Closing the Brief Case: A Fatal Case of SARS-CoV-2 Coinfection with Coccidioides in Texas—Another Challenge We Face

ANSWERS TO SELF-ASSESSMENT QUESTIONS

• 1.Where is Coccidioides endemic in the United States?
  • a.Northeast
  • b.Southeast
  • c.Southwest
  • d.Northwest

Answer: c. The Southwest desert has the highest prevalence of Coccidioides in the United States. It is endemic to California’s Central Valley, Southern Arizona, parts of New Mexico and Nevada, and West Texas. California’s Central Valley harbors mainly Coccidioides immitis, while Coccidioides posadasii predominates in Arizona and West Texas.

• 2.How does prolonged glucocorticoid treatment increase host susceptibility to fungal infection?
  • a.Glucocorticoids suppress the host’s cellular immunity
  • b.Glucocorticoids suppress the host’s humoral immunity
  • c.Glucocorticoids are used as an energy source by many fungi
  • d.Glucocorticoids cause an increase in host respiration rate

Answer: a. Glucocorticoids are well-known suppressors of host cellular immunity, as they have been documented to reduce monocytes, lymphocytes, and many other cells involved in infection and inflammatory processes. Glucocorticoids are not known to be used as an energy source by fungi nor are they documented to directly increase respiration rate.

• 3.Which laboratory tests should be ordered if physicians suspect latent or past Coccidioides infection?
  • a.Respiratory culture
  • b.Coccidioides serology tests
  • c.Coccidioides PCR on sputum
  • d.Fungal blood cultures

Answer: b. While serology tests can be inconclusive, they are considered the most widely used method for diagnosis of coccidioidomycosis, especially latent or past infections. Respiratory culture would be appropriate to help identify acute and active infections, to confirm serology tests, and is considered the gold standard for diagnosis, although a positive culture may be difficult to obtain even after repeated attempts. Coccidioides PCR is not commercially available yet, but laboratory-developed tests have shown comparable sensitivity and specificity to culture and are likely to have a significant role in the future. Fungal blood cultures are unlikely to reveal clinically useful information, as Coccidioides is not often recovered from the blood even in cases of disseminated infection.

See https://doi.org/10.1128/JCM.00163-21 in this issue for case presentation and discussion.

TAKE-HOME POINTS

• During the SARS-CoV-2 pandemic, treatment guidelines, “best practices,” and recommendations are constantly changing, as new information about the virus and treatment efficacy arises. High-dose glucocorticoids are recommended for the treatment of SARS-CoV-2 pneumonia but may have deleterious effects on patients with certain underlying diseases.

• Glucocorticoids have been shown to reduce the number of mononuclear leukocytes and deplete circulating T lymphocytes, which can facilitate reactivation and dissemination of latent underlying infectious diseases, including invasive fungal infections such as coccidioidomycosis.

• Coccidioides is endemic in several parts of the United States from Central and Southern California to desert regions of Nevada, Arizona, New Mexico, and West Texas.

• The genus Coccidioides contains two highly pathogenic species, C. immitis and C. posadasii, which both cause coccidioidomycosis. They are morphologically and phenotypically identical but have different geographical distribution.

• Geographical residence and travel history can be important details to help determine the risk of coccidioidomycosis and if suspected, serology tests should be performed before treatment with glucocorticoids.