Evaluation of Leathers-Awasthi medium for identifying Coccidioides immitis isolates.

Leathers-Awasthi medium (LAM) has been recommended for the definitive identification of Coccidioides immitis isolates recovered from clinical specimens. Studies were undertaken to determine the diagnostic reliability of this medium for identifying fungal cultures. A total of 62 fungi, representing 13 C. immitis isolates and 49 similar pathogenic and saprophytic fungi, were tested in parallel by the LAM and exoantigen tests. All of the 13 C. immitis isolates were positive by the exoantigen test, whereas only 11 were positive on LAM. Of the 49 other fungal isolates, 29 were positive on LAM whereas none was positive by the exoantigen test. LAM does not permit the unequivocal identification of C. immitis isolates.