Epidemiology and risk factors of multidrug-resistant Gram-negative bacilli in healthcare-associated infections: development of an exploratory risk assessment model in a Moroccan regional hospital

Healthcare-associated infections (HAIs) caused by multidrug-resistant Gram-negative bacilli (MDR-GNB) are a growing public health threat, particularly in hospitals. This study identified risk factors for HAIs due to MDR-GNB in a regional hospital via univariate and multivariate logistic regression analyses. We conducted a case–control study at the Regional Hospital of Beni Mellal, Morocco (November 2021–April 2024). Adult inpatients with HAIs due to GNB were included. Cases were defined as MDR-GNB infections, and controls as non-MDR-GNB infections. Demographic, clinical, and exposure data—including prior antibiotic use, hospitalization history, and device utilization—were collected from medical records. Independent risk factors for MDR-GNB infection were identified using multivariate logistic regression. An exploratory bedside risk index was developed and internally validated by bootstrap resampling (1,000 iterations), with discrimination assessed via receiver operating characteristic curve analysis, and calibration was assessed using calibration intercept and slope. Among 188 patients with culture-confirmed GNB infections, 56.4% (n = 106) were MDR-GNB. The most frequent isolates were Escherichia coli (45%), Acinetobacter baumannii (27.4%), and Klebsiella pneumoniae (19.8%). Multivariate analysis identified antibiotic therapy within the previous 90 days (aOR = 14.79; 95% CI: 4.6–47.56), prior hospitalization within 90 days (aOR = 3.91; 95% CI: 1.52–10.07), and Foley catheter use (aOR = 3.69; 95% CI: 1.19–11.47) as independent risk factors for MDR-GNB infection. Conversely, bloodstream infection (aOR = 0.09; 95% CI: 0.01–0.52) and E. coli infection (aOR = 0.28; 95% CI: 0.10–0.75) were associated with lower odds of MDR-GNB infection. A five-variable risk assessment score showed excellent discrimination (AUC = 0.88, bootstrap-corrected AUC = 0.87) and acceptable calibration, accurately stratifying patients into low-, intermediate-, and high-risk groups for MDR-GNB infection. These findings highlight the urgent need to implement strict infection prevention protocols, optimize antibiotic use through stewardship programs, and enhance surveillance to combat the spread of MDR-GNB infections at Beni Mellal Regional Hospital.