Genetic diversity of blaTEM alleles, antimicrobial susceptibility and molecular epidemiological characteristics of penicillinase-producing Neisseria gonorrhoeae from England and Wales

Objectives: The objective of this study was to investigate the genetic diversity of bla(TEM) alleles, antimicrobial susceptibility and molecular epidemiological characteristics of penicillinase-producing Neisseria gonorrhoeae (PPNG) isolates collected in 2012 from England and Wales. Methods: PPNG isolates were from the 2012 Gonococcal Resistance to Antimicrobial Surveillance Programme (GRASP). Their susceptibility to seven antimicrobials was determined using agar dilution methodology. beta-Lactamase production was detected using a nitrocefin test. beta-Lactamase plasmid types were determined and bla(TEM) genes were sequenced. Isolates were also typed by N. gonorrhoeae multi-antigen sequence typing (NG-MAST). Results: Seventy-three PPNG isolates were identified in the 2012 GRASP collection (4.6%, 73/1603). Three different bla(TEM) alleles were identified, encoding three TEM amino acid sequences: TEM-1 (53%), TEM-1 with a P14S substitution (19%) and TEM-135 (27%). The bla(TEM-135) allele was present in nine different NG-MAST types and was found mostly on Asian (60%) and Toronto/Rio (35%) plasmids. By contrast, most TEM-1-encoding plasmids were African (98%). All the TEM-135 isolates displayed high-level ciprofloxacin and tetracycline resistance. Conclusions: The high proportion of bla(TEM-135) alleles (27%) demonstrates that this variant is circulating within several gonococcal lineages. Only a single specific mutation near the beta-lactamase active site could result in TEM-135 evolving into an ESBL. This is concerning particularly because the TEM-135 isolates were associated with high-level ciprofloxacin and tetracycline resistance. It is encouraging that no further TEM alleles were detected in this gonococcal population; however, vigilance is vital as an ESBL in N. gonorrhoeae would render the last remaining option for monotherapy, ceftriaxone, useless.