Didecyldimethylammonium Research Articles

Disinfectant and Antimicrobial Susceptibility Studies of Staphylococcus aureus Strains and ST398-MRSA and ST5-MRSA Strains from Swine Mandibular Lymph Node Tissue, Commercial Pork Sausage Meat and Swine Feces.

Staphylococcus aureus (S. aureus) causes gastrointestinal illness worldwide. Disinfectants are used throughout the food chain for pathogenic bacteria control. We investigated S. aureus bioavailability in swine Mandibular lymph node tissue (MLT) and pork sausage meat (PSM), established susceptibility values for S. aureus to disinfectants, and determined the multilocus sequence type of MRSA strains. Antimicrobial and disinfectant susceptibility profiles were determined for 164 S. aureus strains isolated from swine feces (n = 63), MLT (n = 49) and PSM (n = 52). No antimicrobial resistance (AMR) was detected to daptomycin, nitrofurantoin, linezolid, and tigecycline, while high AMR prevalence was determined to erythromycin (50.6%), tylosin tartrate (42.7%), penicillin (72%), and tetracycline (68.9%). Methicillin-resistant S. aureus (MRSA) strains, ST398 (n = 6) and ST5 (n = 1), were found in the MLT and PSM, 4 MRSA in MLT and 3 MRSA strains in the PSM. About 17.5% of feces strains and 41.6% of MLT and PSM strains were resistant to chlorhexidine. All strains were susceptible to triclosan and benzalkonium chloride, with no cross-resistance between antimicrobials and disinfectants. Six MRSA strains had elevated susceptibilities to 18 disinfectants. The use of formaldehyde and tris(hydroxylmethyl)nitromethane in DC&R was not effective, which can add chemicals to the environment. Didecyldimethylammonium chloride and benzyldimethylhexadecylammonium chloride were equally effective disinfectants. ST398 and ST5 MRSA strains had elevated susceptibilities to 75% of the disinfectants tested. This study establishes susceptibility values for S. aureus strains from swine feces, mandibular lymph node tissue, and commercial pork sausage against 24 disinfectants. Since it was demonstrated that S. aureus and MRSA strains can be found deep within swine lymph node tissue, it may be beneficial for the consumer if raw swine lymph node tissue is not used in uncooked food products and pork sausage.

Assessment of agonistic and antagonistic properties of humidifier disinfectants to the estrogenic and androgenic receptors by transactivation assay.

Before being recalled and banned from the Korean market, humidifier disinfectants (HDs) were added to the humidifier water tank to prevent microbial growth. The known HDs active ingredients included the are oligo(2-(2-ethoxy)ethoxyethyl guanidine (PGH), polyhexamethylene guanidine (PHMG), a mixture of methylisothiazolinone (MIT) and chloromethylisothiazolinone (CMIT), didecyldimethyl ammonium chloride (DDAC), Sodium dichloroisocyanurate (NaDCC), and alkyldimethylbenzyl ammonium chloride (BAC). Previous epidemiological studies have suggested that PHMG induces fatal lung disease in pregnant, post-partum women, and young children. In an animal study, a mixture of DDAC and BAC exhibited decreased fertility and fecundity; increased time to first litter, longer pregnancy intervals, fewer pups per litter, and fewer pregnancies. In this study, endocrine-disrupting effects of HDs were investigated using estrogen receptor (ER) and androgen receptor (AR) transactivation assay based on OECD Test guidelines. Unexpectedly, unlike the previously reported reproductive toxicity data, in the present study, HDs did not show ER and AR transcriptional activation agonist and/or antagonist effects. However, it is difficult to conclude that HDs has no endocrine disruption effects, and further research on the effects of HDs mixtures, and in vivo tests including Uterotrophic bioassay and Hershberger bioassay would be necessary.

Didecyl dimethyl ammonium chloride as a highly efficient corrosion inhibitor for carbon steel in hydrochloric acid solution

PurposeThis paper aims to discover a highly efficient corrosion inhibitor for 45# steel in hydrochloric acid solution and reveal the mechanism of inhibitors.Design/methodology/approachIn this paper, electrochemical measurements, weight loss measurements, surface characterization and theoretical calculation are used to evaluate the inhibition performance and reveal the mechanism of inhibitors.FindingsResults show that didecyl dimethyl ammonium chloride (DDAC), especially in combination with dodecane phenol plyoxyethylene, could provide a good protection performance for the carbon steel in hydrochloric acid. The N atoms and long alkyl chains in DDAC molecular structure play the vital role.Originality/valueUsually, DDAC is used as the compound chemical disinfectant in oilfield sterilization, medicine and health. However, to the best of the authors’ knowledge, no study has shown that it can mitigate the corrosion of carbon steels in HCl solution.

