Emergence in Italy of a Neisseria meningitidis clone with decreased susceptibility to penicillin

Abstract

A rise in invasive diseases due to Neisseria meningitidis C:2b:P1.5 with decreased penicillin susceptibility occurred in Italy during the last 2 years. Real-time PCR identified the Peni phenotype, and the penA sequence revealed the mosaicism of the gene. Molecular analyses assigned the isolates to a single emergent clone of the hypervirulent A4 cluster.

FIG. 1.

(A) Examples of T_m curves for Pen^s and Penⁱ N. meningitidis phenotypes obtained by real-time PCR assay with the mutated 566 codon in the penA gene. (B) Mosaic penA genes of Penⁱ N. meningitidis strains. Each line indicates the proposed origin of the exogenous DNA blocks in the transpeptidase domain of the gene. The arrowheads show the position of the mutated 566 codon used as a marker of penA translocation in the real-time PCR assay. nt, nucleotides; AC#, accession number.

FIG. 2.

PFGE profiles of genomic DNAs from N. meningitidis C:2b:P1.5 strains after digestion with endonuclease NheI. The lambda ladder DNA marker (New England Biolabs) (lane MW) was used as a molecular size standard (48.5 kb). Lane 1, pulse type PTA; lane 2, PTA1; lane 3, PTA2. The arrows identify the band differences.