A new analysis of global data shows that while deaths from lower respiratory infections (LRIs) declined from 1990 to 2021, deaths caused by antibiotic-resistant LRIs in 2021 were nearly three times higher than those caused by susceptible infections.
The burden of deaths from drug-resistant LRIs was most pronounced in low-income countries and adults over 50, researchers reported late last week in Antimicrobial Resistance & Infection Control. And deaths could rise as the bacteria that cause pneumonia and other LRIs become resistant to last-resort antibiotics.
The study, conducted by a team of Chinese researchers, looked at data from the Global Burden of Disease Study 2021, an ongoing research effort that uses global epidemiologic data to quantify the impact of diseases and injuries from 1990 to the present. Their analysis looked at absolute death counts and age-standardized mortality rates (ASMRs) from LRIs (which include infections like bronchiolitis and pneumonia caused by bacteria and viruses) stratified by age, region, and Socio-Demographic Index (SDI) levels (a composite indicator of national socioeconomic development).
More specifically, they focused on LRIs caused by antimicrobial-resistant (AMR) bacteria.
“In 2019, drug resistance in LRIs contributed most significantly to AMR-related mortality, directly causing over 400,000 deaths and indirectly linked to more than 1.5 million fatalities,” the study authors wrote. “The escalating AMR crisis threatens to exacerbate the severity of common infections, potentially transforming minor wounds or respiratory illnesses into life-threatening conditions.”
AMR a ‘critical multiplier’ of LRI deaths
From 1990 through 2021, deaths and ASMRs from LRIs declined significantly. Absolute death counts fell from 4.3 million in 1990 to 3.5 million in 2021, while the ASMR was nearly cut in half, declining from 88.9 to 45.2 per 100,000 population. Bacterial LRIs showed parallel reductions in both absolute death counts and ASMR over the period.
Of the 3.5 million deaths from LRIs in 2021, 2.9 million (82.2%) were caused by bacterial LRIs. The six leading bacterial pathogens—Streptococcus pneumoniae, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Escherichia coli—accounted for more than two-thirds of bacterial LRI deaths. Drug-resistant bacteria accounted for 46.1% of LRI deaths and drug-sensitive bacteria accounted for 17.9%.
The escalating AMR crisis threatens to exacerbate the severity of common infections, potentially transforming minor wounds or respiratory illnesses into life-threatening conditions.
Although deaths caused by resistant S pneumonia, K pneumoniae, and A baumannii declined over the 30-year period, the number of deaths caused by resistant E coli, P aeruginosa, and S aureus showed a slight upward trend. The researchers also noted a rising number of LRI deaths related to carbapenem-resistant A baumannii, E coli, K pneumoniae, and P aeruginosa. Carbapenems are a last-resort antibiotic class for bacteria that have become resistant to all other antibiotic treatments.
“As the effectiveness of these last-resort drugs is compromised, the risk of incurable infections will increase,” they wrote.
When the researchers analyzed deaths by age, they observed significant declines in children under five years old, relative stability in those aged five to 49 years, and increases in the over-50 population. Death counts and ASMR were consistently higher among men compared with women.
By region, the highest death counts from LRIs in both 1990 and 2021 were in South Asia, East Asia, Western sub-Saharan Africa, and Oceania. When stratified by SDI, the standardized death rate for drug-resistant LRIs was substantially higher in regions with low SDI, like sub-Saharan Africa, than in those with high SDI, such as North America and Europe.
The authors say that while AMR affects all countries regardless of income level, “poverty and inequality have exacerbated its driving factors and consequences, with low- and middle-income countries (LMICs) being the most affected.” And, with global surveillance systems already showing “alarming” resistance rates for prevalent bacterial pathogens, particularly in LMICs, the consequences will likely become more severe.
“These findings underscore AMR as a critical multiplier of LRI fatality and confirm its status as a paramount global health threat, as recognized by the World Health Organization,” they wrote. “This escalating crisis highlights the urgent need to strengthen antimicrobial stewardship practices, expand global surveillance coverage, accelerate the development of novel and effective antimicrobial drugs, and implement further measures to ensure equitable access to both existing and new vaccines, diagnostics, and treatment.”
