Case Report Echinocandin resistance due to simultaneous FKS mutation and increased cell wall chitin in a Candida albicans bloodstream isolate following brief exposure to caspofungin Toufeeq Imtiaz, 1 Kathy K. Lee, 2 Carol A. Munro, 2 Donna M. MacCallum, 2 Gillian S. Shankland, 3 Elizabeth M. Johnson, 4 Mark S. MacGregor 1 and Abhijit M. Bal 1 Correspondence Abhijit M. Bal abhijit.bal@nhs.net Received 26 March 2012 Accepted 25 May 2012 1 John Lynch Renal Unit & Department of Microbiology, University Hospital Crosshouse, Kilmarnock, UK 2 School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK 3 Department of Clinical Mycology, Yorkhill Hospital, Glasgow, UK 4 Mycology Reference Laboratory, Health Protection Agency, Bristol, UK Echinocandins are first-line agents for treating severe invasive candidiasis. Glucan synthase gene (FKS1) mutations lead to echinocandin resistance but the role of enhanced chitin expression is not well recognized in clinical isolates. We report a case of bloodstream Candida albicans infection with both Fks1 hotspot mutation and elevated cell wall chitin. Introduction Echinocandins are widely used in the treatment of can- didaemia. An overwhelming majority of strains of Candida albicans are susceptible to echinocandins. We report a rare bloodstream infection with a caspofungin non-susceptible strain of C. albicans that harboured a FKS1 gene mutation and also had enhanced chitin levels. Case report A 51-year-old female was admitted to the intensive care unit (ICU) with pyrexia, acidosis, hypoglycaemia and shock with multi-organ failure. She had advanced liver disease second- ary to alcohol intake. She was put on ventilatory support, inotropic support and renal replacement therapy. The patient was clinically septic with a raised C-reactive protein (51 mg l 21 ) in relation to the extent of her liver failure and leukocytosis (18.8610 9 l 21 ) with neutrophilia (17.8610 9 l 21 ), very high serum transaminases (aspartate aminotrans- ferase 19 388 U l 21 , alanine aminotransferase 8542 U l 21 ), elevated serum bilirubin (72 mmol l 21 ) and normal alkaline phosphatase (132 U l 21 ). She had a history of hepatitis B infection 15 years prior to her admission, but had recovered and seroconverted (hepatitis B surface antigen and envelope antigen negative and envelope antibodies positive). She tested negative for hepatitis A, C and E, cytomegalovirus, Epstein–Barr virus, adenovirus and leptospirosis. The extent of her liver injury led to hepatorenal syndrome with further rise in serum bilirubin (473 mmol l 21 ), increased urea (22.6 mmol l 21 ) and creatinine (288 mmol l 21 ) and an estimated glomerular filtration rate of only 13 ml min 21 . Seven days following admission, she was empirically commenced on intravenous piperacillin–tazobactam and caspofungin (70 mg loading dose, followed by 35 mg once daily as per recommendations for patients with severe hepatic insufficiency), both of which were discontinued after 1 week. Two weeks following discontinuation of caspofungin, cultures from the tracheal aspirate grew Staphylococcus aureus, Aspergillus versicolor and Candida species. Given the extent of her sepsis, she was started on a second course of caspofungin for suspected ventilator-associated chest infection in order to target both A. versicolor and Candida even though we were not sure about the significance of these fungi in the context of her illness. Caspofungin was given for 14 days at dosages mentioned above during this second course (Fig. 1). After a 5 week stay in the ICU, her general condition improved slightly. She was transferred to the renal high dependency unit for dialysis support. During her stay in the high dependency unit, she remained intermittently pyrexial and continued to show features consistent with hepatorenal failure. Blood cultures from the internal jugular line (peripheral cultures were not done) 2 weeks after stopping the second course of caspofungin grew yeasts (Fig. 1). Despite the fact that the patient was severely ill, we com- menced intravenous fluconazole (200 mg once daily) rather than caspofungin. Our decision was based on the recent Abbreviations: ICU, intensive care unit; IDSA, Infectious Diseases Society of America; PKC, protein kinase C. Journal of Medical Microbiology (2012), 61, 1330–1334 DOI 10.1099/jmm.0.045047-0 1330 045047 G 2012 SGM Printed in Great Britain