scope:

CLSI documents M02,¹ M07,² and M1003 describe standardized methods and interpretive criteria for antimicrobial susceptibility testing of common aerobic bacteria, including some fastidious organisms. However, a number of less frequently encountered or fastidious bacteria are not addressed in those CLSI documents despite their potential to cause serious infections. M45 addresses these latter organisms with the goal of providing recommendations for clinical microbiology laboratories on how and when to determine the susceptibility of these diverse organisms. This document also provides guidance for public health laboratory testing of bacteria potentially associated with bioterrorism.

This edition of M45 includes taxonomic updates and several new tables to address organisms more likely to be identified in laboratories using sequencing or matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the identification of bacteria. The intent of this revision is to assist laboratories in determining an approach for testing that is relevant to their individual practice settings.

The methods provided may be used in clinical, public health, and research laboratories.

This guideline does not address commercial susceptibility testing devices.