Understanding Antimicrobial Resistance

Lauren Floris, PharmD; David Cluck, PharmD, BCPS, BCIDP, AAHIVP; Abby Singleton, PharmD, BCPS

Disclosures

US Pharmacist. 2020;45(3):HS-10--HS-16. 

In This Article

Abstract and Introduction

Abstract

Bacteria are remarkably adaptable organisms with an innate ability to circumvent damage if exposed to a toxic environment. Antimicrobial-resistant bacteria are present worldwide, and many common infections are becoming more difficult to treat. Continued resistance is rapidly eliminating treatment options for patients, and the cost burden to treat a multidrug-resistant infection is climbing. Owing to the substantial costs associated with drug development, the introduction of novel antibiotics has lagged behind the increase in bacterial resistance. To address this crisis, pharmacists can take an active role in antimicrobial stewardship and foster understanding of how bacteria evade even the strongest available antimicrobial agents.

Introduction

Bacteria are remarkably adaptable organisms with an innate ability to circumvent damage if exposed to a toxic environment. Since the development of the first antibiotic less than a century ago, there has been an exponential growth in antimicrobial resistance that is disproportionate to the rate at which antibiotics are introduced.[1] The emergence of resistance and the inversely stagnant development of novel antibiotics related to the substantial costs associated with drug development have worsened the impact of infectious diseases on mortality and healthcare costs. Continued resistance is rapidly eliminating treatment options for patients, and the cost burden to treat a multidrug-resistant infection is climbing, reaching more than $2.2 billion annually in the United States.[2] Antibiotic resistance has been found in most bacteria, but several bacteria are particularly problematic and are becoming common among hospital-acquired infections: Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacteriaceae (ESKAPE pathogens).[3–5] The CDC recently published an updated list of the most threatening resistant organisms in the U.S. based on hospitalizations and mortality data from 2017 (Table 1).[6]

The CDC estimates that more than 47 million antibiotic courses are prescribed each year in the U.S. for infections that do not need antibiotic treatment.[7] The misuse and overuse of antibiotics have put the world at risk, and the growing threat prompted the World Health Organization to issue a global action plan for antimicrobial resistance in 2015.[8] In the same year, the U.S. formulated a national action plan for combating antibiotic-resistant bacteria.[6] These initiatives launched the implementation of antimicrobial stewardship (AMS) programs and research to prevent further resistance. Unfortunately, bacteria adapt quickly, and the development of antimicrobial agents is truly a race against time. With each new agent designed to overcome a resistance mechanism, pathogens inevitably establish new strategies to withstand the next antibiotic. Few agents have been introduced since 2010 (Table 2), and even fewer have activity against ESKAPE pathogens.[9] As of June 2019, only 42 antibiotics were in clinical development, and just three in five agents entering phase III trials are approved.[9] Preventing further resistance requires not only persistent AMS to reserve existing agents, but also a fundamental understanding of antibiotic mechanisms of action and the strategies bacteria employ to resist these agents.

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