = 90), environmental samples (n = 140), and human hand swabs (n = 30), were collected. K. pneumoniae was isolated using lactose broth enrichment and MacConkey agar, with molecular confirmation via PCR targeting the gyrA and magA genes. PCR also identified ESBL genes (blaTEM, blaSHV, blaCTX-M, blaOXA-1) and biofilm genes (luxS, Uge, mrkD). Antimicrobial susceptibility was assessed, and the efficacy of five commercial disinfectants was evaluated by measuring inhibition zones. Klebsiella pneumoniae was isolated from poultry (13.3%), equine (8.3%), wild birds (15%), water (10%), feed (2%), and human hand swabs (6.6%). ESBL and biofilm genes were detected in the majority of the isolates, with significant phenotypic resistance to multiple antibiotics. The disinfectants containing peracetic acid and hydrogen peroxide were the most effective, producing the largest inhibition zones, while disinfectants based on sodium hypochlorite and isopropanol showed lower efficacy. Statistical analysis revealed significant differences in the effectiveness of disinfectants against K. pneumoniae isolates across various sample origins (P < 0.05). The presence of K. pneumoniae in animal and environmental sources, along with the high prevalence of ESBL-mediated resistance and biofilm-associated virulence genes, underscores the zoonotic potential of this pathogen. The study demonstrated that disinfectants containing peracetic acid and hydrogen peroxide are highly effective against ESBL-producing K. pneumoniae. Implementing appropriate biosecurity measures, including the use of effective disinfectants, is essential for controlling the spread of resistant pathogens in farm environments.

New commercial wipes inhibit the dispersion and adhesion of Staphylococcus aureus and Pseudomonas aeruginosa biofilms

AIM

Bacterial biofilms can form on surfaces in hospitals, clinics, farms, and food processing plants, representing a possible source of infections and cross-contamination. This study investigates the effectiveness of new commercial wipes against Staphylococcus aureus and Pseudomonas aeruginosa biofilms (early attachment and formed biofilms), assessing LH SALVIETTE wipes (Lombarda H S.r.l.) potential for controlling biofilm formation.

METHODS AND RESULTS

The wipes efficacy was studied against the early attachment phase and formed biofilm of S. aureus ATCC 6538 and P. aeruginosa ATCC 15442 on a polyvinyl chloride (PVC) surface, following a modified standard test EN 16615:2015, measuring Log10 reduction and cell viability using live/dead staining. It was also evaluated the wipes anti-adhesive activity over time (3 h, 2 4h), calculating CFU.mL-1 reduction. Data were analyzed using t-student test. The wipes significantly reduced both early phase and formed S. aureus biofilm, preventing dispersion on PVC surfaces. Live/dead imaging showed bacterial cluster disaggregation and killing action. The bacterial adhesive capability decreased after short-time treatment (3 h) with the wipes compared to 24 h.

CONCLUSIONS

Results demonstrated decreased bacterial count on PVC surface both for early attachment phase and formed biofilms, also preventing the bacterial biofilm dispersion.

Preparation and Activity of Hemostatic and Antibacterial Dressings with Greige Cotton/Zeolite Formularies Having Silver and Ascorbic Acid Finishes

The need for prehospital hemostatic dressings that exert an antibacterial effect is of interest for prolonged field care. Here, we consider a series of antibacterial and zeolite formulary treatment approaches applied to a cotton-based dressing. The design of the fabric formulations was based on the hemostatic dressing TACGauze with zeolite Y incorporated as a procoagulant with calcium and pectin to facilitate fiber adherence utilizing silver nanoparticles, and cellulose-crosslinked ascorbic acid to confer antibacterial activity. Infra-red spectra were employed to characterize the chemical modifications on the dressings. Contact angle measurements were employed to document the surface hydrophobicity of the cotton fabric which plays a role in the contact activation of the coagulation cascade. Ammonium Y zeolite-treated dressings initiated fibrin equal to the accepted standard hemorrhage control dressing and showed similar improvement with antibacterial finishes. The antibacterial activity of cotton-based technology utilizing both citrate-linked ascorbate-cellulose conjugate analogs and silver nanoparticle-embedded cotton fibers was observed against Staphylococcus aureus and Klebsiella pneumoniae at a level of 99.99 percent in the AATCC 100 assay. The hydrogen peroxide levels of the ascorbic acid-based fabrics, measured over a time period from zero up to forty-eight hours, were in line with the antibacterial activities.

