Penetration of antibiotics through cell culture monolayers

Commercial tissue culture chambers were modified in such a way that they contained two portions of medium separated by a horizontal membrane. When grown on this membrane, Vero (monkey kidney) cells formed continuous cell monolayers. By comparing the penetration of antibiotics through monolayer-covered and cell-free membranes, the retention brought about by the cell layer could be measured. Only minor differences were seen between oxacillin, mezlocillin and ciprofloxacin. Penetration of polymyxin B through the cell layer proved to be reduced by about 40% in comparison to oxacillin.