under the microscope
By Rodney E. Rohde, PhD, MS, SM(ASCP)CM SVCM, MBCM, FACSc
Just What Do You Know About Gonorrhea?
In
the most recent publication of CDC’s Antibiotic Resistance
Threats in the United States, 2019 (2019 AR Threats
Report) the latest national death and infection estimates underscore
the continued threat of antibiotic resistance in the United
States. Did you know that there are 2.8 million antibiotic-resistant
infections in the U.S. each year, and more than 35,000 people die
as a result? While many of us have heard about MRSA and other
more common antimicrobial threats, most people do not realize
that Neisseria gonorrhoeae belongs to this threat category. This
bug causes gonorrhea, a sexually transmitted disease (STD) that
can result in life-threatening ectopic pregnancy and infertility,
and can increase the risk of getting and giving HIV.
N. gonorrhoeae and Neisseria meningitidis are genetically very
closely related human pathogens. The genus Neisseria is composed
of 17 species that may be isolated from humans and 6 species that
colonize various animals. The Neisseriaceae are a family of Beta
Proteobacteria consisting of Gram-negative aerobic bacteria from
multiple genera, including Neisseria, Chromobacterium, Kingella,
and others. While there are numerous commensals in this genus,
N. gonorrhoeae causes gonorrhea, and N. meningitidis is the
cause of meningococcal meningitis. N. gonorrhoeae infections
have a high prevalence and low mortality, whereas N. meningitidis
infections have a low prevalence and high mortality.
Unlike several of my past month’s articles in which I discussed
bugs that are typically found in the natural environment, N.
gonorrhoeae has no reservoir outside of humans. N. gonorrhoeae
also known as gonococcus (singular), or gonococci (plural) is a
species of Gram-negative diplococci bacteria isolated by Albert
Neisser in 1879. Most members of this genus are fastidious and
require nutrient supplementation to be cultured in the laboratory.
Neisseria spp. are facultatively intracellular and typically appear
in pairs (diplococci) which classically look like coffee beans in a
gram stain. They do not form endospores and are capable of
twitching motility. They are obligate aerobes (requires oxygen to
grow) which must be considered for culture.
How common is gonorrhea?
This disease, unfortunately, is very common. CDC estimates
that approximately 1.14 million new gonococcal infections occur
in the United States each year and as many as half occur among
young people aged 15-24. In 2018, 583,405 cases of gonorrhea
were reported to CDC. It is a STD via infection of the mucous
membranes of the reproductive tract, including the cervix, uterus,
and fallopian tubes in women, and the urethra in women and
men. N. gonorrhoeae can also infect the mucous membranes
of the mouth, throat, eyes, and rectum. Importantly, a mother
can give the infection to her baby as the baby passes through
the birth canal during delivery sometimes causing blindness.
How is gonorrhea diagnosed?
This STD bug, historically was diagnosed by traditional
microbiology tests, including oxidase positive (possessing
cytochrome c oxidase) and catalase positive (able to convert
hydrogen peroxide to oxygen) as well as by its ability oxidize
only glucose (negative for the other carbohydrates lactose,
maltose, and sucrose). However, in today’s microbiology world
this drug resistant STD is most commonly rapidly diagnosed by
a molecular test.
Urogenital gonorrhea can be diagnosed by testing urine,
urethral (for men), or endocervical or vaginal (for women)
specimens using nucleic acid amplification testing (NAAT). It
can also be diagnosed using gonorrhea culture, which requires
endocervical or urethral swab specimens.
If a person has had oral and/or anal sex, pharyngeal and/or
rectal swab specimens should be collected either for culture or
for NAAT (if the local laboratory has validated the use of NAAT
for extra-genital specimens).
What do you need to know about antibiotic resistance?
Gonorrhea has quickly developed resistance to all but one class
of antibiotics, and half of all infections are resistant to at least
one antibiotic. Tests to detect resistance are not always available
at time of treatment. Gonorrhea rapidly develops resistance to
antibiotics—ceftriaxone is the last recommended treatment.
Gonorrhea spreads easily. Some men and most women are
asymptomatic and may not know they are infected, increasing
spread. Due to this growing problem, clinicians and patients
should seek out information on treatment regimens.
How can gonorrhea be prevented?
● Latex condoms, when used consistently and correctly, can
reduce the risk of transmission of gonorrhea
● Abstain from vaginal, anal, and oral sex
● Long-term mutually monogamous relationship with a partner
who has been tested and is known to be uninfected
Healthcare providers with STD consultation requests can
contact the STD Clinical Consultation Network (STDCCN). This
service is provided by the National Network of STD Clinical
Prevention Training Centers and operates five days a week.
STDCCN is convenient, simple, and free to health care providers
and clinicians. More information is available at www.stdccn.org
While not traditionally found in the natural environment, we
must all continue to work to help fight this antibiotic resistant
organism with respect to its overall impact on the growing global
antimicrobial resistance threat.
Rodney E. Rohde, PhD, MS, SM(ASCP)CM SVCM, MBCM,
FACSc, serves as chair and professor of the Clinical Laboratory
Science Program at Texas State; associate director for the
Translational Health Research Initiative; as well as associate dean
for research in the College of Health Professions. Follow him on
Twitter @RodneyRohde / @TXST_CLS, or on his website: http://
rodneyerohde.wp.txstate.edu/
8 august 2020 • www.healthcarehygienemagazine.com