Assalam alaikum everyone and welcome to a new ATP video
Today we will be talking about the gram-negative bacteria that have diplococcus arrangement.
Probably the only pathogenic bacteria that have this arrangement is Neisseria.
Neisseria has 2 main important species: Neisseria meningitides and Neisseria Gonorrhea.
In this video we will talk about Neisseria Gonorrhea.
But first, let’s start with the shared features between the 2 species
First of all, both gram negative diplococci second of all they are both oxidase positive
For the lab stuff, Neisseria species grow on chocolate agar
Now let’s talk about culturing Neisseria: But what is that? Do we actually use chocolate?
No, not really
Neisseria species can’t grow on blood agar because it is inhibited by some
of the elements in the blood agar, however, when we heat the blood agar,
these inhibitory elements become inactive and thus Neisseria can grow.
This heated blood agar is in fact the famous Chocolate Agar
The other agar that Neisseria grows on is Thayer-Martin agar
which is a selective agar that only allows Neisseria species to grow
while inhibiting other organisms from growing.
This is also known as VCN agar, referring to the antibiotics
used to inhibit the other organisms which are: vancomycin, colistin, and nystatin.
Now let’s move to the shared virulence factors:
• Pilli which allows attachment to mucosal surfaces. These pili also
display antigenic variation (which makes it difficult for our immune system to target)
• IgA protease will cleave IgA antibodies at its hinge point,
this facilitates Neisseria survival along mucosal surfaces (because
remember that IgA antibodies are found predominantly at the mucosal surfaces)
• Since N. meningitides is a gram –ve bacteria, he has the ability of producing endotoxin, but
be aware that Neisseria endotoxin is a little bit different than the original one that you already
know about. It has a Lipooligosaccharide instead of Lipopolysaccharide. You can think of it as an
alternative version of the Lipopolysaccharide found in other gram –ve bacteria.
Lastly, you need to know that patients with C5-C9 deficiency (also known as
terminal complement deficiency) are more susceptible to Neisseria
infection because these particular complement proteins are essential
to form the MAC or membrane attach complex, that is usually used to cause bacteriolysis
So when these proteins are deficient, this will make the patients unable to form the
MAC complex and that will lead them to become more prone to infections.
Now let’s focus on N. gonorrhea
First remember that N. Gonorrhea does not ferment maltose and does not have
polysaccharide capsule like N. meningitides.
Now let's discuss the pathogenesis of N. gonorrhea infection
N. gonorrhea can affect both men and women and result in gonorrhea.
Let’s first discuss the gonococcal disease in men: A man can acquire N. Gonorrhea by having
unprotected sexual intercourse with infected individual. After acquiring the infection,
N. gonorrhea will first damage the urethra and cause inflammation or
urethritis and they will present with painful urination along with purulent
discharge. The infection can complicate and cause prostatitis and epididymitis.
Although some men remain asymptomatic they can
still can pass the infection to another sexual partner.
Now let’s move on to the ladies:
Like men, women can develop urethritis and present with painful urination and purulent discharge,
however unlike men, a large percentage of women will remain asymptomatic.
In addition to urethritis, N. gonorrhea can also affect the cervix and cause inflammation
or cervicitis. Again, a large percentage of these women will remain asymptomatic,
however some will present with lower abdominal discomfort, pain with sexual
intercourse (dyspareunia), and a purulent vaginal discharge.
What is important to remember here is that, the infection of the cervix can ascend and
cause pelvic inflammatory disease, also known as PID, which is the inflammation
of uterus, fallopian tube, and/or the ovaries. PID patient presents with:
• fever • lower abdominal pain
• abnormal menstrual bleeding • and cervical motion tenderness
Cervical motion tenderness is the pain that is elicited when the cervix is moved by the doctor's
examining finger. Cervical motion tenderness is a very important clinical sign for PID.
Now it is important to note that presence of intra uterine device,
which is used for contraception, increases the risk of progression to PID.
Okay now let's focus on the possible complications of PID:
1- Infertility (and the way this happens is that you form a scar
tissue in the fallopian tube which can block it and that will prevent
the egg from meeting the sperm) 2- Scaring and ectopic pregnancy
Do you need where is the most common site for ecotpic pregnancy to happen?
Take a moment A: The ampulla of the fallopian tube
3- Peritonitis, this is when the infection spread from the follapian tube into the peritoneal fluid
4- Fitz-Hugh-Curtis syndrome, in which the Infection spreads to the liver
capsule resulting in formation of adhesions between the liver capsule and the peritoneum
and these adhesions are called “Violin String” adhesions.
Also, in men and women, N. gonorrhea can cause septic arthritis, this happen when N. gonorrhea
spread into the blood and causes inflammation of the joints. Typically, septic arthritis
caused by N. gonorrhea affects more than one joint which is why it's called polyarthritis,
and in addition to that, the condition is associated with skin lesions and tenosynovitis
(or inflammation of the muscle tendon) Now for the last clinically relevant
information about N. gonorrhea, you should know that it can affect neonates as well
The infection is transmitted form infected pregnant woman to her baby during delivery,
through the birth canal, which would then affect the eyes and result in
inflammation of the conjunctiva, also known as purulent conjunctivitis. The
symptoms start to appear within 5 days after delivery. In contrast purulent,
conjunctivitis caused by chlamydia is usually delayed beyond that.
Now for the treatment, we usually use ceftriaxone + azithromycin
Ceftriaxone is a 3rd generation cephalosporin and azithryomycin is a macrolide
For prevention, we sadly don't have a vaccine for
this species yet Do you know why?
It is because of the antigenic variation that the pili display
And that is all what you need to know about N. gonorrhea.
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