Source of Chlamydia Reinfections May Be GI Tract (2014-02-25)

The current standard of care treatment for chlamydia sometimes fails to eradicate the disease, according to a review published ahead of print in Infection and Immunity, and the culprit may be in the gut.

Chlamydia trachomatis not only infects the reproductive tract, but abides persistently—though benignly—in the gastrointestinal tract. There it remains even after eradication from the genitals by the antibiotic, azithromycin, says first author Roger Rank, of the Arkansas Children’s Research Institute, Little Rock. And that reservoir is likely a source of the all-too-common reinfections that follow treatment.

 

The source of the reinfections has long been a conundrum. Some are blamed on continued intercourse with an infected partner. This is not surprising since chlamydia is usually asymptomatic in men.

Chlamydiae have long been assumed often to persist within the genital tract in a non-replicating form, but Rank says there is no evidence for this. “While all agree that chlamydiae may persist in a patient for long periods of time, and that recurrent infections do develop, there has been no agreement on how and where and in what form chlamydiae persist,” says Rank.

In a recent study, coauthor and Arkansas colleague Laxmi Yeruva showed in mice that azithormycin eradicated the genital infection, but not the GI infection.

Rank showed further—also in mice—that chlamydial infection of the GI does not elicit an inflammatory response, and never resolves, unlike in the genital tract.

“However, we found that GI infection does produce a strong immune response that can actually be effective against a genital infection, but that is unable to cure the GI infection,” says Rank.

Clearly, many women become reinfected from an untreated partner; however, researchers propose that women, cured of genital infection, remain at risk for auto-inoculation from the lower gastrointestinal tract.

Since researchers have established above that the natural site of infection in most animal hosts is the GI tract, one must, thus, ask why the natural site of infection in the human cannot also be the GI tract. Even aside from obvious rectal inoculation via anal intercourse, there are many different scenarios by which both men and women may become infected orally.

That men and women can be infected orally was demonstrated by Jones and colleagues. They collected pharyngeal swabs from 706 heterosexual men and 686 women and rectal specimens from 1,223 women at risk for chlamydial infection.
C. trachomatis was isolated from the pharynx of 3.7% of men and 3.2% of women. C. trachomatis was also isolated from rectal cultures of 5.2% of women at risk, but no statistical association was found with positive rectal isolation and a history of anal intercourse.
Furthermore, a strong association was noted between positive genital and rectal cultures with 11% of genital tract positive women also being positive in the rectum, in contrast to only 2.7% of genital swab negative women being positive on rectal swabs.

These data strongly suggested that women were acquiring gastrointestinal
infection although one could not determine whether the GI infection was long-term or not.
It was interesting to note that no patient with a positive pharyngeal culture complained of pharyngitis, so it would appear that an individual could be unaware that oral infection had occurred.
There was a strong correlation between a history of fellatio in women and the acquisition of oral infection, whereas a similar correlation was not seen in men practicing oral-genital sex, suggesting that other means of oral acquisition may have occurred. The authors did comment that the “effect of infection at these sites on transmission of the organisms and on the development of persistent infections requires further study.

Chlamydia trachomatis is the most common cause of sexually transmitted disease in the world. In the US, approximately 1.4 million cases occur annually, according to the Centers for Disease Control and Prevention. Adolescents are most affected, and 6.8 percent of sexually active females ages 14-19 become infected annually.

For more information

“Hidden in plain sight:” Chlamydial gastrointestinal infection and its relevance to “persistence” in human genital infections
Authors
Roger G. Rank and Laxmi Yeruva.

MDN