Mycoplasma pneumoniae Infection


  • Diagnosis
  • Background
  • Lab Tests
  • References
  • Related Topics

Indications for Testing

  • Mild illness consisting of upper or lower respiratory illness with gradual onset of
    • Malaise
    • Fever
    • Headache
    • Sore throat
    • Persistent cough
    • Atypical pneumonia appearance on chest x-ray (patchy unilateral or diffuse bilateral infiltrates)
  • Appearance of extrapulmonary symptoms in addition to severe pneumonia – usually prompts testing
    • Rash, including Stevens-Johnson syndrome
    • Hemolysis, secondary to IgM cold agglutinins
    • Cardiac involvement including conduction disturbances, arrhythmias, congestive heart failure, and chest pain
    • Central nervous system (CNS) involvement
    • Gastrointestinal manifestations, eg, nausea, vomiting, and diarrhea
    • Joint pain
  • If indications are not present, testing for Mycoplasma pneumoniae is not indicated as this is usually a mild, self-limited disease that responds to macrolide antibiotics

Laboratory Testing

  • Polymerase chain reaction (PCR) 
    • Rapid test to identify M. pneumoniae
    • Increased sensitivity if sputum is tested and infection is in early stage (first 21 days after onset)
    • Probably most sensitive test to use, especially in adults who may not mount significant IgM levels early in infection
  • IgG, IgM by enzyme-linked immunosorbent assay (ELISA), complement fixation
    • Usually requires acute and convalescent samples
    • Not effective in early diagnosis
  • Cold agglutinins – especially if hemolysis is present or suspected
    • Negative result does not rule out infection
      • 30-50% of patients with M. pneumoniae will develop cold agglutinins (Fischbach, 2009)
  • Culture
    • Inadequate for acute diagnosis
    • Not recommended; bacteria are relatively fastidious and require a long incubation (up to 4 weeks)
  • Consider concurrent testing for Chlamydia pneumoniae, urinary antigen detection for Legionella, viral studies (eg, PCR panel) for respiratory viruses

Imaging Studies

Chest radiography – patchy unilateral infiltrates or diffuse bilateral interstitial process

Differential Diagnosis

Mycoplasmas, the smallest self-replicating organisms, include M. pneumoniae (pneumonia), M. genitalium, and Ureaplasma urealyticum (urethritis). M. pneumoniae is a common cause of community-acquired pneumonia.


  • Prevalence
    • Responsible for 15-20% of all community-acquired pneumonia; higher rates among school children and people in closed populations (military recruits)
    • 2-5% of patients require hospitalization as compared with 15-20% hospitalization rates for other causes of pneumonia
  • Transmission
    • Respiratory droplet
    • Most common in U.S. during late summer to early fall


  • M. pneumoniae
    • Flask-shaped bacteria with no true cell wall and a very small genome (816 kilobase pairs)
    • Facultative intracellular parasite
    • Cultivation in vitro is difficult
      • Fastidious nature
      • Dependence on externally supplied growth factors (by host organism or in culture medium)
      • Limited metabolic capacity inherent in small genome

Clinical Presentation

  • Most infections are mild and often indistinguishable from other viral and atypical bacterial pathogens
  • Initial symptoms
    • Malaise, myalgias, sore throat, headache (retro-orbital), ear pain, and fever
  • Advanced infection
    • Dry, nonproductive cough occurs 3-5 days after onset of initial nonspecific symptoms
    • Cough may produce mucopurulent sputum later in illness
    • May be accompanied by chills, chest pain, shortness of breath, nausea, vomiting, diarrhea
    • Patients usually seek medical attention after 5-7 days – cough may become paroxysmal and nocturnal
    • Cough may persist several weeks following resolution of constitutional symptoms
    • Pleural effusions more common in severe disease
  • Extrapulmonary manifestations of M. pneumoniae infection
    • Syndromes caused by spread of organism
      • Bullous hemorrhagic otitis
      • Arthritis
      • Acute respiratory distress syndrome
      • Myocarditis with conduction disturbances and chest pain
      • Encephalitis/meningitis
      • Sinusitis
    • Immunologically mediated syndromes
Tests generally appear in the order most useful for common clinical situations. Click on number for test-specific information in the ARUP Laboratory Test Directory.

