The Burden of Comorbidity Is Associated with Antibiotic Resistance Among Institutionalized Elderly with Urinary Infection: A Retrospective Cohort Study in a Single Italian Nursing Home Between 2009 and 2014.

Urinary tract infections (UTIs), which are common among nursing home patients, are associated with adverse outcomes and increased healthcare costs. Antibiotic resistance is an emerging problem, associated with excess morbidity and mortality; it has been suggested that this condition might be more prevalent among subjects with comorbid conditions. The aim of this study was to assess the association, if any, of antibiotic resistance with the burden of comorbidity in elderly with UTIs. This retrospective study enrolled 299 patients with culture-positive UTI consecutively admitted to the nursing home of the "Fondazione San Raffaele Cittadella della Carita", Taranto, Italy, which includes 80 beds under the direction of two geriatricians. The burden of comorbidity was quantified using the Charlson comorbidity score index. Diagnosis of UTI was ascertained by urine culture. Antibiotic resistance was defined according to the European Centre for Disease Prevention and Control expert proposal. Logistic regression was used to assess the adjusted association of the variables of interest with the presence of antibiotic resistance. Antibiotic resistance was detected in 162/299 (54%) patients. In logistic regression, the presence of antibiotic resistance was independently associated with higher Charlson score, after adjusting (odds ratio = 1.06; 95% confidence interval = 1.01-1.10). Antibiotic resistance is highly prevalent among nursing home residents; it is associated with the burden of comorbidity, but not with single diseases. This association and its potential implications should be assessed in dedicated studies.