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Journal of Clinical Microbiology, February 1998, p. 481-485, Vol. 36, No. 2
Division of Disease Control,
Received 23 July 1997/Returned for modification 19 September
1997/Accepted 4 November 1997
The accuracy of pooling urine samples for the detection of genital
Chlamydia trachomatis infection by ligase chain reaction (LCR) was examined. A model was also developed to determine the number
of samples to be pooled for optimal cost savings at various population
prevalences. Estimated costs included technician time, laboratory
consumables, and assay costs of testing pooled samples and retesting
individual specimens from presumptive positive pools. Estimation of
population prevalence based on the pooled LCR results was also applied.
After individual urine specimens were processed, 568 specimens were
pooled by 4 into 142 pools and another 520 specimens were pooled by 10 into 52 pools. For comparison, all 1,088 urine specimens were tested
individually. The sample-to-cut-off ratio was lowered from 1.0 to 0.2 for pooled samples, after a pilot study which tested 148 samples pooled
by 4 was conducted. The pooling algorithm was 100% (48 of 48)
sensitive when samples were pooled by 4 and 98.4% (61 of 62) sensitive
when samples were pooled by 10. Although 2.0% (2 of 99) of the
negative pools of 4 and 7.1% (1 of 14) of the negative pools of 10 tested presumptive positive, all samples in these presumptive-positive
pools were negative when retested individually, making the pooling
algorithm 100% specific. In a population with 8% genital C. trachomatis prevalence, pooling by four would reduce costs by
39%. The model demonstrated that with a lower prevalence of 2%,
pooling eight samples would reduce costs by 59%. Pooling urine samples
for detection of C. trachomatis by LCR is sensitive,
specific, and cost saving compared to testing individual samples.
0095-1137/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Pooling Urine Samples for Ligase Chain Reaction
Screening for Genital Chlamydia trachomatis Infection in
Asymptomatic Women
*
Corresponding author. Mailing address: The Johns
Hopkins University, Division of Infectious Diseases, Ross Research
Bldg., Room 1159, 720 Rutland Ave., Baltimore, MD 21205. Phone: (410) 614-0932. Fax: (410) 955-7889. E-mail:
cgaydos{at}welchlink.welch.jhu.edu.
Journal of Clinical Microbiology, February 1998, p. 481-485, Vol. 36, No. 2
0095-1137/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
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