Microbiological and Toxicological Hazards in Sewage Treatment Plant Bioaerosol and Dust.

Despite the awareness that work in the sewage treatment plant is associated with biological hazards, they have not been fully recognised so far. The research aims to comprehensively evaluate microbiological and toxicological hazards in the air and settled dust in workstations in a sewage treatment plant. The number of microorganisms in the air and settled dust was determined using the culture method and the diversity was evaluated using high-throughput sequencing. Endotoxin concentration was assessed with GC-MS (gas chromatography-mass spectrometry) while secondary metabolites with LC-MS/MS (liquid chromatography coupled to tandem mass spectrometry). Moreover, cytotoxicity of settled dust against a human lung epithelial lung cell line was determined with the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and UHPLC-Q-ToF-UHRMS (ultra-high-performance liquid chromatography-quadrupole time-of-flight ultrahigh-resolution mass spectrometry) analysis was performed to determine the source of cytotoxicity. The total dust concentration in the sewage treatment plant was low and ranged from 0.030 mg m−3 to 0.044 mg m−3. The highest microbiological contamination was observed in sludge thickening building and screenings storage. Three secondary metabolites were detected in the air and sixteen in the settled dust. They were dominated by compounds typical of lichen and plants and Aspergillus, Penicillium and Fusarium genera mould. The settled dust from the sludge thickening building revealed high cytotoxicity to human lung epithelial cells A-549 (IC50 = 6.98 after 72 h). This effect can be attributed to a biocidal compound—didecyldimethylammonium chloride (DDAC-C10) and seven toxic compounds: 4-hydroxynonenal, carbofuran, cerulenin, diethylphosphate, fenpropimorph, naphthalene and onchidal. The presence of DDAC-C10 and other biocidal substances in the sewage treatment plant environment may bring negative results for biological sewage treatment and the natural environment in the future and contribute to microorganisms’ increasing antibiotics resistance. Therefore, the concentration of antibiotics, pesticides and disinfectants in sewage treatment plant workstations should be monitored.

Reproductive toxicity assessment of alkyl dimethyl benzyl ammonium chloride and didecyl dimethyl ammonium chloride in CD® rats.

AimTo determine the potential of alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC) to induce reproductive toxicity in CD® rats in two independent 2‐generation reproduction studies conducted according to Good Laboratory Practices and standardized testing guidelines.Materials and MethodsMale and female rats (parents and offspring) were allowed continual free access to diets containing concentrations of ADBAC (0, 300, 1,000, or 2,000 ppm) or DDAC (0, 300, 750, or 1,500 ppm), beginning with F0 generation adults at 10 weeks prior to breeding.ResultsNo clinical signs of toxicity were observed in parental rats or their offspring in either study. Dietary exposure of parental rats to ADBAC or DDAC at the highest concentrations produced transient decreases in body weight and/or body weight changes with no or minimal corresponding reduction in food consumption. Offspring (F1 and F2) in the highest concentration group in each study also exhibited reduced body weights, often with a corresponding reduction in weight change, beginning on postnatal day (PND) 14 through weaning on PND 28. This reduction in pup body weight corresponded to initiation of self‐feeding.ConclusionsBased on reduced body weights, the no observed adverse effect level (NOAEL) for adult and offspring systemic toxicity was 1,000 ppm for ADBAC and 750 ppm for DDAC (equivalent to approximate daily oral doses of 59 and 45 mg/kg/day, respectively). The reproductive and developmental NOAEL for F0, F1, and F2 generation male and female rats was 2,000 ppm for ADBAC and 1,500 ppm for DDAC (equivalent to approximate daily oral doses of 118 and 91 mg/kg/day, respectively).

Multifunctional Surface, Subsurface, and Systemic Therapeutic (MS3T) Formulation for the Control of Citrus Canker.

