Document Detail

How likely is environmental or patient cross-contamination of Chlamydia trachomatis DNA to lead to false positive results in patients attending our clinic?
MedLine Citation:
PMID:  23038711     Owner:  NLM     Status:  MEDLINE    
OBJECTIVES: Environmental contamination with DNA from Chlamydia trachomatis (CT) has previously been found in Genitourinary Medicine (GUM) clinics. There are no known cases of cross-contamination of clinical samples and no known nosocomial infections. We investigated whether diagnostic samples could become contaminated from the environment by running dummy sample and carrying out a patient-throughput analysis. A total of 29 748 patients attended clinics over a year. Of these, 2860 (9.6%) had a positive Chlamydia test result.
METHOD: (1) A run of dummy samples (60 urine samples and 10 swabs) were processed as normal clinic specimens. (2) Patient-throughput analysis: Patient numbers attending the GUM clinic on a given day was categorised as low, moderate or high. χ(2) Tests were used to look for associations between categorical variables and Chlamydia test positivity. A Poisson regression model was fitted to look at the effect of the number of people in the clinic on the number of positive results in a given day. As some clinics were only run on certain days of the week, a sensitivity analysis was later performed with attendances at non-daily clinics removed.
RESULTS: All dummy samples tested negative and we did not find evidence of an association between daily Chlamydia positivity and clinic attendance.
CONCLUSIONS: It is unlikely that environmental or cross-contamination of CT has lead to significant numbers of false positive results. Laboratories check for possible cross-contamination routinely. The extension of this simple routine practice to all clinical areas could provide quality assurance, improving confidence in the results in clinics.
Sum Yee Chan; Sophie Jose; Rebecca King; Mark R Pakianathan; Caroline Sabin; S Tariq Sadiq; Phillip E Hay; Tim Planche
Publication Detail:
Type:  Journal Article     Date:  2012-10-04
Journal Detail:
Title:  Sexually transmitted infections     Volume:  89     ISSN:  1472-3263     ISO Abbreviation:  Sex Transm Infect     Publication Date:  2013 Mar 
Date Detail:
Created Date:  2013-02-20     Completed Date:  2013-04-15     Revised Date:  2014-02-20    
Medline Journal Info:
Nlm Unique ID:  9805554     Medline TA:  Sex Transm Infect     Country:  England    
Other Details:
Languages:  eng     Pagination:  105-7     Citation Subset:  IM    
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MeSH Terms
Chlamydia Infections / diagnosis*
Chlamydia trachomatis / isolation & purification*
Cross Infection / epidemiology*
DNA Contamination*
Diagnostic Errors / statistics & numerical data*
Environmental Microbiology*
Grant Support
G0901608//Medical Research Council

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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