Antibiotic resistance reversal of multiple drug resistant bacteria using Piper longum fruit extract

Present investigation was aimed to identify natural products of plant-origin as novel antibiotic resistance reversal agents. Aqueous and methanol extracts of Piper longum (fruits) were tested against multiple drug resistant (MDR) clinical isolates of Enterococcus faecalis, Staphylococcus aureus, Salmonella typhi, Shigella sonnei, as well as reference-plasmid-harboring strains of Escherichia coli (RP4) and Bacillus subtilis (pUB110). The crude methanol extract showed significant antibacterial activity with a minimal inhibitory concentration of 400 µg/mL against Bacillus subtilis (harboring pUB110 plasmid). Methanol extract could reverse the antibiotic resistance in clinical isolates of Shigella sonnei, with a curing efficiency of 42%. In comparison with methanol extract, aqueous extract showed antibiotic resistance reversal efficiency against wider range of clinical isolates. Aqueous extract showed strong antibiotic resistance reversal activities against R-plasmid harboring strains of clinical origin- Enterococcus faecalis, Staphylococcus aureus, Salmonella typhi with curing efficiencies of 64%, 50% and 32% respectively. This antibiotic resistance reversal may be attributed to the elimination of R-plasmids as the multiple antibiotic resistance genes are usually located on R-plasmids. Active biomolecules from P. longum may prove to be a source to develop MDR reversal agents of natural origin to contain the development and spread of plasmid borne multiple antibiotic resistances.