A multifunctional surface, subsurface and systemic therapeutic (MS3T) formulation comprised of two bactericides, both didecyldimethylammonium chloride (DDAC) and a zinc (Zn)-chelate, was developed as an alternative to copper pesticides for crop protection. Agricultural grade chemicals were used to prepare MS3T formulations. Minimal inhibitory concentration (MIC) was determined to be tested in vitro against Xanthomonas alfalfae subsp. citrumelonis (herein called Xa), Escherichia coli (E. coli), and Pseudomonas syringae (Ps). Assessment of the phytotoxic potential was carried out on tomato under greenhouse conditions. Moreover, field trials were conducted during three consecutive years on grapefruit (Chrysopelea paradise) groves to evaluate efficacy against citrus canker (Xanthomonas citri subsp. citri), scab (Elsinoe fawcetti), and melanose (Diaporthe citri). In addition to disease control, improvements to both fruit yield and quality were observed likely due to the nutritional activity of MS3T via the sustained release of plant nutrients (Zn and nitrogen). Zn residues of leaf tissues were analyzed via atomic absorption spectroscopy (AAS) at various time points before and after MS3T foliar applications throughout the duration of the 2018 field trial. Field trial results demonstrated MS3T to be an effective alternative to copper (Cu)-based formulations for the control of citrus canker.

Effect of didecyl dimethyl ammonium chloride-impregnated washcloth wipe whole-body bathing on catheter-related blood stream infections and central venous line-associated infections in adult intensive care units

ObjectiveTo investigate the effect of daily whole-body bathing (WBB) using disposable washcloth wipes/caps impregnated with an antiseptic solution containing the quaternary ammonium base compound didecyl dimethyl ammonium chloride (DDAC). MethodsA prospective double-blind randomized crossover trial was conducted to compare WBB of adult intensive care unit (ICU) patients with washcloth wipes/caps impregnated with either regular cleanser/shampoo or the antiseptic DDAC. The clinical trial was performed in a medical ICU (MICU) and a surgical ICU (SICU). The study period was divided into two 6-month intervals with alternating treatment regimens. ResultsA total of 1540 ICU patients (total length of ICU stay 10 470 days) were included in the trial. Compared to controls, DDAC bathing was found to be associated with reduced incidence rates per 1000 patient days for central-venous-line-associated infections (CLAIs) caused by Gram-positive bacteria (GPB) from 16.39 (95%CI 13.1–20.3) in the control group to 7.28 (95%CI 5.2–9.9) in the intervention group (p 0.01). A stratified analysis by unit showed that the incidence rates of CLAI due to GPB were reduced by the intervention in both the MICU and the SICU from 21.2 (95%CI 15.8–27.7) to 9.3 (95%CI 5.8–14.1) (p < 0.01) and from 12.1 (95%CI 8.3–17.0) to 5.7 (95%CI 3.4–9.1) (p 0.01), respectively. There was a trend towards reduction in catheter-related bloodstream infections (CRBSIs) and bloodstream infections (BSIs); however, this did not reach statistical significance due to carry-over effects and small numbers. ConclusionsGiven the growing need for new concepts to prevent and control healthcare-associated infections, DDAC may be a new and promising agent for WBB of ICU patients.

In-vitro evaluation of bactericidal activity of antiseptics and disinfectants commonly used in healthcare settings

