Risk factors for antibiotic-resistant respiratory infections among patients requiring ward admission

Aims: The airway flora has been recognized as non-sterile, and sputum sampling is recommended for hospitalized patients with respiratory infections. Empiric antibiotic treatment is often initiated without culture confirmation, potentially contributing to antimicrobial resistance. This study aims to assess the influence of demographic factors, prior antibiotic use, and other risk factors on resistant respiratory cultures in ward-admitted patients. Methods: A single-center cohort study was conducted in a pulmonary medicine ward of a tertiary hospital between the dates of March 2024 and September 2024. Patients over 18 years old with sputum, bronchoalveolar lavage (BAL), or endotracheal aspiration culture results were included. Demographic characteristics, comorbidities, vaccination status, prior infections, respiratory support needs, antibiotic history, and hospital admission records were collected. Nonparametric statistical analyses were used to evaluate associations, including the Mann-Whitney U and Kruskal-Wallis tests. Results: Among 70 patients (mean age 68 ±9 years, 87% male), chronic obstructive pulmonary disease (COPD) (71.4%) was the most prevalent comorbidity. A total of 75.7% of cultures were from sputum samples, with Pseudomonas spp. (27.1%), Klebsiella pneumoniae (20%) and Escherichia coli (14.3%) being the most frequently isolated organisms. Resistant cultures were more common in patients with intensive care unit (ICU) admission history (p=0.007), intubation history (p=0.003), and non-invasive mechanical ventilation (NIMV) use (p=0.038). No correlation was found between prior antibiotic use and resistance. Conclusion: ICU admission and respiratory support requirements were key risk factors for resistance. Contrary to previous studies, prior antibiotic use and comorbidities did not significantly impact resistance rates. These findings highlight the need for targeted antimicrobial stewardship and careful risk assessment among patients requiring pulmonary ward admission.