History and exam
Key diagnostic factors
common
presence of risk factors
Key risk factors include close community settings and immunosuppression.
age <50 years
Many patients with atypical bacterial pneumonia will be younger than 50 years.
persistent cough
In many cases, patients will complain about persistent cough that does not resolve with time.
dry cough
The presence of a dry cough should prompt suspicion that an atypical pathogen is present.
long duration of symptoms
Prolonged time from onset of symptoms to the presentation can suggest atypical bacterial pneumonia.
Other diagnostic factors
common
recent community exposure
A history of exposure to someone with respiratory infection is a risk factor for atypical bacterial pneumonia.
throat involvement
In many cases of pneumonia due to Mycoplasma pneumoniae and Coxiella burnettii pneumonia, pharyngitis and hoarseness will be present as well.
uncommon
fever
Fever, if present, is usually low grade.
headache
Headache may accompany Mycoplasma pneumoniae and Chlamydophila pneumoniae infections.
diarrhoea
Non-bloody diarrhoea may accompany Legionella infections.
bullous myringitis
Bullous myringitis is rare sign that suggests Mycoplasma pneumoniae infection.
lung rales/crepitations
Clinical signs of pneumonia on physical examination may be mild or absent.
rash
A mainly self-limited maculopapular or vesicular rash can accompany Mycoplasma pneumoniae pneumonia.
Risk factors
strong
close community settings
Many studies have shown that exposure to Mycoplasma pneumoniae and Chlamydophila pneumoniae in close community settings such as boarding schools, college dormitories, army basic training camps, or even hospitals can lead to outbreaks of infection with these pathogens.[5][30] This takes place mainly by person-to-person transmission among people in close proximity to each other.
weak
cigarette smoking
A few studies have shown that people who smoke are at greater risk for developing pneumonia due to infection with Mycoplasma pneumoniae, Legionella pneumophila, and probably Coxiella burnetii.[7][8][13][21] This may be related to damage to ciliated epithelium and/or modification of the host immune response.
chronic lung disease
travel
Travel is associated with heightened risk for infections, probably related to exposure to new water sources that have not been used for a while. Standing water has a higher Legionella pneumophila load.[14][15][31] Frequent travel might predispose patients to influenza and/or newer SARS-CoV-2 strains.
male sex
immunomodulating drugs
One prospective incidence study has shown a possible association between patients receiving tumour necrosis factor (TNF)-alpha antagonists and Legionella pneumophila pneumonia.[12]
Use of this content is subject to our disclaimer