Introduction: Healthcare-associated infections are common problems found in healthcare systems in most of the countries. Proper use of antiseptics and disinfectants is useful in reducing the magnitude of such infections. The aim of this study was to evaluate the bactericidal effect of different concentrations of selected antiseptics and disinfectants. Methods: Bactericidal activity of different concentrations of antiseptics and disinfectants; isopropyl alcohol, povidone iodine, chlorhexidine gluconate, sodium hypochlorite, hypertonic saline, peracetic acid and mixture of 2-aminoethanol, dodecyl dimethyl ammonium chloride, potassium carbonate &amp; bis(3-aminopropyl) dodecylamine were evaluated against nine strains of American Type Culture Collections and 11 strains isolated from the hospitals. Bacterial suspensions were prepared equal to 0.5 McFarland turbidity standards and 100 μl of each was mixed with 3 ml of antiseptic/ disinfectant solution. After desired contact time (1 minute, 15 minutes and 24 hours), 20 μl of reaction mixer was transferred into 4 ml of sterile physiological saline, mixed well and 20 μl of solution was evenly spread throughout Muller Hinton agar/ blood agar plates. Growth control was done using 3 ml of distilled water instead of 3 ml of antiseptic/ disinfectant solution. All plates incubated at 35oC ± 2oC for 18 – 24 hours. Colonies were counted and reduction percentage was calculated. Results: All concentrations of isopropyl alcohol, povidone iodine, chorhexidine, sodium hypochlorite, peracetic acid and the mixture of 2-aminoethanol, didecyldimethylammonium chloride, potassium carbonate and bis(3-aminopropyl)dodecylamine showed 100% bactericidal activities against all tested bacterial strains in1-minute contact time. Bactericidal activity of hypertonic saline was varied against tested bacterial strains with higher bactericidal activity against Gram positive organisms than Gram negative organisms. Conclusions: Currently using concentrations of antiseptics and disinfectants evaluated in this study have 100% bactericidal activity other than hypertonic saline.

Virucidal efficacy of seven active substances in commercial disinfectants used against H9N2 low pathogenic avian influenza virus

Currently, the mass culling of infected poultry as well as those that may have had contact with them is an essential part of prevention and disease control strategy, amidst the growing concerns over the avian influenza virus ( AIV ) spreading nationwide; however, it is largely dependent on effective biosecurity measures, including disinfection. Although many disinfectants are commercially available for veterinary use, information on the virucidal efficacy of individual active components in disinfectants is limited, since most disinfectants are complex formulations of active substances. This study aimed to evaluate the virucidal efficacy of individual active components in commercial disinfectants. Seven representative active substances in commercial disinfectants used against AIV in South Korea during the year 2020, namely potassium peroxymonosulfate ( PPMS ), sodium dichloroisocyanurate ( NaDCC ), malic acid ( MA ), citric acid ( CA ), glutaraldehyde ( GLT ), benzalkonium chloride ( BZK ), and didecyldimethylammonium chloride ( DDAC ), were tested to confirm their individual virucidal efficacy against H9N2 low pathogenic avian influenza virus. The specific selection of active substances and their test concentrations was done based on the formulation of 202 disinfectants approved by Animal and Plant Quarantine Agency as being effective against AIV. Minimal virucidal concentrations are as follows: for PPMS, 0.2%; for NaDCC, 0.1%; for MA, 0.5%; for CA, 0.4%; for GLT, 0.01%; for BZK, 0.4%; and for DDAC, 0.2%. The current study not only highlighted the virucidal efficacy of these active substances against AIV but also indicated its impact on the biosecurity measures, particularly for selection of a disinfectant and its proper application in poultry industry.

The Use of Catalytic Amounts of Selected Cationic Surfactants in the Design of New Synergistic Preservative Solutions

Preservation using combinations of antibacterial molecules has several advantages, such as reducing the level of usage and broadening their antimicrobial spectrum. More specifically, the use of quaternary ammonium surfactants (QAS)—which are profusely used in hair care products and some are known as efficient antimicrobial agents—is limited due to some potential cytotoxicity concerns. This study shows that the concentration of some widely used cosmetic preservatives can be decreased when combined with very small quantities of QAS, i.e., Polyquaternium-80 (P-80) and/or Didecyldimethylammonium chloride (DDAC). The antimicrobial activity of their mixtures was first evaluated by determining the minimum inhibitory concentration (MIC) before and after the addition of QAS. Following up on this finding and targeting an ultimate consumer friendly antimicrobial blend, yet with optimal safety, we chose to utilize the food-grade preservative Maltol as the main natural origin antimicrobial agent mixed with minimum concentrations of QAS to improve its moderate antimicrobial properties. The preservatives were tested for MIC values, challenge tests and synergy using the fractional inhibitory concentration index (FICI). The antimicrobial efficacy of Maltol was found to be synergistically improved by introducing catalytic amounts of P-80 and/or DDAC.

Оценка безопасности кожных антисептиков методом in vitro

InVitro laboratory has investigated and made comparative analysis of irritant effect of disinfectants on rabbits. Main active substances of studied skin antiseptics were: alcohols, chlorhexidine bigluconate, alkyldime­thylbenzylammonium chloride, didecyldimethylammonium chloride, N,N-bis(3-aminopropyl)dodecylamine. Has been developed method for evaluating the irritant effect of skin antiseptics on bull sperm suspensions.

