Upstream migration of bacteria in drainpipes in heathcare settings– effects of piping material and environment

Introduction: Gram-negative rods and Enterobacteriaceae are often detected in hospital sinks and drains. These bacteria can migrate upstream in pipes and cause infections, and their ability to survive in dry conditions makes controlling them difficult. Objective: We investigated bacterial upstream migration in simulated piping modeled after drainage pipes. Materials and Methods: Dry or wet simulated pipes made of stainless steel or polyvinyl chloride (PVC) were put in bacterial suspensions, and a sterilized paper disk was placed on top of the pipe. After an appropriate time, bacterial migration was assessed by culture from the paper disk. Results: Rod-shaped bacteria possessing biofilm-forming ability and flagella, including Pseudomonas aeruginosa, Serratia marcescens, Acinetobacter spp., and Escherichia coli, migrated upstream by 1 inch (25.4 mm) within 30 min in moist simulated pipelines. The nonflagellated Staphylococcus aureus did not migrate upstream in the simulated pipelines. In dry simulated pipes, none of the tested bacterial species exhibited upstream migration. Stainless steel piping suppressed migration more effectively than PVC. Conclusions: Moisture management in drainpipes and the use of stainless-steel pipes may decrease bacterial upstream migration in hospital drainage systems.