Infections due to Rare Cryptococcus Species. A Literature Review

Area of Science:

• Medical Mycology
• Infectious Diseases
• Clinical Microbiology

Background:

• Rare Cryptococcus species infections are infrequently documented, unlike common species like C. neoformans.
• Existing literature lacks comprehensive data on clinical and laboratory aspects of infections caused by less common Cryptococcus species.

Purpose of the Study:

• To conduct a thorough literature review of infections caused by rare Cryptococcus species (excluding common ones).
• To analyze clinical, epidemiological, and laboratory data, including identification and antifungal susceptibility, for these rare infections.

Main Methods:

• Systematic literature search across major databases: PubMed/MEDLINE, ScienceDirect, Scopus, and Google Scholar.
• Analysis of clinical and epidemiological data from reported cases.
• Evaluation of laboratory findings, including species identification methods and antifungal susceptibility testing.

Main Results:

• Fifty-eight cases of rare Cryptococcus species infections were identified from 46 publications (1934-2018), involving 16 different rare species.
• Nervous system infections and fungemias were common. Some species lacked capsules or failed to grow at 37°C.
• Molecular methods like ITS and D1/D2 sequencing were crucial for identification as commercial methods were often insufficient. Amphotericin B showed the most potent activity, though high MICs were observed for 5-fluorocytosine, echinocandins, and fluconazole.

Conclusions:

• This review highlights the limited but significant clinical impact of rare Cryptococcus species.
• Accurate identification often requires molecular techniques. Treatment strategies need careful consideration due to variable antifungal susceptibility.
• The findings provide valuable information for diagnosing and managing these rare fungal infections in the absence of specific guidelines.