[Resistance of enterobacteria and Pseudomonas to old and new antimicrobial agents].

Antibiotic sensitivity to eight common use antibiotics for 9,538 enterobacteria and Pseudomonas strains isolated from hospitalized children was studied using the serial dilution plate technique. Minimum inhibitory concentration to seven new antibiotics for 310 strains was also determined. Enterobacteria showed high resistance (50-80%) to ampicillin, carbenicillin, sulbenicillin, chloramphenicol and trimethoprim/sulfamethoxazole; resistance to piperacillin, gentamicin, tobramycin, and netilmicin was moderate (15-45%), and resistance to amikacin, cefotaxime, moxalactam and aztreonam was low (2-10%). Pseudomonas strains showed less than 20% resistance to carbenicillin, piperacillin, amikacin and aztreonam. Enterobacteria isolated from urine samples showed low resistance to nitrofurantoin and nalidixic acid (15%). Therapeutic recommendation for most frequent infections caused by these etiologic agents based on the resistance values found were elaborated.