Efficacy evaluation of commercial disinfectants by using Salmonella enterica serovar Typhimurium as a test organism

Study of Salmonella spp. from Cage Papers Belonging to Pet Birds in an Argentinean Canary Breeder Championship

Birds, including canaries and other birds, have become increasingly popular as pets. Bird fairs, where breeders gather and show their production in a championship setting, present a setting for possible Salmonella spp. contamination and transmission. Therefore, this study estimated the rate of Salmonella spp. isolation from cage papers, located in the bottom of cages of exotic pet birds, including canaries. Collected Salmonella isolates were used to determine the antimicrobial resistance profile to 52 antibiotics and 17 commercial disinfectants, based on pure or a mixture of acids, alcohols, aldehydes, alkalis, halogens, peroxygen, and quaternary ammonium compounds. The samples consisted of 774 cage papers taken in the 2015 Argentinean canary breeder championship, pooling three cage papers into one sterile sampling bag. Only one pool of the cage papers was positive for Salmonella spp. (0.4%), which belonged to the sample from three frill canary cages. Two strains of Salmonella serotype Glostrup were isolated, which were only resistant to sulfonamides and erythromycin and sensitive to alkali-based product PL301 AS. Although the rate of Salmonella spp. isolation from cage papers in an Argentinean canary breeder championship is low, it should not be discounted because Salmonella ser. Glostrup can be a source of human Salmonella outbreaks and they show high resistance to disinfecting products.

Surface decontamination effectiveness at the "Université des Montagnes" Teaching Hospital: Monitoring in the biomedical analysis laboratory

Background

Many infections in healthcare facilities are associated with the microbiological quality of the work environment, generally due to poor sanitation.

Aim

In order to evaluate the effectiveness of a decontamination protocol (cleaning + disinfection) applied at the "Université des Montagnes" Teaching Hospital, the present study assessed the variation of bacterial loads on surfaces subsequent to decontamination. Susceptibility of bacteria to disinfectants was also evaluated in the same frame.

Methodology

This work was conducted with an adjusted bacterial detection/enumeration and susceptibility test protocols and standard bacterial identification protocols. Sampling on surfaces was performed by wet swabbing before cleaning, between cleaning and disinfection and after disinfection.

Results

Major findings revealed the predominance of Staphylococcus (75.5%) on target surfaces. High bacterial loads recorded on these surfaces before decontamination became undetectable after cleaning with the detergent "Pax lemon". The majority of isolates (98%) were susceptible to the disinfectants tested, (Surfanios® 0.25% and sodium hypochlorite 0.12%).

Conclusion

Overall, these findings indicated process effectiveness on the subjected bacterial populations and suggest the use of either Surfanios® (0.25%) or sodium hypochlorite (0.12%) for work surfaces hygiene, justifying the use of these products in this department for surface decontamination. Also, cleaning with the detergent "Pax lemon" and disinfection with sodium hypochlorite may be sufficient for the types of surfaces subjected in the present research.

Sodium dichloroisocyanurate: improving broiler health by reducing harmful microbial levels in the waterline

