Causes and How It Spreads


Mycoplasma pneumoniae are bacteria that can cause illness by damaging the lining of the respiratory system (throat, lungs, windpipe). People can have the bacteria in their nose or throat at one time or another without being ill.

How It Spreads

A sick young woman sneezing into a tissue

People spread Mycoplasma pneumoniae bacteria to others by coughing or sneezing.

When someone infected with M. pneumoniae coughs or sneezes, they create small respiratory droplets that contain the bacteria. Other people can get infected if they breathe in those droplets.

Most people who spend a short amount of time with someone who is sick with M. pneumoniae do not get infected. However, the bacteria often spread between people who live together since they spend a lot of time together. M. pneumoniae outbreaks occur mostly in crowded settings like schools, college residence halls, military barracks, nursing homes, and hospitals. During school-based outbreaks, if people in the community get sick they are usually family members of ill school children.1,2,3


1Foy HM, Grayston JT, Kenny GE, Alexander ER, McMahan R. Epidemiology of Mycoplasma pneumoniae infection in familiesExternalexternal iconJAMA. 1966;197:859–66.

2Walter ND, Grant GB, Bandy U, et al. Community outbreak of Mycoplasma pneumoniae infection: School-based cluster of neurologic disease associated with household transmission of respiratory illnessExternalexternal iconJ Infect Dis. 2008;198:1365–74.

3CDC. Mycoplasma pneumoniae respiratory illness — two rural counties, West Virginia, 2011MMWR Morb Mortal Wkly Rep. 2012;61:834–8.