Antibiogram of Escherichia Coli and Staphylococcus Aureus Isolated from Suppurative Wound Infections of Hospitalized Patients and their Responses to Bioactive Extratcs of Gongronema Latifolium

Abstract

Issues of multidrug resistance among infectious agents are of growing global concern. Strains of Escherichia coli and Staphylococcus aureus are among such infectious agents creating public health worries by developing resistance to almost all known antimicrobial compounds. They cause infections at different anatomical locations and are sometimes implicated in wound contamination and delayed healing. As the development of bacterial resistance to antibiotics continues, there is need for regular surveillance, identification and development of new antimicrobial agents that are safe and broad spectrum, with low propensity to induce resistance. This study was designed to survey the involvement of Escherichia coli and Staphylococcus aureus in wound infections in patients admitted in some hospitals in Enugu state using basic microbiological methods. Also the work sought to evaluate isolates of these bacterial species for resistance to conventional antimicrobial agents and different extracts of Gongronema latifolium. G. latifolium is a perennial edible shrub of the family Asclepiadaceae. It is widely employed in traditional settings for its nutritional and medicinal effects. There is however paucity of scientific knowledge on its bioactivity and phytochemical composition. G. latifolium was additionally subjected to phytochemical analysis and toxicity tests using Brine shrimp. Phytochemical analysis of the different solvent extracts revealed the presence of different phytochemicals including Glycosides, Tannins, Alkaloids, Saponins, Steroids, Phenols, Hydrogen cyanide, and Reducing sugar in different quantities. From the analysis, Terpenoids, Phenols and Tannin had the highest concentration with Saponin, Steroids and Hydrogen cyanide having the least quantities. Brine shrimp lethality assay had results with lethality against Artemia salina directly proportional to the concentration of the leaf extract. The LC50 of G. latifolium was 0.58 mg/ml which translates to moderate toxicity to the tested Artemia spp. Percentage occurrence of Staphylococcus aureus in the wound samples was 54.22% and that of E. coli was 32.3%. Conclusions can therefore be drawn that these organisms have become major agents of wound infection within the study area and population. Resistance profiling of Staphylococcus aureus against Gram positive antibiotics tested (Ceftadimine, Ceftriaxone, Gentamicin, Erythromycin, Ofloxacin, Augmentin) revealed resistance of 13.95% (Gentamicin), 13.95% (Ofloxacin), and 37.21% (Erythromycin) while that of Escherichia coli against Gram negative antibiotic discs was 33.3%, 50%, and 61.1% for Ofloxacin, Ciprofloxacin and Gentamicin respectively. MIC values for the different antibiotics used on the different isolates were found to be between 500μg/ml and 3.125μg/ml for E. coli and 125μg/ml -3.125μg/ml for Staphylococcus aureus. Methanolic extract showed inhibition zone of 14.00mm (500mg/ml) against Staphylococcus aureus and 6.30 mm (500mg/ml) against E. coli. It also showed an MIC of 250 mg/ml against Staph aureus and E. coli. The aqueous extract had no effect. Ethyl acetate extracts had inhibition zone diameter of 15.00mm against Staphylococus aureus and 8.50mm against E. coli. In vitro combinational effect of the leaf extract with some conventional antibiotics had MIC and MBC values less than 3.125 mg/ml against each of the isolates. These values were lower than those obtained for single effects. These results suggest that the use of Gongronema latifolium as an antibacterial agent in wound infection has great potential which can be fully harnessed when combined with some convectional antibiotics. Findings from this study suggest that subject to further studies, extracts of Gongronema latifolium can be used as healing agents when applied topically on wounds.