Sodium dichloroisocyanurate (NaDCC) is commonly used for treating drinking water, industrial water, and wastewater. This study aimed to investigate the potential effects of NaDCC-treated waterline drinking water on the growth of AA+ broilers by reducing microbial levels in the waterline. A total of 480 healthy 1-day-old AA+ broilers (46.77 ± 0.50 g) were selected for the experiment and randomly divided into four groups with six replicates of 20 birds each. The control group received regular drinking water, while the test groups received drinking water with NaDCC concentrations of 10, 30, and 50 mg/L. The test groups consumed the treated water on specific days throughout the 42-day experimental period. Results showed that NaDCC treatment significantly reduced the levels of E. coli, Salmonella, S. aureus and Moulds in the drinking water at the waterline (p < 0.05). Drinking water with NaDCC also led to reduced broiler fecal emissions of NH3 and H2S, as well as reduced counts of E. coli, Salmonella, S. aureus and Moulds (p < 0.05), particularly at 30 mg/L and 50 mg/L concentrations. Broilers consuming NaDCC at 50 mg/L exhibited a significant increase in ADG from days 1-42 (p < 0.05). The levels of E. coli, Salmonella, S. aureus and Moulds in the drinking water at the waterline were significantly and positively correlated with the bacterial count in the feces (p < 0.05, R > 0.6). Additionally, bacterial levels in drinking water and broiler feces were negatively correlated with broiler production performance indicators, including ADG, ADFI, F/G and AWC. In conclusion, NaDCC can indirectly enhance broiler performance by reducing the levels of harmful bacteria in the waterline without affecting normal drinking water. The addition of 30 mg/L or 50 mg/L of NaDCC to the waterline in poultry production can effectively control harmful microorganisms and improve poultry health. Based on the experiment's results, it is recommended to preferentially use 30 mg/L NaDCC in the waterline to reduce farming costs.

Antimicrobial and Antibiofilm Effect of Commonly Used Disinfectants on Salmonella Infantis Isolates

Salmonella enterica subsp. enterica serovar Infantis is the most prevalent serovar in broilers and broiler meat in the European Union. The aim of our study was to test the biofilm formation and antimicrobial effect of disinfectants on genetically characterized S. Infantis isolates from poultry, food, and humans. For the biofilm formation under various temperature conditions (8 °C, 20 °C, and 28 °C) and incubation times (72 h and 168 h), the crystal violet staining method was used. The evaluation of the in vitro antimicrobial effect of Ecocid^® S, ethanol, and hydrogen peroxide was determined using the broth microdilution method. The antibiofilm effect of subinhibitory concentration (1/8 MIC) of disinfectants was then tested on S. Infantis 323/19 strain that had the highest biofilm formation potential. Our results showed that the biofilm formation was strain-specific; however, it was higher at 20 °C and prolonged incubation time. Moreover, strains carrying a pESI plasmid showed higher biofilm formation potential. The antibiofilm potential of disinfectants on S. Infantis 323/19 strain at 20 °C was effective after a shorter incubation time. As shown in our study, more effective precautionary measures should be implemented to ensure biofilm prevention and removal in order to control the S. Infantis occurrence.

Evaluation of Antimicrobial Effects on Dental Impression Materials and Biofilm Removal by Sodium Dichloroisocyanurate

Dental materials are inevitably contaminated with oral microorganisms. To prevent transmission of infectious diseases, impressions need to be disinfected. In the present study, we examined the disinfection effects on impression materials and biofilm removal by sodium dichloroisocyanurate (SDIC). Exponentially growing Streptococcus mutans, Escherichia coli, Staphylococcus aureus and Candida albicans, and dental plaque bacteria were suspended in phosphate buffered saline (PBS) and exposed for 1, 5 and 10 min to 1 mL of the 10 ppm, 100 ppm, 1,000 ppm, and 10,000 ppm SDIC solutions. The bactericidal effect was evaluated by colony forming units of each microorganisms. Moreover, the effect of SDIC solution on S. mutans biofilm was examined. Bactericidal effects of SDIC solutions on oral bacteria on dental impression surfaces were assessed and the surface quality of dental casts after immersion in SDIC solution for 30 min was observed under a scanning electron microscope. The number of all bacterial strains, including plaque bacteria, were significantly decreased by SDIC solution treatment in a dose-dependent manner. Significant S. mutans biofilm removing activity of SDIC was observed in 1,000 and 10,000 ppm solution. The number of oral bacteria adhering to the surfaces of impressions markedly decreased following 10-min immersion in the 1,000 ppm SDIC solution. The 30-min immersion of dental impression in the 1,000 ppm SDIC solution did not adversely affect the surface roughness of dental casts. The results indicate that SDIC Solution is useful to deactivate oral bacteria on dental impression.

