title: The sac-4 gene of Neisseria gonorrhoeae and co-existing chlamydial infection.
abstract: OBJECTIVE
  Recently, the sac-4 gene in Neisseria gonorrhoeae was postulated to increase the risk of developing mixed gonococcal and chlamydial infection. The aims of this study were to determine the frequency of the sac-4 gene in a larger sample of isolates of different serovars and to assess the prevalence of sac-4 in gonococcal isolates from patients with and without coexisting chlamydial infection.
  
  
  METHODS
  Isolates from 259 episodes of gonorrhoea were tested by a PCR assay for the sac-4 gene. The presence of co-existing chlamydial infection was determined from both laboratory and GUM clinical records.
  
  
  RESULTS
  The overall prevalence of sac-4 was 57.5% (149/259). The prevalence was not the same in all serovars and ranged from 34.9% in serovar 1B2 to 100% in serovar 1B18. Exact logistic regression analysis indicated significant differences in sac-4 prevalence in isolates of different serovars. The prevalence of sac-4 was 69.5% (41/59) in gonococcal isolates from patients with co-existing chlamydial infection compared with 57.9% (62/107) for those without chlamydial infection. Exact logistic regression analysis showed that the slightly increased sac-4 prevalence among chlamydia positive patients (p = 0.2) virtually disappeared when serovar status was taken into account (p > 0.9).
  
  
  CONCLUSIONS
  The sac-4 gene of the gonococcus does not increase the risk for mixed chlamydial infection.
authors.affiliation: Scottish Neisseria Gonorrhoeae Reference Laboratory, Department of Medical Microbiology, Edinburgh University Medical School, Teviot Place, Edinburgh EH8 9AG, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Phillips
authors.forename: C
authors.initials: C
authors.lastname: Patrizio
authors.forename: A
authors.initials: A
authors.lastname: Moyes
authors.forename: H
authors.initials: H
authors.lastname: Young
mesh_terms: D002690:Chlamydia Infections / Q000150:complications*; D005260:Female; D005798:Genes, Bacterial; D006069:Gonorrhea / Q000150:complications*; D006801:Humans; D008297:Male; D009344:Neisseria gonorrhoeae / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D012044:Regression Analysis; D012306:Risk