
A study of more than 50,000 Canadian seniors diagnosed as having COVID-19 during the first 18 months of the pandemic found that antibiotic use within 7 days of diagnosis was associated with detection of antibiotic resistance organisms, researchers reported today in NEJM Evidence.
The population-wide cohort study, led by researchers with the Ottawa Hospital Research Institute, analyzed data on residents of Ontario aged 66 years and older who had a positive test for SARS-CoV-2 (the virus that causes COVID-19) from January 1, 2020, through June 30, 2021.
Because antibiotic use in COVID-19 patients was common in the early months of the pandemic in most countries, particularly in older patients, the researchers wanted to evaluate the relationship between peri–COVID-19 antibiotic exposure (within 7 days of index SARS-CoV-2 reporting) and isolation of an antibiotic-resistant organism from a clinical culture within 6 months.
Of the 53,533 eligible patients included in the study, 8,228 (15%) were prescribed a peri–COVID-19 antibiotic, and 1,477 (3%) had a downstream drug-resistant organism identified. Peri–Covid-19 antibiotic use was significantly associated with the presence of any antibiotic-resistant organism (adjusted odds ratio [aOR], 1.24; 95% confidence interval [CI], 1.09 to 1.41) and the presence of gram-negative antibiotic-resistant organisms (aOR, 1.27; 95% CI, 1.11 to 1.46) but not gram-positive antibiotic-resistant organisms (aOR, 1.02; 95% CI, 0.70 to 1.48).
Stewardship in older adults, nursing home residents
Among all individuals who received an antibiotic, the attributable fraction of downstream antibiotic resistance related to peri–Covid-19 antibiotic use was 17% (95% CI, 7% to 26%). Among all individuals with a SARS-CoV-2 diagnosis, the population-attributable fraction of downstream antimicrobial resistance related to peri–Covid-19 antibiotic use was 4% (95% CI, 2% to 7%).
"As antibiotics are often used in the outpatient setting in patients with Covid-19, without clear indications, this study suggests that a substantial burden of antimicrobial resistance in individuals with Covid-19 may have been avoidable," the study authors wrote
They add that the disproportionate impact on older, more vulnerable patients suggests that antimicrobial stewardship programs targeting antibiotic prescribing in older adults and those residing in nursing homes may be beneficial.