Antimicrobial Resistance Phenotypes and Genotypes of Salmonella spp. Isolated from Commercial Duck Meat Production in Thailand and Their Minimal Inhibitory Concentration of Disinfectants.

Salmonella is an important foodborne bacterium that has become increasingly resistant to critical antimicrobial and disinfectant agents. The aim of this study was to characterize antimicrobial and disinfectant resistance of Salmonella spp. isolated from ducks raised for meat in Nakhon Pathom province, Thailand. A total of 694 fecal samples from ducks were collected in 2018. Of which, 85 samples were positive for Salmonella (12.2%), and 12 Salmonella serovars were identified from 125 Salmonella isolates. The Altona serovar was the predominant serotype found in this study (36.5%). All isolates showed resistance to at least one class of antimicrobial, and 23.2% displayed multidrug resistance (MDR) phenotype. The blaTEM, aadA2, strA, and dfrA12 genes were detected in antibiotic-resistant strains of Salmonella, whereas the genes within a plasmid-borne qnr family that presented in fluoroquinolone-susceptible Salmonella strains were qnrB (3.8%) and qnrS (1.5%). The minimum inhibitory concentrations of benzalkonium chloride (BKC), cetylpyridium chloride (CPC), and hexadecyltrimethyl ammonium bromide (CTAB) ranged between 128 and 512 μg/mL, while that of didecyldimethylammonium chloride (DDAC) was between 32 and 128 μg/mL. The presences of qacEΔ1, mdfA, sugE(c), sugE(p), and ydgE genes were less prevalent (0.8-1.6%). Taken together, our results indicate that duck is an important source of Salmonella with antimicrobial resistance in food-producing animals. Active surveillance programs for antimicrobial and disinfectant resistance in duck production are needed for an early detection of resistance strains of public health importance.

Recovery of zinc and manganese from “black mass” of waste Zn-MnO2 alkaline batteries by solvent extraction technique with ionic liquids, DESs and organophosphorous-based acids

Solvent extraction was used to recover zinc and manganese from the “black mass” (BM) produced in the zinc plant in Poland, the secondary waste from spent zinc-batteries. A lot of methods and extracting solvents such as ionic liquids (ILs), organophosphorous-based acids and Deep Eutectic Solvents (DESs) were investigated. The environmentally friendly method of metal ions extraction without the primary process of waste batteries leaching with sulfuric acid has been proposed. The BM solvent extraction with trihexyltetradecylphosphonium chloride ([P6,6,6,14][Cl], Cyphos IL 101), trihexyltetradecylphosphonium thiocyanate ([P6,6,6,14][SCN]), bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272), and bis-(2-ethylhexyl) phosphoric acid (D2EHPA) has been presented. Process factors and organic to water ratios were studied. A flowchart for zinc and manganese recovery from BM has been presented. The 100 wt% extraction efficiency for Zn(II) was obtained with (Cyanex 272 + diethyl phosphite).Quick and efficient extraction, with 100 wt% recovery of zinc and manganese, was obtained using DES (choline chloride [N2OH,1,1,1][Cl] : lactic acid 1:2, as well as choline chloride [N2OH,1,1,1][Cl] : malonic acid 1:1) with the addition of didecyldimethylammonium chloride surfactant, DDACl. Moreover, the recovery of zinc in the form of a metal deposit was carried out using a potential-control electrolysis from acidic aqueous solutions obtained after extraction with organophosphorous-based acids and diethyl phosphite. For all the systems, the selectivity and distribution ratios have been presented.

2D MXene-Molecular Hybrid Additive for High-Performance Ambipolar Polymer Field-Effect Transistors and Logic Gates.