The Effect of Disinfectants on Quinolone Resistant E. coli (QREC) in Biofilm

The aim of disinfection is to reduce the number of microorganisms on surfaces which is a challenge due to biofilms. In the present study, six quinolone resistant Escherichia coli (QREC) strains with three different biofilm matrix compositions were included to assess the log₁₀ colony forming units (CFU) reduction effect of three disinfectants at various exposure times on biofilm of different ages and morphotypes. Biofilm was formed on stainless steel coupons for two and five days before transferred to tubes with Virocid 0, 25%, VirkonS 1%, and TP990 1% and left for various exposure times. The biofilms were scraped off and serial dilutions were spread on blood agar plates where colony forming units (CFU) were counted. A mean log₁₀ CFU reduction ≥4 was seen on two-day-old biofilm with VirkonS and Virocid (30 min) but not on five-day old biofilm. TP990 did not display sufficient effect under the conditions tested. The bactericidal effect was inferior to that reported on planktonic bacteria. The findings of this study should be considered when establishing both disinfectant routines and standard susceptibility tests, which further should accommodate E. coli biofilms and not only Pseudomonas as is the case today.

Regression of viral pathogen indicators due to improvement of hygiene protocols on boots in a bovine farm

Rotavirus A (RVA), bovine torovirus (BToV), bovine enterovirus (BEV) and bovine coronavirus (BCV) at a bovine farm in Ibaraki prefecture were monitored by one-step multiplex reverse transcription polymerase chain reaction (RT-PCR), with the aim of confirming the reduction of “viral pathogen indicators”. A total of 960 bovine fecal samples were collected from calves less than 2 month-old within the period from October 2016 to October 2018 every 2 months at the bovine farm. In each sampling, 40 samples were taken from calves 3 week-old or less, and 40 samples from calves over 3 week-old, in principle. At the end of September 2017, the farm introduced improvement of hygiene protocols on boots by exchanging boots and appropriate usage of a footbath at the entrance of calf sheds. In the comparison of the virus detection by RT-PCR, prevalence of all 4 viruses was significantly reduced (P<0.01) in calves 3 week-old or less after the improvement. The mortality of calves less than 2 month-old was also significantly reduced after the improvement of hygiene protocols. These data suggest that the proper control of boots at calf sheds is important, perhaps even vital, for rearing hygiene measures at bovine farms so as to attain substantial decrease in the prevalence of pathogens.

In-vitro testing of bacteriostatic and bactericidal efficacy of commercial disinfectants against Salmonella Infantis reveals substantial differences between products and bacterial strains

Salmonella (S.) Infantis is currently the most common serovar in broilers and boiler meat in the European Union. In the field, eradication of S. Infantis in affected poultry flocks is considered extremely difficult. Despite stringent cleaning and disinfection measures between the placement of flocks, recurrent infections are often reported. So far, the efficacy of disinfectants on S. Infantis has rarely been studied. Therefore, in the present in-vitro study the bacteriostatic and bactericidal efficacy of ten commercial disinfectants were tested against seven S. Infantis field isolates. Combinations of aldehyde and quarternary ammonium were the active compounds of five, peroxygen of three, cresol and alkylamines of one disinfectant, respectively. Investigations were performed according to standard protocols and regulations. Different concentrations of disinfectants were used to test the bacteriostatic efficacy. Different temperatures and low and high protein exposures were applied as variables to investigate the bactericidal efficacy. Following neutralization of the disinfectants an additional incubation step was introduced to investigate the revitalisation potential of S. Infantis. The bacteriostatic efficacy could be assessed for seven disinfectants. For three disinfectants a bacteriostatic effect was observed when the recommended concentration was used, whereas with four disinfectants only increased concentrations led to this effect. The bactericidal efficacy was not influenced by temperature, whereas high protein exposure decreased the efficacy of nine disinfectants. Furthermore, reactivation of S. Infantis was revealed after application of disinfectants for the majority of products. Interestingly, the strain of S. Infantis influenced the efficacy of the disinfectants. Overall, products based on aldehydes and quarternary ammonium compounds proved most efficient, followed by peroxgen, cresol and alkylamines.

