Adaptation to a Commercial Quaternary Ammonium Compound Sanitizer Leads to Cross-Resistance to Select Antibiotics in Listeria monocytogenes Isolated From Fresh Produce Environments

The effective elimination of Listeria monocytogenes through cleaning and sanitation is of great importance to the food processing industry. Specifically in fresh produce operations, the lack of a kill step requires effective cleaning and sanitation to mitigate the risk of cross-contamination from the environment. As facilities rely on sanitizers to control L. monocytogenes, reports of the development of tolerance to sanitizers and other antimicrobials through cross-resistance is of particular concern. We investigated the potential for six L. monocytogenes isolates from fresh produce handling and processing facilities and packinghouses to develop cross-resistance between a commercial sanitizer and antibiotics. Experimental adaptation of isolates belonging to hypervirulent clonal complexes (CC2, CC4, and CC6) to a commercial quaternary ammonium compound sanitizer (cQAC) resulted in elevated minimum inhibitory concentrations (2–3 ppm) and minimum bactericidal concentrations (3–4 ppm). Susceptibility to cQAC was restored for all adapted (qAD) isolates in the presence of reserpine, a known efflux pump inhibitor. Reduced sensitivity to 7/17 tested antibiotics (chloramphenicol, ciprofloxacin, clindamycin, kanamycin, novobiocin, penicillin, and streptomycin) was observed in all tested isolates. qAD isolates remained susceptible to antibiotics commonly used in the treatment of listeriosis (i.e., ampicillin and gentamicin). The whole genome sequencing of qAD strains, followed by comparative genomic analysis, revealed several mutations in fepR, the regulator for FepA fluoroquinolone efflux pump. The results suggest that mutations in fepR play a role in the reduction in antibiotic susceptibility following low level adaptation to cQAC. Further investigation into the cross-resistance mechanisms and pressures leading to the development of this phenomenon among L. monocytogenes isolates recovered from different sources is needed to better understand the likelihood of cross-resistance development in food chain isolates and the implications for the food industry.

Designing an ideal alcohol-based hand sanitizer: in vitro antibacterial responses of ethanol and isopropyl alcohol solutions to changing composition

This study aimed to achieve an in vitro quantification of the effects of composition and formulation factors on the killing rates of alcohol-based hand sanitizers. The killing rates of 85% ethyl alcohol (ET) and isopropyl alcohol (IPA) were studied under different conditions such as pH, electrolyte concentration, or inclusion of herbal extracts (cucumber, carrot, and aloe vera), a quaternary ammonium compound, or thickener over different time intervals. Changes in the activities were retested after 3 months as an indication of stability. From two-way ANOVA, both the time of exposure and the sanitizer type affected the activity against Staphylococcus aureus (P = 0.001 for both alcohols), whereas for Escherichia coli, time of exposure was significant (P = 0.027), while sanitizer type was less significant (P = 0.063). Extreme pHs, the presence of ions, and the inclusion of additives such as benzalkonium chloride (BAC), plant extracts, or carbomer impacted the 3-month activity of the samples differently. Important differences existing in the activities of ET and IPA, as a function of formulation factors or use conditions have been quantified using in vitro methods. Formulations should best be tailored for particular purposes and the all-purpose hand sanitizer may not exist. Graphic Abstract

In vitro cytotoxicity and virucidal efficacy of potassium hydrogen peroxymonosulfate compared to quaternary ammonium compound under various concentrations, exposure times and temperatures against African swine fever virus

Background and Aim: The selection and proper application of disinfectants are crucial to the prevention of many diseases, so disinfectants must be evaluated before being used for the prevention of African swine fever (ASF). Three disinfectant products belonging to the group of potassium hydrogen peroxymonosulfates, product A and product B, and a quaternary ammonium compound called product C, were examined in vitro for host cell cytotoxicity and the efficacy of ASF virus inactivation. The study parameters included various concentrations, exposure times, temperatures, and degrees of cytotoxicity. Materials and Methods: Three disinfectant products were evaluated for cytotoxicity using primary porcine alveolar macrophage (PAM) cells at dilutions from 1:200 to 1:51,200. Disinfectants in concentrations of 1:200, 1:400, and 1:800 were prepared, the pH and the virucidal activity were tested. An equal volume of each dilution was mixed with the ASF virus and incubated at room temperature (20°C) or on ice (4°C) for 1 min, 5 min, or 30 min. Hemadsorption (HAD) or rosette formation was observed using an inverted microscope for 5 days after inoculation, and the virus titer was calculated as HAD50/mL. Each treatment and virus control were tested in triplicate, and the titers were reported as means and standard deviations. The reduction factor was used to measure inactivation. Results: Products A, B, and C at 1:400, 1:800, and 1:25,600 of dilution, respectively, did not show significant cytotoxic effects on PAM cells. Products A and B could inactivate ASF virus at 1:200 dilution within 5 min after exposure at 4°C. However, at 20°C, the exposure time had to be extended to 30 min to inactivate the virus. Product C could inactivate the virus at 1:400 dilution within 5 min under both temperature conditions, whereas at 1:800 dilution, the exposure time had to be extended to 30 min to completely inactivate the virus at 20°C. Conclusion: All disinfectants could inactivate ASF virus in various concentrations, under appropriate exposure times and reaction temperatures, and there was no evidence of host cell cytotoxicity. For the control of ASF in pig farms, the appropriate concentration, ambient temperature, and contact time of these disinfectants should be taken into account.

