Effects of aztreonam on fecal flora and on vitamin K metabolism.

The effects of aztreonam on fecal flora and on descarboxy prothrombin (PIVKA-II) in plasma and gamma-carboxyglutamic acid (Gla) in urine as an index of vitamin K metabolism were studied in seven children (age range, 2 months to 2 years) with urinary tract infections. Daily doses of aztreonam were 60 to 80 mg/kg. Stool specimens were obtained before the treatment, on days 3 to 5 of aztreonam use, and from 3 to 5 days after the cessation of treatment. The counts of enterobacteria decreased (P less than 0.01) and those of streptococci increased (P less than 0.05) during aztreonam treatment. The anaerobic organisms, especially bifidobacteria and bacteroides, showed no marked change. PIVKA-II and Gla were investigated before and during the treatment with aztreonam. PIVKA-II was not detected in seven patients before or during aztreonam use. There were no significant differences in the levels of Gla in urine before or during the treatment.