Traditional microbiological work up is slow and sometimes inaccurate, relying on phenotypic culture identification followed by antimicrobial susceptibility testing. Newer technologies, such as matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and real-time molecular detection (antimicrobial resistance genes microarrays) have advanced the diagnostic capabilities of clinical microbiology laboratories and have created an exciting field for research and development. Given the in-depth and highly accurate (sometimes complex) results that are produced by such platforms, careful detailed analyses are required to better understand the clinical significance of the organisms identified and the resistance mechanisms detected. During this fiscal year, we have undertaken a multi-center collaborative study to investigate the role of Streptococcus gallolyticus subsp. pasteurianus in hematopoietic stem cell transplant (HSCT) recipients and to evaluate the performance of two different MALDI-TOF MS systems for the identification of microorganisms to the subspecies level. We are also investigating the performance of a novel real-time PCR assay for the detection of four major carbapenmase genes direct from primary specimens, in parallel with selective culture. Methods to accurately detect extended spectrum beta-lactamases (ESBLs) and vancomycin resistant Enterococci (VREs) from surveillance specimens are also being evaluated in an effort to remove patients from unnecessary and costly infection control precautions, as well as improving the diagnostic specificity for microbiology laboratories. Finally, evaluation of rapid phenotypic methods to detect beta-lactamases from culture and the development of new approaches to detect these enzymes from primary specimens is underway.
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