Development of a Weighted-Incidence Syndromic Combination Antibiogram (WISCA) to Guide Empiric Antibiotic Treatment for Ventilator-Associated Pneumonia in a Mexican Tertiary Care University Hospital

Background Ventilator-associated pneumonia (VAP) is a prevalent and serious nosocomial infection among critically ill patients that leads to significant morbidity, mortality, and increased healthcare costs. The heterogeneity in local epidemiology and antibiotic resistance complicates the selection of effective empirical treatments. The weighted-incidence syndromic combination antibiogram (WISCA) tool has been proposed to optimize empirical antibiotic therapy by leveraging local microbiological data. Objective This study aimed to develop a WISCA tailored for VAP in a Mexican tertiary care university hospital. The objective is to improve empirical antibiotic coverage by considering the unique pathogen landscape and resistance patterns of the institution. Methods This research was conducted from June 2021 to June 2024 using clinical registries and microbiological data from a tertiary hospital in an upper middle-income Latin American country. Data, including demographic and clinical characteristics, were collected from patients who developed VAP. We employed a Bayesian hierarchical logistic regression model to estimate the coverage of various antibiotic regimens. We also analyzed the impact of initial inappropriate empiric treatment on in-hospital mortality and prolonged hospital stays in our population using multivariate logistic regression analysis. Results A total of 197 VAP episodes from 129 patients were analyzed. The median age was 44 years (IQR 35–56), and the median Charlson comorbidity index was 1 (IQR 0–2). The most common pathogens were Acinetobacter baumannii and Pseudomonas aeruginosa . Tigecycline-based combined regimens showed greater median coverage (+ 47.97%) than nontigecycline-based combined regimens, particularly against multidrug-resistant Acinetobacter baumannii . Inappropriate initial empirical treatment was associated with prolonged hospital stays but not directly with in-hospital mortality. However, inappropriate treatment during the entire VAP episode was significantly associated with increased mortality. Conclusions The tailored WISCA model provided robust coverage estimates. This study demonstrated the potential to optimize empirical antibiotic regimens, especially tigecycline-based combinations. This study highlights the importance of local epidemiological data in guiding empirical therapy and reducing the consequences of inappropriate antibiotic use.