Abstract: Disclosed are pharmaceutical compositions of a mixture of minocycline and EDTA (M-EDTA) and methods of using the compositions in maintaining the patency of a catheter port. Methods for inhibiting the formation of polysaccharide-rich glycocalyx (such as the glycocalyx of staphylococcal organisms) are also provided using an M-EDTA solution. The M-EDTA solution may also be used to pretreat a medical device to prevent adherence of infectious organisms, such as S. epidermidis and S. aureus. The compositions destroy and prevent the formation of polysaccharide-rich glycocalyx. Methods for treating infections of S. epidermidis and S. aureus where glycocalyx formation are provided with an M-EDTA solution. The minocycline and EDTA solutions are included together within a pharmacologically acceptable carrier solution, such as saline.