Increasing Prevalence of Penicillin Nonsusceptibility

This study was conducted to evaluate the evolution of the antimicrobial susceptibility ofNeisseria meningitidis causing invasive diseases in Belgium in the period of January 2000 to December 2010. A total of 1,933 cases ofN. meningitidis from invasive infec-tions were analyzed by antimicrobial susceptibility testing at the BelgianMeningococcal Reference Centre. The majority of strains were susceptible to antibiotics that are currently used for the treatment and prophylaxis of meningococcal disease, but the prevalence of clinical isolates with reduced susceptibility to penicillin increased over the years. The phenotyping, genotyping, and determination of MICs of penicillin G were performed. The systematic shift of the curves toward higher penicillin MICs in the susceptible population indicated that this population became less sensitive to penicillin in this period. A 402-bp DNA frag-ment in the 3 = end of penAwas sequenced for the 296 nonsusceptible meningococcal strains isolated between 2000 and 2010 to examine the genetic diversity and evolution of their penA gene. In conclusion, the data obtained in our study support the state-ment that the position of penicillin G as a first choice in the treatment of invasive meningococcal diseases in Belgium should be reexamined. Despite an important number of isolates displaying a reduced susceptibility to penicillin, at present the expanded-spectrum cephalosporins, such as ceftriaxone, are not affected. The follow-up of the evolutionary changes in antimicrobial resis-tance has also proved to be essential for the recommendation of an appropriate antimicrobial treatment for invasive meningo-coccal diseases. Neisseria meningitidis, a human pathogen, colonizes the naso-pharynx of individuals and can cross the epithelial barrier o