Treponema pallidum (Syphilis)
Definitions & Key takeaways
Treponema pallidum is a type of bacterium that causes syphilis, which is a sexually transmitted infection. It can spread through direct contact with a syphilis sore during vaginal, anal, or oral sex. It can cause disease in three stages. The first is localized primary syphilis, and this produces hard chancres. The second is disseminated secondary syphilis, which produces widespread maculopapular rash, and the third is systemic tertiary syphilis, which affects various organs.
Syphilis can be diagnosed by using serological tests and treated with antibiotics like penicillin. If left untreated, it can lead to severe health complications, including organ damage and even death. Syphilis is primarily treated with intramuscular penicillin G benzathine. The main goals of nursing care include the resolution of their infection, and avoiding the spread of the infection among their sexual contacts. Client teaching is aimed at promoting adherence to treatment and follow-up, as well as disease prevention.
Treponema pallidum can be considered a gram negative bacterium. Even though its cell envelope differs from other gram negative bacteria.
You might know t pallidum because it causes syphilis, a sexually transmitted disease that affects the skin and mucous membranes of the external genitalia.
And also sometimes the mouth. Treponema pallidum is an obligate parasite bacteria, meaning it can't survive outside a living body to be more specific outside of a human beings.
Body. They belong to a group of bacteria called spirochaetes which are long and thin and contain endo flagella which are a band of protein filaments that coil within the spirochaetes and give them a spiral shape, kind of like a curly fry but a little less appetizing.
The endo flagella also help the spirochaetes to move around by spinning or twisting a bit like a drill that's slowly boring into a piece of wood.
People that have syphilis can transmit the disease to others in one of two ways. The first way is called acquired syphilis.
And that's when treponema pallidum enters the body through bodily fluids that can happen when there are tiny cuts or breaks in the skin or mucous membranes of the external genitalia or mouth.
And when there's sexual contact, including oral, anal and vaginal sex, it can also happen when people share contaminated needles or when they have direct contact with a skin lesion on an infected person.
Because the skin lesion is covered in this fluid which is rich in spirochetes. The second way is called congenital syphilis.
In acquired syphilis, there are three stages to the infection. The first stage is called primary syphilis or the early localized stage.
And it usually starts 1 to 3 weeks after the t pallidum lands on the skin or mucous membrane. During this stage, the spirochaetes destroy the soft tissue and skin wherever they enter the body.
And that results in the formation of ulcers called syphilitic shanker. A syphilitic shanker is painless and you can remember that by dropping in au to make it shank cure like you're cured of the pain.
These shakers have a hard base, raised borders and are usually covered by a fluid rich in spiro heet. And this can spread to other parts of the body as well as to other individuals in individuals who acquire syphilis through sexual contact, the primary shanker develops around the external genitalia.
However, for individuals that acquire syphilis by physically touching a person or in some other way, the primary shanker might appear on the hands or some other part of the body.
Syphilitic shanker typically heal on their own over a few months. But during that time, some spirochaetes go to nearby lymph nodes where they cause lymphadenopathy, which is lymph node enlargement and then they get into the lymph and finally into the bloodstream.
If syphilis is acquired through something like a blood transfusion, then there may not be any early localized stage at all and no primary shanker.
The second stage is secondary syphilis or the dissemination stage and it occurs about 6 to 12 weeks after the infection.
During this stage, spirochaetes enter the bloodstream which is called spirochetemia. And this causes generalized lymphadenopathy, which is when spirochaetes can be found in lymph nodes throughout the body.
The spirochaetes like to attach to and infect endothelial cells in small capillaries near the skin. This causes a non itchy maculopapular rash which are small bumps that are either flat or raised.
The rash starts on the trunk and spreads out to the arms and legs and eventually to the palms soles, genitalia and other mucous membranes.
These rashes can sometimes be pustular which means they're filled with the white fluid pus or they can be papulosquamous, which is when they're really scaly and hard.
So these various rashes can erupt all over the body and the lesions are chock full of spirochaetes making secondary syphilis.
The most infectious stage, the rashes from secondary syphilis usually resolve within a few weeks to months after secondary syphilis is a latent phase called latent syphilis.
This is when the disease enters a dormant or asymptomatic phase. During this phase.
The spirochaetes can mostly be found in the tiny capillaries of various body organs and tissues. Latent syphilis can be further divided into an early phase and a late phase.
Early latent syphilis occurs within a year of infection. And during that time, the spirochaetes can reenter the blood.
So this means that during early latent syphilis, they can still be found circulating in large numbers in the blood causing symptoms of secondary syphilis.
However, the late latent phase is generally after a year. And that's because the spirochaetes generally stay within the tiny capillaries of various body organs and tissues.
As it turns out only a few spirochaetes are actually found in the capillaries of tissues and organs. But there's a severe immune response.
So severe that it causes tremendous damage to the cells there. And that triggers the next phase, which is tertiary syphilis.
In tertiary syphilis. There's a type four hypersensitivity reaction which means that there's an immune response that's mainly led by the T cells and they recruit phagocytes like macrophages and cause the release of proinflammatory cytokines such as tumor necrosis factor, il one and il six.
