Absence of a Chlamydia trachomatis variant, harbouring a deletion in the cryptic plasmid, in clients of a sexually transmissible infection clinic and antenatal patients in Melbourne
DOI:
https://doi.org/10.33321/cdi.2008.32.10Keywords:
Chlamydia trachomatis, variant, cryptic plasmid, real-time polymerase chain reactionAbstract
A Chlamydia trachomatis (CT) variant, harbouring a 377 bp deletion in the cryptic plasmid, recently identified in Europe, has caused false-negative reporting of CT infections by various assays. This report is aimed at identifying whether this variant is present among clients of a sexual health clinic, or antenatal screening patients in Melbourne. Two hundred CT-positive specimens (by BDProbeTec™ ET assay) from Melbourne Sexual Health Centre (August 2005–November 2006) were tested by COBAS TaqMan 48 PCR assay. Discrepancies were tested by an in-house real-time (Re-Ti) polymerase chain reaction (PCR) assay, amplifying a 274-bp region of the omp1 gene. Additionally, 1,071 consecutive specimens from antenatal screening patients at the Royal Women’s Hospital (December 2006–April 2007) were tested by COBAS TaqMan 48 and omp1 Re-Ti PCR. The CT variant was not detected among the 200 CT-positive specimens (95% confidence interval 0–2.3%). Three tested CT-negative by COBAS TaqMan 48, omp1 Re-Ti PCR and CT mutant-specific PCR, suggesting sample degradation or differential assay sensitivity. Of the 1,071 antenatal screening specimens, 56 tested CT-positive and 1,015 CT-negative by COBAS TaqMan 48. All of the CT-negatives tested negative by omp1 Re-Ti PCR (95% confidence interval 0–0.5%), with 51 of 56 CT-positives testing positive. These findings show there were no CT variants among attendees of a Melbourne sexual health clinic, nor among antenatal screening patients. It is likely that the variant strain has not yet entered circulation in these populations. However, given the current upsurge in urogenital CT-infections, continued surveillance is necessary to ensure timely detection of this variant, should it be introduced into the population. Commun Dis Intell 2008;32:77–81.
Downloads
References
Cates WJ, Wassenheit JN. Genital chlamydial infections: epidemiology and reproductive sequelae. Am J Obstet Gynecol 1991;164:1771–1781.
Quinn TC, Gaydos C, Shepherd M, Bobo L, Hook III W, Viscidi R, et al. Epidemiologic and microbiologic correlates of Chlamydia trachomatis infection in sexual partnerships. JAMA 1996;276:1737–1742.
Gaydos CA, Theodore M, Dalesio N, Wood BJ, Quinn TC. Comparison of three nucleic acid amplification tests for detection of Chlamydia trachomatis in urine specimens. J Clin Microbiol 2004;42:3041–3045.
Lovett M, Kuo KK, Holmes K, Falkow S. Plasmids of the genus Chlamydia. In: Nelson J, Grassi C, editors. Current Chemotherapy and Infectious Diseases. Vol. 2. Washington, DC: American Society for Microbiology; 1980. p. 1250–1252.
Palmer L, Falkow S. A common plasmid of Chlamydia trachomatis. Plasmid 1986;16:52–62.
Ripa T, Nilsson P. A variant of Chlamydia trachomatis with deletion in cryptic plasmid: implications for use of PCR diagnostic tests. Euro Surveill 2006;11 Available from: http://www.eurosurveillance.org/ew/2006/061109.asp#2 Accessed on 5 October 2007.
Herrmann B. A new genetic variant of Chlamydia trachomatis. Sex Transm Infect 2007;83:253–254.
de Barbeyrac B, Raherison S, Cado S, Normandin F, Clerc M, Clairet V, et al. French situation concerning the Swedish Chlamydia trachomatis variant. Euro Surveill 2007;12. Available from: http://www.eurosurveillance.org/em/v12n10/1210–226.asp Accessed on 24 January 2008.
Lynagh Y, Walsh A, Crowley B. First report of the new variant strain of Chlamydia trachomatis in Ireland. Epi-Insight 2007;8. Available from: http://www.ndsc.ie/hpsc/EPI-Insight/Volume82007/File,2424,en.pdf Accessed on 24 January 2008.
Moghaddam, A, Reinton N. Identification of the Swedish Chlamydia trachomatis variant among patients attending a STI clinic in Oslo, Norway. Euro Surveill 2007;12 Available from: http://www.eurosurveillance.org/ew/2007/070301.asp#3 Accessed 5 October 2007.
de Vries HJ, Catsburg A, van der Helm JJ, Beukelaar EC, Morre SA, Fennema JS, et al. No indication of Swedish Chlamydia trachomatis variant among STI clinic visitors in Amsterdam. Euro Surveil. 2007;12. Available from: http://www.eurosurveillance.org/ew/2007/070208.asp#3 Accessed on 5 October 2007.
Sillis M, Skidmore S, Mallinson H, Todd T, Coupland L, Oliver P, et al. No evidence of the Chlamydia trachomatis variant in the UK. Sex Transm Infect 2007;83:488–489.
Soderblom T, Blaxhult A, Fredlund H, Herrmann B. Impact of a genetic variant of Chlamydia trachomatis on national detection rates in Sweden. Euro Surveill 2006;11. Available from: http://www.eurosurveillance.org/ew/2006/061207.asp#1 Accessed 5 October 2007.
Ripa T, Nilsson PA. A Chlamydia trachomatis strain with a 377-bp deletion in the cryptic plasmid causing false-negative nucleic acid amplification tests. Sex Transm Dis 2007;34:255–256.
Microbiology Quality Assurance Program. RCPAQAP NSW, Australia: RCPA QAP Pty Limited:. Available from: http://www.rcpaqap.com.au/micro/index.html [updated on 11 December 2007] Accessed 23 January 2008.
Agresti A, Coull BA. Approximate is better than ‘Exact’ for interval estimation of binomial proportions. Am Stat 1998;52:119–126.
Downloads
Published
How to Cite
License
Copyright (c) 2008 Communicable Diseases Intelligence
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
