Sink Drain Danger? Proximity to Toilets Equals a Reservoir of Bacteria

Sink drains located near toilets in patient rooms were found to have a high prevalence of Klebsiella pneumoniae carbapenemase—producing (KPC) organisms, according to a recent study by investigators from the Medical College of Wisconsin and Froedtert Memorial Lutheran Hospital.

The study, published in the American Journal of Infection Control, found that 87% of sinks near toilets tested positive for bacteria with the bla_KPC resistance gene, with the contamination being 5 times more likely than in sinks near the room’s entrance, which tested positive at a rate of 21.7%. The results were reached using direct polymerase chain reaction assay.

"If sinks next to toilets are indeed a reservoir for bla_KPC, then additional interventions such as modified hand hygiene practices (eg, dedicated sinks), optimization of sink disinfection protocols (eg, increased frequency, optimal disinfectants), and use of engineering controls (eg, splash shields) may be needed to further mitigate the risk of transmission of KPC-producing organisms among health care providers and patients," the investigators wrote in the study.

The study was conducted in the medical intensive care unit of a 600-bed Wisconsin hospital, where rooms include 2 sinks and a toilet, which are surface cleaned daily with separate cloths to avoid cross-contamination. In 4 out of 5 sinks that tested positive near the entry of the room, sinks near the toilets also tested positive.

Klebsiella bacteria, which most recently developed antimicrobial resistance to carbapenem antibiotics, is associated with pneumonia, bloodstream infections, wound infections, and surgical-site infections. The study was conducted in a unit with no documented infections with KPC—producing organism in the past year.

The study suggested that communal pipes between toilets and sinks could be responsible for the contamination of sink drains. The contamination also could be occurring via droplets during flushing. A third possibility is that routine hand washing by patients and health care workers could introduce bacteria.

"We have so much in the patient's room, not just equipment but also furniture. We need to account for cleaning and disinfection that goes beyond just wiping it down," Saskia Popescu, MPH, MA, CIC, infection preventionist with Phoenix Children's Hospital and Contagion^® contributor, said.

Increased attention on antimicrobial-resistant organisms has brought the issue to the forefront.

"It feels like every week we're becoming more cognizant of the risks and the potential for certain things to be reservoirs for contamination, and we're making more strides," Popescu told Contagion^®. "With every new bit of information, we're able to think things through and improve processes."

Although this is the first study to examine sink location in relation to toilets, bathrooms and plumbing systems are a frequent subject of study.

An outbreak of multidrug-resistant Sphingomonas koreensis infections was linked to contamination in the plumbing system at a National Institutes of Health (NIH) Clinical Center in Bethesda, Maryland, in 2016.

A study published last year examined the presence of mycobacteria in showerheads in the United States and Europe. The study found higher levels of mycobacteria in household receiving municipal water, which investigators attributed to higher levels of chlorine and chlorine byproducts, which mycobacteria are more resistant to than other bacteria.

If verified, the new study could highlight a need for new infection control interventions, investigators Blake Buchan, PhD, and Silvia Munoz-Price, MD, PhD, said in a written statement.

“The results of this study demonstrate the importance of remaining vigilant to potential areas of cross-contamination,” Karen Hoffmann, RN, MS, CIC, FSHEA, FAPIC, 2019 president of the Association for Professionals in Infection Control and Epidemiology, said in a written statement. “Maintaining a strong understanding of environmental risks is critical to protecting patient safety, and this is yet another example of how germs can lurk in often the most unexpected of places.”