New Developments in Clinical Bacteriology Laboratories Robin Patel, MD  Mayo Clinic Proceedings  Volume 91, Issue 10, Pages 1448-1459 (October 2016) DOI: 10.1016/j.mayocp.2016.06.020 Copyright © 2016 Mayo Foundation for Medical Education and Research Terms and Conditions

Figure 1 Test ordering guidance for infectious diarrhea. A general guide to laboratory testing for infectious causes of diarrhea is shown. This panel should not be used for chronic diarrhea. Note that culture is necessitated in cases in which antimicrobial susceptibility testing is required and can be tailored to specific isolation of the organism(s) detected by the molecular panel (ie, reflexive culture). The same approach can be used if isolates are needed by public health departments, or stool testing positive by a multiplex gastrointestinal panel can be submitted to a public health department where culture can be performed to isolate the organism(s) detected. aWarning signs and risk factors for severe disease include fever, bloody diarrhea, dysentery, severe abdominal pain, dehydration, hospitalization, and immunocompromised state. bGastrointestinal Pathogen Molecular Panels test for common bacterial, viral and parasitic causes of diarrhea. cSubmit 3 stool collected on separate days for maximum sensitivity. From Mayo Medical Laboratories Test Catalog,7 with permission. Mayo Clinic Proceedings 2016 91, 1448-1459DOI: (10.1016/j.mayocp.2016.06.020) Copyright © 2016 Mayo Foundation for Medical Education and Research Terms and Conditions

Figure 2 A bacterial or fungal colony (typically single) is “picked” from a culture plate to a “spot” on a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry target plate (a reusable or disposable plate with a number of test spots) using a wooden or plastic stick, pipette tip, or loop. One or many isolates may be tested at a time. Cells may be treated with formic acid on the target plate. The spot is then overlain with matrix. After a short drying period, the plate is placed in the mass spectrometer for analysis. A mass spectrum is generated and automatically compared to a database of mass spectra by the software, resulting in the identification of the organism (Morganella morganii in position A4 in the example). Adapted from Communiqué,19 with permission. Mayo Clinic Proceedings 2016 91, 1448-1459DOI: (10.1016/j.mayocp.2016.06.020) Copyright © 2016 Mayo Foundation for Medical Education and Research Terms and Conditions