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Year : 2013  |  Volume : 31  |  Issue : 1  |  Page : 96--97

Detection of N. gonorrhoeae and C. trachomatis infection using urine sample from symptomatic high-risk women by APTIMA Combo2 assay

AR Risbud1, G Rao1, A Das2, P Narayanan2, P Prabhakar2,  
1 Department of Microbiology, National AIDS Research Institute, 73 'G', MIDC, Bhosari, Pune, India
2 FHI, 360, New Delhi, India

Correspondence Address:
A R Risbud
Department of Microbiology, National AIDS Research Institute, 73 SQGSQ, MIDC, Bhosari, Pune
India

How to cite this article:
Risbud A R, Rao G, Das A, Narayanan P, Prabhakar P. Detection of N. gonorrhoeae and C. trachomatis infection using urine sample from symptomatic high-risk women by APTIMA Combo2 assay.Indian J Med Microbiol 2013;31:96-97

How to cite this URL:
Risbud A R, Rao G, Das A, Narayanan P, Prabhakar P. Detection of N. gonorrhoeae and C. trachomatis infection using urine sample from symptomatic high-risk women by APTIMA Combo2 assay. Indian J Med Microbiol [serial online] 2013 [cited 2020 Oct 25 ];31:96-97
Available from: https://www.ijmm.org/text.asp?2013/31/1/96/108756

Full Text

Dear Editor,

Neisseria gonorrhoeae and Chlamydia trachomatis are the common bacterial sexually transmitted infections. [1] Conventional diagnostic methods are cumbersome and less sensitive for detection of these pathogens, while the new diagnostic approach like Automated Probe Transcription Mediation Amplification (APTIMA) Combo2 (AC2) assay has been shown to perform well. Although the cervical swab is considered the ideal sample for this purpose, vaginal swabs and urine have been shown to work equally well in AC2 assay. [2],[3] Considering the concurrent multiple STIs in female sex workers (FSWs) in India, [4] we evaluated the utility of urine sample for detection of N. gonorrhoeae and C. trachomatis infections by AC2 assay among the symptomatic FSWs.

A total of 100 symptomatic FSWs, age 18 years and above, consecutively attending STI clinics in Andhra Pradesh and Maharashtra states, were recruited in this study. First catch urine (FCU) and vaginal swab specimen were collected from each of them. [5] These specimen were tested for N. gonorrhoeae and C. trachomatis infection by AC2 assay. [6],[7] The median age of the study population was 30 years (IQR 6). The majority of the participants were street-based sex workers (75%) with a very low literacy level (14%). Although, 72 of the sex workers had vaginal discharge, speculum examination revealed cervical discharge in 24, cervical erosion in 18 and cervical friability in 10 of them.

Specimens from seven participants yielded equivocal results and were excluded from further analysis. Vaginal swab specimen from 20 (21%) FSW were positive for N. gonorrhoeae while urine samples of 15 of these were positive. Vaginal swabs of 22 (24%) FSW were positive for C. trachomatis while urine samples of 17 of these were positive. Thus, 36 (38.7%) FSW were diagnosed with gonorrhoeae and/or Chlamydia infection using vaginal swab specimen.

Urine sample was found to be 89% sensitive and 95% specific in detecting gonorrhoeae and/or Chlamydia infection, when compared with vaginal swab specimen. Positive and negative predictive values for urine sample for this detection were 92% and 93%, respectively. The concordance rate between vaginal swabs and FCU results for N. gonorrhoeae detection was 90% and for C. trachomatis it was 86%. The agreement between the N. gonorrhoeae and C. trachomatis results obtained with FCU and vaginal swab specimens in symptomatic FSWs was 93% [Table 1].{Table 1}

As reported in earlier studies, we also found that the urine sample was highly specific and almost as sensitive as vaginal swab for diagnosis of gonorrhoeae and/or Chlamydia infection, when tested in AC2 assay. Urine, being non-invasive and easy to collect, may be considered an alternative specimen, especially, in large-scale surveys of women with vaginocervical discharge (VCD) syndrome. However, it should be noted that the use of urine sample may lead to underestimation of prevalence by about 5%.

References

1Global prevalence and incidence of selected curable sexually transmitted infections. Overview and estimates. WHO/HIV-AIDS/2001.02; WHO/CDS/CSR/EDC/2001.10.
2Ferrero DV, Meyers HN, Schultz DE, Willis SA. Performance of the Gen-Probe AMPLIFIED Chlamydia Trachomatis Assay in detecting Chlamydia trachomatis in endocervical and urine specimens from women and urethral and urine specimens from men attending sexually transmitted disease and family planning clinics. J Clin Microbiol 1998;36:3230-3.
3Martin DH, Cammarata C, Van Der Pol B, Jones RB, Quinn TC, Gaydos CA, et al. Multicenter evaluation of AMPLICOR and automated COBAS AMPLICOR CT/NG tests for Neisseria gonorrhoeae. J Clin Microbiol 2000;38:3544-9.
4Risbud A, Gururaj Rao D, Narayan P, Prabhakar P, Das A, Mehendale S, et al. Burden of multiple sexually transmitted infections and associated risk factors among female sexworkers in India. Abstr IUSTI 2011;7:52.
5APTIMA COMBO2 Assay Package inserts. Available from: http://www.gen-probe.com/pdfs/pi/501798-EN-RevC.pdf. [Last Accessed 2010 Sep 26].
6Chong S, Jang D, Song X, Mahony J, Petrich A, Barriga P, et al. Specimen processing and concentration of Chlamydia trachomatis added can influence false-negative rates in the LCx assay but not in the APTIMA Combo 2 assay when testing for inhibitors. J Clin Microbiol 2003;41:778-82.
7Gaydos CA, Quinn TC, Willis D, Weissfeld A, Hook EW, Martin DH, et al. Performance of the APTIMA Combo 2 assay for detection of Chlamydia trachomatis and Neisseria gonorrhoeae in female urine and endocervical swab specimens. J Clin Microbiol 2003;41:304-9.