Phylogeographical Landscape of Citrobacter portucalensis Carrying Clinically Relevant Resistomes

During a surveillance study conducted to assess the occurrence and genomic landscape of critical priority pathogens circulating at the human-animal-environment interface in Brazil, as part of the Grand Challenges Explorations-New Approaches to Characterize the Global Burden of Antimicrobial Resistance program, two multidrug-resistant (MDR) Citrobacter portucalensis carrying bla_CTX-M-15 extended-spectrum β-lactamase (ESBL) genes, isolated from green sea turtles, were characterized. Genomic and phylogeographical analysis of C. portucalensis genomes available in public databases revealed the intercontinental dissemination of clades carrying different arrays of clinically relevant genes conferring resistance to carbapenems, broad-spectrum cephalosporins, cephamycins, aminoglycosides and fluoroquinolones, disinfectants, and heavy metals. Our observations suggest that C. portucalensis could be emerging as critical priority bacteria of both public and One Health importance worldwide. IMPORTANCE The global spread of antibiotic-resistant priority pathogens beyond the hospital setting is a critical issue within a One Health context that integrates the human-animal-environment interfaces. On the other hand, next-generation sequencing technologies along with user-friendly and high-quality bioinformatics tools have improved the identification of bacterial species, and bacterial resistance surveillance. The novel Citrobacter portucalensis species was proposed in 2017 after taxonomic reclassification and definition of the strain A60^T isolated in 2008. Here, we presented genomic data showing the occurrence of multidrug-resistant C. portucalensis isolates carrying bla_CTX-M-15 ESBL genes in South America. Additionally, we observed the intercontinental dissemination of clades harboring a broad resistome to clinically relevant antibiotics. Therefore, these findings highlight that C. portucalensis is a global MDR bacteria that carries intrinsic bla_CMY- and qnrB-type genes and has become a critical priority pathogen due to the acquisition of clinically relevant resistance determinants, such as ESBL and carbapenemase-encoding genes.