Combinatorial antimicrobial potential of secondary metabolites and bacteriophages against multi-drug-resistant uropathogenic Escherichia coli.

BACKGROUND

Uropathogenic Escherichia coli (UPEC), the leading cause of urinary tract infections, has developed resistance to multiple antibiotics, creating an urgent need for alternative therapeutics.

MATERIALS AND

METHODS

A bacterial isolate exhibiting antimicrobial activity against multidrug-resistant (MDR) UPEC was screened. Its secondary metabolites were extracted and analyzed using high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS), and gas chromatography-mass spectrometry (GC-MS). Antimicrobial activity was evaluated for the purified secondary metabolite (SM) extract alone and in combination with bacteriophages.

RESULTS

HPLC revealed a major bioactive peak corresponding to polymyxin B sulfate, confirmed by LC-MS with a dominant peak at 1185 Da. GC-MS identified additional minor pyrrolizidine derivatives with potential antibacterial activity. The polymyxin-like SM (PSM) extract showed potent antimicrobial effects against UPEC and other uropathogens. Notably, co-treatment with bacteriophages significantly reduced the minimum inhibitory concentration (MIC), indicating a synergistic effect.

CONCLUSION

Bacterial secondary metabolites, particularly polymyxin-like extracts, exhibit strong antimicrobial activity against MDR UPEC. Their synergistic interaction with bacteriophages highlights a promising combined antimicrobial approach to combat MDR uropathogens.