In vitro Susceptibilities to caspofungin of Candida spp. isolated from the Polyvalent Intensive Care Unit of Fattouma Bourguiba University Hospital: First report of resistant mutants in Tunisia.

INTRODUCTION

Candida infections are becoming increasingly common in the Intensive Care Unit (ICU) setting representing a real threat to compromised patients. Echinocandins are considered the first-line treatment for the management of these infections. This work aimed to study the susceptibility of Candida species involved in invasive fungal infections at the ICU department of the University Hospital Fattouma Bourguiba of Monastir to caspofungin and evaluate the effect of overuse of this antifungal agent on the evolution of Minimal Inhibitory Concentrations (MICs).

MATERIALS AND

METHODS

This study concerned 269 Candida spp. strains isolated from 152 patients of the ICU from January 2018 to May 2021. The MICs were determined according to the Clinical and Laboratory Standards Institute (CLSI) reference method. The strains categorized as resistant were sequenced at the Hot Spot (HS) region of the FKS gene. Additionally, the relationship between MICs and monthly caspofungin consumption at the ICU department was evaluated using SPSS software.

RESULTS

Candida albicans was the most prevalent species representing 44 % (119/269), followed by C. tropicalis (52/269) and C. glabrata (51/269) (19 % each). A total of 223 isolates were subjected to susceptibility testing. Resistance to caspofungin was detected in 13 C. glabrata isolates (5.8 %). That is to say, in total, 30 % of the tested C. glabrata isolates were categorized as resistant based on their MIC values However, only one strain exhibiting a cross-resistance to anidulafungin, carried a mutation in the HS region of the FKS1 gene underscoring a discrepancy between phenotypic and genetic resistance. The evolution of MIC values was significantly correlated with caspofungin consumption for C. albicans and C. tropicalis species however non-significant for C. glabrata and the remaining species.

CONCLUSION

To prevent the rise of resistance to caspofungin, it is necessary to improve mycological surveillance by elaborating breakpoint values adapted to the local fungal ecology and to rationalize the prescription of this molecule.