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.
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