In health care settings where toilets are shared, toilet droplets generated during urination may be a hidden source of carbapenem-resistant Klebsiella pneumoniae (CR-KP) transmission. In addition, the application of a novel foam layer into a toilet bowl prior to urination was found to effectively eliminate the risk for transmission. These findings were published in Antimicrobial Resistance and Infection Control.

Researchers from the University of Foggia in Italy simulated urination-associated droplet formation in a toilet contaminated with a K pneumoniae isolate (ST101) using variable distances and angles from the toilet. Six culture dishes were attached to the bottom of the toilet lid and incubated overnight to assess whether urination mobilizes the bacteria. In addition, the researchers assessed whether spraying a novel foam into toilets prior to urination decreases the risk for bacterial transmission.

In addition to cleaning action, the novel foam was designed to be biodegradable and sustainable, stable regardless of environment, visible, easy to eliminate, and to have a pleasant appearance and smell. The foam comprised betaine dialkyl carbonate, an anionic surfactant, a fatty alcohol, an ester of a fatty acid, a pH regulator, a deodorizing substance and/or a propellant gas.

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Among toilets that did not include the novel foam layer, the mean number of recovered urine droplets was 1350 ± 137. The researchers found that modifying certain aspects of a toilet’s incoming liquid jet, including angles, heights, flow rates, and durations, decreased the amount of dispersed droplets; however, none of these modifications completely eliminated the risk for urine dispersion The mean number of bacterial colonies recovered from 3 experimental replicates was 0.11 ± 0.05 colony forming units/cm2.

Of note, the researchers found that adding the novel foam layer to a toilet prior to urination was an effective strategy for eliminating the risk for droplet rebound during urination.

This study was limited by its use of only toilet configurations that simulated a high level of contamination during urination. In addition, this study describes only laboratory findings as it was not conducted in a clinical setting.

“Further studies with scaled bacterial loads, different bacterial species, and comparisons between foam and other devices for [decreasing] the risk for infection [are] needed to support these findings,” the researchers concluded.


Arena F, Coda ARD, Meschini V, Verzicco R, Liso A. Droplets generated from toilets during urination as a possible vehicle of carbapenem‑resistant Klebsiella pneumoniae. Antimicrob Resist Infect Control. 2021;10(1):149. doi:10.1186/s13756-021-01023-5

This article originally appeared on Infectious Disease Advisor