Disease/Syndrome

Mycoplasmal pneumonia

Category

Infection, Occupational

Acute/Chronic

Acute-Moderate

Synonyms

Primary atypical pneumonia; Mycoplasma pneumoniae infection

Biomedical References

Search PubMed

Comments

INITIAL SYMPTOMS: Common findings are gradual onset of pharyngitis, headache, paroxysmal cough, pleuritic chest pain, dry cough (and later productive cough), infiltrates, and leukocytosis. [CCDM] FINDINGS: Most patients do not develop pneumonia, but have cough, wheezing, dyspnea, pharyngitis (6-59%), rhinorrhea (2-40%), and bullous myringitis (2-35%). [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] COMPLICATIONS: 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] Erythema multiforme is fairly common, especially in children with Mycoplasma pneumonia. [UpToDate Online 12.2] The organism is not usually visible in sputum Gram stains. About 3/4 of patients develop bronchitis while only about 1/3 of patients develop pneumonia. [Lexi-ID, p. 226-9] A variety of skin eruptions are associated with mycoplasma pneumonia (macular, vesicular, and urticarial). Bullous myringitis and arthritis are rare. Pharyngitis may occur, but without the prominent cervical adenopathy seen in streptococcal sore throat. Arthralgias are common. Neurological complications have been reported, but not proven to be causally related. [PPID, p. 2481-9] LABORATORY: 75% of patients may have cold agglutinin antibodies and a positive Coombs' test, but "clinically significant autoimmune hemolytic anemia is uncommon." [PPID, p. 287] 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] EPIDEMIOLOGY: 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. [Lexi-ID, p. 226-9] Outbreaks occur in institutions and military populations especially in the late summer and fall. [CCDM, p. 476-8] Incidence does not vary much with season, but causes a greater percentage of pneumonia in summer and fall. [5MCC-2013]

Latency/Incubation

6 days to 1 month; usually about 2 weeks;

Diagnostic

Requires 7-14 days to grow in culture; Cold agglutinin titer > 1:32 supportive but not specific; About 89-95% sens/spec to detect DNA in sputum by GenProbe or PCR; IgM (-) for first 7-10 days; [ABX Guide]

ICD-9 Code

483

Effective Antimicrobics

Yes

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