Direct Inhibition of SARS-CoV-2 Spike Protein by Peracetic Acid

Peracetic acid (PAA) disinfectants are effective against a wide range of pathogenic microorganisms, including bacteria, fungi, and viruses. Several studies have shown the efficacy of PAA against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); however, its efficacy in SARS-CoV-2 variants and the molecular mechanism of action of PAA against SARS-CoV-2 have not been investigated. SARS-CoV-2 infection depends on the recognition and binding of the cell receptor angiotensin-converting enzyme 2 (ACE2) via the receptor-binding domain (RBD) of the spike protein. Here, we demonstrated that PAA effectively suppressed pseudotyped virus infection in the Wuhan type and variants, including Delta and Omicron. Similarly, PAA reduced the authentic viral load of SARS-CoV-2. Computational analysis suggested that the hydroxyl radicals produced by PAA cleave the disulfide bridges in the RBD. Additionally, the PAA treatment decreased the abundance of the Wuhan- and variant-type spike proteins. Enzyme-linked immunosorbent assay showed direct inhibition of RBD-ACE2 interactions by PAA. In conclusion, the PAA treatment suppressed SARS-CoV-2 infection, which was dependent on the inhibition of the interaction between the spike RBD and ACE2 by inducing spike protein destabilization. Our findings provide evidence of a potent disinfection strategy against SARS-CoV-2.

A comparative in-vitro study on antimicrobial efficacy of on-market alcohol-based hand washing sanitizers towards combating microbes and its application in combating Covid-19 global outbreak

The coronavirus disease 2019 (COVID-19) outbreak has created endless social, economic, and political fear in the global human population. Measures employed include frequent washing hands and using alcohol-based hand sanitisers and hand rubs as instant hand hygiene products. Due to the need to mitigate the pandermic, there is an increase in the local production of alcohol-based hand sanitisers, whose quality and efficacy against germs and the virus are questionable. Therefore, the current study investigated the in-vitro antimicrobial efficacy of on-market alcohol-based handwashing sanitizers used to mitigate the Covid-19 global outbreak toward combating enveloped bacteria such as E. Coli, P. aeroginosa, S. aureus, and a fungus C. albicans. The antimicrobial effectiveness of alcohol-based hand sanitizer was performed by the agar well diffusion method, and the analysis of variance (ANOVA) model was used for statistical analysis. Results indicate that alcohol hand-based sanitizers were more effective in inhibiting P. aeroginosa, with a mean zone of inhibition of 12.47 mm, followed by E. coli, a gram-negative bacterium with a mean zone of inhibition of 12.13 mm than both S. aureus and C. albicans as gram-positive bacteria, and fungi respectively had the same inhibition average of 11.40 mm. The overall mean diameter of inhibition was statistically significantly different among the fifteen tested products. Only one brand of alcohol-based hand sanitizers was the most effective in inhibiting microbes. Less effective sanitizers may impair Covid 19 mitigation efforts and put the population at risk instead of protecting it. Indicating the need for all materials used to mitigate Covid 19 pandermic, including alcohol-based hand sanitizers, to be evaluated and monitored to ensure public health safety.

No-Touch Automated Disinfection System Based on Hydrogen Peroxide and Ethyl Alcohol Aerosols for Use in Healthcare Environments

Healthcare-related infections are sustained by various bacteria and fungi. In recent years, various technologies have emerged for the sanitation of healthcare-related environments. This study evaluated the effectiveness of a no-touch disinfection system that aerosolizes 5% hydrogen peroxide and 10% ethyl alcohol. After selecting an environment, the Total Bacterial Count and the Total Fungal Count in the air and on a surface of the room were determined to evaluate the effectiveness of the aerosolization system. In addition, sterile stainless-steel plates inoculated with S. aureus, P. aeruginosa, and Aspergillus spp. isolated from hospitalized patients and reference strains were used to evaluate the effectiveness of the system. For each organism, three plates were used: A (cleaned), B (not cleaned), and C (control). The A plates were treated with non-ionic surfactant and the aerosolization system, the B plates were subjected to the aerosolization system, and the plates C were positioned outside the room that was sanitized. Following sanitization, air and surface sampling was conducted, after which, swabs were processed for bacterial and fungal enumeration. The results showed that the air sanitization system had good efficacy for both bacteria and fungi in the air and on stainless-steel plates, particularly for the A plates.

