Common Sexually Transmitted Infections

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Block C4 - Adolescence and Adulthood


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Bacterial[edit]

Chancroid (Haemophilus ducreyi)[edit]

H. ducreyi is the bacterial cause of chancroid, an STD characterized by tender, ragged genital ulcers that are variable in size and tender, enlarged lymph nodes. In the United States, chancroid is not common. According to the National Institute for Health (NIH, 2011), uncircumsized males are at greater risk for contracting chancroid. It is easily treatable by antibiotics.

Diagnosis[edit]

  • The patient has one or more painful genital ulcers;
  • The patient has no evidence of T. pallidum infection by darkfield examination of ulcer exudate or by a serologic test for syphilis performed at least 7 days after onset of ulcers;
  • The clinical presentation, appearance of genital ulcers and, if present, regional lymphadenopathy are typical for chancroid; and
  • A test for HSV performed on the ulcer exudate is negative.

Treatment[edit]

  • Azithromycin 1 g orally in a single dose; or
  • Ceftriaxone 250 mg intramuscularly (IM) in a single dose; or
  • Ciprofloxacin 500 mg orally twice a day for 3 days; or
  • Erythromycin base 500 mg orally three times a day for 7 days

Chlamydia (Chlamydia trachomatis)[edit]

C. trachomatis is an intracellular parasitic bacterium that infects the lining of the urethra, cervix, epididymis, and Fallopian tubes. In the lining of the urethra, it causes the most common form of nongonococcal urethritis (NGU). Chlamydial infections are quite common, especially among teens and young adults, but the infections are not always symptomatic. In women, untreated chlamydial infections can cause pelvic inflammatory disease (PID), potentially leading to infertility or ectopic pregnancies. CDC recommends annual chlamydia screening for all sexually active females 25 and under and for women older than 25 with risk factors such as a new sex partner or multiple partners

Treatment[edit]

Chlamydia can be easily treated and cured with antibiotics. A single dose of azithromycin or a week of doxycycline (twice daily) are the most commonly used treatments.

Gonorrhea (Neisseria gonorrhoeae)[edit]

N. gonorrhoeae is a diplococcus that causes gonorrhea, which can infect the urethra, Bartholin’s glands, cervix, epididymis, and Fallopian tubes. Oral sex can lead to gonococcal pharyngitis and anal sex to gonococcal proctitis. Untreated gonococcal infections can cause PID, potentially leading to infertility or ectopic pregnancies in women and epididymitis in men. In the newborn, it manifests as a conjunctivitis that can cause blindness. Gonorrhea is about one tenth as common as chlamydial infections, although the two infections are frequently found to coexist in an infected person. The classical presentation of gonorrhea is as urethritis.

Syphilis (Treponema pallidum)[edit]

Differential diagnosis of genital ulcers

T. pallidum is the bacterium causing syphilis. It usually begins with a single, painless skin chancre (i.e., an ulcer) that appears on the genitals or mouth, which, if untreated, can progress. The progression of the disease is slow but potentially fatal.

Treatment[edit]

Benzathine penicillin G 2.4 million units IM in a single dose

Viral[edit]

Genital herpes (HSV)[edit]

Differential diagnosis of genital ulcers

HSV comprises two types, HSV-1 and HSV-2. People who have genital HSV infections can have recurring outbreaks of the disease (genital herpes), which are typically shallow erosions that appear as clusters of vesicular lesions that rupture into painful ulcers. As they heal, herpetic ulcers become crusty. Genital herpes can occur throughout the anogenital and perineal region as well as the mouth in the case of oral sex. People infected with genital HSV can shed the virus and transmit the disease even when they have no apparent skin lesions.

Diagnosis[edit]

Numerous herpes diagnostic tests are available. Direct (or virologic) tests detect viable virus, viral antigen, or viral nucleic acid. Viral culture is currently the reference standard for diagnosing genital herpes. HSV culture requires collection of a sample from the sore and, once viral growth is seen, specific cell staining to differentiate between HSV-1 and HSV-2. Nucleic acid amplification techniques (NAATs), such as PCR, test for viral DNA or RNA and allow for more rapid and accurate results.

