In vitro potency of amikacin and comparators against E. coli,K. pneumoniae and P. aeruginosa respiratory and blood isolates

Christina A. Sutherland, Jamie E. Verastegui, David P. Nicolau

The purpose of this study was to define the potency of amikacin and comparator agents against a collection of blood and respiratory nosocomial isolates implicated in ICU based pulmonary infections gathered from US hospitals. Minimum inhibitory concentrations of amikacin, aztreonam, cefepime, ceftazidime, ceftolozane/tazobactam, ceftriaxone, ciprofloxacin, imipenem, meropenem, piperacillin/tazobactam and tobramycin were tested against 2460 Gram-negative isolates. Amikacin had 96 % susceptibility against the combined E. coli and K. pneumoniae isolates and 95 % susceptibility against P. aeruginosa. Ninety-six percent of all of isolates tested were susceptible (i.e., MICs ≤16 mg/L) to amikacin by current laboratory standards which demonstrates a high level of activity to combat infections caused by these organisms including ESBL, MDR, β-lactam and fluoroquinolone resistant strains. Moreover, 99 % of all organisms had amikacin MICs ≤64 mg/L. Overall, these data highlight the continued potency of amikacin and suggest that the achievable lung concentrations of approximately 5000 mg/L with the administration of the amikacin by inhalation (Amikacin Inhale, BAY41-6551) will exceed the MICs typically observed for P. aeruginosa, E. coli and K. pneumoniae in the hospital setting.