Evaluation of the Luminex ARIES HSV 1&2 Assay and Comparison with the FTD Neuro 9 and In-house Real-Time PCR Assays for Detecting Herpes Simplex Viruses

BACKGROUND: Human herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) are responsible for a plethora of human diseases, of which cutaneous and mucocutaneous infections are the most prevalent. In its most severe form, HSV infection can cause meningitis/encephalitis. We compared the Luminex ARIES HSV 1&2 assay (Luminex Corp., Austin, TX, USA), an automated sample-to-result molecular solution, to two non-automated HSV DNA assays. METHODS: A total of 116 artificial controls were used to determine the analytical performance of the ARIES assay. Controls were prepared by spiking universal transport medium (UTM) and cerebrospinal fluid (CSF) samples from patients who tested negative for HSV by an in-house HSV-1 and -2 DNA assay with reference materials (SeraCare Life Sciences, MA, USA; ZeptoMetrix Corp., MA, USA). Another 117 clinical samples were then used to compare the clinical performance of the ARIES assay with those of an in-house assay and the FTD Neuro 9 assay (Fast Track Diagnostics, Junglinster, Luxembourg). RESULTS: The analytical sensitivity (95% limit of detection) of the ARIES assay was 318 copies/mL (UTM samples) and 935 copies/mL (CSF samples) for HSV-1 strain 96 and 253 copies/mL (UTM samples) and 821 copies/mL (CSF samples) for HSV-2 strain 09. No cross-reactivity was observed in samples spiked with 14 non-HSV microorganisms. Compared with the reference result (agreement between the in-house and FTD Neuro 9 results), the ARIES assay had overall concordance rates of 98.2% (111/113) and 100% (113/113) for HSV-1 and HSV-2, respectively. CONCLUSIONS: The ARIES assay appears to be an excellent alternative for rapid detection and differentiation of HSV in skin and genital infections, meningitis, and encephalitis.

Antibiotic resistance in gram-negative bacilli: a Singapore perspective

<p><b>INTRODUCTION</b>Antibiotic resistance in gram-negative bacilli is an area of increasing importance. This prospective study was performed to survey antibiotic resistance in Escherichia coli (E. coli), Klebsiella spp., Pseudomonas aeruginosa and Acinetobacter spp. over a 1-year period.</p><p><b>MATERIALS AND METHODS</b>Non-duplicate isolates of E. coli, Klebsiella spp., P. aeruginosa and Acinetobacter spp. were collected from participating Singapore hospitals during defined collection periods in 2006 and 2007. Confirmatory identification and antibiotic susceptibility testing were performed at Changi General Hospital. Minimum inhibitory concentrations (MIC) to a defined panel of antibiotics were determined using microbroth dilution methods. The presence of extended-spectrum beta lactamases and AmpC beta-lactamases in Enterobacteriaceae was determined by phenotypic methods, and susceptibility results were defined using current breakpoints from the Clinical Laboratory Standards Institute (CLSI).</p><p><b>RESULTS</b>Seven hundred and forty-six gram-negative bacilli were received for testing. Resistance to extended-spectrum cephalosporins was present in a third of Enterobacteriaceae isolates, and extended-spectrum beta-lactamases (ESBL) carriage was present in 19.6% and 30.1% of E. coli and Klebsiella pneumoniae, respectively. AmpC enzymes were also detected in 8.5% and 5.6% of E. coli and K. pneumoniae isolates respectively. All Enterobacteriaceae were susceptible to imipenem and meropenem. The most active antibiotics against P. aeruginosa were amikacin, meropenem and piperacillin-tazobactam. A third of P. aeruginosa showed reduced susceptibility to polymyxin B. Carbapenem resistance was significantly higher in Acinetobacter baumannii (70.5%) than in other Acinetobacter species (25.0%). The most active antibiotic against A. baumannii was polymyxin B.</p><p><b>CONCLUSION</b>Antibiotic resistance is prevalent in gram-negative bacilli isolated from Singapore hospitals. The MIC testing surveillance programme complemented susceptibility data from wider laboratory-based surveillance, and has revealed emerging mechanisms of antibiotic resistance.</p>