784. Efficiency of Quaternary Ammonium Disinfectants against SARS-CoV-2 and Coronavirus 229E

Background The recent pandemic of CoVid19 has increased our need to assess the impact of disinfectants on the inactivation of human coronaviruses. The goals of this study were 1) quantify the disinfection of SARS-CoV-2 and human coronavirus 229 inactivations by various quaternary ammonium formulations, and 2) demonstrate the impact of disinfectants on preventing fomite-to-finger transfer of coronaviruses. Methods We compared the inactivation of both SARS-Covid -2 and coronavirus 229E suspended in 5% fetal calf sera and dried on both metal and plastic surfaces. In addition, studies were conducted with a silinated quaternary ammonium compound that left a residual on the surface. Studies were also conducted on the finger transfer of coronavirus from various surfaces. The virus was allowed to dry on the surface for 30 minutes, then a transfer was conducted by placing the finger pad directly onto the contaminated surface. The finger was tested for the virus. The study was then repeated with virus-contaminated porcelain surfaces that were sprayed with a quaternary product or placed on a surface with a quaternary ammonium compound that left a residual. Results Several readily available quaternary ammonium formulations were evaluated and proved to be effective with greater than a 99.9% reduction in titer after drying on both metal and plastic surfaces. In addition, a silinated quaternary ammonium compound that left a residual on the surface was capable of inactivating SARS-CoV-2 for at least seven days after application. Studies on the finger transfer of coronavirus from various surfaces showed that the amount of virus transfer to the finger varied from 0.46 to 49.0% depending upon the surface. Little or no virus transfer occurred from treated surfaces compared to the untreated controls. In addition, coronavirus 229E appears to be a good model for use in disinfection assessments for SARS-CoV-2. Conclusion Our results demonstrate that various quaternary ammonium disinfectant formulations are effective against human coronaviruses. Finger transfer tests showed that transmission of coronavirus from surfaces can be prevented, reducing the risk of fomite transmission. Coronavirus 229E appears to be a good model for use in disinfection assessments for SARS-CoV-2. Disclosures Charles P. Gerba, Ph.D., Allied Biosciences (Grant/Research Support)Behr (Grant/Research Support)Corning Inc. (Grant/Research Support)PPG (Grant/Research Support)Procter and Gamble (Other Financial or Material Support, donation)Rickett and Coleman (Grant/Research Support)

Effect of Surfosept and Deconex® 53 Disinfectant Agents on the Accuracy and Dimensional Stability of Panasil Dental Impression Materials: An Experimental Study

Aim and Objective. Impression materials and stone casts are the main sources of cross-contamination and transmission of dental infections between dental offices and laboratories. Both Surfosept (alcohol-based) and Deconex® (quaternary ammonium compound) are biocompatible solutions that have superior antimicrobial properties against bacteria, fungi, and viral envelope. Considering the influence of disinfection substances on the dimensions of impression materials, this study aimed to compare the effect of Surfosept and Deconex® 53 on the accuracy and dimensional stability of the Panasil® dental addition silicone material. Materials and Methods. This in vitro study was performed on 30 dental casts. The samples were divided into one control group and two experimental groups to be disinfected with Surfosept (1%) and Deconex® 53 (2%) using a sequential sampling method (10 per group). The impressions in the experimental groups (i.e., Surfosept and Deconex® 53) were rinsed and dried; then, the disinfectant was sprayed on the impressions and remained for 30 seconds before pouring with stone. In the control group, the impressions were only rinsed and dried and were poured in 10 minutes. Cast dimensions were measured by a profile projector device, and the mean values obtained from the experimental groups were compared with those of the control group. Results. There were no significant differences among the groups regarding the height of the resulting dies without undercut ( P = 0.62 ). Moreover, there was no significant difference among the groups regarding the distance between the two dies ( P = 0.77 ). However, the diameter of the dies with undercut and without undercut was different significantly among the control and experimental groups ( P < 0.005 ). Conclusion. In general, no significant difference was encountered between dimensional stability and accuracy of the dental impressions using Surfosept and Deconex® 53 in this study.