Bactericidal efficacy of potassium peroxymonosulfate under various concentrations, organic material conditions, exposure timing and its application on various surface carriers

Four concentrations of potassium peroxymonosulfate (PPMS) were evaluated for bactericidal activities and indicated that the concentration is less than the manufacturing-recommended concentrations, must extend the exposure time for bacterial inactivation. However, even with and without of organic material contamination, did not show marked inactivation difference. In addition, all concentrations were inactivated on all carrier surfaces within 30 sec, except on rubber where inactivation occurred within 1 min. However, quaternary ammonium compounds were inactivated on stainless steel and plastic within 1 min and 30 sec, respectively, but not inactivated within 5 min on rubber surfaces. Conclusion, PPMS inactivated bacteria under optimal concentration, organic material conditions, exposure timing and on carrier surfaces which can useful as an alternative disinfectant for biosecurity enhancement.

Virucidal Efficacy of a Quaternary Ammonium Compound with Food Additive-Grade Calcium Hydroxide Toward Avian Influenza Virus and Newcastle Disease Virus on Abiotic Carriers

The virucidal efficacies of a 0.2% food additive-grade calcium hydroxide [FdCa(OH)₂] solution, a quaternary ammonium compound (QAC) diluted at 1:500 (QACx500), and their mixture [Mix500; FdCa(OH)₂ powder added at a final concentration of 0.2% to QACx500] were investigated as fomites for avian influenza virus (AIV) and Newcastle disease virus (NDV) on abiotic carriers (steel, rubber, and plastic) at two different temperatures (room temperature [RT; 25 ± 2 C] and 2 C). These viruses were seeded on coupons (5 cm×5 cm) of rubber, steel, or plastic with 5% fetal bovine serum. After complete drying, the coupons were covered with the test solutions at RT or 2 C. After fixed incubation periods, viruses were recovered from the coupons and titrated. At RT, Mix500 required a short time (3 min) to inactivate AIV and NDV to effective levels (≥3 log virus reduction) on rubber, steel, and plastic carriers compared with QAC or FdCa(OH)_2. At low temperature, QACx500 inactivated AIV on steel and plastic carriers to effective levels within 60 min, whereas Mix500 did so within 10 min. QACx500 and FdCa(OH)₂ solutions could inactivate NDV on steel and plastic carriers within 20 and 10 min, respectively, and Mix500 could do so within 3 min. Viruses on the carriers required longer incubation periods for inactivation at 2 C than at 25 C. These results demonstrate desirable synergistic virucidal effects of Mix500 for important poultry viruses on abiotic carriers, while indicating high applicability within poultry farming.

Bactericidal efficacies of food additive grade calcium hydroxide toward Legionella pneumophila

Food additive grade calcium hydroxide (FdCa(OH)₂) in the solution of 0.17% was evaluated for its bactericidal efficacies toward Legionella pneumophila with or without sodium hypochlorite (NaOCl) at a concentration of 200 ppm total residual chlorine, at room temperature (RT) (25°C ± 2°C) and 42°C, either with or without 5% fetal bovine serum (FBS). Besides, FdCa(OH)₂ in different concentration solutions were prepared in field water samples (hot spring and bath tab water) and evaluated for their bactericidal efficacies at 42°C. FdCa(OH)₂ (0.17%) inactivated the L. pneumophila to the undetectable level (<2.6 log CFU/ml) within 5 min and 3 min, respectively, at RT and 42°C, with 5% FBS. At RT and 42°C, NaOCl inactivated L. pneumophila to the undetectable level within 5 min, without 5% FBS, but with 5% FBS, it could only inactivate this bacterium effectively (≥3 log reductions). Conversely, at RT and 42°C, the mixture of 0.17% FdCa(OH)₂ and 200 ppm NaOCl could inactivate L. pneumophila to the undetectable level, respectively, within 3 min and 1 min, even with 5% FBS, and it was elucidated that FdCa(OH)₂ has a synergistic bactericidal effect together with NaOCl. FdCa(OH)₂ 0.05% solution prepared in hot spring water could inactivate L. pneumophila to the undetectable within 3 min at 42°C. So, FdCa(OH)₂ alone could show nice bactericidal efficacy at 42°C, even with 5% FBS, as well as in field water samples.

