In-vitro susceptibility of clinical isolates of Pseudomonas aeruginosa to beta-lactam and aminoglycoside antibiotics.

The in-vitro susceptibilities of 198 isolates of Pseudomonas aeruginosa from clinical human specimens were determined by an agar dilution technique against beta-lactams and aminoglycosides. These isolates were susceptible to imipenem, aztreonam and ceftazidime with the minimum inhibitory concentration (MIC) for 90% of the strains tested being 8, 16 and 8 micrograms/ml, respectively. Aminoglycosides, except amikacin, had low activity (MIC90 greater than 128 micrograms/ml).