Penicillin‐binding protein 2 genes of non‐β‐lactamase‐producing, penicillin‐resistant strains of Neisseria gonorrhoeae

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Abstract
Oligonucleotides that correspond to regions of the penicillin-binding protein 2 gene (penA) that differ between penicillin-sensitive and penicillin-resistant strains have been used as probes to classify the penA genes in a collection of penicillin-resistance gonococci isolated in Britain. 44/47 of those gonococcal strains that had minimal inhibitory concentrations of .gtoreq.0.25 .mu.g benzylpenicillin per ml contained extensively altered penA genes which appeared to be very similar (or identical) to one or other of the two classes of altered penA genes that have been described previously. Since these two classes of altered penA genes are related, it appears that the great majority of the altered penA genes of non-.beta.-lactamase-producing pencillin-resistant gonococci have a clonal origin. The other three penicillin-resistant strains had altered penA genes that were different to those described previously. A crucial step in the development of the altered forms of PBP2 with decreased affinity for penicillin appears to have been the insertion of an extra codon within the transpeptidase domain of the penA gene. This insertion was found in the penA gene of all gonococci with minimal inhibitory concentrations of >0.016 .mu.g benzylpenicillin per ml but was not found in any strains with minimal inhibitory concentrations of .ltoreq.0.016 .mu.g per ml.