Clinical Utility of Nanopore Sequencing in the Rapid Diagnosis of a Difficult-to-Treat Providencia stuartii Strain Harboring a Multicopy β-Lactamase Resistance Island

Providencia stuartii (Ps) is a clinically significant opportunistic pathogen often associated with “difficult-to-treat resistance” (DTR) infections due to pan-resistance to first-line antimicrobials. We report the clinical diagnosis and rapid genomic characterization of strain Ps-CMC-4104, recovered from a human splenic abscess in a patient with infected necrotizing pancreatitis. To resolve the complex genetic architecture of this strain, we utilized hybrid sequencing combining Oxford Nanopore (long-read) and Illumina (short-read) technologies. Analysis revealed a 4,504,925 bp circular chromosome featuring a unique genomic resistance island (GRI) closely related to Salmonella SGI1. Notably, the PsGRI contains multiple copies of NDM-1 and PER-1 carbapenem-resistance and -inhibitor genes, a repetitive structure typically unresolvable by standard short-read methods. Additionally, a large 278,489 bp low-copy circular plasmid harbored single copies of these carbapenemase and extended-spectrum β-lactamase genes alongside other antimicrobial resistance determinants and ISCR1 insertion sequences. Nanopore technology allowed us to precisely identify the duplications, providing critical insights into the strain’s pan-resistant phenotype. This study serves as proof-of-concept for the importance of integrating long-read sequencing into clinical workflows to identify complex resistance mechanisms in DTR pathogens, facilitating targeted antimicrobial stewardship and infection control.