Evaluation of cefixime-clavulanate combination by comparative disk diffusion method in Klebsiella pneumoniae clinical isolates-an in-vitro study

Background: resistance to cephalosporins due to β-lactamases is a major concern worldwide. however recent trend is to use β-lactamase inhibitor combinations. potential combination is cefiximeclavulanate. objective: present study aims at the comparative evaluation of fixed‑dose combination (fdc) of cefixime‑clavulanate and cefixime-alone in klebsiella pneumoniae clinical isolates. material and methods: study included 200 clinical isolates of k. pneumoniae. the comparative antimicrobial susceptibility test (ast) of cefixime‑clavulanate (5μg/10μg) combination and cefixime-alone(5μg) was done by measurement and comparison of zone of lysis produced by both. all values were expressed in mean ± sd. paired‘t’ test was used to determine statistical difference between different groups under study. p values < 0.05 were considered statistically significant. isolates were tested for extended- spectrum β-lactamase (esbl),ampc β-lactamase (ampc) and metallo β-lactamase (mbl) production by clinical laboratory standards institute - phenotypic disk confirmatory test (clsi-pdct),ampc β-lactamase sterile disk test and imipenem-ethylene di-amine tetracetic acid – double disk synergy test (imipenem-edta ddst) respectively. results: comparative ast resulted in statistically significant (p < 0.001) increased zones in cefixime‑clavulanate combination than cefixime-alone in all isolates studied. when zones were evaluated separately only in three β-lactamase producing isolates; cefiximeclavulanate combination showed much higher zones in esbl-producers (n=30) (p < 0.001),but not in ampc-producers (n=32) (p = 0.5559) and mblproducers (n=06) (p = 0.7815). conclusion: present study demonstrates the best bactericidal killing effect of cefixime-clavulanate compared to cefixime-alone. it is also of therapeutic significance in the treatment of infections caused by k. pneumoniae producing esbls. we recommend comparative ast method when commercially available newer β-lactamase inhibitor combination,for which no clsi interpretive guidelines are available; to be studied systematically,before implementing it in treatment regimen. © journal of krishna institute of medical sciences university.