Resistance Profile of Bacteria Isolated from Diabetic Wounds: Phytochemicals and Antibacterial Studies of Eriosema robustum Leaf Extracts
Authors: Tsaffo Gael Marius , Djenguemtar Josias , Fodouop Siméon Pierre Chegaing , Merzouk Hafida , Baptiste Sokoudjou Jean , Tchuente Kamsu Gabriel , Bocanestine Laure Feudjio Huguette , Kodjio Norbert , Mebarki Abdelouahab , Gatsing Donatien 
Published: May 2024

Diabetics are susceptible to severe trophic problems and wounds, which are frequently referred to as “unhealable wounds”. Untreated diabetic wounds provide an ideal habitat for the growth of bacteria, which can eventually develop resistance to standard treatments and need amputation. This study aimed to assess the in vitro antibacterial activity of ethanolic and aqueous extracts of Eriosema robustum leaves on the same bacterium, as well as the resistance profile of bacteria isolated from diabetic wounds to conventional antibiotics. Thirty samples from diabetic wounds were collected at the Baleveng Hospital, subjected to bacteria isolation and antibiotics resistance tests using the disk diffusion method. On the other hands, leaves of Eriosema robustum were collected, hydroethanolic extraction were performed. The extract obtained was used for the antibacterial (by determination of the MIC) and antioxidant (DPPH and FRAP tests) activities as well as phytochemicals composition (using HPLC methods) assessment.  Amon the 30 samples analyzed, 19 (63.33 %) showed bacterial infections and Staphylococcus aureus was the most common pathogen (48 %), followed by Pseudomonas aeruginosa (24 %), Klebsiella pneumoniae (19 %), and Streptococcus agalactiae (9 %). Fifty percent (50 %) of S. aureus isolates were MRSA (methicillin-resistant S. aureus). The MIC value obtained 64 μg/mL against S. aureus, Streptococcus agalactiae and Pseudomonas aeruginosa. Phytochemicals analysis of fractions from the 70 ° hydroethanolic leaves of Eriosema robustum revealed the presence of coumarin, gallic acid, quinoline, vanillin, ascorbic acid, caffeic acid, kaempferol, and cinnamic acid. The antibacterial and antioxidant potential of the extracts highlighted in this study could make this plant a good avenue for the discovery of new molecules effective against infected diabetic wounds.
HIGHLIGHTS

In this study, a total of 30 diabetic wounds were examined, and it was found that 63.33 % of them had infections. Staphylococcus aureus was the most frequently occurring bacteria, followed by Pseudomonas aeruginosa, Klebsiella pneumoniae, and Streptococcus agalactiae.
The current study has revealed that, 96 % of the Staphylococcus aureus strains isolated were resistant to both tetracycline and methicillin, with the majority of the bacteria also showing resistance to amoxicillin.
The hydroethanolic and aqueous extracts of Eriosema robustum displayed antibacterial activity against most of the isolated bacteria and the phytochemical analysis (HPLC) of fractions from the 70 ° hydroethanolic leaf extract revealed the presence of several secondary metabolites, including coumarin, gallic acid, quinoline, vanillin, ascorbic acid, caffeic acid, kaempferol, and cinnamic acid.
This study opens up a new horizon in the management of diabetic wounds, and makes Eriosema robustum a potential candidate for the formulation of new drugs active against multi-resistant bacteria found in diabetic subjects.

GRAPHICAL ABSTRACT