Research Paper Prevalence of virulent Candida spp. in complicated urinary tract infection of nephrolithiatic patients from surgical units of tertiary care hospitals Islamabad S. Zafar, K. Fatima, R. Faryal * Department of Microbiology, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan 1. Introduction The rate of Candida infections is growing tremendously, ranking Candida species as the most important opportunistic pathogens among yeasts [1]. This causes superficial as well as systematic infections and is frequently isolated from patients undergoing long-term catheterization [2]. Candida is the major causative agent for cUTI. Various predisposing risk factors of cUTI include age, immunosuppression, use of indwelling devices such as catheter and urinary tract obstruction [3]. Renal stone disease is a worldwide prevailing problem with an enormous socio-economic impact. This disease is also common in Pakistan where these patients represent the majority of urological patients. The stones may clinically be asymptomatic for a long time. But, they cause hindrance and infection to the urinary tract when they rise beyond a size of natural clearance from urinary tract [4]. C. albicans is the common agent responsible for fungal infections but in the recent years some non-albicans species have also emerged with different virulence and sensitivity patterns [5]. Antifungal resistance of Candida has become a serious clinical challenge due to widespread use of the agents like echinocandins and azoles [6]. Adherence to host tissue, phenotypic variability, enzymes and toxins produced by Candida spp. has been listed as virulence factors of Candida species. Different hydrolytic enzymes are responsible for pathogenicity of Candida [7]. These enzymes facilitate the Candida for adherence and penetration to the host tissue [8]. Secreted aspartyl proteinases and phospholipases are the most important extracellular hydrolytic enzymes of Candida [7]. Journal de Mycologie Me ´ dicale xxx (2020) xxx * Corresponding author. E-mail addresses: z.sahar23@gmail.com (S. Zafar), fatimasyed078@gmail.com (K. Fatima), ranifaryal@qau.edu.pk (R. Faryal). A R T I C L E I N F O Article history: Received 2 April 2019 Received in revised form 7 February 2020 Accepted 31 July 2020 Available online xxx Keywords: Candida albicans Nephrolithiasis cUTI A B S T R A C T Candida species are the commensal organisms of human mucosa and opportunistically cause the diseases in susceptible persons. This study aimed to determine the prevalence and virulence of different Candida spp. among nephrolithiatic patients and their association with complicated UTI (cUTI). A total of 164 urine samples were collected from surgical units of two tertiary care hospitals (Poly Clinic and Pakistan Institute of Medical Sciences Hospital, Islamabad). From 74 kidney stone patients, 77 isolates of Candida spp. were confirmed through standard microbiological and molecular characterization. C. albicans was the predominant species with 51 isolates (66.2%) followed by 26 (33.8%) of C. non- albicans. The nephrolithiatic patients suffering from cUTI were more prone to be infected with Candida (P = 0.047). Among all isolates, 83% (64) of the Candida isolates were biofilm formers, 80% (60) showed the esterase production and 64.9% (50) showed phospholipase production. Candida isolates positive for various virulence factors were more prevalently isolated from both catheterized and recurrent UTI patients. Among Candida spp., 16.9% (13) isolates showed resistance to fluconazole and 19.5% (15) against voriconazole and 11 isolates were resistant for both tested antifungals. Candida isolated from cUTI cases showed comparatively enhanced virulence attributes and antifungal resistance, suggesting that these factors might have role in development of cUTI in nephrolithiatic patients. Hence, this work highlights the high prevalence of both C. albicans and non albicans spp. in nephrolithiatic patients. So, there is need to administer evidence based antifungal therapy rather than empirical therapy to reduce the cUTI in nephrolithiatic patients.  C 2020 Elsevier Masson SAS. All rights reserved. G Model MYCMED-101024; No. of Pages 5 Please cite this article in press as: Zafar S, et al. Prevalence of virulent Candida spp. in complicated urinary tract infection of nephrolithiatic patients from surgical units of tertiary care hospitals Islamabad. Journal De Mycologie Me ´ dicale (2020), https://doi.org/ 10.1016/j.mycmed.2020.101024 Available online at ScienceDirect www.sciencedirect.com https://doi.org/10.1016/j.mycmed.2020.101024 1156-5233/  C 2020 Elsevier Masson SAS. All rights reserved.