Comparative clinical evaluation of aztreonam versus aminoglycosides in gram-negative septicaemia

We have conducted an open randomized comparison of aztreonam versus an aminoglycoside in 100 adult, non-granulocytopenic patients with suspected or proven aerobic Gram-negative septicaemia. Forty-three patients with negative blood cultures, with blood isolates resistant to the antibiotic used, or who died within the first 24 h were excluded. Of the 57 evaluable patients, 31 received aztreonam and 26 aminoglycoside (13 gentamicin and 13 tobramycin). Patients in both groups were comparable with respect to age, sex, underlying diseases, sites of local infection and risk factors. There were 39 blood isolates in the aztreonam group and 28 in the aminoglycoside group. The overall cure rate was 83.8% in aztreonam-treated patients and 76.9% in aminoglycoside-treated patients. There were five failures (2 aztreonam, 3 aminoglycoside) and in six patients only clinical improvement could be achieved (3 aztreonam, 3 aminoglycoside). Both antibiotics were well tolerated. Nephrotoxicity was found in seven patients of the aminoglycoside group (P = 0.004), whereas enterococcal superinfections occurred in six of the aztreonam group (P = 0.0124). The results of our study suggest that aztreonam is at least as effective as gentamicin or tobramycin in patients with septicaemic infections due to susceptible bacteria. Aztreonam-treated patients are free of nephrotoxicity but are at risk of enterococcal superinfections.