title: Effects of antibiotics on Chlamydia trachomatis viability as determined by real-time quantitative PCR.
abstract: The objective of this study was to determine the effect of antibiotics on Chlamydia trachomatis viability by using a quantitative real-time PCR assay that measured DNA replication and mRNA transcription of the structural omp1 and omp2 genes, 16S rRNA and the groEL1 gene with and without antibiotics. Ofloxacin, moxifloxacin, azithromycin and doxycycline were tested against the serovar D and L2 reference strains and a derivative mutant resistant to fluoroquinolones, L2-OFXR, obtained by in vitro selection. Using DNA quantification, the antibiotic MIC was calculated when the number of DNA copies was equal to that of the chlamydial inoculum at time zero. This method allowed the easy determination of MICs by DNA quantification of the four selected genes and gave similar results to those obtained by immunofluorescence staining without biased interpretation. By using cDNA quantification, the lowest antibiotic concentration for which no RNA was transcribed corresponded to the minimum bactericidal concentration. C. trachomatis still transcribed the16S rRNA and groEL1 genes, even at concentrations well above the MIC, showing a bacteriostatic effect for all antibiotics tested. This method allows the study of antibiotic activity on growth and viability of C. trachomatis by DNA and RNA quantification at the same time without additional cell-culture passaging.
authors.affiliation: Laboratoire de Bactériologie EA 3671, Infections Humaines à Mycoplasmes et Chlamydiae, Centre National de Référence des Infections à Chlamydiae, Université Victor Segalen Bordeaux 2, Bordeaux, France.
authors.forename: Olivia
authors.initials: O
authors.lastname: Peuchant
authors.affiliation: Laboratoire de Bactériologie EA 3671, Infections Humaines à Mycoplasmes et Chlamydiae, Centre National de Référence des Infections à Chlamydiae, Université Victor Segalen Bordeaux 2, Bordeaux, France.
authors.forename: Jean Philippe
authors.initials: JP
authors.lastname: Duvert
authors.affiliation: Laboratoire de Bactériologie EA 3671, Infections Humaines à Mycoplasmes et Chlamydiae, Centre National de Référence des Infections à Chlamydiae, Université Victor Segalen Bordeaux 2, Bordeaux, France.
authors.forename: Maïthé
authors.initials: M
authors.lastname: Clerc
authors.affiliation: Laboratoire de Bactériologie EA 3671, Infections Humaines à Mycoplasmes et Chlamydiae, Centre National de Référence des Infections à Chlamydiae, Université Victor Segalen Bordeaux 2, Bordeaux, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Raherison
authors.affiliation: Laboratoire de Bactériologie EA 3671, Infections Humaines à Mycoplasmes et Chlamydiae, Centre National de Référence des Infections à Chlamydiae, Université Victor Segalen Bordeaux 2, Bordeaux, France.
authors.forename: Christiane
authors.initials: C
authors.lastname: Bébéar
authors.affiliation: Laboratoire de Bactériologie EA 3671, Infections Humaines à Mycoplasmes et Chlamydiae, Centre National de Référence des Infections à Chlamydiae, Université Victor Segalen Bordeaux 2, Bordeaux, France.
authors.forename: Cécile M
authors.initials: CM
authors.lastname: Bébéar
authors.affiliation: Laboratoire de Bactériologie EA 3671, Infections Humaines à Mycoplasmes et Chlamydiae, Centre National de Référence des Infections à Chlamydiae, Université Victor Segalen Bordeaux 2, Bordeaux, France.
authors.forename: Bertille
authors.initials: B
authors.lastname: de Barbeyrac
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D018834:Chaperonin 60 / Q000235:genetics; D002692:Chlamydia trachomatis / Q000187:drug effects*; D004261:DNA Replication; D006801:Humans; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability; D016133:Polymerase Chain Reaction / Q000379:methods*; D018272:Porins / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D018834:Chaperonin 60; C063931:Omp2 protein, bacteria; D018272:Porins; D012333:RNA, Messenger; D012336:RNA, Ribosomal, 16S; C071677:omp1 protein, Chlamydia trachomatis