Read condition-specific symptoms and clinical context for Mycoplasma pneumoniae. A wall-less bacterium that causes chest colds and the mild pneumonia people often keep walking around with.
PHAC describes M. pneumoniae as a spindle-shaped, pleomorphic bacterium measuring 1 to 2 micrometres long by 0.1 to 0.2 micrometres wide that lacks a cell wall, has a three-layered membrane containing sterols for structural support, and uses gliding motility instead of pili or flagella. CDC states that the bacteria cause respiratory tract infections and can damage the lining of the throat, windpipe and lungs, that the most common presentation is a chest cold while pneumonia is less common, and that it can take 1 to 4 weeks for symptoms to appear after exposure. Having no cell wall is the reason cell-wall antibiotics such as penicillins do not work against it. PHAC describes cyclic epidemics every 3 to 6 years.
PHAC describes an illness developing over several days and persisting for weeks to months. CDC adds that it can take 1 to 4 weeks for symptoms to appear after exposure and that the most common presentation is a chest cold rather than pneumonia.
Possible symptoms: Sore throat; Hoarseness; Fever; Cough; Headaches; Runny nose; Earache; Muscle aches; Chills; General malaise.
CDC describes pneumonia from this organism as often mild enough that people keep going about daily activities. Because the organism has no cell wall, cell-wall antibiotics do not work against it; treatment choice is a clinical decision and is not given here.
PHAC records that shedding persists from 2 to 8 days before onset of symptoms and as long as 14 weeks after infection.
There is by definition no symptom list for the period before symptoms begin or for prolonged shedding after recovery, and none is invented here. PHAC’s shedding window is why outbreaks in schools, households and other closed communities can continue after the first people have recovered. CDC states that people spread M. pneumoniae through coughing or sneezing. This is a shedding state during and around infection, not carriage of a normal human resident.
Shedding is a transmission consideration rather than an illness. Decisions about returning to school or work are made locally and are not given here.
Source check: 2026-09-20. Educational content; independent scientific review remains pending.