In-vitro and in-vivo activities of antimicrobial agents against Acinetobacter calcoaceticus.

The virulence of clinical isolates of Acinetobacter calcoaceticus subsp. anitratus was studied in mice, and in-vitro and in-vivo activities of several antimicrobial agents were evaluated. In in-vitro susceptibility testings, tetracyclines, aminoglycosides, and peptide were highly sensitive, and minocycline and doxycycline were the most active of 21 antibiotics tested against 84 clinical isolates of Acin. calcoaceticus. Virulence tests for mice revealed that some strains exhibited high virulence with LD50 values between 10(3) and 10(4) viable cells/mouse. Against lethal and urinary tract infections produced by Acin. calcoaceticus Ac-54 strain in mice, minocycline, doxycycline, gentamicin, and dibekacin, which were highly active in vitro, were effective.