Delayed Wound Healing: A Focus on Bacterial Intracellular Proteases in Diabetic Wound Ulcers

A diabetic skin ulcer (DSU) is a breach on the skin characterized by progressive destruction of the surface epithelium of the skin and a disintegrating base resulting from wounds obtained by a diabetic patient. This study was aimed at determining DSU wound colonization by bacteria and to quantitatively analyze some intracellular enzymes produced by these bacteria that could affect the wound healing process. Wound swab samples were collected from 150 subjects comprising of diabetic patients with skin ulcers as well as non-diabetics with wounds (control). The wounds were found to be colonized by an array of bacteria which included Pseudomonas aeruginosa, Staphylococcus aureus, Acinetobacter sp, Enterococcus faecalis, Proteus vulgaris, Proteus mirabilis, Klebsiella pneumoniae, Escherichia coli, Coagulase negative Staphylococcus aureus, Klebsiella oxytoca, Alcaligenes faecalis and Citrobacter freudii. These bacterial isolates produced the following proteolytic enzymes: collagenase, caseinase, hyaluronidase, alkaline protease and gelatinase on the DSU in higher amounts than the non-diabetic wounds (control). Intracellularly, S.aureus (0.199 ± 0.000) and E.coli (0.145 ± 0.006) secreted the maximum and minimum amounts of hyaluronidase respectively. For caseinase, S.aureus (0.048 ± 0.001) exhibited the highest activity and K.oxytoca (0.018 ± 0.000) showed the least activity. E.coli (18.173 ± 0.157) secreted the highest amount of gelatinase while P.aeruginosa (5.057 ± 0.496) had the least while maximum intracellular activity for alkaline protease was secreted by P.aeruginosa (0.016 ± 0.001). Bacterial wound flora was found capable of producing and secreting intracellular proteolytic enzymes which could be implicated in impairing proper wound healing.