Antibacterial Effect of the Leaves of Chromolaena Odorata on Pseudomonas Aeruginosa from Wound Infections

Abstract

A wound is a disruption of normal anatomic structure and function of the skin causing breakdown of the protective function of the skin. Wound healing is delayed by infection caused by microorganisms including Pseudomonas aeruginosa which is one of the most common wound pathogens. Due to the emergence of antibiotic resistance, treatment of wound infections has become less effective with conventional antibiotics. This has led to the search for alternative wound healing agents from plants like Chromolaena odorata commonly known as Siam weed, Independence weed, among other names. Pseudomonas. aeruginosa was isolated from wound samples from hospital patients in Enugu State. Methanolic extraction of C. odorata was carried out. The crude extract was fractionated using n hexane, ethyl acetate and methanol. Antibiotic sensitivity testing was carried out by disc diffusion while plant extract antimicrobial testing was carried out by agar well diffusion method on the isolates and the zones of inhibition measured and recorded. The Multiple Antibiotic Resistant Index (MARI) was calculated for the isolates after which the minimum inhibitory concentration (MIC) and minimum bacteriocidal concentration (MBC) of the individual and combined antimicrobial agents were determined. The results of this study showed that the P. aeruginosa isolates were susceptible to the C. odorata extract as the mean values of zones of inhibition which increased with concentration ranged from 7.5mm to 15.5mm. All the isolates were 100% resistant to Ceftazidime (CAZ 30μg), Cefuroxime (CRX 30μg), Ampicilin (AMP 10μg) and Clavulanate Amoxycillin (AUG 30μg); 76.67% resistant to Nitrofurantoin (NIT 300μg), 40% resistant to Ciprofloxacin (CPR 5μg) and 43.33% resistant to Gentamicin (GEN 10μg) and Ofloxacin (OFL 5μg). The MARI of the isolates ranged from 0.5 to 1.0. Ofloxacin presented lower values for MIC (0.125μg to 16μg) and MBC (0.5μg to >128μg). Some of the isolates which were resistant to antibiotics used became susceptible to the plant extract though the MIC and MBC were observed at high concentrations (200mg/ml and 400mg/ml). Though few indifference interactions were observed, the result of the combination therapy presented remarkable increase in bioactivity against the P. aeruginosa isolates compared to the potency recorded when the plant extract was tested separately. The potency of the combinations did not diminish with incubation. Methanolic crude extract of C. odorata contains all the phytochemicals analyzed with tannin, phenol, terpenoid and reducing sugar in abundance (+++). Saponin, steroid, alkaloid and flavonoid were moderately present (++). Methanol and ethyl acetate fractions which exhibited inhibitory effect on the isolates contain tannin, alkaloids, saponin and flavonoids which have been shown to possess antibacterial effects. The n-hexane fraction lack saponin and alkaloid but contains moderate amount of tannin (++) yet did not produce any inhibition at all. The results of this study, therefore, support the folkloric use of C. odorata for the treatment of wounds, especially P. aeruginosa infected wounds.