Comparative study of aztreonam and cefamandole in the treatment of serious urinary tract infections.

In a single blind study we compared the efficacy of aztreonam (Az), a novel monocyclic beta-lactam antibiotic, to that of cefamandole (Cef) in the treatment of serious urinary tract infections (UTIs). Twenty-one patients were studied (6 men and 15 women, 18-75 years old), 12 suffering from an upper and 9 from a lower UTI; 14 of them received Az and 7 Cef (2:1 ratio), according to a prospective randomization schedule. Az or Cef were administered intramuscularly (1 g every 8 hours) for 5 to 10 days. Patients were followed up for 28 to 42 days after end of treatment. The following bacteria were isolated in the urine cultures: E. coli (in 14 cases), Proteus sp. (4), Klebsiella sp. (2) and Pseudomonas sp. (in 1 case). All 21 bacterial isolates were susceptible to Az while 19 of them were susceptible to Cef (the Pseudomonas strain was sensitive to Az but resistant to Cef). During the entire period of observation, we had 13 cures and 1 relapse in Az-group and 5 cures and 2 relapses in the Cef-group. Aztreonam was as equally well tolerated as cefamandole and no major side effects were observed in either group. In 4 Az- and 3 Cef-patients a rise of SGOT and SGPT (up to 2 1/2 times the upper normal limits) was observed, but it subsided a few days after the end of treatment. Our study shows that aztreonam is at least as effective, safe and well tolerated an antimicrobial agent for the treatment of serious urinary tract infections as cefamandole; In the future aztreonam deserves a large scale, systematic trial in all infections caused by gram-negative bacteria.