Potential Impact of a Microarray-Based Nucleic Acid Assay for Rapid Detection of Gram-Negative Bacteria and Resistance Markers in Positive Blood Cultures

We evaluated the Verigene Gram-negative blood culture (BC-GN) test, a microarray that detects Gram-negative bacteria and several resistance genes. A total of 102 positive blood cultures were tested, and the BC-GN test correctly identified 97.9 % of the isolates within its panel. Resistance genes (CTX-M, KPC, VIM, and OXA genes) were detected in 29.8 % of the isolates, with posi-tive predictive values of 95.8 % (95 % confidence interval [CI], 87.7 % to 98.9%) in Enterobacteriaceae and 100 % (95%CI, 75.9% to 100%) in Pseudomonas aeruginosa and negative predictive values of 100 % (95 % CI, 93.9 % to 100%) and 78.6 % (95 % CI, 51.0 % to 93.6%), respectively. In cases of sepsis, timely microbiological diagnosis, includingdata on antimicrobial susceptibility, is crucial for prompt initi-ation of targeted drug therapy (1). This is not possible with cur-rently used methods, thus causing a significant delay in specific treatment and the empirical use of broad-spectrum antimicrobi-als (2–4). Nucleic acid-based assays are considered to be a poten-tial adjuvant tool for improving the microbiological diagnosis of sepsis (5–7). These assays may be classified into one of two groups (5–7): (i) those using positive blood cultures, which are poten-tially useful but burdened by the usual culture-associated draw