Susceptibility Pattern of Extended-Spectrum β-Lactamase (ESBL) Producing Escherichia coli, Klebsiella spp. and Enterobacter spp. to Ciprofloxacin, Amikacin and Imipenem

This study was carried out to determine the susceptibility pattern of Extended-Spectrum β-lactamase (ESBL) producing Escherichia coli, Klebsiella spp. and Enterobacter spp. to ciprofloxacin, amikacin and imipenem. A total of 100 ESBL producing Escherichia coli, Klebsiella spp. and Enterobacter spp. were studied and identified by double disc synergy test (DDST) and were confirmed phenotypically as ESBL producer by phenotypic confirmatory disc diffusion test (PCDDT). Minimum inhibitory concentrations of ciprofloxacin, amikacin and imipenem among ESBL-producing strains were determined using agar dilution method. Out of 75 DDST positive ESBL-producing E. coli, 71 (94.67%) were also positive by PCDDT. All DDST positive Klebsiella spp. and Enterobacter spp. were also positive by PCDDT. All ESBL-producing E. coli, Klebsiella spp. and Enterobacter spp. were 100% susceptible to imipenem by both agar dilution and disc diffusion method. About 7.04% Escherichia coli, 21.05% Klebsiella spp. were resistant but 100% Enterobacter spp. were susceptible to amikacin by both methods. About 85.92% ESBL-producing Escherichia coli, 73.68% Klebsiella spp. and 33.33% Enterobacter spp. were resistant to ciprofloxacin by agar dilution method but 87.32% Escherichia coli, 78.95% Klebsiella spp. and 50% Enterobacter spp. were resistant to ciprofloxacin by disc diffusion method. ESBL-producing Escherichia coli, Klebsiella spp. and Enterobacter spp. showed high resistance to ciprofloxacin. Imipenem and amikacin were most effective against ESBL positive strains.