Emergence of a Neisseria gonorrhoeae clone showing decreased susceptibility to cefixime in England and Wales

Abstract

The third-generation cephalosporins recommended in national guidelines are amongst the last remaining effective agents for treatment of gonorrhoea. This study characterizes gonococcal isolates with decreased cefixime susceptibility from England and Wales. A total of 96 isolates of Neisseria gonorrhoeae exhibiting cefixime MICs of ≥0.125 mg/L, either collected as part of the Gonococcal Resistance to Antimicrobials Surveillance Programme (GRASP) between 2005 and 2008 (54 from a total of 4649 isolates) or referred to the national reference laboratory in 2008 and 2009 (42 isolates), were tested for susceptibility to a range of antimicrobial agents and were typed using N. gonorrhoeae multiantigen sequence typing (NG-MAST). All 96 isolates were also resistant to tetracycline (MIC ≥2 mg/L) and ciprofloxacin (MIC ≥16 mg/L) and 56% showed low-level chromosomal resistance to penicillin. Where data were available, the mean patient age was 31 years, and 88% (83/94) of patients were men. Isolates referred through GRASP were predominantly from men who have sex with men (MSM; 29/44, 66%) and from patients of white British ethnicity (25/43, 58%). The majority of isolates belonged either to sequence type (ST) 1407 (71/96, 74%) or to a highly related ST that shares the tpbB allele (allele 110), but with a different por allele (20/96, 21%). ST1407 was found in both MSM (22/29, 76%) and heterosexual patients (12/15, 80%) and among all eight isolates from patients reporting sex abroad. The emergence of a clonal group of gonococci showing decreased susceptibility to cefixime in England and Wales highlights the need for continued surveillance.