Spread from the Sink to the Patient: In Situ Study Using Green Fluorescent Protein (GFP)-Expressing Escherichia coli To Model Bacterial Dispersion from Hand-Washing Sink-Trap Reservoirs

Abstract

There have been an increasing number of reports implicating Gammaproteobacteria as often carrying genes of drug resistance from colonized sink traps to vulnerable hospitalized patients. However, the mechanism of transmission from the wastewater of the sink P-trap to patients remains poorly understood. Herein we report the use of a designated hand-washing sink lab gallery to model dispersion of green fluorescent protein (GFP)-expressing Escherichia coli from sink wastewater to the surrounding environment. We found no dispersion of GFP-expressing E. coli directly from the P-trap to the sink basin or surrounding countertop with coincident water flow from a faucet. However, when the GFP-expressing E. coli cells were allowed to mature in the P-trap under conditions similar to those in a hospital environment, a GFP-expressing E. coli-containing putative biofilm extended upward over 7 days to reach the strainer. This subsequently resulted in droplet dispersion to the surrounding areas (<30 in.) during faucet operation. We also demonstrated that P-trap colonization could occur by retrograde transmission along a common pipe. We postulate that the organisms mobilize up to the strainer from the P-trap, resulting in droplet dispersion rather than dispersion directly from the P-trap. This work helps to further define the mode of transmission of bacteria from a P-trap reservoir to a vulnerable hospitalized patient.IMPORTANCE Many recent reports demonstrate that sink drain pipes become colonized with highly consequential multidrug-resistant bacteria, which then results in hospital-acquired infections. However, the mechanism of dispersal of bacteria from the sink to patients has not been fully elucidated. Through establishment of a unique sink gallery, this work found that a staged mode of transmission involving biofilm growth from the lower pipe to the sink strainer and subsequent splatter to the bowl and surrounding area occurs rather than splatter directly from the water in the lower pipe. We have also demonstrated that bacterial transmission can occur via connections in wastewater plumbing to neighboring sinks. This work helps to more clearly define the mechanism and risk of transmission from a wastewater source to hospitalized patients in a world with increasingly antibiotic-resistant bacteria that can thrive in wastewater environments and cause infections in vulnerable patients.

Chronic Airway Colonization by Achromobacter xylosoxidans in Cystic Fibrosis Patients Is Not Sustained by Their Domestic Environment

“…These devices are more and more frequently described as reservoirs for pathogens and multidrug-resistant bacteria in both hospitals and domestic environments (21)(22)(23). Moreover, aerosolization and crosstransmission of pathogens from siphons have been demonstrated in recent carefully designed experimental studies (24,25). Our results reinforced recommendations to CF patients for home cleaning that should be targeted to the bathroom, kitchen, and other wet sites, with particular emphasis on wastewater drains, including hidden drains in domestic appliances.…”

Genomic Analysis of Hospital Plumbing Reveals Diverse Reservoir of Bacterial Plasmids Conferring Carbapenem Resistance

“…A recent study by Kotay et al experimentally showed the ease with which E. coli can disperse from a sink after seeding (61). We also detected other CPOs in sinks and housekeeping closets that were highly related to patient isolates, but an epidemiological link could not be established.…”

Building upon current knowledge and techniques of indoor microbiology to construct the next era of theory into microorganisms, health, and the built environment

“…Dampness has also been extensively studied in relation to the exacerbation of asthma symptoms [122], and these efforts are not repeated in this review. Motile Escherichia coli are capable of traveling from sink traps back up the drain into the sink, at a rate of 2.5 cm per day, from where they spread to other areas via droplet spray during sink use [123]. Similarly, water heaters host bacterial communities which can spread Mycobacterium via aerosolization at faucets and showerheads [124][125][126], and Legionella pneumophila can persist in building ventilation systems and infect building occupants [127,128].…”