Recurrent Facial Folliculitis Caused by Klebsiella aerogenes Sequence Type 117 in Men who Have Sex with Men

The study describes 17 cases of recurrent facial folliculitis caused by Klebsiella aerogenes bacteria in men who have sex with men (MSM) in France, Belgium, and the United States. Whole-genome sequencing analysis showed that all isolated bacteria belonged to sequence type 117 or related lineages. Klebsiella aerogenes is a gram-negative bacterium found in the environment and human gut microbiota and rarely causes skin and soft tissue infections. Since 2025, cases of this infection have been reported exclusively in MSM, suggesting possible sexual transmission and the emergence of a new pathogenic lineage. The research team obtained 24 bacterial isolates from 17 patients, with some patients having multiple isolates due to recurrence or longitudinal monitoring.