Treponema pallidum (Syphilis)


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Treponema pallidum (Syphilis)


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Treponema pallidum (Syphilis)

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Treponema pallidum (Syphilis)


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USMLE® Step 1 questions

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High Yield Notes

8 pages


Treponema pallidum (Syphilis)

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USMLE® Step 1 style questions USMLE

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A 58-year-old woman presents to the clinic with a history of fever and painless genital lesions that she first noticed a week ago. Two months ago, she was treated for a urinary tract infection with oral nitrofurantoin. She lives in New Hampshire and goes hiking in the woods often. The patient is sexually active and began a relationship with a new partners six months ago. They use condoms inconsistently. Past medical history is significant for an episode of cervicitis and pelvic inflammatory disease in her teens. Temperature is 37.7°C (100°F), pulse is 99/min, respirations are 20/min, and blood pressure is 120/75 mmHg. Physical examination reveals diffuse cervical lymphadenopathy and a maculopapular rash over the trunk, abdomen, and extremities, including the palms and soles of the feet. The abdomen is soft and nontender. An image of the initial genital examination is demonstrated below.

The patient is started on appropriate pharmacologic treatment, but she returns to the clinic two days later after experiencing a continued fever plus chills, headaches, myalgias, and worsening of the maculopapular rash. Which of the following is the most likely diagnosis?

CDC Public Health library

External References

First Aid









syphilis p. 145


in syphilitic heart disease p. 321

Aortic aneurysm p. 308

syphilitic heart disease p. 321

Aortic insufficiency

syphilitic heart disease p. 321


syphilis p. 145, 180

Argyll Robertson pupils

syphilis p. 145, 180


syphilis p. 145

Charcot joints

syphilis p. 145

Condylomata lata

syphilis p. 145, 180


syphilis p. 181


syphilis p. 145, 180

Hydrops fetalis

syphilis p. 181


syphilis p. 145, 180

Maculopapular rash

syphilis p. 145

Pregnancy p. 657

syphilis in p. 145


syphilis p. 145, 180

Saber shins

syphilis p. 181

Saddle nose

syphilis p. 181

Spontaneous abortion

syphilis p. 181

Stroke p. 529

syphilis p. 145

Syphilis p. 145

as granulomatous disease p. NaN

presentation p. 716

prophylaxis for p. 195

STI p. 180

tabes dorsalis p. 548

testing for p. 145

thoracic aortic aneurysms and p. 308

ToRCHeS infection p. 181

Syphilitic heart disease p. 321

Tertiary syphilis

aortic aneurysms p. 728

as granulomatous disease p. NaN

presentation p. 716

Treponema pallidum

syphilis p. 145

Vasa vasorum

syphilis p. 145



Evan Debevec-McKenney

Jake Ryan

Sam Gillespie, BSc

Jahnavi Narayanan, MBBS

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 being's body. They belong to a group of bacteria called spirochetes, which are long and thin, and contain endoflagella, which are a band of protein filaments that coil within the spirochetes, and give them a spiral shape - kind of like a curly fry, but a little less appetizing. The endoflagella also help the spirochetes 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 lesion is covered in this fluid which is rich in spirochetes. The second way is called congenital syphilis and that’s when a pregnant person has syphilis and Treponema pallidum infects a baby either in the uterus or while the baby exits through the vagina at birth.

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.


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.


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