Immunocompromised patients with pneumonia can have infection with both common pulmonary pathogens and opportunistic pathogens. A basic microbiological workup should be performed in all immunocompromised patients who are hospitalized and considered for outpatients. The need for a more extensive and invasive workup (eg, bronchoscopy for bronchoalveolar lavage transbronchial lung biopsy) should be individualized, considering risk factors for opportunistic pathogens. As part of treating immunocompromised patients with pneumonia, it is important to evaluate whether any immunosuppressive medications can be discontinued or decreased to improve the patient’s level of immunity. Empiric therapy for opportunistic pathogens should be considered in patients who have risk factors for a particular pathogen and when delaying appropriate therapy would increase mortality risk.
Case 3. JR is a 45-year-old man with rheumatoid arthritis that was diagnosed 5 years earlier. He is currently taking long-term high-dose corticosteroids (prednisone, 20 mg daily) and the tumor necrosis factor (TNF)-alpha inhibitor infliximab. JR has had progressive shortness of breath for the past week with nonproductive cough, low-grade fever, and fatigue.
Vital signs include temperature of 100.9°F (38.3°C), heart rate of 110/min, respiratory rate of 24/min, blood pressure of 120/80 mm Hg, and oxygen saturation of 88% on room air. Physical examination reveals bilateral fine crackles on auscultation and mild synovitis of the joints due to rheumatoid arthritis. Laboratory testing shows a white blood cell count of 6,500/μL (6.5 × 10 9/L), hemoglobin of 12 g/dL (120 g/L), and platelet count of 150,000/μL (150 × 10 9/L). Arterial blood gas testing shows a pH of 7.45, partial pressure of carbon dioxide of 35 mm Hg, partial pressure of oxygen of 55 mm Hg, and bicarbonate of 24 mEq/L (24 mmol/L). Chest radiography demonstrates diffuse interstitial infiltrates that are more pronounced in the perihilar regions. Chest computed tomography (CT) demonstrates ground-glass opacities, predominantly in the upper lobes.
Pulmonary infections are among the most common infections in immunocompromised patients. Studies indicate that 20% to 30% of patients hospitalized for pneumonia are immunocompromised.1–4 Immunocompromised patients are often managed by multidisciplinary teams with advanced expertise in specialized clinics and hospitals such as cancer centers. However, as this patient population increases, many first present with pneumonia to general clinics or emergency departments at nonspecialized medical centers. Consequently, family physicians must acquire the necessary skills to manage pneumonia in immunocompromised patients.
Definition and Epidemiology
The Centers for Disease Control and Prevention has outlined a series of medical conditions or treatments that qualify patients as immunocompromised (Table 1).5 In patients with immunosuppression, the immune system is abnormal to the point that patients are at risk of pulmonary infections caused by opportunistic pathogens or pathogens that usually have low virulence.6 With the progression of some medical conditions (eg, advanced HIV infection) or the intensification of treatments (eg, chemotherapy), the immune system may decline to a level considered severely compromised.
In 2013, the Centers for Disease Control and Prevention estimated that 3% of the US adult population was immunocompromised.7 The prevalence of immunocompromised individuals at risk of pulmonary infections is likely much higher today, considering the increasing number of patients who are using biologic immunomodulators for a broad range of rheumatologic, dermatologic, gastrointestinal, and autoimmune conditions.8–10 Additionally, survival has improved in patients with cancer or who have had organ transplants.11
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