By David A. Stevens, MD

Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA; California Institute for Medical Research, San Jose, CA

Dr. Stevens reports no financial relationships relevant to this field of study.

Dear Editor:

Accidental laboratory exposure to Coccidioides species is the major cause of clinical laboratory-acquired fungal infection,1 and coccidiodomycosis is thought to be the least responsive deep mycosis to treatment.2 This letter is written for the benefit of the microbiologist or infectious disease practitioner who is confronted by an accidental exposure, by self or staff, to Coccidioides in the clinical laboratory and, searching for advice from the literature on how to approach the problem, finds our article on the subject.3 We can now update the article, and a literature search could now also locate this update.

We advised that serum be taken at the time of exposure from exposed personnel, for antibody testing, for two purposes. One, to determine whether there had been a prior infection by the fungus, because such prior exposure would extremely lessen the risks of developing an infection from the laboratory exposure. Second, as a baseline to compare to a second serum drawn at a later time, to diagnose infection as a result of the exposure, particularly in the presence of a confusing set of symptoms, or a subclinical infection, almost always in a worker without the prior coccidioidal experience. At the time of publication of our article, there was not a licensed skin test reagent available on the market to assess immunity. However, there now is available a commercial spherule (parasitic phase)-derived reagent to assess delayed-type hypersensitivity, Spherusol (Nielsen Biosciences, San Diego, CA). Spherule-derived antigens have proven sensitive in detection of prior coccidioidal infection in epidemiological studies, with minimal cross-reactivity and no perturbation of the serology.4 Skin testing would be expected to be a better detector of infection because of problems with lessened sensitivity, and possible transience of positivity, with serology.

I would recommend, therefore, at this time that assessment of skin test reactivity be a part of the baseline and followup assessment of exposed individuals, along with serology. ƒÞ

References

  1. Baron EJ, Miller JM. Bacterial and fungal infections among diagnostic laboratory workers: Evaluating the risks. Diagn Microbiol Infect Dis 2008;60:241-246.
  2. Galgiani JN, Ampel NM, Blair JE, et al. Coccidioidomycosis. Practice Guideline, Infectious Disease Society of America. Clin Infect Dis 2005;41:1217-1223.
  3. Stevens DA, Clemons KV, Levine HB, Pappagianis D, Baron EJ, Hamilton JR, Deresinski SC, Johnson N. Expert opinion: What to do when there is a coccidioidal exposure in a laboratory. Clin Infect Dis 2009;49:919-923.
  4. Stevens DA, Levine HB, Deresinski SC, Ten Eyck DR, Restrepo M A. Epidemiological and clinical skin testing studies with spherulin. In: Ajello L, ed. Coccidioidomycosis: Current Clinical and Diagnostic Status; Symposia Specialists, pub.; 1977:107-114.