Postoperative Candida auris Bloodstream Infection Following Cardiac Surgery: Diagnostic Delay and Serial Changes in Azole MIC Values: A Case Report

Background

Candida auris is an emerging multidrug-resistant fungal pathogen associated with healthcare-associated outbreaks and invasive infections, particularly in critically ill patients. Early recognition remains challenging due to nonspecific clinical presentations and overlap with bacterial infections. Postoperative bloodstream infection due to C. auris , especially following cardiac surgery, is still relatively uncommon and may be underrecognized in clinical practice. Case Presentation: A 69-year-old man developed persistent fever, dyspnea, and bilateral postoperative pulmonary infiltrates after modified Morrow surgery and bioprosthetic mitral valve replacement. The pulmonary findings were clinically diagnosed as severe pneumonia, although imaging was nonspecific and also raised the possibility of pulmonary edema or heart failure. Despite broad-spectrum anti-infective therapy, his condition did not improve. Three separate catheter-drawn blood cultures collected on 21, 24, and 28 July 2025 subsequently yielded Candida auris , confirming candidemia. No respiratory specimen yielded C. auris ; therefore, the pulmonary abnormalities were considered concurrent with, rather than microbiologically attributable to, the bloodstream infection. Antifungal susceptibility testing showed persistently high fluconazole MICs, while itraconazole and voriconazole MICs increased in the third isolate. Because validated C. auris -specific clinical breakpoints were unavailable for these agents, the MIC findings were interpreted descriptively. Following adjustment of antifungal therapy and continued supportive care, the patient became afebrile, achieved clinical stabilization, and had a negative follow-up blood culture before discharge.