Molecular Approach for the Study of Penicillin Resistance In Neisseria meningitidis.

Neisseria meningitidis was previously considered extremely susceptible to penicillin, with most isolates showing minimal inhibitory concentrations (MICs) of ≦ 0.06 μg/mL. However, meningococcal isolates with decreased susceptibility to penicillin have been reported from asymptomatic carriers from as long ago as 1964 (1). Since then, meningococcal clinical isolates with decreased susceptibility to penicillin have been widely described in different countries, with MICs between 0.12 μg/mL to 1 μg/mL (2-9).