Treatment of serious gram-negative infections with aztreonam

Aztreonam (SQ 26,776) is the first parenteral monobactam agent to be used in patient trials. The agent has significant activity in vitro against facultative aerobic gram-negative bacteria but not against gram-positive or anaerobic bacteria. Aztreonam was used for a year to treat 106 hospitalized patients with a total of 131 documented gram-negative infections. Important exclusion criteria included granulocytopenia, hyperbilirubinemia, meningitis, patients less than 13 years of age, pregnancy, and history of anaphylaxis to penicillin. In this study of 35 men and 71 women, there were 67 cases of pyelonephritis (25% bacteremic), 19 of pneumonia (16% bacteremic), 10 of skin or soft-tissue infections, 9 cases of osteomyelitis, and 6 cases of postpartum endometritis. During the study period, 159 facultative aerobic gram-negative bacteria were tested for aztreonam susceptibility, and 144 (91%) were found to be susceptible. Eighty percent of infections were cured by both clinical and microbiological criteria and each of the other 26 infections showed clinical improvement. Eradication of the infecting organisms was achieved in 89% of infections without adverse reaction or drug toxicity.