Faropenem

Antibiotic susceptibility of bla_NDM-1 harboring parent strains, transformants and transconjugants were determined by Kirby Bauer disc-diffusion method including piperacillin-tazobactam (100/10 μg), co-trimoxazole (25 μg), amikacin (30 μg), gentamicin (10 μg), ciprofloxacin (5 μg), polymyxin B (300units), netilmicin (30 μg), carbenicillin (100 μg), tigecycline(30 μg) and faropenem (5 μg) (Hi-Media, Mumbai, India). MICs of imipenem, meropenem, ertapenem, cefepime, aztreonam, gentamicin, amikacin, ciprofloxacin, piperacillin-tazobactam & polymixin-B were determined for parent strains harboring bla_NDM-1, as well as transformants and transconjugants by agar dilution method. Each stock solution for the corresponding antibiotic was made at 1 mg/ml concentration in nuclease free water and was stored at −80 °C. The quality control for stock solution was checked each time against E. coli ATCC 25922. The result of the susceptibility testing was interpreted as per CLSI guidelines [24 ]. However, for polymyxin B, faropenem and carbenicillin, the organisms were considered as non susceptible if the MIC value was higher and diameter of the zone of inhibition was lower than the values given in CLSI guidelines for respective antibiotics against E. coli ATCC 25922.

Antibiotic susceptibility testing was performed on Mueller Hinton agar (Himedia, Mumbai, India) plates by Kirby-Bauer disc diffusion method and interpreted as per CLSI recommendations [10 ]. The antibiotics tested viz., meropenem (10μg) ciprofloxacin (5μg), amikacin (30μg), gentamicin (10μg), carbenicillin (10μg), polymixin B (300 μg), ceftazidime (30 μg), Piperacillin-Tazobactam (100/10 μg), faropenem (5μg) (Himedia, Mumbai, India).
Minimum inhibitory concentration (MIC) was determined on Muller Hinton Agar plates by agar dilution method against meropenem and ciprofloxacin (Himedia, Mumbai, India) according to CLSI guidelines and interpreted according to CLSI breakpoint [10 ].