Sensititre YeastOne (SYO) is an affordable alternative to the Clinical and Laboratory Standards Institute (CLSI) reference method for antifungal susceptibility testing. In this study, the MICs of yeast isolates from 1,214 bloodstream infection episodes, generated by SYO during hospital laboratory activity (January 2005 to December 2013), were reanalyzed using current CLSI clinical breakpoints/epidemiological cutoff values to assign susceptibility (or the wild-type [WT] phenotype) to systemic antifungal agents. Excluding Candida albicans (57.4% of all isolates [n ‫؍‬ 1,250]), the most predominant species were Candida parapsilosis complex (20.9%), Candida tropicalis (8.2%), Candida glabrata (6.4%), Candida guilliermondii (1.6%), and Candida krusei (1.3%). Among the non-Candida species (1.9%), 7 were Cryptococcus neoformans and 17 were other species, mainly Rhodotorula species. Over 97% of Candida isolates were susceptible (WT phenotype) to amphotericin B and flucytosine. Rates of susceptibility (WT phenotype) to fluconazole, itraconazole, and voriconazole were 98.7% in C. albicans, 92.3% in the C. parapsilosis complex, 96.1% in C. tropicalis, 92.5% in C. glabrata, 100% in C. guilliermondii, and 100% (excluding fluconazole) in C. krusei. The fluconazole-resistant isolates consisted of 6 C. parapsilosis complex isolates, 3 C. glabrata isolates, 2 C. albicans isolates, 2 C. tropicalis isolates, and 1 Candida lusitaniae isolate. Of the non-Candida isolates, 2 C. neoformans isolates had the non-WT phenotype for susceptibility to fluconazole, whereas Rhodotorula isolates had elevated azole MICs. Overall, 99.7% to 99.8% of Candida isolates were susceptible (WT phenotype) to echinocandins, but 3 isolates were nonsusceptible (either intermediate or resistant) to caspofungin (C. albicans, C. guilliermondii, and C. krusei), anidulafungin (C. albicans and C. guilliermondii), and micafungin (C. albicans). However, when the intrinsically resistant non-Candida isolates were included, the rate of echinocandin nonsusceptibility reached 1.8%. In summary, the SYO method proved to be able to detect yeast species showing antifungal resistance or reduced susceptibility.

The rapid detection and/or identification (ID) of the microbial pathogens responsible for bloodstream infections (BSIs) is pivotal for reducing infection-related mortality and costs (1), particularly for severely ill patients (2, 3). Although blood culture (BC) continues to be essential for BSI diagnosis, the turnaround time for ID can be accelerated using new technologies that are directly applied to positive BC bottles/broths (4).Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was recently demonstrated to improve the clinical management of BSIs (5, 6) and allow patients to receive appropriate antimicrobial therapy earlier (i.e., 24 h from the first positive BC) (7). However, despite its well-documented good performance (8-17), this method often fails to identify polymicrobial BCs in their entirety.Another method is the multiplex PCR-based FilmArray blood culture ID (BCID) panel (bioMérieux, Marcy l'Etoile, France), which is equally as fast as the MALDI-TOF MS (e.g., MALDI BioTyper system [Bruker Daltonics, Bremen, Germany]). This technique was developed for the simultaneous identification of 24 microbial pathogens, including 19 bacterial genera/species and 5 Candida species (and 3 antibiotic resistance determinants). In addition to its high sensitivity and specificity, the FilmArray BCID panel has proven to be accurate for identifying not only monomicrobial but also polymicrobial . Notably, successful results were obtained with BC broths tested before the bottles became positive or even before the bottles were incubated in the BC instrument as usual (24). To date, the extensive use of the FilmArray BCID panel in routine clinical laboratory practice has been hampered by the high cost of reagents/consumables.In this study, we developed a BSI diagnostic algorithm that relied on the direct analysis of positive BC bottles/broths using the MALDI BioTyper system supplemented with the FilmArray BCID panel. We evaluated this algorithm in terms of ID accuracy and turnaround time by comparing the results with a reference culture-based procedure.(This work has been presented in part as a poster at the 24th European Congress of Clinical Microbiology and Infectious Diseases, 10 to 13 May 2014, Barcelona, Spain).

We compared the clinical performances of the BacT/Alert Plus (bioMérieux) and Bactec Plus (Becton Dickinson) aerobic and anaerobic blood culture (BC) media with adsorbent polymeric beads. Patients >16 years old with suspected bloodstream infections (BSIs) were enrolled in intensive care units and infectious disease wards. A single 40-ml blood sample was collected from each and used to inoculate (10 ml/bottle) one set of BacT/Alert Plus cultures and one set of Bactec Plus cultures, each set consisting of one aerobic and one anaerobic bottle. Cultures were incubated <5 days in the BacT/Alert 3D and Bactec FX instruments, respectively. A total of 128 unique BSI episodes were identified based on the recovery of clinically significant growth in 212 aerobic cultures (106 BacT/Alert and 106 Bactec) and 151 anaerobic cultures (82 BacT/Alert and 69 Bactec). The BacT/Alert aerobic medium had higher recovery rates for Gram-positive cocci (P ‫؍‬ 0.024), whereas the Bactec aerobic medium was superior for recovery of Gram-negative bacilli (P ‫؍‬ 0.006). BacT/Alert anaerobic medium recovery rates exceeded those of the Bactec anaerobic medium for total organisms (P ‫؍‬ 0.003), Gram-positive cocci (P ‫؍‬ 0.013), and Escherichia coli (P ‫؍‬ 0.030). In terms of capacity for diagnosing the 128 septic episodes, the BacT/Alert and Bactec sets were comparable, although the former sets diagnosed more BSIs caused by Gram-positive cocci (P ‫؍‬ 0.008). They also allowed earlier identification of coagulase-negative staphylococcal growth (mean, 2.8 h; P ‫؍‬ 0.003) and growth in samples from patients not on antimicrobial therapy that yielded positive results (mean, 1.3 h; P < 0.001). Similarly high percentages of microorganisms in BacT/Alert and Bactec cultures (93.8% and 93.3%, respectively) were identified by direct matrix-assisted laser desorption ionization-time of flight mass spectrometry assay of BC broths. The BacT/Alert Plus media line appears to be a reliable, timesaving tool for routine detection of BSIs in the population we studied, although further studies are needed to evaluate their performance in other settings.

No abstract

No abstract