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TDK conference 2021

Antimicrobial and anti-biofilm activity of the active HOCl-containing disinfectant
Bencsik Luca - year 5
University of Veterinary Medicine Budapest, Department of Pharmacology and Toxicology
Supervisors: Dr. Ádám Kerek, Dr. Adrienn Mercédesz Veres


One of the most significant issues nowadays is the increasing spread of antimicrobial resistance, therefore efforts must be made to slow down this process by reducing the use of antimicrobial agents and putting emphasis on the prevention of infectious diseases. One of the most obvious tools to ensure this is the use of disinfectants to maintain good hygiene, thereby reducing the amount of antimicrobials used on an animal farm, that leads to the decreasing number of antimicrobial-resistant pathogens and significantly reduces on-farm veterinary expenditures. There is no such thing as a perfect disinfectant, but the manufacturers try to create more effective products that can provide maximal protection against pathogens, without damaging the environment or the host. A suitable alternative that can meet these expectations might be hypochlorous acid (HOCl), which is effective against a broad spectrum of pathogens. Most of the studies on HOCl disinfectants have been carried out on human pathogens and the literature regarding to veterinarian field is rather limited.

In our study, we investigated for the first time in Hungary the in vitro efficacy of a disinfectant containing active HOCl against bacterial strains of animal origin – Staphylococcus aureus, Escherichia coli, Salmonella spp., Pseudomonas aeruginosa – and on Candida albicans fungi. It was shown that the tested HOCl product, containing active chlorine in 0,35 mg/ml concentration was still effective in inhibiting the growth of most pathogens when diluted 2 times and it was effective against Pseudomonas aeruginosa and Candida albicans when diluted 4-8x and 2-8x. To determine whether the disinfectant has a bacterio-static/bactericid and fungistatic/fungicid effect, minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC) calculation was performed. According to our results, the MBC/MFC values are equal to the minimum inhibitory concentration (MIC) values (43,75-175 µg/ml), indicating that the disinfectant has bactericidal/fungicidal activity. Based on the results of the kill curve, a 2x dilution of the disinfectant killed all pathogens within 5 minutes, except for Pseudomonas aeruginosa, where 15 minutes were required. A 4x dilution of the original stock-solution was also tested, but it showed bactericidal activity only against Escherichia coli, after 120 minutes. It was also found that the concentrated and 2x diluted solution of the disinfectant had effective biofilm-disrupting properties according to MTS staining of the biofilms of the investigated bacteria.

In conclusion, based on the MIC values and the corresponding MBC/MFC values, it can be said that the concentrated disinfectant has a bactericidal/fungicidal effect up to its 4x dilution.

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