In Vitro Evaluation of BacT/Alert FA Blood Culture Bottles and T2Candida Assay for Detection of Candida in the Presence of Antifungals.

The T2Candida assay is a novel, non-culture-based assay for the diagnosis of candidemia directly from whole blood. The impact of antifungals on the performance of the T2Candida assay and blood culture bottles has not been well described. In this study, the performance of the T2Candida assay was compared to that of blood culture in detecting Candida spp. in spiked blood cultures with or without the presence of antifungals. Clinical bloodstream isolates of Candida spp. were inoculated into human whole blood at low (1 to 5 cells/ml) and high (10 to 50 cells/ml) concentrations with or without the presence of caspofungin and fluconazole. Time to detection (TTD) was assessed for prepared samples using BacT/Alert FA aerobic blood culture bottles or the T2Candida assay. In the absence of antifungals, T2Candida assay sensitivity was comparable to that of blood culture at both the low inoculum and the high inoculum (95% versus 97.5% and 100% versus 100%, respectively) and the assay had an average TTD that was significantly shorter (5.1 h versus 27.2 to 30 h, respectively). Neither caspofungin nor fluconazole was observed to impact the sensitivity or TTD of the T2Candida assay, while fluconazole reduced the overall blood culture sensitivity by 7.5% to 12.5% (at the low inoculum and high inoculum, respectively) and significantly increased the TTD of Candida albicans, C. tropicalis, and C. parapsilosis by 14.8 to 67 h. Neither caspofungin nor fluconazole impacted the performance of the T2Candida assay in vitro, and the assay may be useful for the diagnosis of candidemia in patients receiving antifungal therapy.

Accelerate PhenoTestTM BC Kit Versus Conventional Methods for Identification and Antimicrobial Susceptibility Testing of Gram-Positive Bloodstream Isolates: Potential Implications for Antimicrobial Stewardship.

BACKGROUND: The Accelerate PhenoTestTM BC kit (AXDX) provides rapid organism identification (ID) and antimicrobial susceptibility testing (AST) results. Its potential role for antimicrobial stewardship is unknown. OBJECTIVE: To compare the diagnostic accuracy of AXDX with conventional methods (CMs) and assess AXDX's potential role for antimicrobial stewardship in patients with Gram-positive bloodstream infections (BSIs). METHODS: This retrospective cohort study included adults with Staphylococcus aureus or Enterococcus spp BSIs from July 2014 to January 2016 at a tertiary care medical center. Available isolates were tested on AXDX, and ID and AST results from AXDX were compared with those from CMs (VITEK 2 or ETEST). The following antibiotics were assessed for categorical agreement (CA) and essential agreement (EA) between the methods: ampicillin and daptomycin ( Enterococcus spp only), erythromycin and cefoxitin ( S aureus only), linezolid, and vancomycin. Potential role of AXDX for stewardship was assessed via a retrospective audit by infectious diseases clinicians. RESULTS: We included 231 patients with S aureus (n = 112) or Enterococcus spp (n = 119) BSIs, and 106 unique isolates were available for ID and AST performance analyses. Sensitivity and specificity of AXDX for ID were 98.0% and 99.5%, respectively. CA and EA for the tested antibiotics were >97%. In Monte Carlo simulations, AXDX coupled with stewardship personnel (either 24/7 or Monday to Friday) would have allowed unnecessary therapy to be stopped and active/targeted therapy to be started ≥24 hours sooner in >50% of patients. CONCLUSIONS: Compared with CMs, AXDX had similar diagnostic accuracy and can potentially optimize therapy sooner in patients with Gram-positive BSIs.

Community Environmental Contamination of Toxigenic Clostridium difficile.

BACKGROUND: Clostridium difficile infection is often considered to result from recent acquisition of a C difficile isolate in a healthcare setting. However, C difficile spores can persist for long periods of time, suggesting a potentially large community environmental reservoir. The objectives of this study were to assess community environmental contamination of toxigenic C difficile and to assess strain distribution in environmental versus clinical isolates. METHODS: From 2013 to 2015, we collected community environmental swabs from homes and public areas in Houston, Texas to assess C difficile contamination. All positive isolates were tested for C difficile toxins A and B, ribotyped, and compared with clinical C difficile isolates obtained from hospitalized patients in Houston healthcare settings. RESULTS: A total of 2538 environmental samples were collected over the study period. These included samples obtained from homes (n = 1079), parks (n = 491), chain stores (n = 225), fast food restaurants (n = 123), other commercial stores (n = 172), and hospitals (n = 448). Overall, 418 environmental isolates grew toxigenic C difficile (16.5%; P < .001) most commonly from parks (24.6%), followed by homes (17.1%), hospitals (16.5%), commercial stores (8.1%), chain stores (7.6%), and fast food restaurants (6.5%). A similar distribution of ribotypes was observed between clinical and environmental isolates with the exception that ribotype 027 was more common in clinical isolates compared with environmental isolates (P < .001). CONCLUSIONS: We identified a high prevalence of toxigenic C difficile from community environs that were similar ribotypes to clinical isolates. These findings suggest that interventions beyond isolation of symptomatic patients should be targeted for prevention of C difficile infection.