1. Antimicrobial activities of polyhexamethylene biguanide against biofilm-producing Prototheca bovis causing bovine mastitis.
- Author
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Fidelis, Carlos Eduardo, de Freitas Leite, Renata, Garcia, Breno Luis Nery, Gonçalves, Juliano Leonel, Good, Liam, and dos Santos, Marcos Veiga
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BOVINE mastitis , *CHLORHEXIDINE , *ANTI-infective agents , *MICROBIAL sensitivity tests , *BIGUANIDE , *CATTLE herding - Abstract
Prototheca spp. is a frequent cause of bovine mastitis and is highly resistant to commonly used disinfectants. This study aimed to: (1) evaluate the antimicrobial activity of polyhexamethylene biguanide (PHMB) against mastitis-causing Prototheca spp., and (2) evaluate the biofilm production ability of Prototheca spp. A total of 85 Prototheca bovis and 2 Prototheca blaschkeae isolates from bovine mastitis cases were submitted to biofilm production assays and antimicrobial susceptibility tests against PHMB and disinfectants commonly used in dairy herds (chlorhexidine digluconate, povidone-iodine, sodium dichloroisocyanurate, and sodium hypochlorite). The minimal inhibitory concentration (MIC) and minimal algicidal concentration (MAC) were determined by microdilution assays. We observed that PHMB (MIC 90 : ≥2 µg/mL and MAC 90 : ≥4 µg/mL) and chlorhexidine gluconate (MIC 90 and MAC 90 : ≥2 µg/mL) presented the highest antimicrobial activity against P. bovis isolates, followed by sodium dichloroisocyanurate (MIC 90 and MAC 90 : ≥1,400 µg/mL), sodium hypochlorite (MIC 90 and MAC 90 : ≥2,800 µg/mL), and povidone-iodine (MIC 90 and MAC 90 : ≥3,200 µg/mL). Concerning P. blaschkeae isolates, PHMB (MIC and MAC ≥1 µg/mL) and chlorhexidine gluconate (MIC and MAC ≥1 µg/mL) were the disinfectants that presented the lowest concentration values required to inhibit the isolates. Regarding biofilms formation, 63.5% (n = 54/85) of the P. bovis isolates were classified as strong, 28.3% (n = 24/85) moderate, and 8.2% (n = 7/85) weak biofilm producers. In contrast, the P. blaschkeae isolates were classified as weak and moderate biofilm producers. These findings suggest that PHMB has the potential to be used for teat and milking-equipment disinfection for the prevention of mastitis-causing Prototheca spp. in dairy herds. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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