Cryptococcus neoformans serotype groups encountered in Oklahoma.

Eighty clinical and 28 soil isolates of C. neoformans obtained in Oklahoma were separated into A-D and B-C serotype groups utilizing creatinine-dextrose agar with bromthymol blue. Previously, serotype B-C clinical isolates have been frequent only in patients from Southern California where as many as 50% of the isolates are of this type. In contrast, in patients from the rest of the United States the B-C frequency has been only 6%. Of the 80 C. neoformans isolates from Oklahoma patients, 12 (15%) were serotype B-C. One-half of these 12 Oklahoma patients with serotype B-C isolates had no history of any travel to California, and were long-time residents of Oklahoma. All 28 soil isolates of C. neformans from Oklahoma in this study were serotype A-D. Since serotype B-C recovery from a soil sample has never been reported, attempts are in progress to isolate serotype B-C from the environments of these patients from Oklahoma.