Limited evolution of a Cryptococcus neoformans laboratory strain during human passage following an accidental infection

A laboratory researcher developed primary cutaneous cryptococcosis followingaccidental infection with Cryptococcus neoformans via a needle scrape that was initiallyassumed not to have penetrated the skin. Starting on day eight after the incident, acharacteristic nodular erythematous lesion developed on a finger at the exposure site.Antibacterial therapy was initiated for the clinical impression of bacterial cellulitis as clinicaltests for cryptococcal serum antigen and cultures from the wound site were both negative.Mass spectrometry and whole genome sequencing of yeast grown from wound exudatecollected several days later confirmed the presence of laboratory strain H99 Cryptococcusneoformans var grubii with no protein coding changes compared to the human-passagedisolate. Eight-week fluconazole therapy initiated on day 15 after incident was curative. Twoadditional cases with direct exposures plus two cases with potential exposures to Cryptococcusneoformans in the research lab received prophylactic fluconazole and did not developsymptoms.