LISBON – During the pandemic, critical and acute care hospitals with medium and high rates of antimicrobial resistance (AMR) showed significant increases in antibiotic prescriptions and longer durations of antibiotic treatment among all hospital admissions, and also in those patients who were bacterial culture negative, according to a large U.S.-based study.
The analysis across 271 U.S. hospitals also showed that AMR rates were significantly higher for pathogens during the pandemic period, compared with the prepandemic period in patients who were tested for SARS-CoV-2, and highest in SARS-CoV-2–positive patients.
More than a third of SARS-CoV-2–positive patients who were prescribed antibiotics were bacterial culture negative.
Findings of the study were presented by Vikas Gupta, PharmD, director of medical affairs at medical technology firm Becton Dickinson, at this year’s European Congress of Clinical Microbiology & Infectious Diseases. He conducted the study jointly with Karri Bauer, PharmD, from Merck Sharp & Dohme, Kenilworth, N.J., and colleagues.
“There are differences in AMR that go beyond COVID-positive admissions,” Dr. Gupta told this news organization. “There is opportunity for improvement especially with those hospitalized patients who had a negative culture result, or no culture collected.”
“We found a higher percentage of COVID-positive admissions that were prescribed antibacterial therapy even in those having [tested negative for bacteria] or no culture result,” said Dr. Gupta. “Our data also shows that the percentage of admissions with duration of antibacterial therapy over 3 days was significantly higher in COVID-positive but culture-negative/no culture patients, compared to other groups evaluated.”
Of all admissions prescribed antibiotics during the pandemic, 57.8% of SARS-CoV-2–positive patients were prescribed antibiotics whereas 88.1% of SARS-CoV-2–positive admissions were bacterial culture negative/no culture. Overall, prepandemic, 35% of admissions were prescribed antibiotics.
Duration of antibiotic therapy in the prepandemic era was an average of 3.5 days, compared with an average of 3.8 days overall in the pandemic and 5.7 days in patients who tested positive for SARS-CoV-2. Similarly, the percentage of patients who were bacterial culture negative or had no culture and received antibiotic therapy for more than 72 hours was 17.6% in the prepandemic era, compared with 19.2% overall in the pandemic era, and 41.1% in patients who tested positive for COVID-19.
Dr. Gupta and Dr. Bauer wanted to look at all patients admitted to hospitals segmented by SARS-CoV-2 positive, negative, and not tested, to get a sense of how much antibiotic use there was and how long patients were on antibiotics. “We ultimately want to optimize and not overuse antibiotics and prescribe them for right period of time,” said Dr. Gupta.
“To date, there has been no conclusive evidence about the suggestion that the pandemic has led to increased AMR rates, so we aimed to evaluate the pandemic’s impact on AMR and antibiotic use across U.S. hospitals,” he explained.
The multicenter, retrospective cohort analysis made use of BD’s infection surveillance platform (BD HealthSight Infection Advisor with MedMined Insights) and was conducted across 271 U.S. critical access/acute care facilities, representing approximately 10%-13% of U.S. hospital admissions. It included all hospitalized patients with more than 1 day of in-patient admission. Patients were considered SARS-CoV-2 positive by polymerase chain reaction test or antigen test either 7 days or less prior to or within 14 days of admission.
Patients were categorized as hospitalized during the “prepandemic” period (July 1, 2019 through February 29, 2020) and the “pandemic” period (March 1, 2020 through Oct. 30, 2021) and were stratified based on their SARS-CoV-2 result.
Investigators included all hospital admissions with an AMR event (first positive culture for select gram-negative or gram-positive pathogens that were reported as nonsusceptible across blood, urine, respiratory, intra-abdominal, skin/wound, and other sources).
The investigators calculated AMR rates at the patient-admission level and defined per 100 admissions. Also, they further evaluated AMR rates based on community onset (defined as culture collected ≤2 days from admission) or hospital onset (>2 days from admission). Finally, AMR rates were determined according to whether they related to prepandemic or pandemic periods.
Hospitals were also categorized according to their AMR rates as low (<25%), medium (25%-75%), and high (>75%).
Overall AMR rates were lower in the pandemic period, compared with the prepandemic period. However, reported Dr.Gupta, for hospital-onset pathogens specifically, AMR rates were significantly higher overall in the pandemic period and mostly driven by admissions tested for SARS-CoV-2 (whether positive or negative).
Hospitals with high AMR rates also tended to have more SARS-CoV-2 positive admissions (6.1% in high-AMR hospitals vs. 3% in low-AMR hospitals). The highest antibiotic-prescribing rates and highest duration of antibiotic use was also seen in those hospitals with highest AMR rates.
Of the SARS-CoV-2 patients who were bacterial culture negative/no culture and were prescribed antibiotics, 36.5% were in hospitals with a high AMR rate. “Roughly one-third of patients without culture evidence of a bacterial infection were prescribed antibiotics in hospitals with a high AMR rate,” said Dr. Gupta.
The researchers wanted to tease out whether hospitals with high, moderate, or low AMR rates look different with respect to antibiotic-prescribing patterns. During the pandemic period, they found that hospitals with high and medium AMR rates experienced significant increases in antibiotic prescriptions and longer durations. Prepandemic, the overall hospital-onset AMR rate was 0.8 per 100 admissions, whereas during the pandemic this rose to 1.4 per 100 admissions in high-AMR hospitals and dropped to 0.4 in low-AMR hospitals.
SARS-CoV-2–positive admission rates were higher in facilities with medium (5.6%) and high AMR (6.1%) rates than those with low (3%) AMR rates. “We found that those with medium and high AMR rates were more likely to have COVID-positive admissions than facilities with low AMR rates,” Dr. Gupta said. “It appears as if COVID is contributing to AMR in the facilities.”
Asked for independent comment, Jason C. Gallagher, PharmD, BCPS, clinical professor at Temple University School of Pharmacy in Philadelphia, said in an interview, “It is not surprising that there was more antimicrobial resistance in patients with COVID than those without. Even though antibiotics do not work for COVID, they are often prescribed, and antibiotic use is a major risk factor for antimicrobial resistance. This is likely because clinicians are sometimes concerned about coinfections with bacteria (which are rare) and because hospitalized patients with severe COVID can acquire other infections as they are treated.”