Guidance issued on outpatient testing for fungal infections in CAP

Testing for coccidioidomycosis, histoplasmosis, and blastomycosis is suggested in patients with community-acquired pneumonia (CAP) with continuing symptoms who have lived in or visited areas where these infections are known to be endemic, according to guidance from CDC researchers and others.

To help outpatient clinicians decide when and how to test for these three fungal infections in patients with CAP, experts reviewed the available evidence and developed a diagnostic algorithm for each. The goals of the guidance are to reduce misdiagnoses, unnecessary antibacterial use, and poor outcomes. It was published Oct. 6 by Clinical Infectious Diseases.

For coccidioidomycosis, the guidance recommends considering testing at initial CAP presentation (or if there is erythema nodosum and recent respiratory symptoms) in patients who live in or have traveled to highly endemic regions, including South-Central Arizona or the San Joaquin Valley in California, or who have an epidemiologic link to a coccidioidomycosis outbreak. Testing should also be considered in patients with CAP whose symptoms do not improve after empirical antibiotics and who have lived in or traveled to known endemic areas (Arizona, California, Nevada, New Mexico, Texas, Utah, Washington State, and Central and South America). The guidance suggests initial testing with an enzyme immunoassay (EIA) antibody test with immunodiffusion and complement fixation testing.

For histoplasmosis, the guidance recommends considering testing in patients with CAP whose symptoms do not improve after empirical antibiotics and who live in or have traveled to endemic areas (e.g., Central and Eastern United States and Central Canada, Puerto Rico, Latin America, Central Africa, and Southeast Asia). The guidance notes that Histoplasma distribution is likely nationwide and that testing may also be warranted for those living in or those who have traveled to the Western United States. Testing can also be considered at initial CAP presentation in patients who have extensive exposure to bird or bat droppings, a chest X-ray showing new nodules or lymphadenopathy consistent with histoplasmosis, or an epidemiologic link to a histoplasmosis outbreak, the guidance said. An EIA urine antigen test is suggested as the initial test, and clinicians can consider a concurrent immunodiffusion or complement fixation antibody test to increase sensitivity, according to the guidance.

For blastomycosis, testing should be considered in all patients with CAP who have symptoms that do not improve after empirical antibiotics and who live in or have traveled to endemic areas, including the Midwestern, South Central, and Southeastern United States (particularly around the Ohio and Mississippi River Valleys, the Great Lakes, and the Saint Lawrence River). The guidance notes that the disease may be hyperendemic in Northern Wisconsin and Minnesota. Clinicians can also consider testing at initial CAP presentation if patients have abnormal skin lesions consistent with blastomycosis or an epidemiologic link to a blastomycosis outbreak, the guidance said. An EIA urine antigen test is suggested as the initial test because it has high sensitivity and a quick turnaround time, according to the guidance.

For each infection, the guidance includes advice on managing positive or negative results on initial testing, performing repeated or follow-up testing, and obtaining infectious diseases or pulmonary consultation. For treatment, the guidance refers clinicians to the Infectious Diseases Society of America's individual guidelines on coccidioidomycosis, histoplasmosis, and blastomycosis.