Respiratory infections are attributed to a wide range of pathogens, of which fungi are responsible for a minority of cases. However, fungal organisms present a threat in immunosuppressed patients . Moreover, predisposing factors include AIDS, hematological malignancy, organ transplantation, neutropenia, chronic use of corticosteroids and other immunosuppressive therapy, congenital immune deficiency syndromes, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), and other underlying lung conditions .
Fungal pulmonary infection manifests as bronchitis or pneumonia. In the former, cough is the predominant symptom. Moreover, a cough that continues for more than 5 days is indicative of acute bronchitis . Additionally, nearly half of patients with acute bronchitis produce sputum that may be clear, green or yellow, and occasionally streaked with blood. Patients will also report malaise, sore throat, headache, dyspnea, chest pain, hoarseness, and runny/stuffy nose.
Pulmonary fungal infections may be accompanied by extrapulmonary manifestations. Associated manifestations, for example, will include arthritis, arthralgia, and skin conditions such as erythema nodosum and erythema multiforme. Moreover, fungal infections may disseminate to the brain, blood, bone marrow, kidneys, liver, spleen, sinuses, eye, and muscle.
Also, hypersensitivity reactions such as allergic bronchial asthma and allergic bronchopulmonary aspergillosis (ABPA) may develop secondary to Candida or Aspergillus or species . There are numerous types of other allergic reactions as well.
In cases of pneumonia, persistent fever is one of the initial symptoms. Other vital signs changes include tachycardia and tachypnea. Further manifestations may include pleural rub, pericardial rub, consolidation, rales, and other adventitious sounds. Also, patients often exhibit signs of distress.
The workup of a pulmonary infection includes evaluation of the patient's medical history, risk factors, and exposures as well as any recent travel to regions of endemic fungal infection. Furthermore, the patient warrants a complete physical exam and diagnostic studies.
A complete blood count (CBC) with differential will reveal leukocytosis in immunocompetent patients with endemic infection whereas it shows leukopenia or neutropenia in those with an opportunistic infection. Moreover, eosinophilia is suggestive of aspergillosis .
To determine the etiology of the infection, cultures of sputum, blood, and bronchoalveolar lavage (BAL) fluid are obtained. Another important diagnostic technique is the microscopic analysis of respiratory secretions with specific stains and potassium hydroxide (KOH) preparation .
Depending on the pathogen, certain antigen detection studies with polymerase chain reaction (PCR)  and enzyme-linked immunosorbent assay (ELISA)  are available. Other nonculture methods include galactomannan assays for Aspergillus or Histoplasma  .
Computed tomography (CT) scans are helpful in the assessment of pulmonary lesions found in immunocompromised individuals. Specifically, this imaging modality reveals the "halo sign'" in those with invasive aspergillosis .