School of Public Health

Epi researcher outlines priorities for little-known sexually transmitted infection

UW Epi News
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Tuesday, August 8, 2017

Researchers are getting closer to understanding the long-term impact of Mycoplasma genitalium, the often asymptomatic sexually transmitted infection that bears some resemblance to other well-known STIs like gonorrhea and chlamydia. Understanding the impact of this emerging pathogen is key to determining whether screening is needed and to informing treatment recommendations.

As part of an effort to determine whether it is time for a public health control program for M. genitalium, Dr. Lisa Manhart from the University of Washington’s School of Public Health and Dr. Harold Wiesenfeld from the University of Pittsburgh, summarized what is known about M. genitalium infection in women and outlined recommendations for future research to better understand the implications of M. genitalium in women’s health.

The articles, presented in a supplement to the Journal of Infectious Diseases, share the outcomes of a 2016 National Institutes of Allergy and Infectious Diseases-funded Technical Consultation that brought together M. genitalium researchers to review the current knowledge and concerns around the pathogen. Other articles in the supplement summarize what is known about pathogenesis, infections in men, diagnostic assays, treatment and antimicrobial resistance, and criteria for developing public health control programs.

Drs. Manhart, David Martin from Tulane University and the Louisiana State University Health Sciences Center, and Kimberly Workowski from Emory University co-organized the consultation and co-edited the supplement.

“We reached a tipping point in our research on M. genitalium where there was finally enough data to figure out if we needed a public health response,” said Manhart, a professor in the Departments of Epidemiology and Global Health. “The goal of the consultation was to review the evidence and make some recommendations about whether a national control program in the US was appropriate.”

M. genitalium can cause inflammation in the urethra (urethritis) in men and is associated with female reproductive tract syndromes. It is also commonly asymptomatic in both men and women. Compared to more commonly known STIs in the United States, M. genitalium is more prevalent than Neisseria gonorrhoeae, but less than Chlamydia trachomatis.

When detected, M. genitalium is commonly treated with antibiotics. However, the genetic makeup of the bacteria facilitates the development of antibiotic resistance and rates of this resistance are high, making treatment challenging.

“Antibiotic resistance has gotten worse and worse,” said Manhart. “The currently recommended antibiotics for M. genitalium fail half of the time and the second-line antibiotics fail 15-to-20 percent of the time. For those who fail both therapies, there’s no other treatment available in the U.S. M. genitalium is already an untreatable STI in some places.”

Left untreated, the infection may cause further damage to a woman’s reproductive tract. Data from meta-analyses suggest an association between M. genitalium and pelvic inflammatory disease, infertility, and preterm birth, but prospective studies that can demonstrate that it causes these conditions are limited. For HIV-positive women infected with M. genitalium, the risk of acquiring or transmitting HIV to an uninfected sexual partner also increases.

M. genitalium is less known to the public because it still lies in the research domain. Research has found that it causes disease in men (urethritis), but the evidence has been less consistent on whether it causes disease in women. Until researchers define the long-term impact of M. genitalium in women, a public health recommendation is difficult to make, said Manhart.

“There are also no FDA-approved diagnostic tests for the bacterium, so it’s not easy for someone to test for it in a routine clinical setting,” she said. “This is changing, but FDA-approved tests are still a ways away.”

Manhart and the researchers from the technical consultation identified four main consensus recommendations for future research on M. genitalium before providing recommendations to the public. First, researchers need to design clinical trials to determine whether or not to recommend widespread screening for asymptomatic M. genitalium and treatment in order to improve reproductive health in women. Second, there is a need for more effective antibiotics for treatment of M. genitalium infections given the widespread antibiotic resistance in M. genitalium. Third, diagnostic tests that include the detection of resistance genes to a spectrum of antibiotic drug classes must be developed and made broadly available. Fourth, basic science research is needed to identify new antibiotic targets, potential vaccine targets, and better understand the life-cycle of M. genitalium in reproductive tract tissues.

Over 50 scientists from academia, CDC, and the diagnostics and pharmaceutical industries participated in the technical consultation and development of the consensus recommendations. Contributors to the JID supplement included scientists from the University of Washington (Manhart, Totten, Golden); Louisiana State University (Martin and McGowin); University of Pittsburgh (Wiesenfeld); University of Bristol (Horner); Johns Hopkins University (Gaydos); Monash University (Bradshaw); Statens Serum Institut (Jensen); University of Alabama Birmingham (Waites); Emory University (Workowski); and the US Centers for Disease Control and Prevention (Bolan).