Study of antimicrobial efficacy of teat dip solutions with povidone iodine and chlorhexidine digluconate against P. zopfii algae isolated from bovine mastitis milk

Abstract

Prototheca zopfii is an environmental pathogen that causes chronic bovine mastitis. Reproduction of the pathogen in the mammary gland and regional lymph nodes causes granulomatous inflammation of the udder, damage to mammary parenchyma, atrophy of affected udder quarters, reduction of milk yield, and an increase in the count of somatic cells to 1 000 000/mL [1, 2]. Prototheca mastitis usually occurs due to contact with contaminated water sources or equipment [3]. There are no effective or approved treatment methods for Prototheca mastitis [4]. Prototheca survives pasteurization and is resistant to disinfection with chlorine compounds [5]. Frequent intramammary antibiotic infusions may contribute to the development of Prototheca infection in the udder [6]. It is difficult to eradicate the pathogen from the herd, infected cows are eliminated, and the only disease control measure is prevention. The aim of this study was to determine in vitro sensitivity of P. zopfii isolated from bovine mastitis milk to post-milking teat dips Profidip Iodine and Profidip Chlorhexidine. Research methods. The research was conducted in the Laboratory of Microbiological Research, Institute of Microbiology and Virology, Faculty of Veterinary Medicine, Lithuanian University of Health Sciences. Prototheca zopfii isolated from the milk of cows with chronic bovine mastitis was used. The research was carried out using the agar diffusion method. The activity of the teat dips was assessed in Sabouraud agar (BD DifcoTM, Franklin Lakes, NJ, USA), under aseptic conditions. Wells were formed in the inoculated medium in a Petri dish, each of which were filled with 100 μL of tested dips. The Petri dishes were incubated at 30°C. After 48 hours of incubation, antimicrobial activity was assessed by measuring the diameter of clear zones around wells. Results. The study determined that both teat dips under investigation exhibited anti-Prototheca activity. Profidip Chlorhexidine inhibited the growth of P. zopfii strains,with an average clear zone at 19.1 ± 0.6 mm. Profidip Iodine was reliably more effective (P < 0.05), with an average clear zone at 31.4 ± 0.9 mm, and scanty algal growth on media. Conclusion. Post milking teat dips Profidip Iodine and Profidip Chlorhexidine inhibit in vitro growth of P. zopfii strains. The teat dips exhibit different anti-Prototheca activity, with Profidip Iodine proving more effective (P < 0.05) against the algal cultures than Profidip Chlorhexidine.