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Now Available From CLSI: New Editions of M100-S24 and eM100

Wayne, Pennsylvania, USA—January 2014—The Clinical and Laboratory Standards Institute (CLSI) released a new edition of its document M100-S24—Performance Standards for Antimicrobial Susceptibility Testing; Twenty-Fourth Informational Supplement. This document provides the revised breakpoints, new recommendations, and reporting changes needed to incorporate into routine practice to improve detection and reporting of antimicrobial resistance. M100-S24 provides updated tables for the CLSI antimicrobial susceptibility testing standards M02-A11, M07-A9, and M11-A8.

“M100-S24 has new and critical information that all laboratories performing susceptibility testing on clinical isolates need to know,” notes Maria Traczewski, BS, MT(ASCP), of The Clinical and Microbiology Institute in Wilsonville, Oregon, USA, “Each new M100 has new information that is critical for clinical and reference labs to know about. It is important that labs purchase the new issue each year because changes are made that affect patient care.”

M100-S24 includes revised cefepime disk diffusion and minimal inhibitory concentration (MIC) interpretive criteria along with dosage regimens for using susceptible-dose dependent (SDD) interpretive criteria. The document provides revised doripenem, imipenem, and meropenem disk diffusion and MIC interpretive criteria with dosage regimens on which the breakpoints are based. This edition also includes new cefazolin interpretive criteria and recommendations for use as a surrogate test for uncomplicated urinary tract infections to predict results for oral cephalosporins.

Additionally, M100-S24 includes a definition of susceptible-dose dependent (SDD) with educational information explaining the introduction of SDD interpretive criteria; an example and explanation for antimicrobial agents having only susceptible interpretive criteria; information for reporting first- and second-generation cephalosporins and cephamycins for Salmonella spp. and Shigella spp.; and updated recommendations for the placement of disks on a 100-mm plate. Quality control ranges added and/or revised for M100-S24 include aztreonam-avibactam, biapenem, ceftolozane-tazobactam, eravacycline, surotomycin, and telavancin.

M100-S24 is available in print and electronic PDF formats. CLSI also provides an online implementation of M100-S24 called eM100. Find all of the information from the M100-S24 document brought to life in an interactive, searchable online tool. A free trial and various eM100 packages are available on our website.

Christopher McCoy, the Clinical Pharmacy Coordinator of Antimicrobial Stewardship at Beth Israel Deaconess Medical Center in Boston, Massachusetts, USA, highlighted that eM100 provides, “a faster way to access information on susceptibility breakpoints, cascade reporting, and screening for resistance mechanisms.” Mr. McCoy’s department uses eM100 to, “quickly summarize data on breakpoints for a given pathogen and select antibiotics to teach and share with pharmaceutical and medical providers.”

All versions and packages of M100-S24 and eM100 can be found in the CLSI Online Shop. Membership discounts are available for these items and will be applied at checkout.

CLSI is a not-for-profit membership organization that brings together the varied perspectives and expertise of the worldwide laboratory community for the advancement of a common cause: to foster excellence in laboratory medicine by developing and implementing clinical laboratory standards and guidelines that help laboratories fulfill their responsibilities with efficiency, effectiveness, and global applicability. For additional information, visit the CLSI website at or call 610.688.0100.



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