Abstract

Background:
The use and abuse of antimicrobials in poultry products, dairy products, and beef cattle is a growing global concern. Furthermore, with the rise of bacterial resistance to these drugs, an innovative approach is needed to reduce antimicrobial doses and eradicate resistance.

Aim:
This study aimed to investigate the antibacterial properties of gallic acid and its potential to enhance the efficacy of tylosin.

Methods:
This study morphologically, biochemically, and molecularly identified S. aureus. The molecular diagnostic approach relied upon the polymerase chain reaction (PCR) test to identify the Staphylococcus genus by determining the main specific gene, 16s rRNA. Of the 30 isolates, 20 were positively identified by biochemical and traditional methods. Furthermore, to ensure that all isolates were positively identified as S. aureus species, 10 random samples were identified by PCR. The tube dilution method will then be used to determine the antibacterial MIC and MBC of gallic acid and tylosin. The second step assessed gallic acid and tylosin antibacterial synergy using checkerboard and Chou-Talalay techniques.

Results:
The morphologically, biochemically, and molecularly PCR-identified S. aureus isolates were approved for investigation. The MIC of gallic acid was determined to be 4 μg/ml, with a minimum bactericidal concentration (MBC) of 8 μg/ml. The range of MIC and MBC for tylosin was found to be between 8 and 16 μg/ml. In addition, synergistic interactions were reported when gallic acid was coupled with tylosin, resulting in a record FIC value of 0.357 against the tested isolate.

Conclusion:
Gallic acid synergizes the antibacterial action of tyrosine against S. aureus in a sub-MIC concentration.

Key words: Gallic acid; Tylosin; Antibiotic resistance; Synergistic; S. aureus.