Limitation of the AccuProbe Coccidioides immitis culture identification test: false-negative results with formaldehyde-killed cultures.

The AccuProbe Coccidioides immitis culture identification test (CI test) yielded false-negative results with formaldehyde-killed C. immitis submitted to a reference laboratory. Further evaluation with pure or mixed cultures or stored, heat-killed cultures revealed the CI test to be highly sensitive and specific for C. immitis except when the cultures were pretreated with formaldehyde.

Coccidioidomycosis in New York State.

Coccidioidomycosis, a systemic fungal disease caused by Coccidioides immitis, is endemic in the southwestern United States and in parts of Mexico and Central and South America. Only sporadic cases have been reported in areas (including New York) where the disease is not endemic. We used hospital discharge records and state mycology laboratory data to investigate the characteristics of C. immitis infections among New York State residents. From 1992 to 1997, 161 persons had hospital discharge diagnoses of coccidioidomycosis (ICD9 Code 114.0 - 114.5, 114.9). From 1989 to 1997, 49 cultures from patients were confirmed as C. immitis; 26 of these patients had traveled to disease-endemic areas. Fourteen of 16 isolates had multilocus genotypes similar to those of Arizona isolates, which corroborates the travel-related acquisition of the disease. Our results indicate that coccidioidomycosis may be more common in New York residents than previously recognized. Increased awareness among health-care providers should improve timely diagnosis of coccidioidomycosis and prevention of associated illnesses and deaths among patients in nondisease-endemic areas.

Evaluation of mycology laboratory proficiency testing.

Changes over the last decade in overt proficiency testing (OPT) regulations have been ostensibly directed at improving laboratory performance on patient samples. However, the overt (unblinded) format of the tests and regulatory penalties associated with incorrect values allow and encourage laboratorians to take extra precautions with OPT analytes. As a result OPT may measure optimal laboratory performance instead of the intended target of typical performance attained during routine patient testing. This study addresses this issue by evaluating medical mycology OPT and comparing its fungal specimen identification error rates to those obtained in a covert (blinded) proficiency testing (CPT) program. Identifications from 188 laboratories participating in the New York State mycology OPT from 1982 to 1994 were compared with the identifications of the same fungi recovered from patient specimens in 1989 and 1994 as part of the routine procedures of 88 of these laboratories. The consistency in the identification of OPT specimens was sufficient to make accurate predictions of OPT error rates. However, while the error rates in OPT and CPT were similar for Candida albicans, significantly higher error rates were found in CPT for Candida tropicalis, Candida glabrata, and other common pathogenic fungi. These differences may, in part, be due to OPT's use of ideal organism representatives cultured under optimum growth conditions. This difference, as well as the organism-dependent error rate differences, reflects the limitations of OPT as a means of assessing the quality of routine laboratory performance in medical mycology.

Efficacy of API 20C and ID 32C systems for identification of common and rare clinical yeast isolates.

The abilities of the API 20C and ID 32C yeast identification systems to identify 123 common and 120 rare clinical yeast isolates were compared. API 20C facilitated correct identification of 97% common and 88% rare isolates while ID 32C facilitated correct identification of 92% common and 85% rare isolates.