Is There a Community Microbial Community? A Comparison of Pathogens Between Two Hospital Surgical Intensive Care Units in a Single City.

Abstract

Background: Nosocomial and health-care-associated infections drive increased healthcare costs and negatively affect patient outcomes. The human microbiome has been heavily explored in recent years with incomplete data regarding hospital-specific and community-specific microbial communities. Although bacterial species differ between intensive care units in the same hospital, it is unclear if they differ between similar units in similar hospitals in the same community. Our hypothesis is that pathogens in surgical intensive care units (SICUs) are distinct between hospitals, even in the same community. Methods: From 2017 to 2021, data were collected prospectively from the SICUs of two 400-bed hospitals located three miles apart in the same city (Hospital A and Hospital B). Infections defined using U.S. Centers for Disease Control and Prevention (CDC) criteria were recorded for trauma and general surgery patients, as well as patient demographics, Acute Physiology and Chronic Health Evaluation (APACHE) II score, and causative organism. Results: Overall, Escherichia coli was the most commonly isolated pathogen in Hospital A, whereas Staphylococcus aureus was most commonly isolated at Hospital B. Enterococci were more common in Hospital A, and Haemophilus influenzae and Enterobacter spp. were more common in Hospital B. After stratification between trauma and non-trauma patients, however, these differences disappeared, with the exception of more overall gram-positive organisms and fewer gram-negative organisms among Hospital A trauma patients compared to Hospital B. There were no differences in rates of isolation of either fungi or resistant bacteria between hospitals. Conclusions: At a species level, admission diagnosis appears to be a greater determinant of pathogen isolation than hospital when comparing similar intensive care units (ICUs) in the same geographic area, but a larger body of data is needed to flesh out a distinct microbial map of the organisms occupying a certain geographic region. Further areas for investigation include comparison between hospital units, specific anatomic sites, and ICU versus floor patients.