Effect of cefazolin and vancomycin on osteoblasts in vitro

The effect of cefazolin and vancomycin on osteoblast-like cells was studied. Cells from the MG-63 human osteosarcoma cell line were grown in antibiotic free media and exposed to concentrations of cefazolin and vancomycin at order of magnitude intervals between 0 and 10,000 microg/ml. For cefazolin, a second interval was performed between 100 and 1000 microg/ml to define toxic levels more accurately. Cell number and 3H-thymidine incorporation at 0, 24, and 72 hours were determined. The results of this study show that local levels of vancomycin of 1000 microg/ml and less have little or no effect on osteoblast replication, and concentrations of 10,000 microg/ml cause cell death. Concentrations of cefazolin of 100 microg/ml and less have little or no effect on osteoblast replication, 200 microg/ml significantly decrease cell replication, and 10,000 microg/ml cause cell death. The authors conclude that vancomycin is less toxic than is cefazolin to osteoblasts at higher concentrations and may be a better antibiotic for local administration in the treatment of similarly sensitive bacterial infections.