Trietyloamina. Metoda oznaczania w powietrzu na stanowiskach pracy z zastosowaniem chromatografii gazowej z detekcją płomieniowo-jonizacyjną

Triethylamine (TEA) is a tertiary aliphatic amine. At room temperature it is a colourless liquid with a strong ammonia odor. TEA is used as a substrat in production of quaternary ammonium compound, as a catalyst in polymerization process, as a solvent in organic synthesis and as an emulsifier in the production of dyes and pesticides. Occupational exposure to TEA can cause many adverse effects like skin, respiratory tract or eye irritation. TEA may cause also vision disorder like blurred vision or red-blue vision. The aim of this study was to develop and validate a method for determining TEA in workplace air. The developed method is based on the collection of TEA on sorbent tube filed with two sections of silica gel coated with hydrochloric acid. Silica gel is extracted with methanol:water mixture and resulted solution is analysed with capillary gas chromatography with flame-ionization detector. The study was performed using gas chromatograph equipped with DB-5ms column. The developed method is linear in the concentration range of 7.5–150 μg/ml, which is equivalent to the range of 0.03–6 mg/m3 for 100-L air sample. The analytical method described in this paper makes it possible to determine TEA in workplace air in the presence of other substances. The method is precise, accurate and it meets the criteria for procedures for determining chemical agents listed in Standard No. PN-EN 482. The developed method for determining TEA in workplace air has been recorded as an analytical procedure (see Appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

Influence of New Compound Disinfectant From N-Dodecyl-2-(Piridin-1-Ium)Acetamide Chloride on Pathogenic Microorganisms in Poultry Houses

With the development of large-scale and intensive poultry farming, environmental disinfection has become particularly important, and the effectiveness of disinfection depends upon the performance of the disinfectants. Quaternate ammonium salt is a group of positively charged polyatomic ions with both antibacterial and antiviral activities. In order to prepare an ideal disinfectant for poultry farms, we combined a quaternate ammonium salt N-dodecyl-2-(piridin-1-ium)acetamide chloride with two other disinfectants (chlorhexidine acetate and glutaraldehyde), respectively. The antimicrobial activity, mutagenicity, and safety of the compound disinfectants were assessed by the European Standard methods using ATCC strains and clinical isolates. The results showed that both compound disinfectants meet the requirements of microbial reduction, and their effectiveness was not affected by organic matter. Quaternary ammonium disinfectant resistance genes were not detected in the strains tested indicating that bacteria are less likely to develop resistance to these compound disinfectants. Ames test showed that there was no detectable mutagenicity in the strains treated with the compound disinfectants. In vivo experiment showed that both compound disinfectants did not have significant pathological effect in mice. The bactericidal effect of the compound disinfectants was not significantly different among strains of different sources (p&gt;0.05). Clinical tests showed that compound disinfectant had a good bactericidal effect on the air and ground of poultry farms. These results show that quaternary ammonium salts in combination with other compounds can enhance the bactericidal effect and can be used safely in poultry feedlots. This study provides a technical reference for the development of a new quaternate ammonium compound disinfectant with strong disinfection effect and low irritation.

STUDY OF PHARMACO-TOXICOLOGICAL PROPERTIES OF A QUATERNARY AMMONIUM COMPOUND THAT IS PART OF A DISINFECTANT

The study of the toxicological properties of a new disinfecting quaternary ammonium compound was carried out on laboratory animals of the vivarium of the Kazan State Medical University. Toxicological properties were evaluated on white mice, white rats, guinea pigs and rabbits by forming experimental and control groups. The value of acute oral toxicity, the indicator of the average lethal dose was experimentally determined, allergic properties were determined and the local irritant effect was evaluated. During the tests, it was found that the new quaternary ammonium compound belongs to the third hazard class.

Effectiveness of Quaternary Ammonium in Reducing Microbial Load on Eggs

Table eggs are an affordable yet nutritious protein source for humans. Unfortunately, eggs are a vector for bacteria that could cause foodborne illness. This study aimed to investigate the effectiveness of a quaternary ammonium compound (quat) sanitizer against aerobic mesophilic bacteria, yeast, and mold load on the eggshell surface of free-range and commercial farms and the post-treatment effect on microbial load during storage. Total aerobic mesophilic bacteria, yeast, and molds were enumerated using plate count techniques. The efficacy of the quaternary ammonium sanitizer (quat) was tested using two levels: full factorial with two replicates for corner points, factor A (maximum: 200 ppm, minimum: 100 ppm) and factor B (maximum: 15 min, minimum: 5 min). Quat sanitizer significantly (p < 0.05) reduced approximately 4 log10 CFU/cm2 of the aerobic mesophilic bacteria, 1.5 to 2.5 log10 CFU/cm2 of the mold population, and 1.5 to 2 log10 CFU/cm2 of the yeast population. However, there was no significant (p ≥ 0.05) response observed between individual factor levels (maximum and minimum), and two-way interaction terms were also not statistically significant (p ≥ 0.05). A low (<1 log10 CFU/cm2) aerobic mesophilic bacteria trend was observed when shell eggs were stored in a cold environment up to the production expiry date. No internal microbial load was observed; thus, it was postulated that washing with quat sanitizer discreetly (without physically damaging the eggshell) does not facilitate microbial penetration during storage at either room temperature or cold storage. Current study findings demonstrated that the quat sanitizer effectively reduced the microbial population on eggshells without promoting internal microbial growth.