Potential of Ethanol Extract of Guava (Psidium Guajava L.) Leaves as Adjuvant-Antibiotic on Salmonella Typhi Characterized

Guava (Psidium guajava L.) contains many chemical compounds, including quercetin, myricetin, epicatechin, and tannins which have been shown to have efficacy as an efflux pump inhibitor (EPI) in several pathogenic bacteria. This study aimed to investigate the synergistic effect of the ethanol extract of guava leaves with five common antibiotics on Salmonella typhi isolates expressing active efflux pumps. Bacterial characterization was carried out on clinical isolates of S. typhi, and molecular resistance mechanisms were determined using qRT-PCR by measuring the expression of the Acriflavine resistance protein B (AcrB) efflux pump. Guava leaves were extracted by maceration using 70% ethanol. Tests were carried out using the diffusion method with tetracycline, ampicillin, trimethoprim-sulfamethoxazole, chloramphenicol, and ciprofloxacin. The extract was made in serial concentrations of 0.01, 0.025, 0.05, 0.075, and 0.1%. The results showed that the tested isolates decreased the expression of AcrB from 11.48167 to 7.38818 ρg/mL after adding CCCP. The synergistic effect occurred at (1) extract concentration of 0.1% against tetracycline 30 μg, (2) concentration of 0.05% against ampicillin10μg, (3) concentration of 0.075% against trimethoprim-sulfamethoxazole 23.75-1.25 μg, (4) concentration of 0.05% against chloramphenicol 30 μg, (5) concentration of 0.025% against ciprofloxacin 5 µg. The ethanol extract of guava leaves (Psidium guajava L.) synergized with the studied antibiotics and displayed efflux pump inhibitory activity. Consequently, it could serve as a natural antibiotic adjuvant candidate.