ABSTRACT
Aim: To evaluate the antibacterial activity of selected medicinal plants from South- Eastern Nigeria against ESBL producing Pseudomonas species. Study Design: Agar well diffusion assay for determination of sensitivity and Agar dilution method for determination of MIC were used. Place and Duration of Study: Department of Pharmaceutical Microbiology and Biotechnology, Faculty of Pharmaceutical Sciences, Nnamdi Azikiwe University, Awka, Anambra State, an Igbo speaking South-Eastern State in Nigeria, between February 2010 and october 2010. Methods: The antibiograms of ten (10) ESBL producing Pseudomonas species to selected antibiotics as well as the antibiograms of these isolates against methanol leaf extracts of Anthocleista djalonensis A Chev. (Loganiaceae) (MLEA) (Igbo name- Uvuru or Ayuu), Zapoteca portoricensis H. M. Hem. (Fabeceae/mimosidea) (MLEZ) (Igbo name- Ayuu), Gongrenema latifolium Benth. (Asclepiadaceae) (MLEG) (Igbo name- Utazi) and Psidium guajava Linn. (Myrtaceae) (MLEP) (Igbo name- Gova), using doses of 3000.00 to 21.87 mg/ml using agar disk diffusion and agar well diffusion assays respectively were determined. The MIC of the plant extracts in comparison with that of gentamicin were also evaluated using the agar dilution method. Results: All the ESBL producing Pseudomonas spp. were multi-drug resistant (IZD = 0) but, were all sensitive to imipenem. Only two strains of Pseudomonas monteilli were sensitive to MLEG with sensitivity decreasing with increasing concentrations of the MLEG. All the ESBL producing Pseudomonas spp were sensitive to MLEZ and MLEP. Also, sensitivity decreased with increasing concentration of the MLEZ and MLEP. MLEA showed no antimicrobial activity against the tested ESBL producing Pseudomonas spp. Gentamicin, with an MIC of 0.00015 μg/ml, was more active than the plant extracts. The MLEP was the more active with an MIC of 1 - 4.37 mg/ml, than MLEZ and MLEG which had MICs of 150 and 75 mg/ml respectively. Active constituents of these plant extracts especially that of Psidium guajava, may thwart the emerging resistance to carbapenems. Conclusion: Development of a complex mixture of the active constituents or single active constituent(s) of Psidium guajava as antimicrobial agent(s) that will be effective against ESBL producing Pseudomonas species.