Comparative study of the antimicrobial properties of three Combretum species against clinical isolates of Eschericia Coli

The Combretum species – C. racemosum, C. paniculatum and C. dolichopetalum are used in folklore medicine in South Eastern Nigeria for the treatment of urinary tract infection (UTI). In this study therefore, the antimicrobial activity of the extracts of these Combretum species were investigated against clinical isolates of Escherichia coli, the most common pathogenic organism implicated in UTI and the result compared with published works from southern Africa. Agar dilution and Agar cup plate methods were employed. Ciprofloxacin was used as positive control. The result revealed that both the hot water and methanol leaf extracts of C. paniculatum and C. dolichopetalum had no antimicrobial activity unlike their root extracts. Comparison of the inhibition zone diameter (IZD) of both hot water and methanol root extracts showed similar results except for methanol root extract of C. racemosum which showed more activity than the hot water root extract counterpart. All the root extracts maintained an IZD of 1 mm except for methanol root extract of C. racemosum with an IZD of 4 mm. All the leaf extracts showed no activity but for C. racemosum which maintained an IZD of 4 mm for each of both methanol and hot water extract. Of the 3 species, only C. racemosum maintained an activity both in root and leaf for both hot water and methanol extracts. The minimum inhibitory concentration was between 75-300 mg/ml with C.dolichopetalum and C. racemosum having the least and highest values respectively. Compared with published works from southern Africa, it is observed that the very poor activity observed against E. coli from this work is consistent with reports from southern Africa. In this respect, the southern African Combretum species is comparable to the Nigerian species.Keywords: Combretum species, Escherichia coli, urinary tract infection, comparative study, antimicrobial propertiesJournal of Pharmaceutical and Allied Sciences, Vol. 7 No. 4 (2010