netilmicin and Pneumonia--Pneumococcal

Streptococcus pneumoniae is responsible for 2% of all neonatal sepsis. The results of epidemiological studies suggest that newborns acquire infection by the ascending route or during the passage through the birth canal. It has been hypothesized that colonization of the maternal genital tract with S. pneumoniae might be caused by contamination of obstetric instruments with the microorganism or by sexual practices, particularly oro-genital contact. From our NICU's database, two cases of newborn sepsis due to Streptococcus pneumoniae, occurred between 1988 and 1996 have been found; the first case presented a fatal disseminated intravascular coagulation (DIC), the second a severe respiratory failure. Antibiotic treatment of women carrying S. pneumoniae in the genital tract and their infants should be strongly recommended, on the basis of the potentially serious consequences for the infants.

Topics: Age Factors; Amikacin; Ampicillin; Anti-Bacterial Agents; Bacteremia; Diagnosis, Differential; Drug Therapy, Combination; Female; Follow-Up Studies; Gentamicins; Humans; Infant, Newborn; Male; Netilmicin; Penicillins; Pneumonia, Pneumococcal; Radiography, Thoracic; Time Factors; Vancomycin

An experimental model in mice, incorporating the intraperitoneal inoculation of a Streptococcus pneumoniae type 3, was used to evaluate the effect in vivo after single-dose administration of the three aminoglycosides, gentamicin, tobramycin and netilmicin, and to correlate this effect with their in vitro activity against the pathogen, in particular the bactericidal rate. The minimal inhibitory concentrations (MIC's), which were equal to the minimal bactericidal concentrations (MBC's), were 12.5 micrograms/ml for netilmicin, and 25 micrograms/ml for the two other aminoglycosides, respectively. All three antibiotics showed excellent bactericidal activities even at concentrations 1/4 times the MIC's, but the bactericidal rate was clearly lower for tobramycin than for the two other aminoglycosides. The effect in vivo measured as the 50% effective dose (ED50) closely reflected the relative bactericidal activities of the drugs. Of the pharmacokinetic parameters investigated on dosages equal to the ED50's for the three drugs, the best to correlate with the bactericidal rates in vitro were the peak serum concentrations.

Topics: Animals; Dose-Response Relationship, Drug; Gentamicins; In Vitro Techniques; Metabolic Clearance Rate; Mice; Microbial Sensitivity Tests; Netilmicin; Pneumonia, Pneumococcal; Streptococcus pneumoniae; Tobramycin