  History & Disease Patterns   Mycoplasma pneumoniae (M.
pneumoniae) was discovered in 1944 in a patient with “atypical”
pneumonia. It was first thought to be a virus or fungus, which
is why the name “mycoplasma” (Greek for “fungus-formed”) was
chosen. It was eventually learned to be a bacterium, but unlike
many other bacteria, it has many unique characteristics. For
example, it does not have a rigid cell wall, which affects the
types of antibiotics that work well against it. This is why it
is classified as an “atypical” bacterium. It is also the
smallest organism capable of living and reproducing on its own.
Smaller germs, like viruses, have to live and reproduce inside
cells.  Disease Patterns  M. pneumoniae infections are common in
the United States. The number of infections varies over time,
with peaks of disease every 3 to 7 years. An estimated 2 million
cases of M. pneumoniae infections occur each year in the United
States.1,2 However, many infections are not diagnosed, so the
actual number is likely hi