Study Highlights Healthcare Infection Risks From Bacteria in Hospital Sink Drains

Hundreds of sinks can be found in every hospital ward, including operating rooms and intensive care units, but a new study warns they are often home to dozens of harmful bacteria, some of which pose a serious threat to patients.

In a study published in the journal Frontiers in Microbiology on February 13, researchers report finding 67 different types of bacteria in the drains of hospital sinks. Some of those strains are known to cause ventilator-associated pneumonia and deadly sepsis blood infections.

Health professionals and organizations have indicated for years that finding ways to prevent and treat hospital-acquired infections is a growing problem in the U.S. and worldwide. For example, a patient who needs heart or abdominal surgery, may become infected with some form of bacteria during their hospital stay. In other instances, a patient may be treated in the intensive care unit (ICU) for an injury suffered during a car crash but contract a bacterial infection while hospitalized.

Research published in 2020 indicates that patients who contract infections while in the hospital face a much higher risk of death. Data also indicates hospital-acquired infections cost the U.S. healthcare system an estimated $10 billion every year.

In the U.S., hospital-acquired infections are the sixth leading cause of death. The problem is compounded by growing antibiotic resistance, with one in seven hospital infections resistant to antibiotics in the U.S.

For the new study, researchers from the University of the Balearic Islands in Spain, led by Dr. Margarita Gomila, evaluated bacterial diversity across five hospital wards from March 2022 to March 2023. They sampled six drains in each ward, including the ICU, general medicine, hematology, short-stay unit and the microbiology laboratory. Each sink underwent four samplings across one year.

According to the data,1,058 isolates of bacteria were found, and a total of 67 different species were detected. ICUs and the general medicine wards contained the most bacteria, posing significant risks to the patients treated in those wards, researchers determined. The microbiology lab had the lowest levels of bacteria, the samples indicate.

The most common bacteria found was Pseudomonas aeruginosa, a bacterium that causes ventilator-associated pneumonia and sepsis.

The data indicates that every bacterium tested, except one, was resistant to multiple types of antibiotics. In fact, 21% of P. aeruginosa were resistant to at least one class of antibiotics and many Klebsiella and Enterobacter were resistant to third-generation cephalosporin antibiotics.

Other bacteria found included Klebsiella pneumoniae and Acinetobacter johnsonii found in the general medicine wards, Acinetobacter ursingii found in general medicine and ICU wards, Enterobacter mori and Enterobacter quasiroggenkampii found in the short stay ward, and Staphylococcus aureus found in the ICU and hematology wards.

During the study, a new intensive care unit opened in July 2022, testing positive for high levels of bacteria. Researchers said the levels were similar to those found in ICUs that had been operating for much longer.

Difficulties Cleaning Hospital Sinks

The drains in the hospital sinks were routinely cleaned with bleach and disinfected with chemicals. They were pressure steam cleaned every two weeks, and every year the drain pipes were hyperchlorinated at a low temperature.

Despite those efforts, hospital sinks carry significant levels of bacteria, even with strict disinfecting protocols. The bacteria may come from many sources, such as human skin, the outside environment and medical equipment, the researchers noted.

Gomila’s team concluded there is a clear link between human activity, sink use and the presence of dangerous bacteria, warning that, once in the drains, the bacteria can spread and sicken patients.

Hospital sink drains may offer research insight into finding the best strategies for preventing the proliferation of bacteria, especially in settings where patients are at the highest risk, the researchers noted.