Mycoplasma genitalium is one of the least known sexually transmitted diseases in the world, but this minute bacteria is thought to be even more widespread than the gonorrhea bug.
In fact, it wasn’t until recently that doctors began to notice the microbe was in some patients.
This is changing thanks to Hologic, Inc.’s sexually transmitted disease department. The company, which was responsible for bettering automated blood tested for diseases like hepatitis B and C as well as HIV, has just gotten FDA approval for its mycoplasma genitalium test. The first in the nation to do so!
However, it wasn’t long before a Swiss multinational diagnostic and pharmaceutical company joined Hologic. In May, the FDA approved Roche’s test. And, a third company – this time from Australia – SpeedDx was able to get approval for its test that would detect M. Gen. infections.
M. Gen., unlike other diseases, is relatively new to the STD category. It was first identified in 1980 by the U.S. Center for Disease Control and Prevention, but it wasn’t until 2015 that they declared it an “emerging issue.” The CDC estimate there is a 30 percent of recurring infections in both men and women. In men, the infection is found in the urethra. In women, the bacteria is found in the cervix area.
According to various studies, an M. Gen. infection can cause pelvic inflammatory disease, infertility and birth complications, but there is no scientific proof of this.
However, with FDA approval for testing, researchers may be one step closer to understanding how M. Gen. affects the body.
University of Washington School of Public Health Epidemiology professor Lisa Manhart has been studying mycoplasma genitalium. She said the tests for the bacteria would help doctors give patients the right medication causing their symptoms.
Manhart said when the FDA approves a test, the number of doctors using it to test their patients grows. She said testing could eventually lead to observational studies to find a link between M. Gen. and pelvic inflammatory disease. PID, in severe cases, will lead to infertility.
Additional studies need to be done to prove that this is the case for reproductive health. Manhart said there had been several studies that have tried to tie the two together, but the results are minuscule but the correlation is there even without definitive proof.
Researchers, in order to prove that the test works, took about 12,000 specimens from 3,300 patients and compared them to three distinct analysis. It found that the Holigic’s test for M.Gen. could detect the bacteria from 77.8 percent to 99.6 percent. There were more consistent results when proving it wasn’t present at 97.8 percent and 99.6 percent in both men and women’s urine samples – thus, ruling any infection out.
The company’s senior key scientist and research and development director Damon Getman said that was intentional. He said sensitivity is the test’s capability to find the existence of an organism and allowing it to rule out infections.
Getman said the test was created solely to help narrow down the chances of false positives – a person being told they have an STD when they really do not. He said there is no perfect test that offers perfection in terms of sensitivity and specificity, which means using imperfect tools where perfection must be. This means trying to think where your focus needs to be.
This comes down to test design.
There are several kinds of mycoplasma bacteria that live in the human body (most are not dangerous). To detect the presence of M. Gen., the tool uses ribonucleic acid using the replication process Gen-Probe developed and was later purchased by Hologic in 2012.
Getman said there is plenty of RNA in M. Gen. with roughly 1,000 copies in every cell. However, looking at the sequences between M. Gen.’s RNA and other mycoplasma bacteria, there’s not much difference. The base pairs have longer genetic sequences, and the differences may be noted in a minute number of paired molecules.
It’s here where scientists create special primers and probes that bond to the sites inside the RNA of M. Gen., making it a minute bit different than the other mycoplasma species. These small tools can then narrow in on the tiny targets.
Getman said the area for detection was just 80 nucleic acid base pairs out of a 500,000+ string. Since the primers wouldn’t be likely to attach themselves to their targets, researchers knew it was possible for missed infections to occur, but the tight attention on the sport is what separates M. Gen. from other types of mycoplasmas. And, this is what decreasing the chances for false positives.
It took several months – not years – to choose the right design and target to ensure it worked. And, even though it was another 10 years of working with researchers to use the tool on various patients, Getman is excited about the results. He said it’s sensational to see a tool being used to help detect a potential threat – going from design to real-world testing so quickly.
Written by Mark Riegel, MD
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