MIC and MBC of Honey and Gold Nanoparticles against methicillin-resistant (MRSA) and vancomycin-resistant (VRSA) coagulase-positive S. aureus isolated from contagious bovine clinical mastitis

Staphylococcus aureus is one of the major causative agents of the bovine clinical mastitis. This study aimed to isolate and identify S. aureus from cases of bovine clinical mastitis followed by phenotypic detection of MRSA and VRSA. The genotypic detection of MRSA was done through PCR detection of the resistance mecA gene. Furthermore, this study aimed to investigate the in vitro MIC and MBC of the Dodonaea angustifolia plant extract, Honey, and AuNPs against the clinically isolated MRSA and VRSA. Of 93 mastitis milk samples examined, 54 (58.1%) S. aureus were isolated and identified {CP S. aureus = 46 (85.2%) and CN S. aureus = 8 (14.8%)}. The whole MRSA, VRSA, MSSA, and VSSA detected were 19 (35.2%), 7 (13%), 35 (65%), and 47 (87%) respectively. The mean counts of S. aureus were between 8.6 × 104 ± 3.5 × 105 CFU/ml. The oxacillin and vancomycin MICs against MRSA and VRSA respectively, were >256 µg/ml. AuNPs sized 30 nm produce observable in vitro anti-MRSA and anti-VRSA activities. Imtenan® citrus blossom honey has also antibacterial activities against MRSA and VRSA with general MBC and MIC range values were observed at a concentration of 0.625, 1.25, 2.5, and 5 (%v/v). In the present study, the most significant result obtained when AuNPs was mixed with Imtenan® citrus blossom honey (1:1 = v:v) with the best MBC was observed at the concentration of 0.56 × 109:0.3 (NP/ml: honey %v/v).