Mycoplasma amphoriforme, M. genetalium, M. hominus, M. incognitus, M. pneumoniae. They all lack cell walls and are not gram stainable.
Person to person spread, M. pneumoniae is spread by coughing; rates go up when it is humid (PubMed).
Up to 25% of vectors, I mean young children, can be asymptomatic carriers. Since asymptomatic carriage is common, it makes false positive tests likely (PubMed).
M. pneumoniae: most have a URI, some go on to pneumonia with the CXR looks worse than the patient. Cold agglutinins, hemolytic anemia, bullous myringitis, encephalitis, myocarditis and pericarditis, erythema nodosum, urticaria, Stevens-Johnson, and polyarthralgias are part of this endlessly curious disease. Maybe methemoglobinemia (PubMed)
The neurologic manifestations may be due to cross reacting antibodies rather than direct CNS invasion (PubMed).
A new Mycoplasma (Hemoplasma) can cause a severe hemolytic anemia with fever (PubMed).
Mycoplasma amphoriforme causes pneumonia, including chronic/relapsing pneumonia in patients with primary antibody deficiency (PubMed).
Macrolides (although resistance is increasing espcially in Asia) OR doxycycline. The quinolones are also active. As of 2012, 8.2% are resistant to macolides (PubMed), although depending on the population, up to 66% of Mycoplasma pneumoniae can be macrolide resistant. In severe cases, steroids get the patient better faster (PubMed).
Mycoplasma genitalium may be better treated with 1 gram of azithromycin rather than doxycycline (PubMed, PubMed) but moxifloxacin is the only drug always effective (PubMed). 10% are resistant and resistance is increasing to quinolones and macrolides (PubMed). Other studies have found macrolide resistance in 38% of the M. genitalium patients, with 43% resistance in patients tested at sexually transmitted disease clinics (PubMed).
Resistance to macrolides can be as high at 69% in some series and is associated with a prolonged fever.
Pristinamycin is effective in treatment failures (PubMed).