Detection and survival of Candida albicans in soils

Abstract

Candida albicans is the most common human fungal pathogen. This yeast is described as a commensal of human and animal mucosa, and very few studies have focused on its isolation in natural environments. We investigated the presence of C. albicans in a large panel of French soils. Because a culture‐based method didn't allow isolation of the yeast in a panel of 70 soils, we adapted a nested‐PCR for detecting C. albicans DNA in a panel of 460 soils. Only 7 of the 460 soil samples (1.5%) were PCR‐positive for Candida albicans. To understand which parameters influence the survival of the yeast, we studied the decline of a population of C. albicans over a period of one month in a collection of 20 soils collected throughout France. C. albicans was able to survive up to 30 days in 80% of the soils tested. Using a Spearman correlation test, we showed that the short‐term survival of C. albicans in soils was correlated with some soils chemical factors such as pH and presence of some minerals (Al, Mn, and Na). Concerning survival after 30 days, Cation Exchange Capacity (CEC) and clay content were identified as beneficial determinants of the long‐term survival of C. albicans in soils.

Environmental reservoirs of the drug-resistant pathogenic yeast Candida auris

“…Soil can support the survival of a wide range of human pathogens, including C . albicans that can persist in soil for more than 30 days [ 30 ]; however, the ability of C . auris to persist in soil has not yet been examined.…”

“…Lower pH and higher minerals (aluminium, manganese, and sodium) can increase survival of C . albicans during the early stages of soil contamination, while cation exchange capacity (CEC) and clay content, which influences the exchangeable minerals in soil, appears to be crucial for longer-term survival in soil [ 30 ]. C .…”

“…In contrast to pathogenic moulds and non-Candida human pathogenic yeast (such as Cryptococcus neoformans), which are known to inhabit diverse environmental niches, pathogenic Candida species primarily exist as human commensals or as contaminants in clinical environments from where they can cause opportunistic infections. However, several species of pathogenic Candida have been isolated from nonhuman or nonclinical environmental samples [26,27], which could provide novel exposure routes for human infection [26,[28][29][30]. Candida albicans was previously thought to exist mainly as a human commensal [30], but has now been widely isolated from nonclinical environmental samples, e.g., soil, wetlands, and plants (Table 1).…”

“…However, several species of pathogenic Candida have been isolated from nonhuman or nonclinical environmental samples [26,27], which could provide novel exposure routes for human infection [26,[28][29][30]. Candida albicans was previously thought to exist mainly as a human commensal [30], but has now been widely isolated from nonclinical environmental samples, e.g., soil, wetlands, and plants (Table 1). In addition, the 5 most common pathogenic Candida species [31] as well as C. lusitaniae and C. haemulonii, 2 human pathogenic Candida species closely related to C. auris [5], have also been isolated from nonclinical environmental samples (Table 1).…”

Diagnosis and Treatment of Invasive Candidiasis

“…PCR-based tests, which are highly effective in the diagnosis of infections caused by pathogenic bacteria or viruses, have lower reliability in the diagnosis of invasive candidiasis. The problem arises from the low number of Candida cells in the blood, often under 1 CFU/mL, and the wide distribution of fungus and its DNA in the human body and the environment, as well as similarity between human and fungal DNA [ 27 , 118 , 119 ]. Still, further development of PCR tests could increase the rate of detection of invasive candidiasis.…”