Resistance to beta-lactam antibacterial agents in hospitals.

In recent years, due to the frequent use of antimicrobial agents, strains resistant to antibiotics have been seen with increasing frequency among hospital isolates. We have compared the susceptibility to different beta-lactam drugs of Pseudomonas spp. and Staphylococcus aureus strains, isolated during a 10-yr period (1974-1984) from pathological specimens of different units of Spedali Civili of Brescia Medical School. We have also analyzed the plasmid DNA profile of representative Staphylococcus aureus strains isolated in 1984.