Evaluating the frequency and risk factors of multidrug-resistant bacteria in biliary samples.

Background and objectives: This study aimed to evaluate the frequency of multidrug-resistant (MDR) bacteria in biliary samples, MDR-bacteria risk factors, and the relationship between MDR-bacteria positivity and some clinical outcomes.

Materials and methods: The study was conducted between May 2018 and May 2023, including patients over the age of 18 who had positive culture results in biliary samples. The frequency of MDR-bacteria in biliary samples was evaluated. Risk factors for MDR bacteria were assessed using univariate and multivariate analyses. MDR and non-MDR groups were compared inappropriate empirical antibiotic treatment, total antibiotic treatment duration, length of stay, and in-hospital mortality.

Results: 342 microorganisms were isolated from 202 patients. Escherichia coli was the most commonly (37.2%) isolated Gram-negative microorganism, and Enterococcus spp. was the most commonly (70.2%) isolated Gram-positive microorganism. The incidence of MDR microorganisms was 42.3%. Gastrointestinal malignancy (OR: 1.96; 95% CI, 1.03-3.71) and previous antibiotic use (OR: 2.26; 95% CI, 1.09-4.68) were independent risk factors for MDR-bacteria. In the MDR group, inappropriate empirical antibiotic treatment (56.6% vs. 41%, p = 0.091), total antibiotic treatment duration (13 vs. 8 days, p = 0.054), length of stay (24 vs. 15 days, p = 0.001), and in-hospital mortality (27.3% vs. 22.3%, p = 0.416) were higher compared to the non-MDR group.

Conclusion: MDR-bacteria positivity is associated with inappropriate antibiotic treatment, prolonged hospitalization, and increased mortality. Screening, antibiotic prophylaxis, and empirical treatment approaches should be carefully performed in patients with malignancy and recent antibiotic use, which are significant risk factors for MDR-bacteria.