Proteus spp.—taxonomy, clinical significance, and antibiotic resistance of a highly versatile pathogen

SUMMARY Proteus spp. are members of the Enterobacterales order and are widely found in humans, animals, and the environment. Some species, particularly P. mirabilis, are highly pathogenic and are among the most frequent causes of urinary tract and bloodstream infections. Proteus spp. possess a variety of virulence factors, such as swarming and urease activity, leading to persistent and severe infections. An increasing resistance to antibiotics has been reported for isolates and poses a substantial threat to global health. In recent years, several new Proteus spp. have been described, but their potential as pathogens has not yet been determined. Here, we provide an update on the taxonomy, virulence factors, and antibiotic resistance of Proteus spp.