title: Cefpodoxime 10 μg disc screening test for detection of Neisseria gonorrhoeae with mosaic PBP2 and decreased susceptibility to extended-spectrum cephalosporins for public health purposes.
abstract: Antimicrobial resistance (AMR) in Neisseria gonorrhoeae remains a global public health problem. Susceptibility to first-line treatment extended-spectrum cephalosporins (ESCs) is decreasing worldwide resulting in therapeutic failures with oral ESCs. This study describes a cefpodoxime 10 μg disc test for screening for gonococci containing a penA mosaic allele encoding a mosaic penicillin-binding protein 2 (PBP2) and decreased ESC susceptibility. Selected clinical gonococcal isolates (n = 315), containing a high proportion of gonococci with decreased ESC susceptibility and high geographical, temporal and genetic diversity, were examined using agar dilution (n = 149; cefpodoxime and ceftriaxone) and Etest (n = 315; cefixime), and disc diffusion using a commercially available cefpodoxime 10 μg disc (n = 315). penA sequencing was performed on all isolates. The 2008 WHO gonococcal reference strains (n = 8) were included as quality controls. Using a ≤11 mm annular radius of growth inhibition as the breakpoint for the cefpodoxime 10 μg disc, all 78, with exception of one isolate (13 mm), mosaic PBP2-containing isolates, which also displayed decreased susceptibility to oral ESCs, were identified. In addition, 85 non-mosaic PBP2-containing isolates (44% of which contained a PBP2 A501 alteration) had annular radii ≤11 mm and raised minimal inhibitory concentrations to the ESCs. Screening for detection of mosaic PBP2-containing gonococci and decreased ESC susceptibility, most pronounced to oral ESCs, using a commercially available cefpodoxime 10 μg disc was rapid, inexpensive and sensitive. This test can be used in AMR surveillance programmes for public health purposes especially in less-resourced settings. Further studies to refine this disc testing-based approach are in progress.
authors.affiliation: WHO Collaborating Centre for STD, Microbiology Department, The Prince of Wales Hospital, Randwick, Sydney, Australia.
authors.forename: Athena
authors.initials: A
authors.lastname: Limnios
authors.forename: John
authors.initials: J
authors.lastname: Tapsall
authors.forename: Jenny
authors.initials: J
authors.lastname: Kahlmeter
authors.forename: Tiffany
authors.initials: T
authors.lastname: Hogan
authors.forename: Sanghamitra
authors.initials: S
authors.lastname: Ray
authors.forename: Anne
authors.initials: A
authors.lastname: Lam
authors.forename: Magnus
authors.initials: M
authors.lastname: Unemo
mesh_terms: D000483:Alleles; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D020682:Cefixime / Q000494:pharmacology; D015296:Ceftizoxime / Q000031:analogs & derivatives* / Q000494:pharmacology; D002443:Ceftriaxone / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D024881:Drug Resistance, Bacterial; D006069:Gonorrhea / Q000382:microbiology; D008826:Microbial Sensitivity Tests / Q000379:methods; D009344:Neisseria gonorrhoeae / Q000187:drug effects* / Q000235:genetics*; D046915:Penicillin-Binding Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D000097623:Cefpodoxime
chemical_list: D000900:Anti-Bacterial Agents; D020682:Cefixime; D015296:Ceftizoxime; D002443:Ceftriaxone; D002511:Cephalosporins; D046915:Penicillin-Binding Proteins; D000097623:Cefpodoxime