History and exam
Key diagnostic factors
common
HIV-positive
Presence of known HIV or HIV risk factors.
Other diagnostic factors
common
oropharyngeal candidiasis
Thrush is an independent predictor of Pneumocystis pneumonia.[11]
recurrent bacterial pneumonia
A history of recurrent bacterial pneumonias is an associated factor for risk of Pneumocystis pneumonia.
weight loss
A history of weight loss is an associated factor for risk of Pneumocystis pneumonia.
longer duration of symptoms (HIV-positive patients)
The duration of symptoms is typically longer for HIV-positive patients.
rapid onset of symptoms (HIV-negative patients)
HIV-negative patients have a more rapid and more severe clinical course.[43]
fever
In HIV-positive patients, there is usually an insidious onset of symptoms with fever present for more than 2 weeks.
dry cough
Generally non-productive. Purulent sputum suggests another aetiology of pneumonia.
dyspnoea
In HIV-positive patients, there is usually an insidious onset of symptoms.
fatigue
In HIV-positive patients, there is usually an insidious onset of symptoms.
normal chest examination
The patient typically has an unremarkable chest examination; rales may occasionally be present.
tachycardia
Non-specific sign.
tachypnoea or respiratory distress
Non-specific sign.
uncommon
cyanosis
Children may present with this.
extrapulmonary manifestations
Rarely, infection causes extrapulmonary manifestations in those with advanced HIV; however, in patients with advanced AIDS or in HIV-positive patients who are not taking their prophylaxis, there may be systemic infection with visual symptoms, cognitive impairment owing to central nervous system involvement, and gastrointestinal symptoms, such as diarrhoea.
pleuritic chest pain
May be a sign of pneumothorax but is uncommon in Pneumocystis pneumonia without a pneumothorax.
unilateral diminished breath sounds
Diminished breath sounds unilaterally may be a sign of pneumothorax.
Risk factors
strong
CD4 cell count below 200 cells/microlitre
A normal CD4 cell count in a man without HIV infection will be approximately 400 to 1200 cells/microlitre. HIV-positive patients with a CD4 cell count of <200 cells/microlitre have approximately 5 times greater risk of developing Pneumocystis pneumonia than patients with CD4 cell counts of >200 cells/microlitre; the risk increases the lower the CD4 cell count falls below this point.[11][12]
immunocompromised state
HIV-negative patients who have T-lymphocyte immune defects are susceptible.
Other groups at risk include patients with haematological malignancies, haematopoietic cell or solid-organ transplant recipients, patients with certain primary immunodeficiencies (e.g., severe combined immunodeficiency), or patients on chronic immunosuppressive treatment, such as tumour necrosis factor-alpha antagonists.[31][38][39][40][41][42][43][44]
chronic corticosteroid therapy
The use of corticosteroids chronically for conditions such as rheumatoid arthritis, or other auto-immune or inflammatory conditions, is an important risk factor for the development of opportunistic infections, especially Pneumocystis pneumonia (PCP).
In one study of HIV-negative patients who presented with PCP, 90.5% had received a daily dose of corticosteroids of at least 16 mg to 20 mg of prednisone (prednisolone) for longer than 1 month.[25]
In a series of patients with granulomatosis with polyangiitis being treated with daily glucocorticoids and immunosuppressive agents, approximately 6% developed PCP.[45]
prior Pneumocystis pneumonia
A history of previous Pneumocystis pneumonia is a strong risk factor for repeated episodes.
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