MXenes are highly conductive layered materials that are attracting a great interest for high-performance opto-electronics, photonics, and energy applications.. Their non-covalent functionalization with ad hoc molecules enables the production of stable inks of 2D flakes to be processed in thin-films. Here, the formation of stable dispersions via the intercalation of Ti3 C2 Tx with didecyldimethyl ammonium bromide (DDAB) yielding Ti3 C2 Tx -DDAB, is demonstrated. Such functionalization modulates the properties of Ti3 C2 Tx , as evidenced by a 0.47eV decrease of the work function. It is also shown that DDAB is a powerful n-dopant capable of enhancing electron mobility in conjugated polymers and 2D materials. When Ti3 C2 Tx -DDAB is blended with poly(diketopyrrolopyrrole-co-selenophene) [(PDPP-Se)], a simultaneous increase by 170% and 152% of the hole and electron field-effect mobilities, respectively, is observed, compared to the neat conjugated polymer, with values reaching 2.0 cm2 V-1 s-1 . By exploiting the balanced ambipolar transport of the Ti3 C2 Tx -DDAB/PDPP-Se hybrid, complementary metal-oxide-semiconductor (CMOS) logic gates are fabricated that display well-centered trip points and good noise margin (64.6% for inverter). The results demonstrate that intercalant engineering represents an efficient strategy to tune the electronic properties of Ti3 C2 Tx yielding functionalized MXenes for polymer transistors with unprecedented performances and functions.

Contact sensitizations to disinfectants containing alcohols or quaternary ammonium compounds are rarely of clinical relevance.

The use of disinfectants is part of the everyday life of people, especially in the medical profession. During the coronavirus disease 2019 (COVID-19) pandemic, the use of disinfectants continues to increase and is of fundamental importance in infection control. To determine the frequency of sensitization and the value of patch testing to didecyldimethylammonium chloride (DDAC) and the alcohols ethanol, 1-propanol, and isopropanol. Clinical patch test data of 145 patients with suspected contact allergy to disinfectants were retrospective analysed. Among the 145 patients patch tested with the different alcohols, only one nurse was detected with a possible allergy to 1-propanol. Additional patch testing in 84 patients with DDAC 0.05% resulted in five patients with weakly positive reactions only, without clinical relevance. Patch testing with DDAC 0.03% showed no positive reactions at all on day 3 readings. DDAC and alcohols are rarely responsible for allergic contact dermatitis. The accused products of the patients should be checked for other allergens and further additives with skin-irritating properties. Individual susceptibility and mishandling of the disinfectants should be considered.

Colorimetric detection of residual quaternary ammonium compounds on dry surfaces and prediction of antimicrobial activity using bromophenol blue.

Controlling and monitoring the residual activity of quaternary ammonium compounds (QACs) are critical for maintaining safe yet effective levels of these agents in the environment. This study investigates the utility of bromophenol blue (BPB) as a safe, rapid and user-friendly indicator to detect in situ residual QACs dried on hard, non-porous surfaces, as well a means to assess their antimicrobial efficacy. At pH 7, BPB has a purple colour which turns blue upon its complexation with QACs such as didecyldimethylammonium chloride (DDAC). BPB itself has no antimicrobial properties up to 400ppm. Within the range of 0-400ppm, BPB colour change was tied to specific DDAC antimicrobial performances with a detection threshold of 100ppm. BPB concentration and application volume could be adjusted such that a colour shift from purple to blue correlated with a set percent reduction (>99·9%) in test bacteria (Staphylococcus aureus and Klebsiella aerogenes). The BPB solutions developed in this study yielded similar colour shifts on polycarbonate and stainless steel surfaces and did not cross-react with chemical ingredients commonly found in sanitizers and disinfectant products. Overall, this study suggests that BPB provides a simple solution to safely monitor the post-application level and biocidal activity of residual dried QACs on surfaces.

Prenatal developmental toxicity of alkyl dimethyl benzyl ammonium chloride and didecyl dimethyl ammonium chloride in CD rats and New Zealand White rabbits.

