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This research aims to analyze the characteristics of hospital-acquired gram-negative bacterial infections and their resistance profiles.

July 5, 2026Open Access

Clinical characteristics, causative organisms, and antimicrobial resistance profiles of hospital-acquired invasive gram-negative bacterial infections at a tertiary-care center in Saudi Arabia: a five-year retrospective cohort study (2020–2024)

Key Points

This research aims to analyze the characteristics of hospital-acquired gram-negative bacterial infections and their resistance profiles.
Retrospective cohort study of 377 adult patients with invasive gram-negative infections after 48 hours of admission to KAMC.
Analysis included demographic and clinical data, infection types, pathogens, and resistance patterns using statistical tests and logistic regression.
Infections were classified per CDC/NHSN definitions.
Klebsiella pneumoniae and Pseudomonas aeruginosa accounted for the majority of infections.
Mortality was 39.9% overall; higher rates in patients with cardiovascular disease (48.8%, p=0.011) and diabetes (adjusted OR 2.82, 95% CI 1.11-7.17).
High resistance rates were observed for ciprofloxacin (44.4%), ceftazidime (40.2%), and meropenem (34.3%).

Abstract

BACKGROUND: Hospital-acquired gram-negative bacterial (HA-GNB) infections are a leading cause of nosocomial morbidity and mortality, yet local epidemiological data to guide empirical therapy remain limited. METHODS: We conducted a retrospective cohort study of 377 adult patients with culture-confirmed invasive gram-negative infection acquired ≥ 48 h after admission to King Abdulaziz Medical City (KAMC), Jeddah, Saudi Arabia (2020-2024). Demographics, comorbidities, infection type, microbiology, susceptibility, complications, and outcomes were analyzed using chi-square/Fisher's exact tests and t-tests/Mann-Whitney U tests; multivariable logistic regression was used to identify independent predictors of multidrug-resistant (MDR) infection and in-hospital mortality. Infection types were classified according to U.S. Centers for Disease Control and Prevention / National Healthcare Safety Network (CDC/NHSN) surveillance definitions. RESULTS: Mean age was 64.6 ± 17.7 years (59.4% male). Hypertension (61.0%), diabetes (54.6%), and cardiovascular disease (40.8%) were the commonest comorbidities. Pneumonia predominated (47.1%), followed by bloodstream infection (33.0%), surgical-site infection (15.7%), and ventilator-associated pneumonia (9.6%). Klebsiella pneumoniae (41.9%), Pseudomonas aeruginosa (34.0%), and Escherichia coli (15.4%) were the predominant pathogens. Resistance was highest for ciprofloxacin (44.4%), ceftazidime (40.2%), and cefepime (39.9%), and 34.3% for meropenem. Overall morbidity was 68.6% and mortality 39.9%. Mortality was significantly higher in patients with cardiovascular disease (48.8% vs. 34.3%, p = 0.011), hypertension (45.4% vs. 31.5%, p = 0.015), and COPD (100.0% vs. 39.2%, p = 0.025). Diabetes was strongly associated with multidrug-resistant infection (OR 3.60, 95% CI 1.44-9.04; p = 0.004) and remained an independent predictor in multivariable logistic regression adjusting for age, sex, cardiovascular disease, and pneumonia (adjusted OR 2.82, 95% CI 1.11-7.17). CONCLUSIONS: HA-GNB infections at this Saudi tertiary center are dominated by K. pneumoniae and P. aeruginosa, carry a roughly two-in-five case fatality, and show worrying resistance to commonly used empirical agents. Within the constraints of a single-center, retrospective design, these findings support local antibiogram-informed review of empirical protocols, continued antimicrobial stewardship, and heightened infection-control attention to high-risk subgroups, particularly patients with diabetes and cardiopulmonary comorbidities; confirmation in prospective, multi-center studies is warranted.

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