Pesquisadores from USP and Instituto from Pesca from São Paulo identified the bacteria Citrobacter telavivensis in fresh oysters sold at Brasil. The discovery occurred in samples purchased on São Paulo and Santa Catarina markets. The species is classified by Organização Mundial of Saúde as critical priority due to high antibiotic resistance. Nenhum batch failed current health tests. The finding was published in August 2025 and reinforces concerns about the presence of superbugs in the food chain.
Antimicrobial resistance takes on a new shape with this detection outside the hospital environment. Ostras act as natural seawater filters. Elas retain microorganisms and substances present in the environment. The study also recorded other resistant bacteria, such as Klebsiella pneumoniae and Escherichia coli.
Bactéria identified in oysters from two states
The oysters analyzed came from five different markets. The researchers examined 108 samples in total. Citrobacter telavivensis appeared for the first time in food in the country. Antes, the oldest record was from 2010, in a hospital in Israel.
- Samples contained strains resistant to next-generation antibiotics
- Concentrações of arsenic above the Anvisa limit appeared in 35% of cases
- Co-selection between heavy metals and drug residues favors resistance
- Protocolos inspection does not evaluate antimicrobial profile of bacteria
Essa combination shows how environmental pollution contributes to the problem. Oysters expose what circulates in the water where they are raised or caught.
Antimicrobial Resistência advances as a global threat
Saúde’s Organização Mundial considers resistance to be one of the top ten threats to public health. The October 2025 GLASS report found that one in every six bacterial infections between 2018 and 2023 already showed resistance. The percentage represents an increase of more than 40% in the period.
In May 2025, Assembleia Mundial of Saúde approved an action plan for the period 2026-2036. Especialistas estimate that superbugs could cause up to 39 million deaths per year by 2050 without effective measures. The number exceeds current projections for cancer mortality in some scenarios. The traditional focus on hospitals now expands to the food chain.
Ostras reveals contamination in the marine environment
Mollusks filter large volumes of water to feed themselves. Qualquer element present in the region is retained in its microbiota. Essa feature turns oysters into environmental sentinels. What appears on them indicates seawater conditions.
The study detected not only Citrobacter telavivensis, but also signs of arsenic pollution. The interaction between the metal and antibiotic residues creates selective pressure. Bactérias survive better when they tolerate both. Pesquisadores call the co-selection process. The phenomenon accelerates the spread of resistance.
The situation gains relevance because oysters are frequently consumed raw. Minimal preparation preserves the risk if contamination is present.
Protocolos toilets do not detect bacterial resistance
Inspeções and Brasil follow international standards such as HACCP and good manufacturing practices. The tests check temperature, general hygiene and specific pathogens such as Salmonella and Listeria. The antimicrobial resistance profile is outside the current scope. A batch with superbugs can pass if the total number of microorganisms is within the limit.
Essa gap exists because the protocols were created before the current scale of the problem. Inspection still targets classic threats. The evolution of bacteria requires updating. Especialistas advocate the inclusion of tests for resistance in fish and shellfish.
Biofilmes protect bacteria in processing plants
Resistant Bactérias also form protected communities called biofilms. Essas structures adhere to equipment, piping and surfaces. The external matrix makes bacteria up to a thousand times more resistant to sanitizers and antibiotics. Presence in industrial environments increases the risk of cross-contamination.
Pesquisas seek biological alternatives to combat biofilms. An enzyme called lugdulisin, produced by another bacterium, showed the ability to degrade these structures in laboratory tests. The path is still experimental, but it indicates possible directions for new control methods.
Mudanças necessary for fish surveillance
Ministério of Agricultura maintains a national plan against antimicrobial resistance in agriculture. The second stage, in 2023, monitors Salmonella in poultry, pigs and cattle. Pescados and shellfish do not yet enter full coverage.
Três fronts emerge as priorities. The first is to expand resistance surveillance to include oysters and other seafood. The second involves updating quality standards with traceability and specific tests. The third calls for more resources for research into biotechnological solutions.
The Brazilian fishing sector may face barriers in exports. Países as members of União Europeia and Estados Unidos require strict resistance controls. Internal Falhas affect economic competitiveness in addition to health risk.
The discovery reinforces that pressure on bacteria is not limited to hospitals. The excessive use of antibiotics in aquaculture and livestock farming, combined with inadequate disposal, drives the cycle. Citrobacter telavivensis in oysters serves as a warning about the path that resistance follows in nature.