The prenatal developmental toxicity potential of alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC) was evaluated in regulatory‐compliant studies. Pregnant female CD rats (25/group) and New Zealand White rabbits (16/group) were administered ADBAC (0, 10, 30, or 100 mg/kg/day and 0, 1, 3, or 9 mg/kg/day, respectively), or DDAC (0, 1, 10, or 20 mg/kg/day and 0, 1, 3, or 10 mg/kg/day, respectively), by oral gavage on gestation days (GD) 6–15 for rats and GD 6–18 for rabbits. At scheduled termination (GD 21 for rats; GD 29 for rabbits), maternal necropsies were conducted and live fetuses were weighed and examined for external, visceral, and skeletal malformations and variations. Clinical signs of maternal toxicity were observed in rats and rabbits dosed with ADBAC, resulting in no‐observed‐adverse‐effect levels (NOAELs) of 10 and 3 mg/kg/day, respectively. Despite the treatment‐related maternal toxicity of ADBAC, the NOAEL for prenatal developmental toxicity was 100 and 9 mg/kg/day for rats and rabbits, respectively, the highest doses evaluated. Repeated oral doses of DDAC resulted in maternal toxicity in both species at the top two doses, with 25% mortality noted in rabbits at 10 mg/kg/day. No teratogenic effects were observed at any dose for either species. However, increased incidence of dead fetuses per litter and decreased fetal body weights were observed in rabbits at the maternally lethal dose of 10 mg/kg/day. The NOAEL for maternal toxicity of DDAC was 1 mg/kg/day for both species and the NOAEL for prenatal developmental toxicity was 20 and 3 mg/kg/day, for rats and rabbits, respectively.

Preliminary Study on Disinfectant Susceptibility/Resistance Profiles of Bacteria Isolated from Slaughtered Village Free-Range Chickens in Nairobi, Kenya.

Disinfectants are regularly used for cleansing poultry slaughterhouses to control microorganisms. However, the microorganisms such as bacteria are developing resistance to disinfectant(s) and complicate control of bacterial infections. The aim of this study was, therefore, to determine disinfectant susceptibility/resistance patterns manifested by bacteria (to commonly used disinfectants), which were isolated from intestines of slaughtered indigenous chickens in Nairobi, Kenya. The method used was agar well diffusion, and the six disinfectants (their active ingredients are in brackets) tested were as follows: Kupacide® (glutaraldehyde; benzalkonium chloride); TH4+® (didecyl dimethyl ammonium HCl; dioctyl dimethyl ammonium HCl; octyl decyldimethyl ammonium HCl; alkyl dimethyl ammonium HCl; and glutaraldehyde); Noro cleanse® (glutaraldehyde; coco-benzyl-dimethyl-ammonium chloride); Dettol® (chloroxylenol); Savlon® (chlorhexidine gluconate; cetrimide; and N-propylalcohol); and Jik® (sodium hypochlorite). At recommended user concentration by the manufacturer, isolates showed various resistance to the respective disinfectants. E. coli isolates were resistant to five of the tested disinfectants (Jik®, TH4+®, Noro cleanse®, Dettol®, and Kupacide®); however, they were susceptible to Savlon®; Staphylococcus isolates were resistant to disinfectants to Jik® and TH4+® and susceptible to the rest disinfectants; Streptococcus isolates were only resistant to Jik® and susceptible to the remaining disinfectants. Some E. coli and Staphylococcus isolates showed resistance to more than one disinfectant. This study has demonstrated resistance of the bacterial isolates to various disinfectants at recommended user concentrations, although some of them were susceptible at higher concentration(s) and lower concentrations. This will interfere with the cleansing of the respective premises, resulting in contaminated products, which may end-up causing disease in the humans consuming them. Hence, it is recommended that one ascertains the efficacy of respective disinfectant by carrying out disinfectant susceptibility testing to know the effective ones and the appropriate concentration to use.

Abstract PS13-51: A phase II study of neoadjuvant weekly carboplatin/paclitaxel followed by dose-dense doxorubicin/cyclophosphamide (DD AC)in patients with triple negative breast cancer (TNBC): Wisconsin oncology network (WON) study

