Four-year surveillance of Major Gram-negative pathogens in a Saudi tertiary hospital: clinical distribution, comorbidity profiles, and antimicrobial resistance.
Abstract
Purpose
To describe four-year diagnostics, clinical distribution, pathogen burden, and antimicrobial resistance patterns of major Enterobacterales and Pseudomonas aeruginosa within a tertiary-care surveillance framework. PATIENTS AND
Methods
We retrospectively included the first non-duplicate isolate per patient, organism, and calendar year from 2022 through 2025 at a Saudi tertiary-care hospital. Organisms were identified and diagnosed by automated platforms; GeneXpert Carba-R diagnostics was used parallel to culture where indicated. Susceptibility was interpreted using the CLSI breakpoints in force during the years of testing. Annual trends were assessed with grouped binomial logistic regression, and Benjamini-Hochberg false-discovery-rate correction was applied within prespecified analysis families.
Results
Among 1,857 isolates, Klebsiella pneumoniae was most frequent (36.2%), followed by P. aeruginosa (33.4%), Escherichia coli (17.9%), and Enterobacter cloacae (12.3%). The mean patient age was 64.8 years, 51.3% of isolates were from intensive care, 37.4% were from urine, and 80.8% had a documented comorbidity. K. pneumoniae had the highest overall ESBL (76.6%), CRE (59.9%), MDR (69.3%), panel-defined XDR (64.7%), and panel-defined PDR (15.2%) frequencies. Enterobacterales ESBL positivity increased from 58.1% to 76.8% (q < 0.001), whereas meropenem non-susceptibility decreased from 52.6% to 33.2% (q < 0.001). In P. aeruginosa, ceftazidime non-susceptibility increased from 55.2% to 78.6% (q < 0.001), meropenem decreased from 46.8% to 32.9% (q = 0.031), and tobramycin increased from 22.2% to 45.7% (q = 0.030). Crude comorbidity differences did not remain significant after false-discovery-rate correction.
Conclusion
The single-center surveillance study shows a persistent and species-specific Gram-negative resistance burden, led by K. pneumoniae and accompanied by substantial P. aeruginosa non-susceptibility. The findings support organism-specific detections, antibiograms and continued multicenter surveillance linked to antimicrobial exposure, genomic data, and patient outcomes.