Genetic Resistance Determinants for Cefixime and Molecular Analysis of Gonococci Isolated in Italy

A strictly defined subset of gonococci (n = 65) isolated in Italy from 2011 to 2014 was characterized by antimicrobial susceptibility for cefixime (CFM) and ceftriaxone (CRO) and by sequencing of resistance determinant genes (penA, mtrR, porB1b, ponA) for extended-spectrum cephalosporins and Neisseria gonorrhoeae multiantigen sequence typing (NG-MAST). The penA mosaic alleles XXXIV and XXXV were found in all resistant (R) and decreased susceptibility (DS) gonococci to CFM, except for one. They were associated with an adenine deletion in the mtrR promoter plus amino acid substitutions, H105Y or G45D, in the coding region and ponA L421P. The penA mosaic allele XXXIV, and one variant, was found exclusively among genogroup (G) 1407 and its closely related sequence types (STs), as in CFM-DS as well as in CFM-R isolates. Single or combined mutation patterns in penA, mtrR, porB1b, and ponA genes were associated with different CFM susceptibility patterns and NG-MAST STs. Genotyping and antimicrobial resistance (AMR) determinant analyses can be valuable to enhance the gonococcal AMR surveillance.