Air Disinfection—From Medical Areas to Vehicle

Cars with air conditioning systems have become the norm, but these systems can be dangerous for human health as a result of the accumulation of different microorganisms, including pathogenic ones, causing severe allergy or inflammation problems. The novel purpose of this study is 2-fold: on the one hand, to test different disinfection agents on a new area, that is, automobile cabins, and on the other, to compare activity in the gas phase of these agents for disinfection of car air conditioning and cabin surfaces. This study shown that tested disinfectant agents dedicated for decontamination medical areas (agent based on peracetic acid and an agent containing didecyldimethylammonium chloride, 2-phenoxyethanol with cinnamaldehyde) can be successfully used for disinfection car air conditioning and cabin surfaces. Both disinfectants were examined in comparison to a commercial “ready-to-use” spray from a local supermarket dedicated to car air conditioning disinfection. Our research found that very effective agents in this regard were acid stabilized by hydrogen peroxide applied by fumigator, and a combination of didecyldimethylammonium chloride, 2-phenoxyethanol, and cinnamaldehyde applied by atomizer. Tested disinfection procedures of car air conditioning significantly influence the quality of cabin air and surfaces by reducing the amount of microorganisms. The comparison of disinfection properties studied agents in the gas phase reveal statistically significant differences between it effect for disinfection car air conditioning and cabin surfaces. Our research found that very effective agents in this regard were acid stabilized by hydrogen peroxide applied by fumigator, and a combination of didecyldimethylammonium chloride, 2-phenoxyethanol, and cinnamaldehyde applied by atomizer. Tested disinfection procedures of car air conditioning significantly influence the quality of cabin air and surfaces by reducing the amount of microorganisms.

An Artefactual Cluster of Mycobacterium abscessus Pneumonia among Cancer Patients Arising from Contamination

The Mycobacteriumabscessus complex (MABC) is a group of rapidly growing, nontuberculous mycobacteria that are ubiquitous in soil, urban water pipes, swimming pools, and drinking water. Members of the MABC are considered opportunistic pathogens. The aim of this study was to investigate the origins of MABC detected in broncho-lavage (BL) samples from asymptomatic cancer patients. We turned our attention to washing and disinfection procedures for bronchoscopes; we also assessed water and disinfectant samples. Of 10 BL and 34 environmental samples tested, four BL samples (40%) and seven environmental samples (20.6%) tested positive for MABC. We hypothesized that contamination could arise from the prewashing machine and/or the water used because no patient had clinical or radiological signs consistent with MABC respiratory tract infection. Our study highlights the importance of evaluating cleaning and disinfection procedures for endoscope channels to reduce the potential spread of microorganisms and artefactual results arising from contamination.

Upregulation of abeM, amvA, and qacEΔ1 efflux pump genes associated with resistance of Acinetobacter baumannii strains to disinfectants

BACKGROUND AND AIMS

Acinetobacter baumannii is among the most concerning cause of nosocomial infections due to its high level of antibiotic resistance and high mortality. The aim of this study was to determine the role of efflux pumps in resistance of A. baumannii strains to three disinfectants, including MICROZED ID-MAX, NANOSIL D2, and OPIDEX OPA.

METHODS

Twenty-eight environmental and clinical isolates of A. baumannii were collected from selected hospitals of central Iran. The minimum inhibitory concentrations of the disinfectants were determined and real time reverse transcriptase-PCR was performed to investigate the expression level of qacEΔ1, amvA, abeM, and adeB efflux pump genes.

RESULTS

Considering both clinical and environmental isolates, there was a significant difference in the mean expression level of qacEΔ1 gene between susceptible and resistant strains to MICROZED ID-MAX disinfectant, of amvA and abeM genes between susceptible and resistant strains to NANOSIL D2 disinfectant and of abeM gene in susceptible and resistant strains to OPIDEX OPA disinfectant (all P ˂ .05). The expression levels of abeM and amvA genes were higher in the environmental isolates that were resistant to NANOSIL D2 disinfectant compared to those that were susceptible (P ˂ .05).

CONCLUSIONS

This study provided evidence for the role of abeM and amvA genes in the resistance of environmental isolates to disinfectants, particularly hydrogen peroxide derivatives.

Effect of Disinfectants with Different Active Ingredients on Biofilm Formation in Pseudomonas aeruginosa

We compared the effects of disinfectants on biofilms of 10 Pseudomonas aeruginosa strains isolated from different loci of patients with purulent-septic infections. Identification was carried out by standard bacteriological methods. To substantiate the prospects of using in hospitals and to assess the effect of disinfectants on P. aeruginosa biofilms, the following disinfectants were used in various concentrations: Sekusept Aktiv, A-DEZ, and Monitor Oxy. All clinical strains of P. aeruginosa showed the ability to form biofilms. Both oxygen-containing and quaternary ammonium compounds effectively inhibited the formation of biofilms. In more than 50% cases, disinfectants with different active ingredients did not destroy pre-formed of P. aeruginosa biofilms.

A Possible Outbreak by Serratia marcescens: Genetic Relatedness between Clinical and Environmental Strains

Serratia marcescens (SM) is a Gram-negative bacterium that is frequently found in the environment. Since 1913, when its pathogenicity was first demonstrated, the number of infections caused by SM has increased. There is ample evidence that SM causes nosocomial infections in immunocompromised or critically ill patients admitted to the intensive care units (ICUs), but also in newborns admitted to neonatal ICUs (NICUs). In this study, we evaluated the possible genetic correlation by PFGE between clinical and environmental SM strains from NICU and ICU and compared the genetic profile of clinical strains with strains isolated from patients admitted to other wards of the same hospital. We found distinct clonally related groups of SM strains circulating among different wards of a large university hospital. In particular, the clonal relationship between clinical and environmental strains in NICU and ICU 1 was highlighted. The identification of clonal relationships between clinical and environmental strains in the wards allowed identification of the epidemic and rapid implementation of adequate measures to stop the spread of SM.

