[Microbiological study of 386 strains of Pseudomonas aeruginosa isolated in a 30-month span in the Isernia area with special reference to an antimicrobial assay carried out with the ABAC system on 214 of them].

386 strains of Pseudomonas aeruginosa isolated in the "F. Veneziale" Hospital Laboratory and Public Health Laboratory in Isernia (Italy) from April 1982 to September 1984 were examined by serological typing according to Habs scheme. Susceptibility to 16 antibiotics was evaluated for 214 of them with the ABAC system. Strains from hospitalized patients were also considered for isolation site and hospital service. Among the 14 different serotypes isolated the O12 serotype ranked first accounting for 31.6% of all isolates. Only 25 strains were untypable (6.5%). Tobramycin resulted the most effective antibiotic in inhibiting Ps. aeruginosa in vitro. No clear relationship was found between serotypes and antibiotic susceptibility patterns. Hospital strains showed marked antibiotic resistance compared to community strains from both patients and healthy carriers. Temporal analysis of antibiograms revealed an increasing incidence of resistant Ps. aeruginosa over time. The spread of antibiotic resistance, however, involved mainly hospital strains and was confined to aminoglycosides and anti-Pseudomonas beta-lactam agents.