Whole Genome Analysis of Proteus mirabilis in a Poultry Breeder Farm Reveals the Dissemination of bla NDM and bla CTX-M Mediated by Diverse Mobile Genetic Elements

Proteus mirabilis is a significant foodborne opportunistic pathogen associated with various nosocomial infections. Chicken farms may serve as an important reservoir for P. mirabilis . However, research on antibiotic resistance and genomic features of P. mirabilis in China’s poultry industry is limited. This study isolates P. mirabilis from a breeder farm in China and investigates the dissemination of P. mirabilis and clinically significant antibiotic resistance genes (ARGs), including bla NDM and bla CTX-M . From 510 samples, 69 isolates were obtained, classified into 11 sequence types (STs), with ST135 and ST175 predominating. A total of 39 ARGs were detected, including fosA3 , floR , bla CTX-M-3 , bla CTX-M-65 , and bla NDM-1 . Genetic analysis revealed that bla NDM-1 was exclusively located on Salmonella genomic island 1 (SGI1), while bla CTX-M was found in various mobile genetic elements (MGEs), including Tn 7 , SXT/R391 integrative conjugative elements (ICEs), Proteus mirabilis genomic resistance island 1 (PmGRI1), and SGI1. Notably, many isolates carried multiple MGEs, suggesting frequent horizontal transfer of ARGs in P. mirabilis . These findings underscore the role of P. mirabilis in carrying and spreading antibiotic resistance, posing significant risks to the poultry industry and public health.