Multicenter Evaluation of Candida QuickFISH BC for Identification of Candida Species Directly from Blood Culture Bottles

Abstract

A total of 415 samples contained a single fungal species, with C. glabrata (n ‫؍‬ 129; 30.8%) being the most common isolate, followed by C. albicans (n ‫؍‬ 125; 29.8%), C. parapsilosis (n ‫؍‬ 59; 14.1%), C. tropicalis (n ‫؍‬ 37; 8.8%), and C. krusei (n ‫؍‬ 17; 4.1%). The overall agreement (with range for the three major Candida species) between the two methods was 99.3% (98.3 to 100%), with a sensitivity of 99.7% (98.3 to 100%) and a specificity of 98.0% (99.4 to 100%). This study showed that Candida QuickFISH BC is a rapid and accurate method for identifying C. albicans, C. glabrata, and C. parapsilosis, the three most common Candida species causing BSI, directly from blood culture bottles. Candida species are ranked as the third or fourth most common etiologic agents associated with nosocomial bloodstream infections (1, 2). Mortality rates are estimated to be as high as 45% (3, 4), due in part to slow diagnostic methods and to inappropriate initial antifungal treatment (5, 6). Candida albicans and other yeasts reside as commensals of the skin and mucous membranes of the gastrointestinal and genitourinary tracts, causing infection when the host becomes debilitated or immunocompromised. Risk factors for invasive candidiasis include central venous catheters, parenteral nutrition, organ transplantation, hemodialysis, surgery, burns, long-term stay in an intensive care unit, and previous administration of broad spectrum antimicrobial and immunosuppressive agents (7,8).The most common Candida species found in healthy individuals include C. albicans, C. glabrata, C. tropicalis, and C. parapsilosis (9). These species cause more than 90% of invasive infections (10). However, the prevalence of these different Candida species varies widely geographically, and their antifungal susceptibilities are species specific (11). Consequently, rapid, accurate identification of the causative Candida species is critical for successful treatment.Currently, blood culture is the gold standard method for the diagnosis of fungal bloodstream infection (12). When growth is detected, blood culture medium is drawn for Gram stain and subculture on agar plates for subsequent phenotypic identification (13), which typically takes at least 72 h (14). To overcome this relatively long turnaround time of identification, several molecular methods have been evaluated for identification of yeasts directly from blood culture bottles such as real-time PCR, matrixassisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, and peptide nucleic acid fluorescence in situ hybridization (PNA-FISH) (15,16). A method to detect Candida directly from patient's blood specimens within 3 h has also been developed (17, 18).The first generation of yeast PNA-FISH (AdvanDx, Woburn, MA) distinguishes between the five commonest Candida species directly from positive blood cultures within 90 min. The method uses fluorescence-labeled probes to complement species-specific rRNA sequences: C. albicans and C. parapsilosis fluoresce green, C. tropicalis fluor...

Diagnostic Molecular Microbiology

“…Our laboratory has been involved in clinical trials of AdvanDx PNA-FISH products and our data showed high sensitivity and specificity of these products as well as the ease of use. [13][14][15][16] Although the popularity of PNA-FISH as a diagnostic test in large laboratories is declining, the FISH technique is being used by Accelerate Diagnostics (Tucson, AZ) to facilitate organism identification in positive blood culture bottles.…”

A PCR-Reverse Dot Blot Hybridization Based Microfluidics Detection System for the Rapid Identification of 13 Fungal Pathogens Directly After Blood Cultures Over a Period of Time

“…In addition, several commercial kits can detect partial Saccharomyces from positive blood culture bottles, such as the PhenoTest blood culture kit 14 and Candida PNA FISH assay. 15 The former only targets Candida albicans and Candida glabrata , while the latter can detect Candida albicans, Candida glabrata, Candida tropicalis, Candida parapsilosis , and Candida krusei . However, the detection range is narrow, easily causing missed detection.…”

Evaluation of QuickFISH and maldi Sepsityper for identification of bacteria in bloodstream infection

“…This technique requires prior Gram staining and subsequently the slide is viewed under a fluorescence microscope, turn-around time 1.5-3 h. Recent introduction of the next-generation test, the QuickFISH V R , the time for processing has been further reduced and the turn-around time is currently around 0.5 h. A number of different QuickFISH V R assays have been developed and validated, each capable of detecting up to a maximum of three different species per assay. Staphylococcus QuickFISH V R differentiates Staphylococcus aureus from coagulase-negative staphylococci (CoNS) [9][10][11][12], Enterococcus QuickFISH V R for identification of Gram-positive cocci in cluster differentiates Enterococcus faecalis from other Enterococcus spp., including Enterococcus faecium [12][13][14], the Gram-Negative QuickFISH V R which differentiates Escherichia coli from Pseudomonas aeruginosa and Klebsiella pneumonia [12], and finally the Candida QuickFISH V R assay differentiating Candida albicans from Candida glabrata and Candida parapsilosis [15].…”