Concentrations of ceftazidime, tobramycin and ampicillin in the cerebrospinal fluid of newborn infants.

Thirty-five neonates with suspected septicaemia were randomized to treatment with tobramycin or ceftazidime, both in combination with ampicillin. Concentrations of antibiotics in the CSF were measured 1 h after the third, fourth or fifth injection. In 13 of 17 neonates tobramycin CSF concentrations were below 0.5 mg/l. Ceftazidime CSF concentrations ranged from 2.5 to 17 mg/l, which should be sufficient for treatment of infections with group B streptococci and most aerobic gram-negative bacilli but not all strains of Staphylococcus aureus. Ampicillin CSF concentrations ranged from 1 to 80 mg/l, which should be sufficient for treatment of meningitis caused by enterococci and Listeria monocytogenes, the most important neonatal pathogens not covered by ceftazidime.