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Discordant Antibiotic Use Can be Common, and Deadly
Empiric antibiotic therapy in suspected bloodstream infections is vital. Unfortunately, a new study shows that discordant use is both fairly common, and potentially lethal.
A retrospective study published in The Lancet Infectious Diseases 
highlights that 19% of patients (roughly 1 in 5) with confirmed blood stream infections received inappropriate empirical antibiotic therapy.
Ineffective therapy was associated with an antibiotic-resistant pathogen in nearly half of the cases, as well as an increased likelihood of mortality, even in patients without sepsis or septic shock. Surprisingly, there was also an increased risk of mortality with discordant antibiotic usage in patients with antibiotic-susceptible pathogens.
Critical AST Data from the Clinical Microbiology Laboratory
In addition to early identification of pathogens and potential presence of resistance in suspected bloodstream pathogens, harnessing antibiograms and antimicrobial susceptibility test (AST) data from the clinical microbiology lab is one way to help optimize the use of empiric therapy, and potentially save lives.
Antibiograms, also known as cumulative antimicrobial susceptibility reports, are one way to improve empiric drug choice. These provide an overview of pathogen susceptibly to a variety of antimicrobials within an institution or healthcare system. Data are typically aggregated and shown as percentages of organisms that are susceptible. Reports are used to help guide the selection of the best empiric therapy when known susceptibility results are pending. Many labs have AST platforms that can generate data specific to patient populations such as pediatric, or even locations within the organization, Emergency Room or Critical/Intensive Care Units, for example.
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Antibiograms can also be useful in detecting and tracking emerging resistance in local patient populations. Data that are summarized and compared over time can identify trends in reduced susceptibilities of pathogens or to specific agents/classes of antimicrobials.
Leverage Cascade and Selective Reporting to Optimize Clinical Decisions
The way in which AST results are reported can influence antimicrobial prescribing as well. Microbiology laboratories have two important reporting mechanisms to help guide the best clinical decisions, cascade reporting and selective reporting. Cascade reporting drives providers to choose more narrow spectrum agents when possible, preserving the clinical utility of broader-spectrum or new newer agents when a pathogen has known susceptibility to narrower spectrum agents. Selective reporting drives providers to make the preferred choices in varying clinical scenarios, reducing inappropriate and unnecessary antibiotic prescriptions.
| Cascade Reporting | Selective Reporting | |
|---|---|---|
| Definition | Reporting broader antimicrobials only if more narrow spectrum agents are resistant | Suppressing select agents based on needs (formulary, Antimicrobial Stewardship Program (ASP), etc) |
| Example | Only report ertapenem if ceftriaxone is resistant | Suppress fluoroquinolone results from urine cultures to support ASP initiative to decrease their use in the treatment of cystitis. |
Timely and correct use of empiric antimicrobial therapy remains a key factor in the survival of critically ill patients, including sepsis patients. Decisions made in complex clinical situations are increasingly difficult due to the rising threat of antimicrobial resistance. Leveraging clinical microbiology results and data enables physicians to make the treatment decisions that improve patient safety and optimize outcomes.