They thrive everywhere and infect their surroundings: researchers have found dangerous bacteria in hospitals.

Behind the impeccably white walls and gleaming surfaces of hospital wards lies an invisible battleground teeming with microbes. A new study conducted in Spain has uncovered an unexpected hotspot for antibiotic-resistant bacteria: sink drains. Despite stringent sanitation protocols, researchers found a thriving ecosystem of potentially harmful microbes lurking in these inconspicuous recesses, as reported by StudyFinds.

The researchers conducted their study at a university hospital in Mallorca from February 2022 to February 2023 across five different departments, including intensive care units and a microbiology laboratory. Even with regular bleach cleaning, biweekly chemical disinfection, and high-pressure steam treatment, the researchers discovered that bacteria persisted, adapted, and thrived.

The findings published in the journal Frontiers in Microbiology reveal a grim reality — hospital sinks, intended to maintain hygiene, may inadvertently facilitate the spread of dangerous pathogens. Senior author Margalida Gomila from the University of the Balearic Islands noted that bacterial populations changed over time, despite strict cleaning measures.

During the study, scientists identified 1,058 bacterial isolates from 67 species, raising alarms about the presence of antibiotic-resistant strains. The most concerning were Pseudomonas aeruginosa, a notorious culprit of hospital-acquired infections, and Klebsiella pneumoniae, exhibiting resistance to key antibiotics. Each department revealed different bacterial communities, with the greatest microbial diversity observed in general medicine and intensive care units.

Even in a newly established intensive care unit opened in July 2022, bacterial communities resembling those of the older unit quickly formed, indicating rapid and inevitable contamination of the areas. Particularly alarming was the presence of the blaVIM gene in strains of Pseudomonas aeruginosa found in several departments. This gene confers resistance to carbapenem antibiotics — often the last line of defense against multidrug-resistant infections.

Once established, these resilient bacteria can persist, evolve, and even exchange resistance genes, exacerbating the global crisis of antibiotic resistance. Despite thorough disinfection, these microbial communities continue to exist, likely seeded by patients, healthcare staff, and the environment. Study author José Lasso emphasized the need to track the sources of bacteria and their transmission pathways to develop more effective containment strategies.

As hospitals worldwide grapple with the growing threat of antibiotic-resistant infections, these results underscore the urgent need to reassess even the most fundamental aspects of hospital hygiene. In an era where antimicrobial resistance looms as a significant public health crisis globally, no detail in infection control is too trivial to overlook, according to the authors.

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