Effect of a β-lactamase inhibitor, tazobactam, on growth and penicillin-binding proteins of Borrelia burgdorferi

The effects of tazobactam, a relatively new β-lactamase inhibitor, were investigated on growth and penicillin-binding proteins (PBPs) of Borrellia burgdorferi. A previous communication from our group demonstrated several proteins capable of binding labelled penicillin in this organism. Of these proteins, 94-kDa and 57-kDa PBPs possessed the highest affinity for penicillin and were assumed to be essential proteins involved in cell-wall synthesis. In these experiments, tazobactam was used in competition binding experiments as well as on whole spirochetes. Only the 94-kDa and 57-kDa PBPs were affected by increasing amounts of tazobactam during competition-binding experiments and growth of B. burgdorferi was also inhibited. These results may explain the in vitro activity of β-lactamase inhibitors in general and suggest a utility for these compounds when examining PBPs with hydrolysing activity and/or organisms with β-lactamases.