Hospital-acquired infections associated with antimicrobial resistance (AMR) increased during the COVID-19 pandemic by 32% and remain 13% higher post pandemic compared with prepandemic levels, showed a study of US hospital data that compared AMR levels before, during, and post pandemic.
The largest increase in infections was seen with those caused by gram-negative, carbapenem-resistant organisms including Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacterales, where levels during the pandemic rose by over 50% compared with the prepandemic period and remained 35% higher than prepandemic levels in 2022.
Christina Yek, MD, from the US National Institute of Allergy and Infectious Diseases, presented the findings as a poster at this year’s European Society of Clinical Microbiology and Infectious Diseases Global Congress (formerly ECCMID).
The high rates of gram-negative carbapenem-resistant infections could exist for several reasons, Yek told Medscape Medical News. “Empiric and inappropriate antibiotic use rose drastically during the pandemic. We suspect that antibiotic exposure both within the patient and in their surroundings drove the development of gram-negative resistance as gram-negative bacteria more readily exchange and acquire resistance, for example, through plasmids,” she said. But it may also be an artifact of the relative ease of detection versus other infections. “These infections are more severely symptomatic and more likely to be picked up.”
The study also found that hospitals with high volumes or surges of severely ill COVID-19 patients showed the greatest increases in hospital-acquired AMR infections, as did larger hospitals with higher bed capacity. Yek added that these data have not yet accounted for the increased risk of hospital-acquired AMR infections among people with COVID-19 and other severely ill patients, which will be addressed in the next stages of analysis.
Pre-, During- and Post-Pandemic Data
Data on adult patients were drawn from 120 US hospitals through the PINC-AI database and related to a period before pandemic (January 2018 to December 2019), during the pandemic (March 2020 to February 2022), and post pandemic (March 2022 to December 2022). The study focused on six pathogens: Methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, extended-spectrum cephalosporin-resistant Enterobacterales, carbapenem-resistant Enterobacterales (CRE), carbapenem-resistant A baumannii (CRAB), and carbapenem-resistant P aeruginosa (CRPA).
Yek explained that their study built on data from the US Centers for Disease Control that reported an increase in hospital-acquired resistant infections of 12% during the first year of the pandemic. Yek wanted to extend this period of study into 2021 when hospitals saw a greater surge in COVID-19 patients than in 2020.
“During these surges, hospitals were overwhelmed with Covid patients and others too. Our groups have looked at these surges in US hospitals and the associated mortality, and then we combined these data together to ask — given there’s more AMR, as well a rise in the number and size of COVID-19 surges, how do these elements interact over 2020-2021 and 2021-2022?” explained Yek.
COVID Surges, Hospital Size, and AMR Patterns
During the pandemic, the overall prevalence of AMR infections increased by 6.3% (from 181.9 to 193.3 per 10,000 hospitalizations), driven primarily by a steep rise in hospital-acquired resistant infections, which rose at least 32%, while community-acquired resistant infections increased just 1.4% over the same period.
The increase was driven almost entirely by resistant gram-negative bacterial infections, which rose by almost 20% compared with prepandemic levels, while resistant gram-positive infections fell by 4.2%. In particular, the greatest increases were seen for hospital-acquired CRAB (+151.1%), followed by hospital-acquired CRE (+62.2%) and CRPA (+54.2%).
Yek said there are several factors that could contribute to the association between COVID surges and hospital-acquired gram-negative, carbapenem resistant organisms. “Various groups postulate that COVID patients have a different physiology due to immunosuppressive states, and they often have comorbidities, as well as receive a lot of invasive interventions such as central lines,” she said. All of these are risk factors for hospital-acquired infections.
Other research groups have shown that COVID-19 patients are at increased risk of infections, but so are non-COVID patients, she added. “As such, we can’t blame it all on COVID. Something else is going on.”
The study also looked at the impact of hospital size and hospital COVID-19 patient surge strain. Larger hospitals with greater bed capacity had a higher incidence of hospital-acquired AMR. Patients in a hospital with a bed capacity of 100-199 were 1.25 times as likely to acquire an infection as those in a hospital with < 100 beds, while those in a hospital with > 500 beds were 2.44 times as likely to be infected.
Hospitals that experienced the biggest surges of COVID-19 patients also experienced more AMR infections. “There’s a stepwise increase in the odds as we increase the level of surge strain and hospital size,” said Yek, adding that, “there is a caveat here that bigger hospitals tend to have the sicker patients and critical care units, and we haven’t adjusted for that here.”
David Greenberg, MD, from UT Southwestern Medical Center in Dallas, Texas, told Medscape Medical News that the increase in gram-negative infections is no surprise because they are increasing generally and were increasing prior to the pandemic. But the study is a reminder that viral pandemics — whether COVID or influenza — can have secondary consequences beyond the viral infections themselves, and there are downstream consequences for AMR.
“We’ve known about secondary infections for a long time, but this reminds us that a viral pandemic can lead to these secondary infections, and in particular, these might be drug-resistant organisms. And as antibiotic resistance increase worldwide, these events after a viral pandemic are only going to become more common,” said Greenberg.
Yek and Greenberg had no relevant financial disclosures.
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