Human vitreous levels of cefamandole and moxalactam

We gave 2-g intravenous doses of either cefamandole or moxalactam to 22 patients before vitrectomy. At 1 1/2 to 2 1/2 hours after administration, cefamandole vitreous concentrations varied from 0.36 to 2.05 micrograms/ml (mean, 0.94 micrograms/ml). Individual levels above the minimum inhibitory concentration of cefamandole for 90% (MIC90) of Staphylococcus aureus were found in five of 11 patients. Levels above the MIC90 for S. epidermidis were found in only two of 11 samples. Vitreous concentrations above the MIC90 of cefamandole for common gram-negative pathogens were found in only two patients. Moxalactam concentrations in the vitreous varied from 1.1 to 4 micrograms/ml 30 minutes to six hours after administration. These levels were not above moxalactam's MIC90 for S. aureus or S. epidermidis but were many times higher than the MIC90 of moxalactam for Enterobacteriaceae excluding Pseudomonas.