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Chlamydia review shows need for greater study uniformity
The study of Chlamydia trachomatis organism load during genital infection needs to be refined to account for differences in specimen type and sampling sites in men and women, according to a recent literature review.
“This systematic review has identified that load varies by specimen type and the site of sampling and that it is possible that the load of viable organisms is more important than the total load,” Jane S. Hocking, PhD, of the University of Melbourne, Australia, and colleagues wrote in The Journal of Infectious Diseases. “However, the role of load in chlamydia transmission, ascending infection, treatment failure, and sexually transmitted infection transmission remains unclear.”
Hocking and colleagues searched Embase, PubMed and Medline databases for literature published through August 2014, and included 29 publications involving 40,883 participants in their review.
They found that for women, organism load was highest in cervical swabs, followed by vaginal swabs and then urine specimens. Among men, organism load was highest for anorectal swabs, and similar for urethral swabs and urine specimens.
“This means that the same specimen type and site of sampling should be used for any investigation of load and that any comparisons of load between men and women are of little value,” the researchers wrote. “Evidence for the association between load and age, serovar, hormone levels, concurrent STIs, and signs and symptoms varied considerably.”
Researchers wrote that this variability may be the result of several factors, including the use of different laboratory assays. Cultures detect viable organisms but are less sensitive, while the nucleic acid amplification test (NAAT) is more sensitive for detecting chlamydianucleic acid but is unable to distinguish between viable and nonviable organisms. Eight of nine culture-based studies found an association between load and signs and symptoms, in contrast with only three of eight NAAT-based studies (P = .03).
Differing study designs and populations also may have played a role in the variability, according to Hocking and colleagues.
The researchers wrote that there is a clear need for “well-designed cohort studies with serial sampling, to determine when chlamydia was acquired, and comprehensive data collection, to control for confounding.” – by David Jwanier
Disclosure: The researchers report no relevant financial disclosures.