Microbial growth inhibiting solutions and methods of employing the microbial growth inhibiting solutions in flushing and coating medical devices are disclosed. In alternative embodiments, the microbial growth inhibiting solutions include combinations of a chelating agent with a C4-C9, C10 or C12 carboxylate antimicrobial agent, for example, such as n-capric, n-lauric, or n-octanoic acid. Methods of using these microbial growth inhibiting solutions for coating a medical device and for inhibiting catheter infection are also disclosed.