Evaluation of synergism between Cefotaxime and Allium sativum against Extended-spectrum beta-lactamase and Ambler class C co-producers

ABSTRACT

The present study evaluates the synergistic association between Cefotaxime and aqueous garlic (Allium sativum)extract (AGE) on extended spectrum beta-lactamase (ESBL) and Ambler Class C (AmpC) co-producing Escherichiacoli strains from skin and soft tissue infections (SSTIs). Ceftazidime-resistant E. coli strains were screened for betalactamase production by phenotypic confirmatory disc diffusion test (PCDDT) and E-test. Antibacterial activity ofAGE was examined by the disc diffusion method and the minimum inhibitory concentration (MIC) of Cefotaximeand AGE was determined. The synergistic association between Cefotaxime and AGE was evaluated by calculatingthe fractional inhibitory concentration (FIC) index, time-kill kinetics assay (TKA), and scanning electron microscopy(SEM). The zone of inhibition by AGE against the 27 E. coli co-producers of ESBL and AmpC ranged from 17 to 30mm. The average MIC of Cefotaxime and AGE was found to be 570 μg/ml and 0.86% (4.28 mg/ml), respectively. TheFIC index obtained by the checkerboard method established a synergistic association between Cefotaxime and AGEin 10 (37%) test strains, which was confirmed by TKA. The SEM analysis revealed complete cell degradation at 8hours on the treatment with Cefotaxime-AGE combination. It can be stated that the AGE may aid Cefotaxime in thetreatment of beta-lactamase producing E. coli strains from SSTIs