Abstract
Candida tropicalis is a frequently isolated yeast species causing bloodstream, urinary tract and other infections particularly in patients admitted to intensive care units (ICUs) and those requiring prolonged urinary catheterization (UC) or receiving broad-spectrum antibiotics (BSA). This study investigated clinical characteristics and genetic relatedness among C. tropicalis strains isolated from patients at Al-Amiri Hospital in Kuwait. C. tropicalis strains (n = 63) isolated from blood, genito-urinary, respiratory (RT) and digestive (GIT) tracts and wound sites from 54 patients were used. All isolates were phenotypically identified and tested against six antifungal drugs by using Vitek 2 system. Molecular identification was performed by PCR amplification of rDNA. Fingerprinting was achieved by 6-loci-based multilocus sequence typing (MLST) and data were analyzed by BioNumerics software for phylogenetic relationships. Patients mean age was >65 years and >20% patients were hospitalized in ICUs. Most patients had underlying conditions that included UC, BSA, diabetes and RT/GIT abnormalities. Most candiduria cases had UC, ureteric stent or suprapubic catheters. All isolates were identified as C. tropicalis by Vitek 2 and by species-specific PCR. Sixty-two isolates were susceptible to all tested antifungal drugs. MLST identified 59 diploid sequence types (DSTs) including 54 newly-identified DSTs. C. tropicalis isolates from multiple sites of same patient usually belonged to different DSTs. Interestingly, 56 of 57 isolates from 48 patients belonged to unique genotypes. Only six isolates from six patients belonged to three DSTs (clusters), however, C. tropicalis strains in each cluster were isolated >3 months apart. Our data show diverse origins of C. tropicalis infections in Kuwait as most isolates were unique strains. There was no obvious correlation between cluster isolates with time of isolation and/or hospital ward of their origin. This study presents the first MLST analysis of C. tropicalis isolates from Middle East and may be useful for studying genetic relationships among global C. tropicalis strains.
Highlights
Candida spp. are important constituent of human microbial flora of skin, mucous membranes of mouth and vagina and gastrointestinal tract
The majority (38 of 63, 60%) of the isolates were obtained from urine samples from patients with candiduria while only five isolates were obtained from bloodstream of candidemia patients
Four C. tropicalis isolates were obtained from four patients who were attending the clinic or out-patient department while the remaining 59 isolates were cultured from 50 hospitalized patients including 12 (22%) patients from an intensive care units (ICUs), six patients from the emergency room, three patients from the dialysis unit and 29 patients from different wards in the hospital
Summary
Candida spp. are important constituent of human microbial flora of skin, mucous membranes of mouth and vagina and gastrointestinal tract. The infections range in severity from mild superficial infections to life-threatening bloodstream and invasive infections inflicting considerable morbidity and mortality, in immunocompromised and hospitalized patients [1, 2]. 90% of invasive Candida infections are caused by only four species or species complexes which include Candida albicans, Candida glabrata, Candida parapsilosis, and Candida tropicalis [3,4,5,6]. Candida tropicalis is the second most frequently isolated Candida from bloodstream in many countries and is the leading cause of nosocomial fungemia and invasive fungal infections in patients with hematologic and other malignancies in several countries [5,6,7,8,9,10]. Antifungal drug susceptibility testing of Candida spp. isolates have shown that the frequency of fluconazole-resistant (including isolates that show intermediate susceptibility) C. tropicalis strains is high (~10%) and is comparable to that of C. glabrata isolates in some Asian countries [6, 12, 13]
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