Pseudomonas aeruginosa carriage and associated risk factors in healthy individuals and patients from Rotterdam, Rome, and Jakarta.

Pseudomonas aeruginosa may colonize humans, however, epidemiological data are scarce. Here, we determined overall and body site-specific carriage rates and associated risk factors among healthy individuals and newly admitted patients in three major cities. This cross-sectional study was conducted in Rotterdam (The Netherlands), Rome (Italy), and Jakarta (Indonesia) between 2022-2024. Adult healthy individuals and newly admitted patients were asked to provide throat, navel, and rectal/perianal swabs, and to complete a questionnaire. Univariable and multivariable analyses were performed to determine factors associated with P. aeruginosa carriage. Carriage rates differed significantly between cities (p < 0.001), and were lowest in Rome (healthy individuals 4.8%; patients 6.5%), followed by Rotterdam (healthy individuals 12.0%; patients 12.7%), and Jakarta (healthy individuals 28.6%; patients 24.0%). In carriers from Rotterdam, P. aeruginosa was most often detected in perianal swabs, while mostly in throat swabs among carriers from Rome and Jakarta. P. aeruginosa carriage had a seasonal association in patients from Rotterdam (p = 0.014) and Jakarta (p = 0.020). Among patients from Jakarta, female sex (aOR 1.98, 95% CI 1.02-3.84; p = 0.045) was associated with P. aeruginosa carriage. Overall, P. aeruginosa carriage rates and colonized body sites differ between cities and are likely associated with climate differences. Our findings warrant setting-specific adaptations of screening strategies and surveillance programs.