Antibacterial Activity of Halophilic Bacteria Against Drug-Resistant Microbes Associated with Diabetic Foot Infections

Abstract

Bacteria causing diabetic foot infections (DFI) are chronic and generally multidrug resistant (MDR), which calls urgently for alternative antibacterials. The present study focused on potential metabolite producing bacteria from a saltpan environment and screened against MDR pathogens isolated from DFI patients. Molecular identification of the DFI pathogens provided Klebsiella quasivariicola, Staphylococcus argenteus, Escherichia coli, Staphylococcus hominis subsp. novobiosepticus, Bacillus australimaris, and Corynebacterium stationis. Among 34 isolated halophilic bacteria, the cell-free supernatant of strain PSH06 provided the largest inhibition zone of 23mm against K. quasivariicola [D1], 21mm against. S. argenteus [D2], 19mm against E. coli [D3], and a minimum inhibition zone was found to be 14mm against C. stationis [D8]. The potent activity providing stain confirmed as Pseudomonas aeruginosa through molecular identification. On the other hand, ethyl acetate extract of this strain showed excellent growth inhibition in MIC at 64µg/mL against K. quasivariicola. Distressed cell membranes and vast dead cells were observed at MIC of ethyl acetate extract by SEM and CLSM against K.quasivariicola and E. coli. GC-MS profile of ethyl acetate extract exposed the occurrence of Bis (2-Ethylhexyl) Phthalate and n-Hexadecanoic acid and shows 100% toxic effect at 24mg/mL by Artemia nauplii. The active extract fraction with above compounds derived from saltpan bacteria provided highest antibacterial efficacy against DFI-associated pathogens depicted with broad spectrum activity compared to standard antibiotics.