These include group specific antigen which are present in all treponeme species specific antigen, which are specific to T pallidum and cardiolipin, which is a lipid antigen, which interestingly is present within the spirochaetes as well as the cells in our body.
Now, plasma cells like to get themselves involved in the immune reaction by producing antibodies against these antigens.
In some cases, the immune cells start to huddle around and form a granulomatous lesion called agama. And this has lots of different types of immune cells that get surrounded by an outermost layer of fibroblasts often funnily enough.
There aren't any Spiros at all in these lesions. It's just like the immune cells are getting over excited and huddling up for no obvious reason.
The tissue at the center of the gumma often ends up without oxygen and that can lead to a coagulative necrosis. In tertiary syphilis, various organs get damaged like the heart and blood vessels, which is called cardiovascular syphilis, the brain and the spinal cord called neurosyphilis and also the liver joints and testes which haven't yet earned their own special names in cardiovascular syphilis.
There's endarteritis which is inflammation of the tiny arterioles called vasa vasorum, which supply blood to large arteries like the aorta.
The result is that parts of the aorta are damaged resulting in aortitis or inflammation of the aorta. And this can cause aortic aneurysms in neurosyphilis, the spirochaetes set up camp in the capillaries, supplying the posterior or back part of the spinal cord.
And this can result in something called tes dorsalis, which literally translates as wasting or loss of the back of the spinal cord.
The protective sheath which covers the nerves running along the back of the spinal cord is damaged and this results in a loss of vibration, sensation and a loss of proprioception, which is the sense of position of the joints and other body parts like the hands and the feet.
So that's what happens when syphilis damages the posterior spinal cord. But sometimes the spirochaetes invade the capillaries supplying the anterior or front of the spinal cord.
And that results in general paresis which causes loss of sensation and weakness or sometimes even paralysis mostly in the legs.
If spirochetes get into the capillaries serving the brain, then that can cause slurred speech, altered behavior, memory loss, difficulty coordinating muscle movements and even paralysis.
When there's a nearby object, it just doesn't do anything when it's too light. In congenital syphilis, the spirochaetes can infect the baby either via the placenta or during childbirth in the birth canal in early disease, which is in the first two years.
The result can range from a baby being stillborn or dying within the womb to having classic features like a maculopapular rash of the palms and soles of the feet and snuffles, which is when the nose is blocked by increased secretions which contain spirochaetes.
Babies may also have organ damage to the liver and spleen causing hepatosplenomegaly and damage to the eyes as well like optic neuritis in late disease, which is after a child is two years old.
Classic features often include a saddle nose which is a bony destruction of the nose, saber shins, which is when the tibia gets bent Hutchinson teeth, which is when the teeth develop little notches and hearing loss.
Diagnosis of acquired syphilis starts with identifying spirochaetes in the fluid from shanker. And this can be done using dark field microscopy.
A dark field microscope shines thin slivers of light on a slide so that the background appears dark while the extremely thin spirochetes light up, you know how we can see dust particles better in a dark room and there's just a stream of light shining through the door.
It's kind of like that. Now, the diagnosis is confirmed with serological tests and these look for antibodies against the T pallidum antigens.
There are non treponemal tests like the rapid plasma reagin test or RPR and the venereal disease research laboratory test or VDRL as well as tests that detect anticardiolipin antibodies called reagin in the blood.
The key though is that these are not specific to syphilis. For example, cardiolipin is also released by damaged cells in our body.
Then we have the treponema tests which include T pallidum particle agglutination or T PPA and fluorescent treponemal antibody absorbed or F TAA BS.
These treponemal tests detect antibodies that target T pallidum diagnosing congenital syphilis, as you might imagine is a bit different in congenital syphilis.
The diagnosis involves looking at the mother's and the baby's results in parallel. For example, if a baby's nontreponemal serologic titer is four times greater than the mother's titer.
Like if the baby's RPR is 1 to 64 and the mother's is 1 to 16, then that suggests that the baby has congenital syphilis in general for any baby whose mother was inadequately treated for syphilis or is suspected of having congenital syphilis.
For a different reason. It's helpful to get CSF fluid for VDRL as well as cell counts and protein.
It's also helpful to perform long bone x rays as well as an eye exam and a hearing screen. The main treatment for syphilis is penicillin, but in some cases, doxycycline can be used as well when using penicillin.
Though it's important to watch out for a Yaris Herx heimer reaction, which is when spirochetes die and break open, releasing a lot of antigens all at once and making the immune system go into overdrive.
When that happens, it results in sudden fevers sweating and muscle and joint pains that may last for a few hours up to a few days.
All right, it's a quick recap. So, syphilis is a sexually transmitted disease and it's caused by the spirochete called treponema pallidum.
It can cause disease in three stages. The first is a localized primary syphilis and this produces hard shakers.
The second is disseminated secondary syphilis which produces widespread maculopapular rash. And the third is systemic tertiary syphilis and that affects various organs.
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