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Kerala Veterinary and Animal Sciences University, Wayanad

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20211
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Subject: Veterinary Pharmacology and Toxicology × Author: ARYA MOHAN ×
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    ThesisItemOpen Access
    COMPARATIVE STUDY OF BERBERINE AND CAPSAICIN AS EFFLUX PUMP INHIBITORS IN QUINOLONE RESISTANT STAPHYLOCOCCUS AUREUS ISOLATES FROM BOVINE MASTITIS
    (COLLEGE OF VETERINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR, 2021-08-30) ARYA MOHAN; Nisha A.R.
    Antimicrobial resistance which causes failure of antibiotic therapy has become a global issue nowadays. Bacteria develop resistance towards an antibacterial agent via many mechanisms, the most important one is the drug efflux mediated through efflux pumps. Bacterial resistance causes reduction in the usage of several chemotherapeutic agents in the treatment of bacterial diseases. In this context, research on natural products from plants which can be used as plausible candidates to combat antimicrobial resistance will be of utmost importance. Hence, a study was undertaken to assess the antibacterial activity and resistance modulation through down regulation of norA, norB, and norC by two plant alkaloids berberine and capsaicin against quinolone-resistant S. aureus from bovine mastitis. Disc diffusion assay and broth microdilution assay were performed to assess the antibacterial activity of berberine and capsaicin alone (at various concentrations viz 8 g/L to 0.25 g/L) and in combination of antibiotics with enrofloxacin, norfloxacin and nalidixic acid. Resistance modulating potential through efflux pump inhibition by berberine and capsaicin in combination with quinolones at sub inhibitory concentration in down regulating norA, norB, and norC was executed by reverse transcription and quantitative real-time PCR. Antibiofilm assay was conducted for various combinations of quinolones with berberine and capsaicin using congo red agar plate method. In silico studies were carried out using autodock software to analyse the binding of berberine and capsaicin to NorA protein. The findings of disc diffusion assay revealed that berberine and capsaicin in combination with enrofloxacin, norfloxacin and nalidixic acid increased the zone of inhibition significantly (p-value < 0.05) in a dose-dependent manner. Checkerboard assay showed that berberine lowered the MIC of antibiotics tested up to eightfold and capsaicin up to fourfold. The combination of enrofloxacin with berberine exhibited synergy and with capsaicin exhibited partial synergy. The combination of norfloxacin with test compounds exhibited partial synergy and the combination of berberine and capsaicin with nalidixic acid exhibited additivity. Gene expression studies indicated downregulation in the expression of norA and norC genes, while norB was not expressed in any of the isolates. Berberine and capsaicin in combination with quinolones could inhibit the biofilm formation by S. aureus isolates in a dose dependent manner. In silico studies revealed that capsaicin bind to NorA protein. To consolidate, berberine and capsaicin can be promising drug molecules in modulating the drug resistance mediated by the Nor efflux pumps in S. aureus from bovine mastitis. Thus, berberine and capsaicin can be used as an adjunct to antibiotics for the treatment of bacterial diseases.