The role of cefamandole in the treatment of Haemophilus influenzae infections in infants and children.

Forty patients with suspected non-CNS Hib infections were treated with cefamandole at a dosage of 100 to 150 mg/kg/day. Hib was isolated from 19 patients; three of the isolates were Blac+. All patients responded well without complications except for two children, both infected with Blac+ organisms, who subsequently developed meningitis, one three weeks following treatment for buccal cellulitis and bacteremia, the other while being treated with cefamandole for empyema. All strains of Hib were uniformly susceptible to cefamandole regardless of beta-lactamase production when tested with an inoculum of 10(4) cfu/ml. With 10(7) cfu/ml an inoculum effect was seen which was more pronounced with Blac+ strains. Moreover, "heavy" inoculum of Blac+ strains inactivated cefamandole in four to eight hours resulting in bacterial overgrowth. Similar results were obtained for ampicillin; chloramphenicol killed all strains regardless of inoculum size or beta-lactamase production. We conclude that cefamandole may be hydrolyzed by Blac+ organisms when present in large numbers, resulting in treatment failure. Extreme care should be taken in the choice of cefamandole for young infants with Hib infections, since this antibiotic neither cures nor prevents meningitis.