A recent study led by the University of Turku, Finland, analysed the DNA map of more than 14,000 gut metagenomes in a global dataset and found that there are differences in antibiotic resistance between genders. In high-income countries, women had more antibiotic resistance genes than men.

Antibiotic resistance is one of the most serious global health threats. Antibiotic resistance causes antibiotics to lose their effectiveness, which can make it difficult or in some cases impossible to treat bacterial infections. The resistance is estimated to cause more than 1.3 million deaths annually, and the number is growing rapidly.

This recent study is the first to examine the differences of antibiotic resistance between the genders in a large international dataset.

Researchers at the University of Turku analysed a global dataset of 14,641 publicly available human gut metagenomes encompassing 32 countries. The study was carried out in a research group led by Professor of Data Science Leo Lahti. In high-income countries, an average of nine percent higher total antibiotic resistance gene load was observed in women than in men. This suggests that women may be more frequently exposed to antibiotics, bacteria resistant to antibiotics, or are more often carriers of resistant bacteria.

In low- and middle-income countries, men had a higher load of antibiotic resistance genes than women. However, the difference was not statistically significant when covariates such as age and differences in living conditions between countries were taken into account. Interestingly, the differences emerged in adulthood.

“This suggests that lifestyle, biological differences or healthcare-related factors may influence these differences more in adulthood than in childhood,” says Postdoctoral Researcher Katariina Pärnänen from the University of Turku.

In addition, a slightly higher diversity of resistance genes was found in women in high-income countries compared to men, suggesting a broader resistance variation in the gut microbiota.

Antibiotic resistance varies by age and geography

Age and country of residence were strongly associated with the number and diversity of antibiotic resistance genes. These were particularly high in infants and the oldest age group.

High antibiotic use was associated with higher resistance gene loads and diversity. High levels of resistance were also found in low-income countries, which may be explained by factors such as poor hygiene and sanitation.

The study highlights the complex interaction of gender, age, socio-economic status, and geography in the distribution of antibiotic resistance. The research results could help develop better ways to fight antibiotic resistance.

“Understanding gender differences in antibiotic resistance is key to designing equitable and effective healthcare interventions. Our study will lay the groundwork for further research to reduce health inequalities related to antibiotic resistance," concludes Pärnänen.

The research article "Gender differences in global antimicrobial resistance" has been published in npj Biofilms and Microbiomes on 19 May 2025.