[Aztreonam treatment of severe infections caused by gram-negative aerobic bacilli]

Twenty nine patients of an intensive care unit (9 women and 20 men), aged 63.9 +/- 15.8 years, with a mean body weight of 62.5 +/- 11.8 kg were treated during 9.4 +/- 2.1 days by aztreonam (2 x 1 g/24 h) administered by short infusion (30 min) for a severe infection due to a Gram-negative bacilli. The primary (n = 25) or nosocomial (n = 4) infection sites were a peritonitis (14), a septicaemia (6), a cholecystitis (6), a pyelonephritis (5), a cholangitis (2), a subphrenic abscess (1) or a pneumonia (2). The isolated Gram-negative bacilli were all susceptible to aztreonam, their MIC being less than or equal to 0.5 micrograms/ml, except for a Pseudomonas aeruginosa (MIC = 4 micrograms/ml). Aztreonam was administered as a single therapy to 7 patients and in association with metronidazole (18) and/or penicillin G (14) to 22 patients; in fact, anaerobes were isolated in ten patients. The mean serum concentrations of aztreonam, as measured by HPLC, before and after the 7th administration respectively were 83.2 +/- 17.5 and 6.1 +/- 5.5 micrograms/ml for peak and through levels. The treatment of the 29 infections was a success in all the cases. No complication occurred due to the presence of Gram positive cocci (n = 4) in the first bacteriological sample, or due to the emergence (n = 12) of Gram positive cocci, except for one case of sepsis of the abdominal wall by Staphylococcus aureus. Aztreonam (2 x 1 g/24 h) may be a suitable alternative for the treatment of severe infections of intensive care units, mostly due to Gram-negative bacilli.