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Coccidioides immitis

Shmuel Shoham, M.D., John G. Bartlett, M.D.
Coccidioides immitis is a topic covered in the Johns Hopkins ABX Guide.

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  • Causative organisms:
    • Coccidioides immitis 
    • Coccidioides posadasii  
    • Note: previously, all cases were attributed to C. immitis.
      • Now known that infections acquired in California are generally due to C. immitis while those acquired elsewhere (e.g. SW US, Mexico, Central and South America) are posadasii.
  • Dimorphic fungal characteristics:
    • Environmental form: filamentous with septated hyphae that grows in soil. When a dry spell follows rain, the hyphae become brittle and small (~3-5 μm in diameter) fungal particles termed arthroconidia break off, become airborne and potentially inhaled.
    • Invasive form at 37°C: following inhalation or occasionally via percutaneous entry, arthroconidia transform into large (~60-75 µm in diameter) structures termed spherules that contain hundreds of small (~2-5 µm in diameter) structures termed endospores. When the mature spherules rupture, endospores are released, which can in turn form additional spherules [Fig].
  • Preferentially grows in regions of California, Southwest U.S. and parts of Mexico that have hot summers, moderate winters and little rainfall.
    • Isolated pockets of C. posadasii are also found in parts of South and Central America.
    • Growth of the fungus as far north as central Washington state has been described.
  • Micro: grows readily on standard fungal media.
    • Coccidioides grown in culture can be a significant laboratory hazard and must be handled cautiously in an appropriate safety cabinet. Alert micro lab if suspected when submitting specimens.

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Last updated: January 29, 2017


Shoham, Shmuel, and John G Bartlett. "Coccidioides Immitis." Johns Hopkins ABX Guide, The Johns Hopkins University, 2017. Pediatrics Central, peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540139/all/Coccidioides_immitis.
Shoham S, Bartlett JG. Coccidioides immitis. Johns Hopkins ABX Guide. The Johns Hopkins University; 2017. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540139/all/Coccidioides_immitis. Accessed April 24, 2019.
Shoham, S., & Bartlett, J. G. (2017). Coccidioides immitis. In Johns Hopkins ABX Guide. Available from https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540139/all/Coccidioides_immitis
Shoham S, Bartlett JG. Coccidioides Immitis [Internet]. In: Johns Hopkins ABX Guide. The Johns Hopkins University; 2017. [cited 2019 April 24]. Available from: https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540139/all/Coccidioides_immitis.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Coccidioides immitis ID - 540139 A1 - Shoham,Shmuel,M.D. AU - Bartlett,John,M.D. Y1 - 2017/01/29/ BT - Johns Hopkins ABX Guide UR - https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540139/all/Coccidioides_immitis PB - The Johns Hopkins University DB - Pediatrics Central DP - Unbound Medicine ER -