Targeting Microbial Biofilms and Promoting Wound Healing in MRSA-Infected Diabetic Rats using Postbiotics of Lactiplantibacillus plantarum.

Recalcitrant wounds in diabetic patients are difficult to treat and often require debridement and surgical intervention. Methicillin-resistant Staphylococcus aureus (MRSA), a common pathogen isolated from the diabetic wounds, further delays healing. This study investigates the wound-healing properties of the postbiotics of Lactiplantibacillus plantarum 2034 in MRSA-infected diabetic rats. Ethyl acetate extract (EAE) of L. plantarum was prepared, and its antimicrobial and antibiofilm properties against various pathogens were determined. EAE exhibited broad spectrum antimicrobial activity against various Gram-positive and Gram-negative bacterial pathogens including MRSA. At sub-MIC concentration, EAE inhibited biofilm formation by various pathogens, resulting in maximum inhibition of 82.6% for Bacillus subtilis, 73% for MRSA, and 43% for Salmonella typhi. At MBC concentration, EAE successfully disrupted preformed biofilms of the pathogens, probably due to interference with quorum sensing as shown by its ability to inhibit violacein pigment production by a biosensor Chromobacterium violaceum CV026. Carbopol 934 gel of EAE was formulated and applied to MRSA-infected wounds in diabetic rats. EAE gel showed significant (P < 0.05) reduction in the counts of MRSA on day 4 and complete clearance by day 12. EAE-treated wounds showed significantly (P < 0.05) faster wound closure rate compared to the untreated and standard drug-treated wounds. Histological analysis showed restoration of normal architecture of skin in EAE-treated wounds compared to the untreated and standard drug-treated groups. Furthermore, EAE treatment normalised the mRNA expression of proinflammatory cytokine interleukin (IL)-6 and doubled the levels of anti-inflammatory cytokine IL-10 compared to the untreated control. In conclusion, the dual antimicrobial and anti-inflammatory properties of the EAE gel make it a strong candidate for treating chronic MRSA-infected diabetic wounds. Gas chromatography-mass spectrometry analysis of EAE revealed the presence of several antimicrobial and antioxidant compounds.