The decision by the Brazilian Health Regulatory Agency (Anvisa), announced on May 7, to suspend production and order the recall of a batch of products from the Ypê brand has raised concerns about the risks of contamination with the bacterium Pseudomonas aeruginosa. Identified in batches of laundry detergent in November 2025, the microorganism may now also be present in dishwashing liquids, liquid soaps, and disinfectants produced in Amparo (SP) by the manufacturer Química Amparo. Although the announcement has generated concern, the bacterium does not always pose a threat and, in addition to being an important subject of scientific study, can in some cases be found naturally in the environment and even in the human body.

“Pseudomonas aeruginosa is an environmental bacterium that lives mainly in water and soil and can be associated with plants or animals without causing disease”, explains Regina Baldini, a researcher at the Institute of Chemistry of the University of São Paulo (IQ/USP) and at the Center for Research in Biology of Bacteria and Bacteriophages (CEPID B3). “It is not common, but it can also be part of our microbiota”, she adds.

According to the researcher, under normal conditions, the body’s own defense system is capable of protecting against the pathogen and preventing it from causing disease. The risk arises when there is some form of vulnerability – such as in immunocompromised individuals or those with pre-existing conditions. In these cases, the bacterium behaves opportunistically and may then cause illness. “It can colonize catheters and ventilators, for example – causing urinary tract infections and pneumonia in hospitalized patients, in individuals with cystic fibrosis, in patients undergoing chemotherapy, or in those receiving other treatments that compromise immunity”, Baldini explains.

Just as soil, water, the human body, and hospital equipment can harbor these microorganisms, so too can equipment in sanitation product industries. “This happens because it can synthesize a class of molecules called rhamnolipids – a kind of natural detergent that protects the bacterium from other types of detergents, such as those we use for cleaning”, notes Nathan Rodrigues, a PhD student at CEPID B3 supervised by Baldini, who studies signaling and defense pathways in this bacterium. He adds that the pathogen can even degrade cleaning products and use them as a source of energy to survive in that environment.

How science studies Pseudomonas aeruginosa

Its ability to survive in different environments and conditions, combined with resistance and adaptability, makes Pseudomonas aeruginosa one of the most clinically, scientifically, and epidemiologically relevant bacteria in the world. Multiple research lines are dedicated to uncovering its mechanisms of survival and reproduction, as well as to seeking alternatives for treating infections caused by this microorganism.

Baldini, who leads part of these studies at the Laboratory of Gene Expression Regulation in Microorganisms at CEPID B3 (IQ/USP), explains that one focus of her research is precisely to analyze how the bacterium survives in different contexts. “We want to understand how bacteria adapt to different conditions by investigating the molecular basis of these behaviors”, she emphasizes. “We are also interested in understanding its ability to form ‘communities’ – biofilms – and its resistance to antibiotics”, she adds.

Studies on this species can also help elucidate, directly or indirectly, mechanisms that occur in the human body. At the Laboratory of Bacterial Molecular Genetics, also affiliated with CEPID B3 and based at the Institute of Biomedical Sciences (ICB) at USP, Rodrigo Galhardo’s team investigates bacterial genes that correspond to human genes, as well as mechanisms involved in the response to DNA damage. In a recent article, the group analyzed the response of Pseudomonas aeruginosa to stress caused by UV-C radiation and demonstrated that the bacterium can activate a coordinated response aimed at survival.

At the Laboratory of Biochemistry of Bacterial Complexes at the Institute of Biology of the University of Campinas (IB/Unicamp), Leonardo Talachia Rosa and his team take another approach – focusing on Pseudomonas bacteriophages, viruses capable of infecting only this pathogen and preventing its survival or reproduction. “We are part of a task force among CEPID B3 groups regarding these viruses,” explains the researcher. “In our laboratory, we carry out the structural characterization of these bacteriophages using cryo-electron microscopy”, he adds. This line of research may contribute to the development of bacteriophage-based therapies, considered promising alternatives to traditional antibiotics, especially for treating infections caused by resistant strains.

Is the bacterium found in Ypê products dangerous?

In light of ongoing studies and expert assessments, the recent case involving cleaning products raises an important question: does the presence of Pseudomonas aeruginosa in these items actually pose a health risk? “In short, it does not pose risks to healthy individuals; we are in constant contact with it, and our immune system is capable of preventing infection,” explains Baldini. “However, if there are individuals with any vulnerability in the household – such as newborns, elderly people, cancer patients, transplant recipients, or individuals with wounds or extensive burns – it is best not to use the products and to wait for recommendations from the manufacturer or Anvisa”, she adds, emphasizing that caution is always advisable.

Beyond highlighting the importance of surveillance and reliable information in dealing with situations like this, the episode also shows how common microorganisms can play different roles depending on the context – and underscores why closely monitoring their behavior in specialized research centers such as CEPID B3 remains essential both for public health and for the advancement of science.