Implication of genotypes for prognosis of Candida glabrata bloodstream infections

Abstract

Background Genotyping isolates of a specific pathogen may demonstrate unique patterns of antimicrobial resistance, virulence or outcomes. However, evidence for genotype–outcome association in Candida glabrata is scarce. We aimed to characterize the mycological and clinical relevance of genotypes on C. glabrata bloodstream infections (BSIs). Methods Non-duplicated C. glabrata blood isolates from hospitalized adults were genotyped by MLST, and further clustered by the unweighted pair group method with arithmetic averages (UPGMA). A clonal complex (CC) was defined by UPGMA similarities of >90%. Antifungal susceptibility testing was performed by a colorimetric microdilution method and interpreted following CLSI criteria. Results Of 48 blood isolates evaluated, 13 STs were identified. CC7 was the leading CC (n = 14; 29.2%), including 13 ST7. The overall fluconazole and echinocandin resistance rates were 6.6% and 0%, respectively. No specific resistance patterns were associated with CC7 or other CCs. Charlson comorbidity index (adjusted OR, 1.49; 95% CI, 1.05–3.11) was the only predictor for CC7. By multivariable Cox regression analyses, CC7 was independently associated with 28 day mortality [adjusted HR (aHR), 3.28; 95% CI, 1.31–8.23], even after considering potential interaction with neutropenia (aHR, 3.41; 95% CI, 1.23–9.42; P for interaction, 0.24) or limited to 34 patients with monomicrobial BSIs (aHR, 2.85; 95% CI, 1.15–7.08). Also, the Kaplan–Meier estimate showed greater mortality with CC7 (P = 0.003). Fluconazole resistance or echinocandin therapy had no significant impact on mortality. Conclusions Our data suggested comorbid patients were at risk of developing CC7 BSIs. Further, CC7 was independently associated with worse outcomes.