Genitourinary System Diseases

Bacterial Sexually Transmitted Diseases

Gonorrhea, chlamydia, and syphilis are common sexually transmitted disease caused by bacteria, and while all three are readily treatable, they can also lead to more serious conditions.

While vaginitis and vaginosis tend to be short-lived infections that affect the lower reproductive tract, bacteria are also able to cause much more serious chronic diseases. One example of this is the sexually transmitted disease gonorrhea. Gonorrhea is caused by a gonococcus, the gram-negative bacterium Neisseria gonorrhoeae, which infects both males and females but often shows no symptoms in females. It can also cause production of discharge, urethritis, and the sensation of burning during urination for both males and females. Gonorrhea can be diagnosed by culturing the gonococcus from discharge samples or by using polymerase chain reaction (PCR), and it is treated with an antibiotic combination of ceftriaxone and azithromycin. Antibiotic resistance to fluoroquinolones is common. If left untreated, N. gonorrhoeae infection can last for months and can eventually spread to the bloodstream and cause much more serious systemic disease, including gonorrheal endocarditis, an infection of the heart's inner lining, arthritis, and meningitis.

Chlamydia, a sexually transmitted disease caused by the organism Chlamydia trachomatis, infects the upper reproductive system (uterus, fallopian tube, and ovaries), causing inflammation and production of discharge. C. trachomatis is an example of a gram-negative bacterium, and the symptoms of chlamydia can be similar to those of gonorrhea. Most who are infected have no symptoms, though those that do tend to experience production of discharge, fever, and pain during urination. C. trachomatis is also capable of infecting eye and joint tissue, causing blindness or arthritis, respectively, if left untreated. Chlamydia can be treated with erythromycin or doxycycline antibiotics.

Both C. trachomatis and N. gonorrhoeae infections can potentially spread further into the reproductive system and develop into a more complicated disease in women called pelvic inflammatory disease. Pelvic inflammatory disease is a chronic bacterial infection of the upper reproductive tract in females that is responsible for inflammation of the fallopian tubes, the uterus, and the cervix. While C. trachomatis and N. gonorrhoeae are found in the vast majority of cases, more than one bacterial infection is usually involved in the disease. The resulting symptoms are fever, vaginal discharge, pain during urination, irregular menstruation, and lower abdominal pain. If left untreated, pelvic inflammatory disease can cause considerable tissue damage and can result in infertility, ectopic pregnancies—pregnancy outside of the uterus, such as in the fallopian tubes—and ovarian cancer. Pelvic inflammatory disease is typically treated with antibiotics similar to those used to treat gonorrhea and chlamydia.
Pelvic inflammatory disease (PID) is an infection of the upper reproductive tract in females, caused primarily by Neisseria gonorrhoeae (scanning electron microscope) and Chlamydia trachomatis (light microscope, 200x).
Credit: NIAID (left), CDC/Dr. E. Arum; Dr. N. Jacobs (right)License: CC BY 2.0 (left)
Genital ulcers can be caused by syphilis, a sexually transmitted disease caused by the bacterium Treponema pallidum. When syphilis is in its early stage, it can be spread through vaginal, anal, and oral sexual contact. If a pregnant woman has active syphilitic ulcers, the disease can be spread from mother to fetus through vertical transmission. There are three active stages of syphilis and a latent phase.

During the primary phase, one or several ulcers develop at the site of infection, but may go unnoticed because they are not painful. Antibiotic treatment, typically with beta-lactam antibiotics such as penicillin, during the primary phase will stop the infection from spreading and causing further complications. Penicillin is the drug of choice for treatment, though resistance to is common. Macrolide antibiotics are used for patients allergic to penicillin, and T. pallidum resistance to both beta-lactam antibiotics or macrolide antibiotics is common.

The secondary phase can include fever, spreading skin rash on the genital area, ulcers in mucous membranes of the mouth, vagina, or anus, and swelling of the lymph nodes. The symptoms of the primary and secondary phases will abate even without treatment, and the infection will transition into the latent phase, during which no symptoms will present for many years. If left untreated, T. pallidum can spread throughout the body and cause life-threatening systemic infection during the tertiary phase. In the tertiary phase, T. pallidum causes neurological damage can be misdiagnosed as mental illness.

Diagnosing syphilis is accomplished through observation of symptoms or examination of samples from ulcers with a microscope. More direct and precise diagnosis is achieved with PCR to detect the presence of syphilis genes or a fluorescently labeled antibody test to detect specific T. pallidum antigens.
Treponema pallidum is a spirochete bacterium and causative agent of the sexually transmitted disease syphilis.
Credit: CDC/Dr. Edwin P. Ewing, Jr.