Abstract Background: The CALGB 40603 and BrighTNess studies found that adding high dose carboplatin every 3 weeks to the standard neoadjuvant DD AC - paclitaxel regimen in TNBC increased the pathologic complete response (pCR) rate to 54-58% but with the cost of increased treatment related toxicities resulting in decreased completion of the full course of treatment. Our hypothesis is by changing the high dose carboplatin every 3 weeks to low dose weekly carboplatin, it will retain the same benefit in pathologic response rate and minimize the treatment related toxicities, which in turn permits the full course of neoadjuvant treatment given to patients. Patients and Methods: This multi-center study was conducted through the WON (NCT03301350). Eligible TNBC patients for neoadjuvant chemotherapy received weekly carboplatin (AUC=2) and paclitaxel 80 mg/m2 for 12 doses, followed by dose dense doxorubicin 60 mg/m2 and cyclophosphamide 600 mg/m2 every 2 weeks with granulocyte growth factor support for 4 cycles. A one-week break was added before DD AC after the first 22 patients in order to minimize prolonged cytopenia. Primary end point was pCR. Secondary endpoints were frequency of dose modification and treatment related toxicities. Results: Accrual target was 50 with 80% power to detect a 20% difference using a one-sided binomial test at an alpha significance level of 0.025, but study was terminated earlier. Twenty-nine eligible patients consented for the study from November 2017 to February 2020. Median age was 52 year-old (range, 33-80). Twenty-eight patients received the study regimen. Three were removed due to early study termination and one (3.8%) died from grade 5 neutropenic sepsis after the last cycle of DD AC before surgery. Thus, 24 patients were evaluable for the primary outcome and 26 were evaluable for dose modification and toxicity outcomes. Eight patients (33%) achieved pCR and another 4 patients (17%) had minimal (ypT1aN0) residual disease. Of 26 patients, 24 (92%) were able to receive the full course of treatment +/- dose modification. One patient required the discontinuation of weekly carboplatin/paclitaxel completely due to severe infusion reaction and one did not finish the treatment before the study was terminated. Eight patients (31%) required dose delay with 5 of them during the weekly carboplatin/paclitaxel treatment. Seven patients (27%) also required dose reduction with 5 of them during the weekly carboplatin/paclitaxel treatment. Seventeen patients (65%) experienced severe adverse event (grade 3 or 4) with the majority of events (12/17) relating to grade 3-4 neutropenia or neutropenic fever. Conclusion: Although our study showed a lower pCR rate of 33% in compare to the previous CALGB 40603 (54%) and BrighTNess (58%) studies, we demonstrated that the majority of patients (92%) were able to receive the full course of study treatment. This weekly carboplatin with paclitaxel - AC regimen was used in the recent Keynote 522 study as the backbone chemotherapy to combine with check-point inhibitor immunotherapy in TNBC. However, any dosing schedules of carboplatin, weekly or every 3 weeks, add substantially to grade 3 or 4 toxicity of paclitaxel - AC. Aggressive supportive care management is needed when carboplatin is used. Citation Format: Yee Chung Cheng, Ruth O'Regan, Lubna N Chaudhary, Sailaja Kamaraju, Harvey Einhorn, Emmanuel Sampene, Marialane Pigsley, Mark E Burkard, Christopher R Chitambar, Kari B Wisinski. A phase II study of neoadjuvant weekly carboplatin/paclitaxel followed by dose-dense doxorubicin/cyclophosphamide (DD AC)in patients with triple negative breast cancer (TNBC): Wisconsin oncology network (WON) study [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS13-51.

Extensively-drug-resistant Klebsiella pneumoniae ST307 outbreak strain from north-eastern Germany does not show increased tolerance to quaternary ammonium compounds and chlorhexidine

An outbreak of extensively-drug-resistant Klebsiella pneumoniae strain ST307 in a cluster of hospitals in north-east Germany gave rise to the assumption that the epidemiological success of the strain could be based on increased tolerance to biocides. The tolerance of the outbreak strain was compared with epidemiologically unrelated clinical isolates of K.pneumoniae, and reference strains of Pseudomonas aeruginosa (ATCC 15442) and Escherichia coli K12 (NCTC 10538). Tests were performed in a miniaturized assay based on European Standard EN 1040. The widely used biocides benzalkonium chloride (BAC) and didecyl dimethyl ammonium chloride (DDAC), their commercial formulation Descosept spezial (DS), and the antiseptic agent chlorhexidine digluconate (CHG) were selected as test substances. These biocides are used regularly in the hospitals involved in the outbreak. All biocides had a bactericidal effect against all tested strains in the quantitative suspension test within 5 min at typically used concentrations and dilutions. The effectiveness of BAC and DDAC alone and in combination, and CHG antisepsis were not impaired under tested conditions. The outbreak strain did not show significantly increased tolerance towards biocides regarding the antiseptic. Thus, the epidemiological success of the strain has to be ascribed to other causes, such as inadequate hand hygiene of visitors.