Non-neoformans Cryptococcal Infections: a Systematic Review

Abstract

Non-neoformans cryptococci have been generally regarded as saprophytes and rarely reported as human pathogens. However, the incidence of infection due to these organisms has increased over the past 40 years, with Cryptococcus laurentii and Cryptococcus albidus, together, responsible for 80% of reported cases. Conditions associated with impaired cell-mediated immunity are important risks for non-neoformans cryptococcal infections and prior azole prophylaxis has been associated with antifungal resistance. The presence of invasive devices was a significant risk factor for Cryptococcus laurentii infection (adjusted OR = 8.7; 95% CI = 1.48-82.9; p = 0.003), while predictors for mortality included age > or =45 years (aOR = 8.4; 95% CI = 1.18-78.82; p = 0.004) and meningeal presentation (aOR = 7.0; 95% CI = 1.85-60.5; p= 0.04). Because clinical manifestations of non-neoformans cryptococcal infections are most often indistinguishable from Cryptococcus neoformans, a high index of suspicion remains important to facilitate early diagnosis and prompt treatment for such infections.

Perspectives on non-neoformanscryptococcal opportunistic infections

“…C. laurentii is found worldwide, although its natural habitat remains largely unknown [2,3]. It is the most common yeast inhabiting the soil of traditionally hostile environments, including tundra, the Antarctic, the Himalayas, the Caribbean, and the prairies.…”

“…It is the most common yeast inhabiting the soil of traditionally hostile environments, including tundra, the Antarctic, the Himalayas, the Caribbean, and the prairies. This survivability may be attributed to its psychrophilic abilities, with an optimal culture temperature of 15.0°C, and poor growth at temperatures >30.0°C [3,6]. Historically, it has been used as a biological pesticide to prevent the decay of fruits and has been demonstrated as a contaminant in the fermentation process of wines and beer [1,7].…”

“…Additionally, C. laurentii has been isolated in cases of bovine mastitis [5]. There have been approximately 18 reported cases of C. laurentii infections in the literature, most commonly disseminated, pulmonary, and cutaneous forms [3]. …”

“…However, a literature review demonstrates an increasing prevalence in opportunistic infections [1–3]. The Cryptococcus genus consists of >70 species of anamorphic, basidiomycetous, encapsulated yeast [4].…”

“…However, there has been an increased incidence in recent decades of opportunistic infections involving the skin, lungs, bloodstream, and central nervous system (CNS). It has been theorized that this increasing incidence may be secondary to a growing number of at-risk or immunocompromised patients, improved awareness, or advancements in laboratory technology [3]. Within the non- neoformans cryptococcal species, C. laurentii and C. albidus account for 80% of pathogenic infections [1–5].…”