Monitoring intracellular replication of Chlamydophila (Chlamydia) pneumoniae in cell cultures and comparing clinical samples by real-time PCR.
Strains of Chlamydophila pneumoniae may be associated with respiratory disease or atherosclerosis. Two real-time quantitative PCR assays targeting the species-specific genes Cpn0278 and ArgR were developed to compare the in vitro growth of respiratory strains AR39 and K6 with that of atherosclerotic strain A03 and to quantify C. pneumoniae in clinical samples. A third real-time PCR assay was designed to assess contamination with Mycoplasma spp. The assays targeting C. pneumoniae detected DNA concentrations corresponding to 10(4) to 10(-4) inclusion-forming units (IFU)/reaction and were highly specific. AR39 exhibited the longest lag phase and period of exponential growth; K6 augmented growth rates at higher inocula; and A03 grew at highest rates. Contamination with Mycoplasma spp. of AR39 and A03 unlikely accounted for growth differences between them. Numbers of IFU in C. pneumoniae-positive respiratory secretions varied within 4 to 5 orders of magnitude. The assays described may prove valuable for pathogenicity studies.
Division of Infectious Diseases, University Children's Hospital of Zurich, CH-8032 Zurich, Switzerland.
Athos
A
Bonanomi
Claudia
C
Dohm
Zaira
Z
Rickenbach
Martin
M
Altwegg
Joachim
J
Fischer
Daniel
D
Gygi
David
D
Nadal
D001483:Base Sequence; D002455:Cell Division / Q000502:physiology*; D002478:Cells, Cultured; D023521:Chlamydophila Infections / Q000175:diagnosis; D016993:Chlamydophila pneumoniae / Q000254:growth & development* / Q000302:isolation & purification*; D003470:Culture Media; D004269:DNA, Bacterial / Q000032:analysis; D006801:Humans; D008969:Molecular Sequence Data; D009305:Nasopharynx / Q000382:microbiology; D011336:Probability; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity
D003470:Culture Media; D004269:DNA, Bacterial