Association between clinical frailty and multidrug-resistant positive cultures in hospitalized older adults

Frailty is a key determinant of adverse outcomes in older adults. The association between clinical frailty and multidrug-resistant (MDR) positive cultures in hospitalized older adults remains insufficiently defined. Understanding this association may improve early risk stratification and inform infection control strategies in acute care. We conducted a prospective, observational, single-center cohort study in an internal medicine ward. Patients aged ≥ 65 years admitted with clinical suspicion of bacterial infection requiring microbiological testing and antibiotic therapy were eligible. The diagnosis of infection was based on clinical, laboratory, and imaging findings as assessed by the treating physician, regardless of microbiological confirmation. Among 208 eligible patients with confirmed infection, participants were stratified by culture results into negative, non-MDR, and MDR + groups. Frailty was assessed using the Clinical Frailty Scale (CFS) and Primary Care Frailty Index (PC-FI), while comorbidity burden was evaluated with the Cumulative Illness Rating Scale (CIRS). Multinomial logistic regression was used to explore variables associated with MDR-positive culture status. Of the 208 patients, 57% were culture-negative, 29% had non-MDR infections and 14% MDR +. Frailty increased progressively across groups: median CFS was 5, 6, and 6 (p = 0.004), and median PC-FI was 0.20, 0.24, and 0.28 (p = 0.021). The prevalence of frailty rose from 56 to 70% to 83% (CFS > 4; p = 0.015). MDR + patients more frequently required full-time caregiving and had longer hospitalization and antibiotic duration. In multivariable analysis, CFS remained associated with MDR-positive culture status after adjustment for age and comorbidity burden (OR 1.57, 95% CI 1.17–2.11) although residual confounding cannot be excluded. In this selected single-center cohort of hospitalized older adults, clinical frailty was associated with MDR-positive cultures. These findings should be considered hypothesis-generating and should not be interpreted as supporting broader empirical antibiotic therapy based on frailty alone.