Mycoplasma pneumoniae by PCR 0060256
Method: Qualitative Polymerase Chain Reaction

Mycoplasma pneumoniae Antibodies, IgG & IgM 0050399
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Cold Agglutinins 0050175
Method: Semi-Quantitative Hemagglutination

Explify Respiratory Pathogens by Next Generation Sequencing 2013694
Method: Massively Parallel Sequencing

General References

Atkinson TP, Balish MF, Waites KB. Epidemiology, clinical manifestations, pathogenesis and laboratory detection of Mycoplasma pneumoniae infections. FEMS Microbiol Rev. 2008; 32(6): 956-73. PubMed

Fischbach F, Dunning M. Chapter 8: Overview of Immunodiagnostic Studies. A Manual of Laboratory and Diagnostic Tests, 8th. Philadelphia: Lippincott Williams & Wilkins, 2009.

Loens K, Goossens H, Ieven M. Acute respiratory infection due to Mycoplasma pneumoniae: current status of diagnostic methods. Eur J Clin Microbiol Infect Dis. 2010; 29(9): 1055-69. PubMed

Thurman KA, Walter ND, Schwartz SB, Mitchell SL, Dillon MT, Baughman AL, Deutscher M, Fulton JP, Tongren JE, Hicks LA, Winchell JM. Comparison of laboratory diagnostic procedures for detection of Mycoplasma pneumoniae in community outbreaks. Clin Infect Dis. 2009; 48(9): 1244-9. PubMed

Waites KB. What's new in diagnostic testing and treatment approaches for Mycoplasma pneumoniae infections in children? Adv Exp Med Biol. 2011; 719: 47-57. PubMed

Zhang L, Zong Z, Bin Liu Y, Ye H, Lv X. PCR versus serology for diagnosing Mycoplasma pneumoniae infection: a systematic review & meta-analysis. Indian J Med Res. 2011; 134: 270-80. PubMed

References from the ARUP Institute for Clinical and Experimental Pathology®

Diaz MH, Benitez AJ, Cross KE, Hicks LA, Kutty P, Bramley AM, Chappell JD, Hymas W, Patel A, Qi C, Williams DJ, Arnold SR, Ampofo K, Self WH, Grijalva CG, Anderson EJ, McCullers JA, Pavia AT, Wunderink RG, Edwards KM, Jain S, Winchell JM. Molecular detection and characterization of Mycoplasma pneumoniae among patients hospitalized with community-acquired pneumonia in the United States. Open Forum Infect Dis. 2015; 2(3): ofv106. PubMed

Diaz MH, Cross KE, Benitez AJ, Hicks LA, Kutty P, Bramley AM, Chappell JD, Hymas W, Patel A, Qi C, Williams DJ, Arnold SR, Ampofo K, Self WH, Grijalva CG, Anderson EJ, McCullers JA, Pavia AT, Wunderink RG, Edwards KM, Jain S, Winchell JM. Identification of bacterial and viral codetections with Mycoplasma pneumoniae using the TaqMan Array Card in patients hospitalized with community-acquired pneumonia. Open Forum Infect Dis. 2016; 3(2): ofw071. PubMed

Dunn JJ, Malan AK, Evans J, Litwin CM. Rapid detection of Mycoplasma pneumoniae IgM antibodies in pediatric patients using ImmunoCard Mycoplasma compared to conventional enzyme immunoassays. Eur J Clin Microbiol Infect Dis. 2004; 23(5): 412-4. PubMed

Medical Reviewers

Content Reviewed: 
September 2017

Last Update: October 2017