Emergence of Genotype 2.3.1 Multidrug-Resistant Salmonella enterica Serovar Typhi Strain, West Africa, 2021–2025

Since 2021, a new strain of Salmonella Typhi genotype 2.3.1 has been detected in West Africa that is resistant to ciprofloxacin and multiple drugs. This strain gradually acquired two different multidrug-resistant plasmids over approximately 25 years and later underwent chromosomal integration of the MDR region from the IncHI1 plasmid. Subsequently, it acquired a gyrA mutation that increases resistance to fluoroquinolones. In 2021, approximately 7.1 million cases of typhoid fever were recorded worldwide, causing 93,300 deaths. The French national reference center received a total of 1,603 Salmonella Typhi isolates during 2016–2025, of which 167 were genotype 2.3.1. Among patients with this genotype, 80.8% had traveled to Africa, with a median age of 28 years.