Older adults are expected to bear the brunt of rising drug-resistant infections in coming decades, with new modelling warning that ageing populations will drive a sharp increase in bloodstream infections caused by resistant bacteria.

Published in PLOS Medicine [link here], the study forecasts a steep climb in antimicrobial resistance (AMR) burden across Europe by 2030, particularly among those aged over 65, offering insights for Australia’s own ageing population and AMR planning.

Associate Professor Benn Sartorius. Source: University of Queensland

The international team of researchers, including Associate Professor Benn Sartoriuous from the University of Queensland, analysed more than 12 million blood test results collected from 29 European countries between 2010 and 2019. Drawing on age- and sex-specific data for 38 bacteria-antibiotic combinations, they projected infection trends to 2050 and found that rates of drug-resistant bloodstream infections (BSIs) will climb fastest in older age groups – while stabilising or falling in younger populations.

“We see the steepest increases in incidence projected in older age groups, particularly the over 65s, meaning that simply preventing further rises in resistant bloodstream infections would already be a major public health achievement,” said lead author, Professor Gwenan Knight of the London School of Hygiene and Tropical Medicine.

The researchers noted a consistent trend across six of the eight bacterial species studied showing that men were more likely than women to experience a rise in resistant BSIs, and countries varied widely in projected burdens – driven in part by differences in demographic structure.

To understand how these shifts might affect efforts to curb AMR, the team modelled the impact of interventions, including those aligned with the United Nations’ goal of reducing resistant infections by 10% by 2030. Even under the most optimistic scenarios, that target was achievable for only about two-thirds of bacteria-antibiotic combinations.

“We show that even with very successful public health interventions 32% (12/38) of the included bacteria-antibiotic combinations would not achieve a 10% reduction in infection burden by 2030, and some that do reach it may subsequently bounce back,” the team wrote.

The study focused on high-priority pathogens commonly implicated in hospital- and community-acquired BSIs including Escherichia coli resistant to aminoglycosides, Staphylococcus aureus resistant to methicillin (MRSA), Klebsiella pneumoniae resistant to third-generation cephalosporins, and Pseudomonas aeruginosa resistant to carbapenems.

“Our study shows that the future burden of drug-resistant infections won’t be uniform – there will be substantial differences between countries, as well as across age groups and between sexes,” Professor Knight said in a statement. “What I found most interesting was bringing together different strands of data to show the bigger picture. Age and sex are still rarely considered in antimicrobial resistance projections, yet they make a real difference to who is most affected,” she added.

She said that excluding demographic factors like age and sex from models underestimates the true burden of AMR in nearly half of cases, highlighting a blind spot in current surveillance and planning efforts.

“The key implications of our results are the importance of age and sex disaggregation of AMR burden and the difficulty in achieving the AMR targets under the expected demographic population shifts,” investigators stressed.

Co-author Dr Catrin Moore said the findings should help guide more targeted responses to AMR. “This is a fantastic step forward in understanding the way that age and sex will influence the burden of drug-resistant infections in different European countries in the coming years,” she said. “This will help us design intervention studies focusing on the populations most at risk in the future to reduce the mortality and morbidity associated with drug-resistant infections.”

Although the modelling focused on Europe, the researchers noted that its methodology could be adapted globally, especially in regions like Australia where AMR is a growing concern and the population is ageing rapidly.

“Given projected increases in infections across most countries and bacteria–antibiotic combinations, simply achieving a plateau in the burden of antibiotic-resistant infections would represent meaningful progress,” investigators concluded.