Phage-types and susceptibility to 26 antibiotics of nosocomial strains of Acinetobacter isolated in Portugal.

Sixty-two strains of Acinetobacter calcoaceticus isolated from pathological samples or from the environment in several hospitals in Lisbon, were studied by means of two complementary phage-typing systems. Eighteen phage-types or sub-types, one group of uncommon types (9.6%) and one group of untypable strains (20.9%) were found. A new phage-type (No. 104) and a new sub-type (No. 18) were defined among the Portuguese strains. The in vitro activity of 26 antibiotics against 48 nosocomial strains was studied by the Kirby-Bauer method. The most active antibiotics were, in decreasing order, amikacin, carbenicillin, tobramycin, minocycline, dibekacin, doxycycline, sisomycin, trimethoprim-sulphamethoxacole, ticarcillin and piperacillin. The strains were also tested against 4 new beta-lactam antibiotics, and the MICs were determined by an agar dilution method. N-formimidoyl-thienamycin was found to be the most active against Acinetobacter and ceftazidime was considerably more active than apalcillin and cefotaxime.