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.

Synergism vs Additivity - Defining the Interactions between Common Disinfectants

Many of the most common disinfectant and sanitizer products are formulations of multiple antimicrobial compounds. Products claiming to contain synergistic formulations are common, although there is often little supporting evidence. The antimicrobial interactions of all pairwise combinations of common disinfectants (benzalkonium chloride, didecyldimethylammonium chloride, polyhexamethylene biguanide, chlorocresol and bronopol) were classified via checkerboard and validated by time-kill analyses. Combinations were tested against Acinetobacter baumannii NCTC 12156, Enterococcus faecalis NCTC 13379, Klebsiella pneumoniaeNCTC 13443 and Staphylococcus aureus NCTC 13143. Synergistic interactions were only identified between cholorocresol with benzalkonium chloride, and chlorocresol with polyhexamethylene biguanide. Synergism was not ubiquitously demonstrated against all species tested and was on the borderline of the synergism threshold. These data demonstrate that synergism between disinfectants is uncommon and circumstantial. Most of the antimicrobial interactions tested were characterised as additive. We suggest that this is due to the broad, non-specific mechanisms associated with disinfectants not providing opportunity for the combined activities of these compounds to exceed the sum of their parts.

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.

Assessment of the safety of skin antiseptics by the method of 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.

Susceptibility patterns of bacteria isolated from the hospital environment towards disinfectants commonly used for surfaces and medical devices

This study aimed to evaluate the bactericidal activity of common disinfectants used for surfaces and medical devices. Sodium hypochlorite (D1), disinfectant (D2) composed of N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine, chloride de didecyldimethylammonium, and disinfectant (D3) composed of Didecyldimethylammonium chloride and Polyhexamethylene biguanide hydrochloride, were tested against 15 strains isolated from the hospital environment and four reference bacteria. The microdilution method was performed to assess antimicrobial activity. The susceptibility was evaluated by comparing the minimum inhibitory dilution with the dilution of disinfectant recommended by the manufacture. D1 and D2 were active against Staphylococcus epidermidis, Staphylococcus saprophyticus, Enterobacter cloacae, Escherichia coli, Pseudomonas fluorescens, Methicillin-resistant Staphylococcus aureus, Bacillus spp, Corynebacterium spp, Gram-positive bacillus, Escherichia coli ATCC 25922, Bacillus subtilis ATCC 3366, and Pseudomonas aeruginosa ATCC 27853 strains but not active against Micrococcus spp, and Staphylococcus aureus ATCC 29213. D3 was ineffective against Micrococcus spp, Bacillus Gram Positive, Staphylococcus epidermidis, and Escherichia coli ATCC 25922. Therefore, D1 and D2 can eliminate most pathogenic bacteria in hospitals, in comparison to D3. It is necessary to monitor the antibacterial activity of disinfectants against reference strains but also against those usually present on surfaces. The obtained results could have promising applications in controlling the emergence of nosocomial infections.

Liquid chromatography–mass spectrometry analysis of dyes formed by in situ oxidative methods then purified by absorption and extraction from hair wefts

The dye mixtures formed from three commercial hair colour formers were purified by absorption onto human hair wefts, washed and dried, extracted with dichloromethane:trifluoroacetic acid (75:25) and then analysed by liquid chromatography–mass spectrometry. Only 1–2 dyes were identified from each complex mixture of commercial aromatic amines along with a broad UV absorption mainly consisting of mixtures of quaternary ammonium salts from shampoos and some surfactants. Mecetronium ethyl sulfate and didecyldimethylammonium chloride were the main ammonium salts.

Increased Sensitivity of Amoeba-Grown Francisella Species to Disinfectants

Francisella tularensis is a highly infectious, intracellular bacterium and it is the causative agent of tularemia. The bacterium has been isolated from more than 250 species, including protozoa. Previous studies have shown that the growth of Legionella pneumophila within the amoeba results in a dramatic increase in the resistance to disinfectants. Since Francisella persists in the environment for years, this study investigates whether Acanthamoeba castellanii-grown F. novicida exhibits an alteration in the resistance to disinfectants. The disinfectants used are didecyldimethylammonium chloride (DDAC) combined with isopropyl alcohol (D1), benzalkonium chloride combined with DDAC and formic acid (D2), and polyhexamethylene biguanide (PHMB, D3). The effect of disinfectants on the bacterial viability is determined by a colony-forming unit (CFU), by transmission electron microscopy (TEM), by fluorescence microscopy, and the damage of the bacterial membrane. Our data has shown that only a one-log10 loss in bacterial viability is exhibited upon treatment of agar-grown Francisella, while in amoeba-grown Francisella there was a three-log10 difference with D3. The D1 disinfectant sterilized the bacteria within 10 s. The treatment of agar-grown F. novicida with D2 reduces bacterial viability by seven-log10 within 10 s and 15 min, respectively. Surprisingly, the treatment of amoeba-grown F. novicida with D2 results in a total loss of bacterial viability. In conclusion, A. castellanii-grown F. novicida is more susceptible to many disinfectants.

Disinvasive action of aldehyde and chlorine disinfectants on the test-culture of Toxocara canis eggs

Disinfection of environmental objects with highly effective disinfectants is a reliable and effective means of preventing the occurrence of outbreaks of infectious and parasitic diseases. The purpose of our work was to determine the disinfection properties of modern disinfectants based on the test culture of Toxocara canis helminths and to establish the optimal modes of their use. It has been proven that an aldehyde disinfectant containing didecyldimethylammonium chloride (2.25%), benzalkonium chloride (8.0%), glutaraldehyde (15.0%), phosphoric acid, nonionic surfactants, water exhibits disinvasive activity against test cultures of Toxocara canis eggs at a concentration of 2.0-4.0% at a temperature of 20±0.5°C and an exposure of 3-24 hours, and the ovocidal efficiency is from 90.60% to 99.70%. Aldehyde disinfectant can be used for disinfection of soil (black earth, sandy loam, loamy) contaminated with Toxocara canis eggs, at a concentration of 4.0% at 6:00 exposure and a consumption rate of 3000 cm3/m2. Chlorine agent, contains dichlorantin, dimethylhydantoin (12.4-16.4%), dispersant (9.0-12%), nonionic surfactants, corrosion inhibitor, filler exhibits disinvasive activity against Toxocara canis test culture in a concentration of 3.0-4.0% with an exposure of 3-24 hours, and the ovocidal efficiency in this case ranges from 97.40% to 98.82%. The chlorine agent is effective for soil disinfection only at a depth of up to 2 cm at a concentration of 4.0% at a consumption rate of 1000 cm3/m2 and an exposure time of 24 hours.