Rapid Molecular Screening for Gram-Negative Antimicrobial-Resistance Genes with Commercially Available Methods

Antibiotic-resistant bacteria threaten the well-being of many hospitalized patients and cause an added financial burden on health care systems. There is a particular challenge in identification of the antimicrobial-resistance phenotype for Gram-negative microbes, which are emerging as a serious global public health threat. Infections by multidrug-resistant Gram-negative bacteria are defined as those caused by bacteria with resistance to at least one agent in three or more antimicrobial categories. Of particular importance, cases of infections due to extended-spectrum β-lactamase and/or carbapenemase producers are increasing. Although active surveillance for Gram-negative bacilli is not as common as that for Gram-positive microbes, rapid identification of Gram-negative pathogens via passive surveillance is very common. As with other drug-resistant microbes, rapid identification of antimicrobial resistance is key to proper treatment and infection control with carbapenem-resistant bacilli and extended spectrum beta-lactamase producers. Their presence increasingly drives the need to screen infected and colonized patients in an attempt to improve patient management and infection control. Here, we briefly review commercially available molecular detection methods with focus on a new multiplex microfluidic PCR test (Acuitas MDRO Gene Test) that detects the hundreds of gene subtypes from the carbapenemase and extended-spectrum β-lactamases families, as well as the vancomycin resistance gene, vanA, found in Gram-positive microbes. We also describe the new Acuitas Resistome Test, which is a multiplex PCR test for 44 families of antibiotic resistance genes from culture isolates of Gram-negative bacilli.