Newer β-Lactamases: Clinical and Laboratory Implications, Part II*

For optimal patient care, clinical laboratories should be capable of detecting clinically significant, novel β-lactamases produced by gram-negative pathogens. However, with over 700 β-lactamases now described, it is a struggle to keep abreast of the various types of β-lactamases, their clinical relevance, and methods for detection. Furthermore, the increasing prevalence of isolates that produce multiple β-lactamases increases the difficulty of accurate detection. Clinical Laboratory Standards Institute (CLSI, formerly NCCLS) recommendations for detection of β-lactamases do not keep pace with this rapidly evolving field. While perfection may not always be possible, it is important that clinical laboratories provide a relevant diagnostic service to ensure appropriate antibiotic therapy and infection control. Part II of this article will provide a discussion of AmpC β-lactamases and other β-lactam resistance mechanisms, along with methods for their laboratory detection.