title: Characterisation of blaTEM genes and types of β-lactamase plasmids in Neisseria gonorrhoeae - the prevalent and conserved blaTEM-135 has not recently evolved and existed in the Toronto plasmid from the origin.
abstract: BACKGROUND
  Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a major concern worldwide. It has been recently feared that the blaTEM-1 gene is, via blaTEM-135, evolving into an extended-spectrum β-lactamase (ESBL), which could degrade all cephalosporins including ceftriaxone. The aims of the present study were to characterize the blaTEM genes, types of β-lactamase plasmids, the degradation of ampicillin by TEM-135 compared to TEM-1, and to perform molecular epidemiological typing of β-lactamase-producing N. gonorrhoeae strains internationally.
  
  
  METHODS
  β-lactamase producing N. gonorrhoeae isolates (n = 139) cultured from 2000 to 2011 in 15 countries were examined using antibiograms, blaTEM gene sequencing, β-lactamase plasmid typing, and N. gonorrhoeae multiantigen sequence typing (NG-MAST). Furthermore, the blaTEM gene was sequenced in the first described Toronto plasmid (pJD7), one of the first Asian plasmids (pJD4) and African plasmids (pJD5) isolated in Canada. The degradation of ampicillin by TEM-135 compared to TEM-1 was examined using a MALDI-TOF MS hydrolysis assay.
  
  
  RESULTS
  Six different blaTEM sequences were identified (among isolates with 125 different NG-MAST STs), i.e. blaTEM-1 (in 104 isolates), blaTEM-135 (in 30 isolates), and four novel blaTEM sequences (in 5 isolates). The blaTEM-1 allele was only found in the African and Asian plasmids, while all Rio/Toronto plasmids possessed the blaTEM-135 allele. Most interesting, the first described gonococcal Toronto plasmid (pJD7), identified in 1984, also possessed the highly conserved blaTEM-135 allele. The degradation of ampicillin by TEM-135 compared to TEM-1 was indistinguishable in the MALDI-TOF MS hydrolysis assay.
  
  
  CONCLUSIONS
  blaTEM-135, encoding TEM-135, is predominantly and originally associated with the Rio/Toronto plasmid and prevalent among the β-lactamase producing gonococcal strains circulating globally. blaTEM-135 does not appear, as previously hypothesized, to have recently evolved due to some evolutionary selective pressure, for example, by the extensive use of extended-spectrum cephalosporins worldwide. On the contrary, the present study shows that blaTEM-135 existed in the Toronto plasmid from its discovery and that blaTEM-135 is highly conserved (not further evolved in the past >30 years). Nevertheless, international studies for monitoring the presence of different blaTEM alleles, the possible evolution of the blaTEM-135 allele, and the types of β-lactamase producing plasmids, remain imperative.
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Muhammad
authors.forename: Daniel
authors.initials: D
authors.lastname: Golparian
authors.forename: Jo-Anne R
authors.initials: JA
authors.lastname: Dillon
authors.forename: Asa
authors.initials: A
authors.lastname: Johansson
authors.forename: Makoto
authors.initials: M
authors.lastname: Ohnishi
authors.forename: Sunil
authors.initials: S
authors.lastname: Sethi
authors.forename: Shao-chun
authors.initials: SC
authors.lastname: Chen
authors.forename: Shu-ichi
authors.initials: S
authors.lastname: Nakayama
authors.forename: Martin
authors.initials: M
authors.lastname: Sundqvist
authors.forename: Manju
authors.initials: M
authors.lastname: Bala
authors.affiliation: Department of Laboratory Medicine, WHO Collaborating Centre for Gonorrhoea and other Sexually Transmitted Infections, National Reference Laboratory for Pathogenic Neisseria, Microbiology, Örebro University Hospital, SE-701 85, Örebro, Sweden. magnus.unemo@orebroll.se.
authors.forename: Magnus
authors.initials: M
authors.lastname: Unemo
mesh_terms: D002443:Ceftriaxone / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D009344:Neisseria gonorrhoeae / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification*; D010957:Plasmids / Q000235:genetics*; D015995:Prevalence; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D002511:Cephalosporins; D002443:Ceftriaxone; D001618:beta-Lactamases