SCREENING AND ISOLATION OF STAPHYLOCOCCUS AUREUS FROM WOUND SWABS AND THEIR SUSCEPTIBILITY PATTERNS TO EXTRACTS OF VERNONIA AMYGDALINA (Del.).

Abstract

This study was designed to isolate Staphylococcus aureus from wound infections and to compare their susceptibility patterns to extracts of Vernonia amygdalina and commercial antibiotics. Wound swab samples were collected from patients attending four hospitals: State Specialist Hospital Akure, Mother and Child Hospital Akure, Police Clinic and Miracle Hospital Akure. Isolation of S. aureus from the samples was done using standard bacteriological procedures. The leaf extraction of V. amygdalina was done using four solvents (ethanol, cold water, hot water and chloroform). The isolates were subjected to antibiotics susceptibility testing using disc diffusion method and selected multidrug resistant isolates were subjected to plasmid profiling and curing. Agar well diffusion technique was used to determine the susceptibility patterns of the isolates to the extracts. The in-vivo effect of the ethanolic leaf extract of the plantin Swiss Albino rats infected with S. aureuswas determined using haematological parameters and histopathological studies. This study revealed that males had a lower percentage occurrence (41.38%) of S. aureus in wounds, while females had a higher percentage occurrence (46.21%). Compared to other antibiotics used in this study, the isolates showed the lowest percentage resistance to Ofloxacin (8.26%) and Vancomycin (2.75%). Multiple plasmids ranging in sizes from 95 to 12.5 Kb were discovered in the selected multidrug resistant isolates. The qualitative phytochemical screening of the extracts revealed various constituents which include: flavonoids, alkaloids, phenols, saponins and tannins. Comparatively, the quantitative phytochemical analysis of the extracts showed that ethanol extract of the plant had the highest values for flavonoids (12.30 ± 0.10 mg/g) and tannins (5.23 ± 0.84mg/g); cold water extract had the highest value for phenols (9.77 ± 0.13mg/g) and saponin (5.09 ± 0.07mg/g); hot water extract had the highest value for alkaloids; while chloroform extract had the lowest values for alkaloids (8.23 ± 1.79mg/g), flavonoids (5.10 ± 0.12 mg/g) and saponin. The ethanolic extract of the plant showed the lowest minimum inhibitory concentration (MIC) value (12.5mg/ml), and also showed the highest zone of inhibition (15.33mm) against the typed S. aureus (ATCC 25923) isolate at 100mg/ml, while the chloroform extract exhibited the lowest zone of inhibition (10.33mm) at same concentration. The rats infected with S. aureus and treated with the ethanolic extract of the plant showed increase in haematological values of: red blood cell (7.73± 0.08b) x106mm-3, packed cell volume (39.67± 0.33b) % and white blood cell (9.64 ± 0.11c) x103mm-3. The histopathological results of the organs examined in this study strongly suggest that the extract at 200mg/kg has the ability to revert histological damages caused to these organs by S. aureus. Findings from this study suggest that Vernonia amygdalina leaf extracts could serve as a potential herb for drug development for the treatment of infections caused by Staphylococcus aureus.