EFFICACY OF AZTREONAM IN THE TREATMENT OF SEVERE GRAM-NEGATIVE INFECTIONS IN CRITICALLY ILL PATIENTS

The goal of this study was to analyze the value of a combination of aztreonam and amikacin as first intention therapy to treat nosocomial infections due to gram negative bacilli in severely ill patients. During a six months period twenty-five patients were enrolled in the study. Five patients were excluded early for : absence of clinical isolates (2 pts), infections due to staphylococci (2 pts) and resistance to aztreonam of the responsible bacteria (Acinetobacter calcoaceticus). The twenty other patients had nosocomial infections due to gram negative bacteria. They were hospitalized in our medical intensive care unit and most of them were judged immunocompromised ; their mean simplified Apache scoring system index and OSF score were 13.8 and 1.4, respectively. All the responsible bacteria were susceptible to aztreonam and amikacin, and most of them were resistant to penicillins and 2nd generation cephalosporins. The complete course of therapy combining 6 g/d of aztreonam and 15 mg/kg/d of amikacin, both given intravenously, was achieved in all patients; three had also vancomycin to treat combined staphylococcal infection. Complete recovery was obtained in 18 patients and 16 were finally discharged from the hospital. Bacterial eradication was observed in all patients and no resistant strains emerged during the study. Superinfection was seen in five patients due to S. aureus (2 patients), C. albicans (1 patient) and aztreonam-resistant Gram negative bacilli (P. aeruginosa and S. marcescens) in two patients. The tolerance was quite satisfactory, with only slight abnormalities of liver function. The combination of aztreonam and amikacin is a good alternative to ceftazidime and imipenem in the treatment of severe infections in critically ill patients and can be used as first step therapy to preserve the ecology of the patients.