Story at a glance
- Antimicrobial resistance is an ongoing problem in which microbes become untreatable by existing antibiotics.
- A new study looks at national data from 271 hospitals.
- The results suggest that AMR events could be getting worse in some subsets of patients.
Since early in the pandemic, infectious disease specialists have been concerned that antimicrobial resistance (AMR) could get worse due to increased hospitalizations and burden on health care systems. Due to a mix of antibiotic use and conditions in hospitals, AMR has been trending worse for years but until now there hasn’t been a clear picture of what’s happening during the coronavirus pandemic. Researchers at Merck and Becton Dickinson recently presented findings from a database of antibiotic use and AMR events from March 2020 to October 2021.
The team analyzed hospital admissions, antibiotic use and AMR event data from the Becton Dickinson Insights research database, including data from 271 hospitals in the U.S. An AMR event is when a type of microbial infection is found which is less treatable by existing antibiotics. As more AMR events happen, this increases the risk that the microbes become resistant to these drugs and become untreatable.
Overall decrease, but increase for some
It’s not unexpected that AMR is getting worse, and it has been for quite some time. “We certainly know even before the pandemic that antimicrobial resistance rates have continued to increase both here in the U.S. and worldwide,” says Karri Bauer, who is a scientific director of medical affairs supporting infectious diseases including COVID-19 at Merck. The study results were presented at the European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) in Lisbon, Portugal.
From their analysis, the team found that in more than 2 million patients tested for SARS-CoV-2, regardless of a positive or negative result, there was a statistically higher rate of AMR compared to pre-pandemic rates. The differences between people who were and were not tested could be from their condition when they arrived at the hospital like whether they had respiratory symptoms.
This contrasts with an overall decrease in the rate of AMR events per 100 admissions for all patients, whether or not they were tested for the coronavirus. About 1.6 million patients were not tested, making the total number of patients admitted to hospitals in this study just over 3.7 million people.
Community acquired versus hospital onset
Bauer thinks that this overall decrease was because of the differences in the patient populations. COVID-19 patients may have needed to stay in the hospital for longer, and unfortunately that could mean they are exposed to pathogens in the hospital environment. This could lead to hospital onset infections, meaning that a subset of patients acquired microbial infections during their time at the hospital. The data suggest that the rate for AMR events for this group was almost double what it was before the pandemic in some hospitals.
There were some limitations to consider with the data. For example, the researchers needed to use surrogates for comorbidities and heart disease, although those metrics have been validated by previous studies. And while the hospitals are in a variety of places including urban and rural settings, some geographic regions may be more represented in the database than others.
One part of the dataset Bauer is especially keeping an eye on is how long patients are on antibiotics, especially those who had a negative culture or no culture was ever collected. Their study found that patients at high AMR hospitals were taking antibiotics for longer periods of time. They split hospitals into categories by high, medium and low rates of AMR events pre-pandemic and compared the numbers from during the pandemic. The facilities that had the high AMR had a higher total days of therapy for every 1000 days (387 days compared to 318 days on average pre-pandemic) as well as longer duration for the average patient (5.3 versus 4.2 days), according to the study.
Taking a culture sample is how doctors test patients for bacterial and other microbial infections. The results typically come back within 48 to 72 hours. When it comes to antibiotic stewardship, the practice of preventing antibiotic overuse in order to slow the development of resistance, that 72 hour mark is termed the antibiotic timeout. That’s when the clinician should have culture information back and should make the decision if they can stop antibiotic therapy because the cultures are negative and the patient clinically looks good too, says Bauer.
Nobody would be faulted in starting a patient on antibiotics, she continues. Particularly early on when we were still learning a lot about the coronavirus, health care providers needed to be cautious. But now that we do have therapeutics for SARS-CoV-2 and understand a lot more about the disease, if a patient is responding, signs and symptoms are improving and cultures are negative, doctors can stop the antibiotics. “That’s a really important basic stewardship principle that hasn’t changed,” Bauer tells Changing America.
To be continued
Bauer is hopeful that additional analysis with data through March 2022, which would include data from the omicron wave, will provide even more insight into the pandemic’s impact on AMR. One of the advantages of this database is that it is updated in near real time, says Bauer. “I think it will be interesting to continue to look at the pandemic’s impact on AMR one to even five years from outside of the pandemic,” says Bauer. “Is this kind of the new reset point or will we be able to go back to some of those strides we made pre-pandemic?”