On 24-26 January, Susan Sharp, chair of the ASM Public and Scientific Affairs Board Committee on Laboratory Practices, represented ASM at the Clinical Laboratory Standards Institute (CLSI) committee meeting on antimicrobial susceptibility testing (AST).  During the meeting, AST committee members discussed breakpoints for Enterobacteriaceae, Staphylococcus, and anaerobes.

The CLSI-AST committee plans to release revised carbapenem breakpoints for the Enterobacteriaceae in a supplement sometime in 2010. Wording in a footnote would indicate that isolates with MICs in the intermediate range might have a carbapenemase, and there is still some uncertainty about the response of these isolates to carbapenems; clinicians could be advised about maximum FDA-approved dosing regimens. This will negate the need for modified Hodge testing for confirmation of carbapenemase-producing Enterobacteriaceae.

Three new Intrinsic Resistance Tables (currently under development) will include bug-drug combinations that laboratories should definitely report as "R." These tables will include an introductory paragraph outlining the basis for the table, define intrinsic resistance, and explain how the table can be used by clinical microbiology laboratories. The first table will be for the Enterobacteriaceae, the second for nonfermentative bacilli, and the third table for gram-positive bacteria. The committee will be working on devising a Staphylococcus screening test for VISA to replace the vancomycin disk diffusion test, particularly for low resource laboratories that rely on disk diffusion.

The committee has decided to include all anaerobic (M11 document) tables in the yearly M100 updates. According to CLSI, changes noted to CLSI documents M02, M07, and M100 are not to be considered "final" or "published" until those documents have completed the CLSI consensus process and have been approved for publication. The next CLSI-AST meeting will be held 13-15 June in Atlanta, Ga. For more information about this summary, please contact Susie Sharp at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .