Antimicrobial susceptibility testing (AST) and reporting for antimicrobials informs and optimizes prescribing and detects resistance.1
It also serves as an important component of hospital antimicrobial stewardship (AMS) efforts to combat urgent multidrug-resistant (MDR) Gram-negative infections. When facing a critically ill patient with a suspected Gram-negative bacterial infection, delayed appropriate therapy can be lethal. This represents a particular challenge with the rapid pace at which resistant Gram-negative organisms emerge and render our existing antimicrobial arsenal less effective. In addition, lack of information about the nature of the infection is a weak link that contributes to antimicrobial resistance through improper prescribing. AMS remains critical in the race against antimicrobial resistance.
The value that AST provides to clinicians to inform antimicrobial selection in support of AMS efforts cannot be overstated. The Joint Commission recently issued Standard MM.09.01.01, effective January 1, 2017, requiring hospitals, critical access hospitals, and nursing care centers to implement and prioritize AMS programs.2
The standard outlines core components that should be present in all AMS programs; calls for education of clinicians, staff, and patients about antimicrobial resistance and the appropriate use of antimicrobials; and requires that hospitals and nursing care centers collect, analyze, and report data on their AMS programs and use these data to improve them. However, the standard does not address the role of AST in AMS or the challenges surrounding AST. Thus, it misses a key element in rapidly identifying infectious organisms and selecting the appropriate antimicrobial agents for treatment.
AST for Off-label Indications
Antimicrobials are widely used in critically ill adults, and in a significant number of cases, antimicrobials are used off label. Anywhere from 19% to 43% of critically ill patients with Gram-negative bacterial infections are treated with off-label antimicrobials.1
On the basis of in vitro
and pharmacokinetic data, clinicians often prescribe antimicrobial agents for infections that are not listed specifically in the US Food and Drug Administration (FDA)-approved label, but represent logical uses. For example, a drug approved for complicated intra-abdominal infections might also show good concentrations in the lung; thus, a clinician might select that drug for a critically-ill patient with pneumonia when circumstances demand less conventional options. With highly-resistant pathogens, off-label antimicrobials may be the only active options. Off-label AST reporting and antimicrobial prescribing are vital in both AMS and patient care, particularly for Gram-negative organisms. In some cases, without off-label reporting, there would be no way to conduct AST for Gram-negative infections.