Simple assay for clindamycin in the presence of aminoglycosides

Anaerobic plate method for assaying antimicrobial agents in serum

An anaerobic agar plate method was devised for the assay of antimicrobial agents in serum by using a strain of Clostridium bifermentans. The method gave reproducible and accurate in assays of chloramphenicol, clindamycin, and metronidazole alone or in the presence of beta-lactam or aminoglycoside antibiotics.

Pharmacokinetics of nafcillin in infants with low birth weights

The pharmacokinetics of nafcillin were studied in 13 premature neonates with suspected sepsis. The mean weight of the infants studied was 1.19 kg (range, 0.73 to 2.21 kg). Infants less than 7 days of age were given 100 mg of nafcillin per kg per 24 h (every 12 h), and infants more than 7 days of age were given 100 mg of nafcillin per kg per 24 h (every 8 h). Blood samples were obtained before the first dose on day 3 of therapy and at 0.5, 1.5, 3, and 6 h thereafter. Nafcillin concentrations were measured by a microbiological assay. A mean volume of distribution of 326 ml/kg and an elimination rate constant of 0.2040 h-1 were obtained in 10 patients less than 21 days of age. Three patients from 24 to 68 days of age had a mean volume of distribution of 303 ml/min and a mean elimination rate constant of 0.3944 h-1 (P less than 0.05). These data suggest that doses of nafcillin lower than those currently recommended may be adequate to achieve desired peak plasma levels of approximately 75 microgram/ml in infants with low birth weights.

Use of sodium polyanethol sulfonate to selectively inhibit aminoglycoside and polymyxin antibiotics in a rapid blood level antibiotic assay

Sodium polyanethol sulfonate inhibits aminoglycoside and polymyxin classes of antibiotics in direct proportion to its concentration. Aminoglycoside and polymyxin class antibiotics are selectively inactivated; penicillin, including the semisynthetic penicillins, cephalothin, chloramphenicol, clindamycin, tetracycline, erythromycin, and vancomycin are not inhibited. By incorporating sodium polyanethol sulfonate directly into the test medium it is possible, in a 4-h antibiotic blood level assay, to selectively obviate the activity of the aminoglycosides and polymyxins to determine the concentration of other antibiotics present in the same serum sample.