UC Merced

I initiated the collection of Gram-negative clinical isolates of bacteria expressing resistance to extended spectrum β-lactam antibiotics. That collection has proved to be a valuable resource for studying the evolution of antibiotic resistance in the Central Valley. It has been used to study in hospitals, agricultural settings and to study the evolution of specific resistance phenotypes. To answer questions about where the major reservoirs of resistance lie, where resistance evolves, and how we might better identify the sources of new resistance as it enters a population. Firstly, Urinary tract infections (UTIs) are the most common bacterial infection among hospitalized patients at Dignity Health Mercy Medical Center (DHMMC). Secondly, CTX-M and OXA have high frequencies at DHMMC and lastly hospitals can have some effect on but are not a major contributor to the evolution of antibiotic resistance. Overall, we have found that the population dynamics of ESBLs rely on transmission of urinary tract infections and that hospital, agricultural and community settings are all important in the transmission of ESBLs.