African Journal of Biotechnology Vol. 5 (13), pp. 1284-1288, 3 July 2006   

ISSN 1684–5315 © 2006 Academic Journals        

Full Length Research Paper

A study of the in vitro interaction of cotrimoxazole and ampicillin using the checkerboard method

IBEZIM, E. C.¹, ESIMONE, C. O.¹, OKORIE, O.², ONYISHI, I. V.², NNAMANI, P. O.¹, BROWN, S. A.³ and OBODO, C. E.⁴

¹Department of Pharmaceutics, University of Nigeria, Nsukka.

²Department of Pharmaceutical Technology and Industrial Pharmacy, University of Nigeria, Nsukka.

³Department of Pharmaceutics and Pharmaceutical Technology, University of Uyo.

⁴Department of Clinical Pharmacy and Pharmacy Management, University of Nigeria, Nsukka.

*Corresponding Author’s E-mail: ecibezim@yahoo.com.

Accepted 28 April, 2006

In this study, the in vitro interaction of two standard antibiotics – cotrimoxazole and ampicillin trihydrate were studied by the checkerboard technique, using clinical isolates of P. aeruginosa, Staphylococcus aureus and Salmonella typhi. The organisms were exposed to the individual antibiotics as well as different combination ratios of the same, and the zones of inhibition as well as the minimum inhibitory concentrations (MICs) measured. Synergistic interactions were recorded by the antibiotics against Staph. aureus and S. typhi while indifferent interaction occurred with P. aeruginosa. P. aeruginosa however, showed resistance to the two antibiotics when they were used alone. The implication is that cotrimoxazole and ampicillin can be used in combination as a superior treatment of infections caused by Staph. aureus and S. typhi.

Key words: In vitro interaction, cotrimoxazole, ampicillin, Peudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi.