title: Examination of Chlamydia trachomatis infection in environments mimicking normal and abnormal vaginal pH.
abstract: BACKGROUND
  It has long been assumed that a healthy acidic vaginal environment inhibits infection by Chlamydia trachomatis. The research objectives were to evaluate the effect of pH on C trachomatis infection by two in vitro methods, to assess pH effect at different serial dilutions of C trachomatis elementary bodies (EBs), and to examine protection by an antibiotic peptide, protegrin (PG-1), over a pH range.
  
  
  OBJECTIVE
  The goals of this study were to test the hypothesis that acidic pH inhibits C trachomatis infection and to determine the ability of PG-1 to provide protection at acidic and neutral pH.
  
  
  METHODS
  The effect of pH on C trachomatis was examined using two pH-adjusted preincubation shell vial assays. C trachomatis EBs (serovars L2, D, and E) were exposed to pH-adjusted media, with and without PG-1, and infection was assessed by inclusion forming unit (IFU) formation in McCoy cell monolayers.
  
  
  RESULTS
  Acidic pH in preincubation media markedly decreased IFUs by both in vitro methods. Serial dilution experiments showed a 3- to 10-fold reduction in IFUs for C trachomatis (L2 and E) at pH 5.0, compared with those at pH 7.5. C trachomatis (D) showed a 17- to 23-fold reduction in IFUs (serial dilutions 1:1-1:4). PG-1 protected McCoy cell monolayers from infection by C trachomatis after exposure to varied pH environments.
  
  
  CONCLUSIONS
  Acidic pH exposure significantly reduced C trachomatis infection in vitro. Our results support the hypothesis that a healthy acidic vaginal environment protects women from C trachomatis infection. In addition, antibiotic peptides may provide protection as topical microbicides, regardless of vaginal pH.
authors.affiliation: Department of Pathology and Laboratory Medicine, UCLA School of Medicine, Los Angeles, California 90095-1731, USA.
authors.forename: Bushra
authors.initials: B
authors.lastname: Yasin
authors.forename: Mabel
authors.initials: M
authors.lastname: Pang
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Wagar
authors.forename: Robert I
authors.initials: RI
authors.lastname: Lehrer
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides; D002460:Cell Line; D002690:Chlamydia Infections / Q000382:microbiology*; D002692:Chlamydia trachomatis / Q000187:drug effects / Q000472:pathogenicity* / Q000502:physiology*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008826:Microbial Sensitivity Tests; D011506:Proteins / Q000494:pharmacology; D012661:Semen / Q000502:physiology; D014621:Vagina / Q000737:chemistry* / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D011506:Proteins; C094880:protegrin-1