History and exam
Key diagnostic factors
common
presence of risk factors
Risk factors include: close community settings, recent exposure, cigarette smoking, age <30 years.
persistent cough
May indicate Mycoplasma pneumoniae infection. Often does not resolve with time.
dry cough
May indicate Mycoplasma pneumoniae infection.
prolonged symptoms
Prolonged time from the onset of symptoms to the presentation may suggest Mycoplasma pneumoniae infection.
fever
May indicate Mycoplasma pneumoniae infection. Low-grade fever most common.
adventitious sounds on physical examination
May be mild or absent. Coarse crackles will change to fine crackles at a late phase (3-5 days after initial onset).
exposure to a person with respiratory tract infection
In many cases the patient will report close contact with a person who has had respiratory symptoms in the last few days or weeks.
Other diagnostic factors
common
throat involvement
Pharyngitis and hoarseness may be present with Mycoplasma pneumoniae.
rash
May accompany Mycoplasma pneumoniae pneumonia in 10% to 20% of cases.
uncommon
headache
May be present with Mycoplasma pneumoniae infection.
bullous myringitis
Rare sign (5%) suggesting Mycoplasma pneumoniae infection.
hepatitis
The presence of hepatitis with pneumonia may suggest that Mycoplasma pneumoniae is a pathogen.
Risk factors
strong
close community settings
recent exposure
Exposure to someone with respiratory infection.
cigarette smoking
age <30 years
Children and young adults appear to be the most susceptible population to Mycoplasma pneumoniae infection.[26]
weak
immunosuppression
Immunosuppressed patients tend to have more severe and invasive disease.[4]
Mycoplasma other than Mycoplasma pneumoniae have been isolated from invasive disease in HIV and other immunosuppressed patients.
Hypogammaglobulinaemia is also associated with increased risk of respiratory and joint infections due to M pneumoniae.[4]
asplenia
Sickle cell anaemia patients with functional asplenia tend to have more severe Mycoplasma pneumoniae disease.[27]
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