<< Chapter < Page Chapter >> Page >

Chlamydia

Chlamydia trachomatis is the causative agent of the STI chlamydia ( [link] ). While many Chlamydia infections are asymptomatic, chlamydia is a major cause of nongonococcal urethritis (NGU) and may also cause epididymitis and orchitis in men. In women, chlamydia infections can cause urethritis, salpingitis , and PID. In addition, chlamydial infections may be associated with an increased risk of cervical cancer .

Because chlamydia is widespread, often asymptomatic, and has the potential to cause substantial complications, routine screening is recommended for sexually active women who are under age 25, at high risk (i.e., not in a monogamous relationship), or beginning prenatal care.

Certain serovars of C. trachomatis can cause an infection of the lymphatic system in the groin known as lymphogranuloma venereum . This condition is commonly found in tropical regions and can also co-occur in conjunction with human immunodeficiency virus (HIV) infection. After the microbes invade the lymphatic system, buboes (large lymph nodes, see [link] ) form and can burst, releasing pus through the skin. The male genitals can become greatly enlarged and in women the rectum may become narrow.

Urogenital infections caused by C. trachomatis can be treated using azithromycin or doxycycline (the recommended regimen from the CDC). Erythromycin, levofloxacin , and ofloxacin are alternatives.

a) Micrograph showing brown coloration inside cells. B) photo of a swollen region on either side of the penis.
(a) Chlamydia trachomatis inclusion bodies within McCoy cell monolayers. Inclusion bodies are distinguished by their brown color. (b) Lymphogranuloma venereum infection can cause swollen lymph nodes in the groin called buboes. (credit a: modification of work by Centers for Disease Control and Prevention; credit b: modification of work by Herbert L. Fred and Hendrik A. van Dijk)
  • Compare the signs and symptoms of chlamydia infection in men and women.

Syphilis

Syphilis is spread through direct physical (generally sexual) contact, and is caused by the gram-negative spirochete Treponema pallidum . T. pallidum has a relatively simple genome and lacks lipopolysaccharide endotoxin characteristic of gram-negative bacteria. However, it does contain lipoproteins that trigger an immune response in the host, causing tissue damage that may enhance the pathogen’s ability to disseminate while evading the host immune system.

After entering the body, T. pallidum moves rapidly into the bloodstream and other tissues. If not treated effectively, syphilis progresses through three distinct stages: primary, secondary, and tertiary. Primary syphilis appears as a single lesion on the cervix, penis, or anus within 10 to 90 days of transmission. Such lesions contain many T. pallidum cells and are highly infectious. The lesion, called a hard chancre , is initially hard and painless, but it soon develops into an ulcerated sore ( [link] ). Localized lymph node swelling may occur as well. In some cases, these symptoms may be relatively mild, and the lesion may heal on its own within two to six weeks. Because the lesions are painless and often occur in hidden locations (e.g., the cervix or anus), infected individuals sometimes do not notice them.

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Microbiology' conversation and receive update notifications?

Ask