Discussion questions

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  What was the aim of this study?

  
  
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  What was the study design?

  
  
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  What were the results?

  
  
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  What is the difference between incidence and prevalence?

  
  
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  What direction might future research take?

M ycoplasma genitalium (M genitalium) is a fairly unfamiliar entry in the catalog of sexually transmitted microorganisms. In fact, information on its role in urethritis and cervicitis is new to the Center for Disease Control and Prevention’s most recent Sexually Transmitted Diseases (STDs) Treatment Guidelines. Yet, this parasitic bacterium is now linked to 15-25% of the nongonoccocal urethritis cases that occur in the United States. Limited data also indicate that like Chlamydia trachomatis (C trachomatis) and Neisseria Gonorrhoeae, M genitalium can be a culprit in cervicitis and pelvic inflammatory disease (PID). In a new study, Bjartling and colleagues determined the prevalence of M genitalium in a gynecologic emergency clinic and then assessed all associated outcomes.

Impressive enrollment

Journal Club members agreed that the researchers chose to explore an important issue, given prior conflicting data on the subject. The study was well done, and its biggest strength was the high rate of recruitment; close to 90% of potential subjects agreed to take part. As a result, readers can be reassured that selection bias was minimized.

The researchers discovered 106 subjects with M genitalium , 116 with chlamydia, and 10 with both infections. Thus, the prevalence of M genitalium was 2.1% and of chlamydia, 2.8%. M genitalium and C trachomatis were both independently associated with PID and cervicitis, though the magnitude of the association was greater for C trachomatis . One concern regarding the study was the relatively wide confidence intervals for some of the associations. While a large number of women were enrolled into the study, there were actually a small number of cases of PID and cervicitis. The degree of precision of a point estimate is largely driven by the number of events. Thus, in this case, the confidence intervals were quite wide. However, the point estimates were rather high, so it seems likely that these are real associations.

It should be noted, however, that in contrast to most other research on M genitalium infection, the women in this study were recruited from a general gynecologic emergency facility—not an STD clinic or other setting where sexually transmitted infection, including HIV, was a primary complaint, and the prevalence would be expected to be higher. Their goal was to examine the infection’s prevalence in a heterogeneous population, including women who were in the early months of pregnancy, and this was another strong point.