Evaluation of the superficial antistaphylococcic power of extracts of combretum racemosum P. beauv. (Combretaceae)

Abstract

Staphylococcus Aureus and Staphylococcus epidermidis are commensal bacteria of humans and farm animals. They are identified as opportunistic, multi-resistant pathogens, and agents of fatal infections and severe food poisoning in farm animals and humans. In Côte d'Ivoire, little information is available concerning these bacteria of human origin. The objective of this study was to develop a new natural antistaphylococcal and food preserva˗ tive, through the in-vitro determination of the antistaphylococcal power of C. racemosum leaves. For this purpose, a total of 5 crude aqueous and hydro-organic extracts of the leaves of C. racemosum were tested on 4 clinical isolates of S. aureus and S. epidermidis resistant to methicillin, bacterial species often encountered in infections of farm animals and humans. All isolates such as S. aureus (ATTC 25923), S. aureus (Méti-R 2062C/15), S. aureus (Méti-R 2063/15) and S. epidermidis (Méti-R 2070C/15) demonstrated sensitivity to each plant extract according to a dose-response relationship at concentrations ranging from 3.125 to 100 mg/mL. Sensitivity was most observed towards Eeth, which constitutes the most effective antibacterial extract on all the staphylococci studied. This partly justifies the use of C. racemosum in Ivorian traditional therapy against superficial infections of the skin, cutaneous appendages and mucous membranes. For all the extracts tested, the recorded MICs ranged between 3.125 ± 0.00 mg/mL and 100 ± 0.00 mg/mL, while the CMBs ranged between 6.25 ± 0.00 mg/mL and 100 ± 0, 00 mg/mL. Five (5) groups of biomolecules including alkaloids, saponins, steroids, terpenoids and tannins (catechic and gallic) were highlighted at various degrees of concentration by triphytochemistry. The most active extract in this study (Eeth) contains in average concentrations the same biomole˗ cules mentioned above. This study made it possible to retain that the macerated crude hydro-ethanolic extract (Eeth) constitutes the most active fraction of all the crude extracts tested in this work. Consequently, it could, subject to toxicological study, be used for the preservation of food against staphylococci and the treatment of staphylococci of the skin, mucous membranes and cutaneous appendages in farm animals and humans.