Treatment[edit]

  • Acyclovir 400 mg orally three times a day for 7–10 days; or
  • Acyclovir 200 mg orally five times a day for 7–10 days; or
  • Famciclovir 250 mg orally three times a day for 7–10 days; or
  • Valacyclovir 1 g orally twice a day for 7–10 days
  • Acyclovir ointment for topical therapy.

Genital warts (Condyloma acuminata) (HPV)[edit]

HPV infections can be sexually transmitted even when an infected person has no visible symptoms. The common types of genital HPV infections can cause anogenital warts, called condyloma acuminata. Less common types of genital HPV infections appear to cause cervical, vulvar, or penile cancer. HPV infections often disappear spontaneously or may need to be excised.

Human immunodeficiency virus (HIV)[edit]

HIV infections deplete the immune system of cells, including a subclass of T lymphocytes called CD4 cells. Eventually, the immune system can become so ineffective that cancers and opportunistic infections (OIs) by other organisms can get a foothold and spread. At this stage, the HIV-infected person is said to have developed AIDS. HIV can be transmitted through sexual contact, and if AIDS develops, the secondary urinary and genital tract diseases that can develop include OIs of the vulva, vagina, cervix, prostate, epididymis, and testis, and cancers of the cervix and testis.

Treatment[edit]

  • Acyclovir 400–800 mg orally twice to three times a day; or
  • Famciclovir 500 mg orally twice a day; or
  • Valacyclovir 500 mg orally twice a day

Molluscum contagiosum (MCV)[edit]

MCV causes a common, mild, and self-limiting skin disease (molluscum contagiosum) of children, characterized by small, dimpled papules or vesicles. In adults, MCV also causes genital skin lesions that can be spread through sexual.

Treatment[edit]

  • Imiquimod immunotherapy
  • Cryosurgery: uses liquid nitrogen to freeze and destroy lesions.

Protozoal[edit]

Trichomoniasis (Trichomonas vaginalis)[edit]

Trichomonas vaginalis. T. vaginalis lives inside cells along the lower genital tract of females and along the urethra and the prostate of males. Symptoms of trichomoniasis are more common in women, where vaginitis is the typical clinical manifestation.

Diagnosis[edit]

  • In women, vaginal trichomoniasis has historically been diagnosed by wet mount microscopy. (sensitivity: 50-70%)
  • T. vaginalis cultures. (sensitivity: higher than microscopy and 81-100% when combined with microscopy)
  • OSOM Trichomonas Rapid Test. (sensitivity: 83%)
  • Affirm VP III Microbial Identification Test. (sensitivity: 97%)
  • APTIMA Trichomonas vaginalis ATV Assay. (sensitivity: 74-98%, specificity: 87-98%)
  • PCR methods. (sensitivity: 84%, specificity: 94%)
    • Amplicor, an FDA-approved PCR assay for gonorrhea and chlamydia modified to detect T vaginalis, was found to have a sensitivity of 88-97% and specificity of 98-99%

Treatment[edit]

  • 5-Nitroimidazole drugs such as metronidazole and tinidazole.

Parasitic[edit]

Pubic lice (Pediculosis pubis)[edit]

Pubic lice, also called crabs or pediculus pubis, live alongside coarse human hairs on which they lay their eggs (nits). Pubic lice cause itching and skin irritation, and an infestation of pubic lice is treated with topical insecticides

Scabies (Sarcoptes scabiei)[edit]

Itch mites cause the skin disease scabies. In scabies, mites burrow into the upper layer of the skin, where they lay eggs and cause a rash and intense itching. Scabies is also treated with topical insecticides. This disease is not confined to genital areas and is usually diagnosed by visual inspection and history


Links[edit]