title: Decreased affinity of mosaic-structure recombinant penicillin-binding protein 2 for oral cephalosporins in Neisseria gonorrhoeae.
abstract: OBJECTIVE
  In Neisseria gonorrhoeae, the mosaic structure of penicillin-binding protein 2 (PBP 2), composed of fragments of PBP 2 from Neisseria cinerea and Neisseria perflava, was significantly associated with decreased susceptibility to cephalosporins, particularly oral cephalosporins. The aim of this study was to determine the affinity of mosaic PBP 2 for cephalosporins in N. gonorrhoeae.
  
  
  METHODS
  Two types of non-mosaic PBP 2 from the type strain of N. gonorrhoeae (ATCC 19424) and a clinical strain (GU01-29), as well as the mosaic PBP 2 from a clinical strain (GU01-89), were expressed in insect cells, and recombinant PBP 2s were purified. ATCC 19424 and GU01-29 were susceptible to cephalosporins. GU01-89 showed decreased susceptibility to cephalosporins. Bindings of fluorescent penicillin to PBP 2 were characterized by the Scatchard plot analysis. The affinity of the recombinant PBP 2s for cefdinir, cefixime and ceftriaxone was determined by PBP 2 competition assays with fluorescent penicillin.
  
  
  RESULTS
  The K(d) value of mosaic PBP 2 for fluorescent penicillin was higher than that of non-mosaic PBP 2s. The affinity of mosaic PBP 2 for cefdinir or cefixime was lower than that of the non-mosaic PBP 2s. The affinity of the mosaic PBP 2 for ceftriaxone was not changed, compared with that of the non-mosaic PBP 2s.
  
  
  CONCLUSIONS
  Other mechanisms may be involved in clinical isolates with decreased susceptibility to cephalosporins, but this study suggests that the decreased affinity of mosaic-structure recombinant PBP 2 for oral cephalosporins may contribute to decreased susceptibility to these antibiotics in N. gonorrhoeae.
authors.affiliation: Research and Development Department, Mitsubishi Kagaku Bio-Clinical Laboratories, Inc., 3-30-1 Shimura, Itabashi-Ku, Tokyo 174-8555, Japan. ochiai.susumu@mg.medience.co.jp
authors.forename: Susumu
authors.initials: S
authors.lastname: Ochiai
authors.forename: Satomi
authors.initials: S
authors.lastname: Sekiguchi
authors.forename: Akio
authors.initials: A
authors.lastname: Hayashi
authors.forename: Mitsunobu
authors.initials: M
authors.lastname: Shimadzu
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ishiko
authors.forename: Rie
authors.initials: R
authors.lastname: Matsushima-Nishiwaki
authors.forename: Osamu
authors.initials: O
authors.lastname: Kozawa
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Yasuda
authors.forename: Takashi
authors.initials: T
authors.lastname: Deguchi
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism* / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D016367:Baculoviridae / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D002511:Cephalosporins / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D008297:Male; D009030:Mosaicism; D009344:Neisseria gonorrhoeae / Q000187:drug effects* / Q000378:metabolism; D046915:Penicillin-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D018411:Spodoptera
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002511:Cephalosporins; D046915:Penicillin-Binding Proteins; D011994:Recombinant Proteins