Course-based undergraduate research experiences (CUREs) are an effective method of engaging large numbers of students in authentic research but are associated with barriers to adoption. Short CURE modules may serve as a low-barrier entryway, but their effectiveness in promoting expansion has not been studied. The Prevalence of Antibiotic Resistance in the Environment (PARE) project is a modular CURE designed to be a low-barrier gateway into CURE use. In a series of interviews, we track and characterize use of PARE in 19 PARE-interested instructors throughout the Innovation-Decision Process described by Rogers' Diffusion of Innovations theory. The majority (16/19) implement PARE at least once, and a majority of these implementers (11/16) expanded use by the final interview. Three of four cases of discontinuance were due to a disruption such as moving institutions or a change in course assignment and occurred for community college faculty. Expanders expressed fewer personal challenges than nonexpanders. Overall analysis shows that perception of barriers is nuanced and impacted by the innovation itself, the institutional context, and one's own experiences. These results suggest that a short duration, low barrier CURE can serve as a catalyst for implementation of a longer duration CURE.