Characterization of Enterobacteriaceae and Vibrio spp. Occurrence in Aquatic Systems

Abstract

Vibrio spp., such as Vibrio cholerae, Vibrio vulnificus, and Vibrio parahaemolyticus, are naturally occurring bacteria in aquatic ecosystems. Vibrio spp. are pathogenic if they enter an open wound or ingested, which can cause life-threatening disease such as necrotising fasciitis and cholera. Vibrio spp. are detected by culturing from clinical and environmental samples, and reporting cases to local health departments, according to CDC regulation. Some Vibrio species are known to form symbiotic biofilms with other bacteria, which suggests that enterobacteria may co-occur in the environment. Previous studies have suggested that Vibrio spp., may be negatively correlated with other enterobacteria in the environment, but there are limited quantitative models to explore this relationship. This project will characterize this co-occurrence relationship to determine if non-Vibrio enterobacteria can be used as a proxy to predict the presence of Vibrio and prove that Vibrio spp. are naturally occurring in the environment. By analyzing these relationships, public health officials will be able to make faster and more informed decisions on when to issue water quality warnings and mitigate the risk for environmentally acquired Vibriosis infections. State-level and species-specific bacterial isolate data from the CDC’s Bacteria, Enterics, Ameba, and Mycotics (BEAM) dashboard were used to create a co-occurrence matrix in Python. An enrichment p-value was calculated using Fisher’s Exact Test and adjusted using False Discovery Rate (FDR). Effect size was calculated using odds ratios and plotted using heatmaps and volcano plots. Co-occurrence patterns for cholera and non-cholera vibriosis in Maryland were assessed using incidence rates for each county. A Spearman correlation coefficient and FDR adjusted p-value were calculated for each disease pair for each year between 2018 and 2024 and were plotted using a heatmap. These methods yielded mostly statistically insignificant co-occurrence in the environment and complete insignificance of case correlation. The preliminary data show that Vibrio spp may occur when other enteric bacteria are not present, hence the insignificant co-incidence that supports existing hypotheses.