Detection of gram-negative β-lactamase producing pathogens in the clinical lab.

Pathogens that produce extended spectrum β-lactamases (ESBLs), plasmid-mediated AmpC β-lactamases, and carbapenemases may appear falsely susceptible to β-lactam antibiotics in the laboratory. Infected patients may be treated with inappropriate antibiotics if laboratories do not perform accurate tests to detect these resistance mechanisms. Furthermore the resistant pathogens may spread undetected to amplify the therapeutic and infection control challenge. This review makes a case for why and how laboratories should perform tests to detect β-lactamase-mediated resistance in gram-negative pathogens.