Comparison of susceptibility of gentamicin-resistant and -susceptible "Acinetobacter anitratus" to 15 alternative antibiotics.

Fifty-four clinical isolates of "Acinetobacter anitratus" separated cleanly into gentamicin-susceptible (16 strains) and gentamicin-resistant (38 strains) subpopulations. When tested with a 10(4)-CFU inoculum, gentamicin resistance was associated with a greater than fourfold increase in the MICs of norfloxacin, ciprofloxacin, A-56620, tobramycin, and amikacin for 50% of the strains. Antimicrobial agents with MICs for 90% of gentamicin-resistant strains in the susceptible range were ciprofloxacin, A-56619, A-56620, imipenem, SCH-34343, ceftazidime, aztreonam, carbenicillin, ticarcillin, and piperacillin. These agents may be useful alternative drugs for treating infections caused by aminoglycoside-susceptible and -resistant "A. anitratus."