An infection that previously was mostly seen in children, over the past 15 years has been showing up more frequently in older adults. With its extended incubation period (2-4 weeks), it is difficult to diagnose, and capable of emerging as bronchitis or pneumonia.
And it is caused by the smallest free-living organisms — Mycoplasma pneumoniae — that were originally thought to be viruses, but have been shown to be bacteria. Unlike most bacteria they lack a cell wall and are bounded by only a thin plasma membrane.
These unique properties extend to their clinical features. Hence, the individual patient can have an extended period of “feeling like they are getting sick, but not really being sure.” Then the steamroller hits, often presenting as bronchitis or pneumonia, along with symptoms in other areas: headache, muscle aches, arthritis and GI symptoms. It can also cause a very painful type of ear infection with blisters on the ear drum.
Because of its lack of a cell wall it’s very difficult to grow in a culture and can be “missed” by this test; a fairly accurate blood test exists. It may be best recognized by its slow onset with attendant non-respiratory symptoms. It does respond to a few specific antibiotics: tetracyclines, macrolides and fluoroquinolones.