Common findings are gradual onset of pharyngitis, headache, paroxysmal cough, pleuritic chest pain, dry cough (and later productive cough), infiltrates, and leukocytosis. [CCDM, p. 469]
Most patients do not develop pneumonia, but have cough, wheezing, dyspnea, pharyngitis (6-59%), and rhinorrhea (2-40%), [Cohen, p. 175] Fever is usually in the 101-103 range. 3/4 of patients have rales and rhonchi. Each of the following is present in about 1/4 to 1/2 of patients: runny nose, myalgias, chest pain, sore throat, and hoarseness. About 1/4 of patients have leukocytosis. About 1/4 of adults with pneumonia have pleural effusions. Blood-tinged sputum is rarely seen. [ID, p. 504-7, 1366] About 23% of community-acquired pneumonia is caused by Mycoplasma. Cases of upper respiratory tract infection are about 20 times more common than cases of pneumonia. About 17% of patients had a rash (maculopapular, vesicular, petechial, or urticarial) in some case series. If anemia occurs, it is usually in the second or third week. [Harrison ID, p. 740-2]
CNS complications occur in about 1/1000 cases (meningoencephalitis, cranial nerve neuritis, neuropathy, and Guillain-Barre syndrome). Other rare complications are erythema nodosum, pericarditis, nephritis, Stevens-Johnson syndrome, and aplastic or hemolytic anemia. [ID, p. 504-7, 1366] A variety of skin eruptions are associated with mycoplasma pneumonia (maculopapular, vesicular, and urticarial). Rhinitis, pharyngitis, and otitis media may occur. Arthralgias are common. Neurological complications (meningoencephalitis, myelitis, and stroke) occur in up to 7% of hospitalized patients. [PPID, p. 2187]
Cold agglutinins develop in 50-75% of patients 1-2 weeks after infection; hemolysis may be severe, but it is not usually clinically significant. [Cohen, p. 1803] The organism has no cell wall and is not visible by Gram stain. [Harrison ID, p. 742]
The infection tends to spread in families in a slow step-wise manner with a 2-3 week delay between family members. The highest attack rates occur in children and young adults 5-20 years of age. [Cecil, p. 1912] Outbreaks occur in institutions and military populations especially in the late summer and fall. [CCDM, p. 470] Incidence does not vary much with season, but Mycoplasma causes up to 50% of pneumonia cases in the summer. [5MCC-2015]
For updated text and symptoms of infectious diseases, see iddx.com.