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.

in vitro Activity of Hydrogen Peroxide and Hypochlorous Acid Generated by Electrochemical Scaffolds Against Planktonic and Biofilm Bacteria

Hydrogen peroxide (H₂O₂) and hypochlorous acid (HOCl) are biocides used for cleaning and debriding chronic wound infections, which often harbor drug resistant bacteria. Here, we evaluated the in vitro activity of H₂O₂ and HOCl against 27 isolates of eight bacterial species involved in wound infections. Minimum inhibitory concentrations (MICs) and minimum biofilm bactericidal concentrations (MBBCs) were measured. When compared to their respective MICs, MBBCs of isolates exposed to H₂O₂ were 16- to 1,024-fold higher and those exposed to HOCl were 2- to 4-fold higher. We evaluated selection of resistance after exposure of Staphylococcus aureus and Pseudomonas aeruginosa biofilms to 10 iterations of electrochemically generated HOCl or H₂O₂ delivered using electrochemical scaffolds (e-scaffolds), observing no decrease in anti-biofilm effects with serial exposure to e-scaffold-generated H₂O₂ or HOCl. 24-hour exposure to H₂O₂-generating e-scaffolds consistently decreased colony forming units (CFUs) of S. aureus and P. aeruginosa biofilms by ∼5.0-log₁₀ and ∼4.78-log₁₀ through 10 iterations of exposure, respectively. 4-hour exposure to HOCl-generating e-scaffolds consistently decreased CFUs of S. aureus biofilms by ∼4.9-log₁₀, and 1-hour exposure to HOCl-generating e-scaffolds consistently decreased CFUs of P. aeruginosa biofilms by ∼1.57-log₁₀ These results suggest that HOCl has similar activity against planktonic and biofilm bacteria, whereas the activity of H₂O₂ is less against biofilm than planktonic bacteria, and that repeat exposure to either biocide, generated electrochemically under the experimental conditions studied, does not lessen antibiofilm effects.

Efficacy of Three Commercial Disinfectants in Reducing Microbial Surfaces' Contaminations of Pharmaceuticals Hospital Facilities

To evaluate and validate the efficacy of disinfectants used in our cleaning procedure, in order to reduce pharmaceutical hospital surfaces' contaminations, we tested the action of three commercial disinfectants on small representative samples of the surfaces present in our hospital cleanrooms. These samples (or coupons) were contaminated with selected microorganisms for the validation of the disinfectants. The coupons were sampled before and after disinfection and the microbial load was assessed to calculate the Log₁₀ reduction index. Subsequently, we developed and validated a disinfection procedure on real surfaces inside the cleanrooms intentionally contaminated with microorganisms, using approximately 10⁷-10⁸ total colony forming units per coupon. Our results showed a bactericidal, fungicidal, and sporicidal efficacy coherent to the acceptance criteria suggested by United States Pharmacopeia 35 <1072>. The correct implementation of our cleaning and disinfection procedure, respecting stipulated concentrations and contact times, led to a reduction of at least 6 Log₁₀ for all microorganisms used. The proposed disinfection procedure reduced the pharmaceutical hospital surfaces' contaminations, limited the propagation of microorganisms in points adjacent to the disinfected area, and ensured high disinfection and safety levels for operators, patients, and treated surfaces.

The Role of Urban Wastewater in the Environmental Transmission of Antimicrobial Resistance: The Current Situation in Italy (2010-2019)

Scientific studies show that urban wastewater treatment plants (UWWTP) are among the main sources of release of antibiotics, antibiotic resistance genes (ARG) and antibiotic-resistant bacteria (ARB) into the environment, representing a risk to human health. This review summarizes selected publications from 1 January 2010 to 31 December 2019, with particular attention to the presence and treatment of ARG and ARB in UWWTPs in Italy. Following a brief introduction, the review is divided into three sections: (i) phenotypic assessment (ARB) and (ii) genotypic assessment (ARG) of resistant microorganisms, and (iii) wastewater treatment processes. Each article was read entirely to extract the year of publication, the geographical area of the UWWTP, the ARB and ARG found, and the type of disinfection treatment used. Among the ARB, we focused on the antibiotic resistance of Escherichia coli, Klebsiella pneumoniae, and Enterococci in UWWTP. The results show that the information presented in the literature to date is not exhaustive; therefore, future scientific studies at the national level are needed to better understand the spread of ARB and ARG, and also to develop new treatment methods to reduce this spread.