Ideally, the evaluation of respiratory symptoms and suspected pneumonia in a person with HIV infection is aimed at establishing a definitive diagnosis. However, definitive diagnosis may require invasive diagnostic procedures such as bronchoscopy and may require sophisticated laboratory techniques, which are frequently unavailable in many clinical settings throughout the world. Regardless of the setting, the goal of any evaluation is to narrow the differential diagnosis to a single probable diagnosis such that appropriate therapy can be initiated and, depending on available resources, appropriate diagnostic testing can be obtained. The challenge of HIV infection is that the clinical and radiographic presentations of HIV-associated opportunistic pneumonias overlap and also that persons with HIV infection may present with more than one concurrent pneumonia.
The evaluation begins with a history and physical examination (). The history should include information on the most recent CD4 cell count, the person's HIV risk factors and habits, history of prior opportunistic infections and current use of opportunistic infection prophylaxis and combination antiretroviral therapy, and information on residence in or travel to regions prevalent for TB and endemic fungi. The presenting complaints and the tempo and duration of these complaints should be obtained. The physical examination should look for signs suggesting extrapulmonary or disseminated disease that may tie together the respiratory complaints and pulmonary findings. Based on the history and physical examination, chest radiography is indicated for persons with suspected pneumonia. Often, the specific chest radiographic findings - combined with the CD4 cell count - evoke a differential diagnosis and plan for management and treatment ( and ). Selected laboratory testing may be indicated to assess for specific diseases (e.g., serum Cryptococcal antigen, CrAg) or disease severity (e.g., arterial blood gas, ABG). In some cases, chest tomography (CT) may be indicated. Where feasible, further evaluation should seek to establish a definitive diagnosis, with microbiologic evaluation of sputum for stains and cultures, and bronchoscopy in certain cases.
Evaluation of HIV-associated Opportunistic Pneumonias
Figure 1 Diagnostic assessment for an HIV-infected patient with respiratory symptoms and CD4 cell count >200 cells/μl. AFB, acid-fast bacilli; BP, bacterial pneumonia; CT, chest computed tomography; HRCT, chest high-resolution computed tomography; (more ...)
Figure 2 Diagnostic assessment for an HIV-infected patient with respiratory symptoms and CD4 cell count of <200 cells/μl. *Some of the diagnoses occur when the CD4 cell count is ≤100 cells/μl or even ≤50 cells/μl. (more ...)
HIV-associated opportunistic pneumonias can progress rapidly to respiratory failure and death without appropriate therapy. Thus, empiric therapy for the suspected diagnosis(es) should be initiated while awaiting the results of diagnostic studies. In the U.S., the National Institutes of Health (NIH), the Centers for Disease Control and Prevention (CDC), and the HIV Medicine Association of the Infectious Diseases Society of America (HIVMA/IDSA) publish “Guidelines for Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents” that provide recommendations for first-line and alternative therapies for treatment and prevention.(5
) Although available therapies and recommendations may differ in different areas of the world, for the purposes of this review, the NIH/CDC/HIVMA/IDSA guidelines will be provided as the basis for recommended treatment and prophylaxis regimens.