Objective: The aim of this study was to compare and evaluate three methods of DNA extraction for the amplification of Chlamydia trachomatis in uterine cervical samples collected in PreservCyt solution. ThinPrep is the trade name for the slide preparation.
Methods: Thirty‐eight samples collected in LCx buffer medium, which were identified as C. trachomatis infected by ligase chain reaction (LCR), were selected for this study. DNA from the PreservCyt samples was extracted by three methods: (i) QIAamp kit, (ii) boiling in Tris‐EDTA buffer with Chelex purification, and (iii) Proteinase K digestion with Chelex purification. Sample DNA was tested for the presence of C. trachomatis by PCR using cryptic plasmid research (CTP) primers and major outer membrane protein research momp gene (MOMP) primers. Real‐time (LightCycler) PCR for relative C. trachomatis quantification following DNA extraction was performed using primers (Hsp 60) for the 60 kDa heat‐shock protein hsp60 gene.
Results: Amplification using CTP primers was the most successful with each of the extraction protocols. Boiling in buffer was the least successful extraction method. QIAamp was the best extraction method, yielding the most positives with both the CTP and MOMP primers. Proteinase K‐Chelex extraction gave similar sensitivity to QIAamp extraction with CTP primers but lower for MOMP primers.
Conclusions: The DNA extraction method must be carefully selected to ensure that larger PCR amplicons can be successfully produced by PCR and to ensure high sensitivity of detection of C. trachomatis. In this study it was found that the QIAamp extraction method followed by PCR with the CTP primers was the most successful for amplification of C. trachomatis DNA.
Objective: The aim of this study was to determine the prevalence of cervical Chlamydia trachomatis infection by polymerase chain reaction (PCR) in urban women undergoing routine cervical cytological screening and to investigate the relationship with age, cytology, smoking status and concurrent human papillomavirus (HPV) infection.
Methods: A total of 996 women (age range 16–69 years) attending general practitioners for routine liquid‐based cervical smear screening in the Dublin area were recruited in the study of prevalence of C. trachomatis. Informed consent was obtained and liquid‐based cytology (LBC) specimens were sent for cytological screening. DNA was extracted from residual LBC and tested for C. trachomatis by PCR using the highly sensitive C. trachomatis plasmid (CTP) primers and for HPV infection using the MY09/11 primers directed to the HPV L1 gene in a multiplex format.
Results: The overall prevalence of C. trachomatis was 5.4%. Prevalence was highest in the <25 years age group (10%). Coinfection with HPV and C. trachomatis occurred in 1% of the screening population. A higher rate of smoking was observed in women positive for C. trachomatis, HPV infections or those with abnormal cervical cytology. Chlamydia trachomatis infection was not associated with abnormal cytology.
Conclusions: Women (5.4%) presenting for routine cervical screening are infected with C. trachomatis. Opportunistic screening for C. trachomatis from PreservCyt sample taken at the time of cervical cytological screening may be a possible strategy to screen for C. trachomatis in the Irish female population.
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