The Impact of the Pandemic on Antimicrobial Resistance
A Centers for Disease Control and Prevention (CDC) study looked at the pandemic's effect on hospital-onset infections. Study lead author Hannah Wolford offers insights on it including what patient populations were most affected, and the significance of infection prevention strategies.
Hannah Wolford
Image credit: Linkedin
This is part of an ongoing series looking at the impact of the COVID-19 pandemic on American public health.
In a recent CDC study published in JAMA Network Open, investigators found antimicrobial resistance in hospitals declined from 2012 to 2019, but rose again during the acute COVID-19 pandemic years (2020-2021).1
This observational study provided updated rate estimates for hospital-onset and community-onset antimicrobial-resistant infections caused by 6 pathogens in the US between 2012-2022. The CDC and the World Health Organization have identified these pathogens as high priority to be aware of and the need to address with the development of new treatments.
This study focused on the following pathogens:
- Methicillin-resistant Staphylococcus aureus (MRSA)
- Vancomycin-resistant Enterococcus spp. (VRE)
- Extended spectrum cephalosporin-resistant Escherichia coli and Klebsiella spp. (excluding Klebsiella aerogenes) (ESCR-EK) suggestive of extended-spectrum beta-lactamase production
- Carbapenem-resistant Enterobacterales (CRE)
- Carbapenem-resistant Acinetobacter spp. (CRAsp)
- Multidrug-resistant (MDR) Pseudomonas aeruginosa.1
“The percentage resistant for MRSA, VRE, CRE, CRAsp, and MDR P aeruginosa was stable or decreased from 2012 to 2022,” the investigators wrote. “Among hospital-onset E coli and Klebsiella spp, the percentage of ESCR-EK cases in nonsterile body sites increased from 12.2% (95% CI, 10.7%-13.6%) in 2012 to 19.7% (95% CI, 17.7%-21.7%) in 2022; and increased from 17.5% (95% CI, 14.4%-20.7%) to 24.5% (95% CI, 21.5%-27.4%) among normally sterile body sites.”1
Lead author of the study, Hannah Wolford, who works in the CDC’s Epidemiology, Research, and Innovations Branch, spoke with Contagion on the study and the findings behind the increased resistance during the acute pandemic stage.
Contagion: How did changes in health care use during the COVID-19 pandemic contribute to the rise in hospital-onset resistant case rates
Wolford: Antimicrobial-resistant hospital-onset infections increased during the COVID-19 pandemic compared to previous years, peaking in 2021. Changes to health care use during the COVID-19 pandemic, such as decreases in overall admissions, surges in high-risk patients with COVID-19, and higher proportions of very sick patients who did not have COVID-19 may have contributed to increased rates of antimicrobial-resistant hospital-onset infections.
Learn more: CDC: Hospitals Experiencing Inconsistent Declines in Resistant Infections
Contagion: Can you elaborate on which patient populations were most affected?
Wolford: In the majority of our study time period, rates for hospital-onset cases were highest among patients ages 55 to 74. This age group experienced increased rates of healthcare-associated antimicrobial-resistant infections during the pandemic and had the highest rates for every pathogen in 2020 and 2021. Males had higher antimicrobial-resistant infection rates throughout the study period for hospital-onset methicillin-resistant Staphylococcus aureus, carbapenem-resistant Enterobacterales, carbapenem-resistant Acinetobacter species, and multidrug-resistant Pseudomonas aeruginosa; however, both sexes experienced increased rates during the pandemic
Contagion: What does the increase in average patient days per hospitalization from 2020 to 2022 indicate about patient health trends during and after the pandemic?
Wolford: We found an increase in average patient days per hospitalization in 2020 to 2022 compared with prior years. This suggests an increase in patients with high severity of illness that continued when COVID-19 hospitalizations declined and may reflect larger trends in an aging US population with increased chronic illness or a move to manage less acute patients in outpatient care.
Contagion: In what ways did the pandemic impact infection control practices, and how might this have influenced antimicrobial resistance rates?
Wolford: The pandemic challenged the implementation of infection prevention and control practices. Activities such as contact precautions for patients with some resistant pathogens and monitoring excess antimicrobial use decreased during the pandemic, which may have led to increased antimicrobial resistance.
Contagion: Based on your findings, what types of prevention interventions are most critical to ensure resilience in infection control during future health care system strains?
Wolford: Antimicrobial resistance is an urgent public health threat. We determined that there were approximately 570,000 antimicrobial-resistant infections among hospitalized patients in 2022 in the United States. We also identified increases in antimicrobial-resistant hospital-onset infections during the pandemic, although we could not directly assess the underlying reasons for these increases. There are prevention-focused public health actions that we know work to combat antimicrobial resistance, including effective implementation of existing infection prevention and control strategies, accurate laboratory detection, rapid response, and appropriate antibiotic and antifungal use. Investing in the capacity to maintain robust implementation of infection control during times of healthcare strain and also developing innovative prevention strategies will help ensure our ability to combat antimicrobial resistance in the future. Continuing to track national data on healthcare-associated infections and antimicrobial-resistant pathogens can identify areas that need improvement or increased focus for infection prevention and control.
Reference
1. Wolford H, McCarthy NL, Baggs J, et al. Antimicrobial-Resistant Infections in Hospitalized Patients. JAMA Netw Open. 2025;8(3):e2462059. doi:10.1001/jamanetworkopen.2024.62059
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