Evaluation of Polymorphic Locus Sequence Typing for Candida glabrata Epidemiology

Area of Science:

• * Medical mycology
• * Infectious disease epidemiology
• * Molecular typing

Background:

• * Candida glabrata is an opportunistic yeast causing increasingly drug-resistant healthcare-associated infections.
• * Accurate strain typing is crucial for understanding C. glabrata epidemiology and guiding treatment.
• * Existing methods like PFGE, MLST, and WGS have limitations for routine use.

Purpose of the Study:

• * To evaluate the utility of novel commercial sequence-based typing services (CgMT-J and CgMT-M) for Candida glabrata.
• * To assess the epidemiological relatedness of C. glabrata isolates from different patient cohorts.
• * To investigate the genetic basis of antifungal resistance in C. glabrata.

Main Methods:

• * Evaluation of CgMT-J and CgMT-M services using 56 C. glabrata isolates.
• * Analysis of isolates from patients with suspected nosocomial transmission and varied antifungal susceptibility.
• * Pdr1 sequencing to investigate the independent emergence of fluconazole resistance.

Main Results:

• * CgMT-J and CgMT-M provided congruent results, differentiating isolates into 24 and 20 alleles, respectively.
• * Evidence of nosocomial transmission was observed in one patient cohort.
• * Antifungal resistance, specifically to fluconazole, arose independently in different patients.
• * Isolates from another patient cohort suggested the presence of a dominant clone.
• * All isolates from a third patient cohort showed shared alleles, consistent with previous PFGE findings.

Conclusions:

• * Commercial sequence-based typing services (CgMT-J and CgMT-M) are effective for routine C. glabrata strain typing.
• * These methods can elucidate transmission patterns and the independent evolution of antifungal resistance.
• * Phylogenetic analysis of typing data can aid in understanding the genetic basis of resistance.