CLSI Publishes Guideline on Methods for Antimicrobial Susceptibility Testing for Human Mycoplasmas
By Ken B. Waites
Chairholder, CLSI Antimicrobial Susceptibility Testing Subcommittee for Human Mycoplasmas
The Clinical and Laboratory Standards Institute (CLSI) has published Methods for Antimicrobial Susceptibility Testing for Human Mycoplasmas; Approved Guideline (M43-A). This document is the result of more than a decade of work by members of the IRPCM Chemotherapy Working Team and other microbiologists from 10 different laboratories representing government, academia, and industry in the United States, Canada, and France. IOM members who co-authored this document are Ken Waites, Lynn Duffy, Cecile Bébéar, Pat Totten, George Kenny, Deborah Talkington, and Maureen Davidson.
M43-A is the first published method that provides standardized step-by-step procedures for performing agar and broth microdilution testing for Mycoplasma pneumoniae, Mycoplasma hominis, and Ureaplasma urealyticum that specifies designated reference strains for each species and the expected minimal inhibitory concentration ranges for specific drugs that should be obtained when they are tested; the quality control procedures that must be performed with each assay, acceptable media formulations, and interpretive minimal inhibitory concentration breakpoints for several antimicrobial agents. The information and procedural guidelines contained in the M43-A document was derived through a rigorous multilaboratory consensus process under the oversight of the CLSI with emphasis on inter- and intra-laboratory test reproducibility. The availability of this document will provide diagnostic laboratories as well as research laboratories a standardized method for in vitro susceptibility testing that should improve reliability of results and lessen ambiguity and misinformation that can sometimes arise when nonstandard methods are used without rigorously defined quality control procedures, as has been the case for many years in mycoplasmology.
Antimicrobial susceptibility testing is indicated for any organism that contributes to an infectious process warranting antimicrobial chemotherapy, if its susceptibility cannot be reliably predicted from knowledge of the organism’s identity. Standardized in vitro antimicrobial susceptibility tests are also needed in order to evaluate new antimicrobials against mycoplasmas and ureaplasmas in comparison with existing agents. Acquired resistance to one or more classes of antimicrobial agents has emerged in all of the mycoplasmal and ureaplasmal species that infect humans, so there is a need to establish accurate and reproducible methods to measure antimicrobial activities in vitro with these organisms. M43-A effectively satisfies this demand. This guideline is intended for use by hospital clinical laboratories; reference microbiology laboratories; and government, industry, and academic research organizations that perform diagnostic testing and/or conduct research in mycoplasmal diseases that affect humans.
The M43-A document can be purchased for $60 U.S. by CLSI members or $120 U.S. by non-CLSI members and is available in printed and electronic versions. Information regarding purchase of the document can be obtained through the following internet link or by contacting CLSI:
http://www.clsi.org/source/orders/Product_Display.cfm?section=Shop&task=3&CATEGORY=MI&PRODUCT_TYPE=SALES&SKU=M43A
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