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.

A sick young woman sneezing into a tissue

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

How it spreads

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.

Common outbreak settings

M. pneumoniae outbreaks occur mostly in crowded settings like schools, college residence halls, military training facilities, long-term care facilities, and hospitals. During school-based outbreaks, family members of ill school children are the most likely community members to be affected.