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The AmpliVue HSV 1+2 assay was compared to the ELVIS HSV ID and D3 Typing Culture System for the qualitative detection and differentiation of herpes simplex virus 1 (HSV-1) and HSV-2 DNA in 1,351 cutaneous and mucocutaneous specimens. Compared to ELVIS, AmpliVue had sensitivities of 95.7 and 97.6% for detecting HSV-1 and HSV-2, respectively. Following arbitration of discordant results by an independent molecular method, the AmpliVue assay had a resolved sensitivity and specificity of 99.2 and 99.7%, respectively, for both HSV-1 and HSV-2, whereas ELVIS had a resolved sensitivity of 87.1% for HSV-1 and 84.5% for HSV-2.

dClostridium difficile is a Gram-positive bacterium commonly found in health care and long-term-care facilities and is the most common cause of antibiotic-associated diarrhea. Rapid detection of this bacterium can assist physicians in implementing contact precautions and appropriate antibiotic therapy in a timely manner. The purpose of this study was to compare the clinical performance of the Quidel Lyra Direct C. difficile assay (Lyra assay) (Quidel, San Diego, CA) to that of a direct cell culture cytotoxicity neutralization assay (CCNA) and enhanced toxigenic culture. This study was performed at three geographically diverse laboratories within the United States using residual stool specimens submitted for routine C. difficile testing. Residual samples were tested using the Lyra assay on three real-time PCR platforms, and results were compared to those for direct CCNA and enhanced toxigenic culture. The test results for all platforms were consistent across all three test sites. The sensitivity and specificity of the Lyra assay on the SmartCycler II, ABI 7500 Fast DX, and ABI QuantStudio DX instruments compared to CCNA were 90.0% and 93.3%, 95.0% and 94.2%, and 93.8% and 95.0%, respectively. Compared to enhanced toxigenic culture, the sensitivity and specificity of the Lyra assay on the SmartCycler II, ABI 7500, and QuantStudio instruments were 82.1% and 96.9%, 89.3% and 98.8%, and 85.7% and 99.0%, respectively. Overall, the Lyra assay is easy to use and versatile and compares well to C. difficile culture methods.

The Shiga Toxin Direct molecular assay (ST Direct) relies on nucleic acid amplification and solid array-based amplicon detection to identify Shiga toxinproducing Escherichia coli (STEC) in preserved stool specimens. Genes encoding Shiga toxin (stx 1 and stx 2 ), as well as the E. coli serotype O:157-specific marker rfbE, are simultaneously detected within 2 h. ST Direct was evaluated using 1,084 prospectively collected preserved stool specimens across five clinical centers. An additional 55 retrospectively collected, frozen specimens were included to increase the number of positive specimens evaluated. Results were compared to results from routine culture and an enzyme immunoassay (EIA) specific for the recovery and identification of STEC. ST Direct was found to be 93.2% sensitive and 99.3% specific for detection of stx 1 and stx 2 and 95.7% sensitive and 99.3% specific for detection of E. coli serotype O:157. All specimens with false-positive results were found to contain stx 1 or stx 2 or were found to be positive for serotype O:157 when analyzed using alternative molecular methods. All 4 false-negative stx 1 or stx 2 results were reported for frozen, retrospectively tested specimens. In all cases, the specimens tested positive for stx by an alternative FDA-cleared nucleic acid amplification test (NAAT) but were negative for stx 1 and stx 2 following nucleic acid sequence analysis. Based on these data, culture and EIA-based methods for detection of STEC are only 33% sensitive compared to molecular tests. A retrospective cost analysis demonstrated 59% of the cost of routine stool culture to be attributable to the identification of STEC. Taken together, these data suggest that ST Direct may provide a costeffective, rapid molecular alternative to routine culture for the identification of STEC in preserved stool specimens.

The iC-GPC assay (iCubate, Huntsville, AL) provides a molecular option for the rapid, on-demand analysis of positive blood cultures. A preliminary evaluation of the iC-GPC assay using 203 clinical or seeded specimens demonstrated a sensitivity of 93.8% to 100% and a specificity of 98.0% to 100% for the identification of five Gram-positive bacterial species (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Enterococcus faecalis, and Enterococcus faecium) and three associated genetic resistance determinants (mecA, vanA, and vanB) in positive blood culture broths.T he rapid identification of bacterial and fungal pathogens in positive blood culture broths by use of a variety of methods has been described. These methods include peptide nucleic acid fluorescence in situ hybridization (PNA-FISH), matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and real-time PCR (RT-PCR) or microarray-based molecular tests (1-10). The ability to reliably identify a specific bacterium or yeast present in a positive blood culture within 1 to 3 h of culture positivity using these methods has resulted in significant reductions in time to effective antimicrobial therapy, length of hospital/intensive care unit (ICU) stay, 30-day mortality, and cost of care (6,7,(11)(12)(13). Importantly, while organism identification alone can provide some benefit, the most significant benefits are achieved when the presence of resistance markers, such as mecA, vanA, or carbapenemases, is identified concomitantly (11,12,(14)(15)(16).The research-use-only (RUO) iC-GPC assay (iCubate, Huntsville, AL) is a molecular target amplification assay capable of detecting and identifying Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Enterococcus faecalis, and Enterococcus faecium as well as the genetic resistance determinants mecA, vanA, and vanB directly from positive blood culture broths. The system consists of an automated processor (iC-Processor), a reader (iC-Reader), and single-use, closed-system test cassettes. Each test cassette contains all reagents necessary for cell lysis, nucleic acid extraction, target amplification, and amplicon hybridization to an array of immobilized capture probes. Each immobilized capture probe has a unique nucleic acid sequence, which can hybridize to the target. A second fluorescence-labeled gene-specific detection probe contained within the closed cassette was used to detect the target after capture.(A portion of the data collected in this study was presented at the 115th General Meeting of the American Society for Microbiology, New Orleans, LA, 30 May to 2 June 2015.)We conducted a preliminary evaluation of the iC-GPC assay using a total of 215 positive blood culture broths containing Gram-positive cocci (GPC). Positive broths were enrolled and tested at three clinical laboratories. The cohort included 107 prospectively collected blood cultures and was augmented with 108 simulated blood cultures seeded with organisms less frequent...