Risk factors for fluconazole resistance in patients with Candida glabrata bloodstream infection: Potential impact of control group selection on characterizing the association between previous fluconazole use and fluconazole resistance

Background: Although Candida glabrata is an emerging infection, risk factors for fluconazole resistance in patients with C glabrata bloodstram infection (BSI) have not been well elucidated. Methods: A case-control study was conducted to evaluate the primary risk factor of interest, previous fluconazole use, adjusting for demographics, comorbidities, time at risk, and antimicrobial exposure and assessing for effect modification. Secondary analyses were performed limiting the case group to C glabrata BSIs with a minimum inhibitory concentration (MIC) >= 64 mu g/mL. Results: Previous fluconazole use was not a significant risk factor for fluconazole-resistant C glabrata BSI in primary analysis (adjusted odds ratio [aOR], 1.5; 95% confidence interval [CI], 0.7-3.2) but was borderline significant in secondary analysis (aOR, 3.2; 95% CI, 0.9-11.3). Increased time at risk was an independent risk factor in primary (aOR, 1.02; 95% CI, 1.002-1.04) and secondary analyses (aOR, 1.03; 95% CI, 1.004-1.06). Conclusion: Increased time at risk was the only significant risk factor for fluconazole resistance. Future studies are needed to further evaluate the relationship between previous fluconazole use and fluconazole-resistant C glabrata BSI isolates with MIC >= 64 mu g/mL.