Bactericidal efficacy of a quaternary ammonium compound with food additive grade calcium hydroxide toward Salmonella Infantis and Escherichia coli on abiotic carriers

The bactericidal efficacies of 0.2% food additive grade calcium hydroxide (FdCa(OH)2) solution, a quaternary ammonium compound (QAC) diluted at 1:500 (QACx500) and their mixture-Mix500 (FdCa(OH)2 powder added at final concentration 0.2% to QACx500)-were investigated at two different temperatures (room temperature (RT) (25 ± 2°C) and 2°C), using varying contact time, with or without presence of organic materials (5% fetal bovine serum: FBS), either in suspension or on abiotic carrier (steel, rubber and plastic). In the suspension test, QACx500 could inactivate Salmonella Infantis at effective level (≥3 log reductions), within 30 sec and 5 sec, respectively, with or without 5% FBS at RT; however, at 2°C it required 30 min and 1 min, respectively. Mix500 revealed the same efficacy as QACx500 at RT, but, at 2°C it required 1 min and 30 sec, respectively with or without FBS. Whereas, 0.2% FdCa(OH)2 solution alone could inactivate S. Infantis within 1 min and 3 min, respectively at RT and 2°C, even with 5% FBS. In the carrier test, single disinfectant required bit more (3 or 5 min) contact time to reduce bacterial load (S. Infantis or Escherichia coli) down to the effective level on rubber surface than that on steel and plastic surface. However, Mix500 could inactivate both bacteria on carrier surfaces within 1 min, even at 2°C. Thus, synergistic effects were observed in the suspension test and the carrier test at both temperatures toward both bacteria.

The study of effect of didecyl dimethyl ammonium bromide on bacterial and viral decontamination for biosecurity in the animal farm

Aim:

The aim of this study was to determine the effectiveness of the fourth-generation quaternary ammonium compounds, didecyl dimethyl ammonium bromide (DDAB), on the efficacy of bacterial and viral decontamination against pathogens commonly found in livestock industry including Salmonella infantis (SI), Escherichia coli, and avian influenza virus (AIV).

Materials and Methods:

The DDAB was prepared at 500, 250, and 125 parts per million (ppm) for absent and present organic material. Meanwhile, 5% of fetal bovine serum in DDAB solution sample was used to mimic the presence of organic material contamination. 400 µl of each DDAB concentration was mixed with 100 µl of each pathogen (SI, E. coli, and AIV) and then incubated at room temperature or 4°C at various time points (5 s, 30 s, 1 min, 5 min, 10 min, 15 min, and 30 min). The activity of DDAB treatment was stopped using 500 µl of FBS. Each treatment sample was titrated on either deoxycholate hydrogen sulfide lactose agar plates or Madin-Darby canine kidney cells for bacteria and AIV, respectively. Each treatment was conducted in triplicates, and the pathogen inactivation was considered effective when the reduction factor was ≥3 log₁₀.

Results:

Our current study revealed that the DDAB inactivated SI, E. coli, and AIV under the various concentrations of DDAB, organic material conditions, exposure temperature, and exposure timing. In addition, the comparison of bactericidal and virucidal efficacy indicated that bacteria were more susceptible to be inactivated by DDAB as compared to viruses. However, DDAB showed marked inactivated differences in the absence or presence of organic materials.

Conclusions:

The DDAB may be a potential disinfectant for inactivating bacteria and viruses, especially enveloped viruses, in livestock farms. It can be useful as a disinfectant for biosecurity enhancement on and around animal farm.