COMPARATIVE SUSCEPTIBILITIES OF b - LACTAMASE PRODUCING ISOLATES OF PROTEUS MIRABILIS TO CEFTRIAXONE ALONE AND IN COMBINATION WITH SULBACTAM

Abstract

Objective: To evaluate the increase in Susceptibilities of Ceftriaxone resistant clinical isolates of Proteus

mirabilis by combining sulbactam with ceftriaxone.

Material and Methods: An institution based analytic observational study was carried out at Department

of Microbiology, Khyber Medical College Peshawar. b - lactamase producing Proteus mirabilis were

identified and cultured in Mueller Hinton medium in Petri dishes. The antibiotics disks containing

ceftriaxone alone and in combination with sulbactam were placed in the same Petri dishes about 24 –

30mm apart. The zones of inhibition were measured by following National Committee for Clinical

Laboratory Standards zone diameter criteria in using disk diffusion method.

Results: The disks containing the combination of ceftriaxone and sulbactam showed larger zones of

inhibition. The ceftriaxone alone had some anti bacterial activity against Proteus mirabilis. But by

combining 20, 30 and 40 μg ceftriaxone with sulbactam in 1:1 ratio, the sensitivity was increased by

32.5%, 55% and 62.5% respectively. In 2:1 ratio, the combination produced 47.5%, 60% and 67.5%

increase in sensitivity.

Conclusion: The sensitivities of Proteus mirabilis to Ceftriaxone can be restored by adding sulbactam.