Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link



Margaret R. Hammerschlag

, MD, State University of New York Downstate Medical Center

Last full review/revision May 2021| Content last modified May 2021
Click here for the Professional Version

Mycoplasmas are bacteria that cause infections in the respiratory tract and the urinary and genital tracts.

Mycoplasmas are different from other bacteria because they do not have cell walls. Many antibiotics, such as penicillin, kill bacteria by weakening cell walls. Because Mycoplasmas do not have cell walls, many antibiotics cannot kill them.

Mycoplasma pneumoniae is a common cause of community-acquired pneumonia in all age groups. Outbreaks have occurred in schools, camps, and military camps.

Mycoplasma genitalium can cause sexually transmitted infections of the urethra (urethritis) and sometimes, in women, pelvic inflammatory disease.

Symptoms of Mycoplasmas

Symptoms of pneumonia due to M. pneumoniae are typically mild, including low-grade fever, tiredness, sore throat, and cough. This infection is sometimes called "walking" pneumonia, which is a nonmedical term for mild pneumonia that does not require bedrest or hospitalization. Some people even feel well enough to go to work and participate in other daily activities. However, M. pneumoniae sometimes causes a more serious pneumonia that requires hospitalization.

Many people with urinary and genital infection with mycoplasma, especially women, have no symptoms. When symptoms are present, they are similar to those of urinary and genital infection with chlamydia and vary by sex and location of infection:

  • Women may have an abnormal vaginal discharge or a burning sensation while urinating.

  • Men may notice a burning sensation while urinating and sometimes a discharge from the penis.

Diagnosis of Mycoplasmas

  • Nucleic acid amplification tests

Mycoplasmas can sometimes be identified by doing nucleic acid amplification tests (NAATs) on respiratory secretions or on vaginal or urethral swabs. NAATs look for an organism's unique genetic material, its DNA or RNA (which are nucleic acids). NAATs use a process that increases the amount of the bacteria's DNA or RNA so that it can be more easily identified. 

Prevention of Mycoplasmas

As with other respiratory infections, prevention includes covering the mouth when coughing or sneezing and washing hands often with soap and water.

Safe sex practices are recommended to decrease risk of sexually transmitted infection.

There is no vaccine for M. pneumoniae infections.

Treatment of Mycoplasmas

  • Antibiotics

Mycoplasmal infections are treated with antibiotics such as azithromycin, doxycycline, or, sometimes, levofloxacin or moxifloxacin.

More Information

The following are English-language resources that may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version


Chlamydial Infections and Mycoplasmas
Others also read

Test your knowledge

Chickenpox is a highly contagious viral infection that tends to be fairly mild in most cases. Which of the following groups has the lowest risk of complications from chickenpox?
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID