DIAGNOSTIC ADVANCES IN VANCOMYCIN-RESISTANT ENTEROCOCCI: CONVENTIONAL TO MOLECULAR METHODS

Abstract

VRE has become an important nosocomial pathogen that is now linked with increased morbidity, mortality, LOS and costs. There are numerous issues related to infection control and antimicrobial stewardship, as many cases are reported with VRE, particularly E. faecium and E. faecalis, at the international level. The proper and prompt diagnosis is still critical for proper patient management and prevention of hospital-associated outbreaks. The laboratory has been using traditional methods like culture based, disk diffusion, broth microdilution, and biochemical characterization, routinely. However, there are some disadvantages to these methods, including low sensitivity of the possible resistance phenotypes and slow turn-around time. The last years have seen a revolution in VRE detection using molecular diagnostic methods such as polymerase chain reaction (PCR), multiplex PCR, real-time PCR, loop-mediated isothermal amplification (LAMP), DNA microarrays, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), next-generation sequencing (NGS), and DNA sequencing. The technologies promote rapid detection of resistance associated genes, such as vanA, vanB, vanC, vanD, vanE and vanG, which helps to implement better diagnostic and infection control procedures. This study compares the development of previous diagnostic methods from the traditional microbiological methods to molecular diagnostics platforms. Comparative analysis reveals that there are significant advancements in sensitivity, specificity, speed and in epidemiological surveillance. For most investigations, molecular diagnostics had sensitivities >95% compared to definitive results from conventional diagnostics that took 24-72 hours. New diagnostic and antimicrobial resistance monitoring capabilities are expected to further enhance the diagnostic and surveillance capabilities based on biosensors and genomic platforms. The results highlight the need to incorporate molecular tools into routine clinical microbiology labs to aid in managing and controlling VRE infections.