A drug-resistant bacteria, historically confined to hospital settings, is increasingly spreading throughout the wider community in São Paulo, Brazil, according to a novel study published February 19, 2026. The research, conducted by the Associação Fundo de Incentivo à Pesquisa (Afip) in partnership with the Escola Paulista de Medicina at the Universidade Federal de São Paulo (Unifesp), analyzed over 51,500 cases of Staphylococcus aureus infection between 2011 and 2021.
The study, published in the journal Research Connections from Oxford University Press, reveals a significant shift in transmission patterns. Although hospital-acquired infections of the bacteria decreased during the study period, infections contracted within the community rose, indicating the bacteria is no longer primarily contained within healthcare facilities. Researchers found an average annual reduction of 2.48% in hospital-associated MRSA (Methicillin-resistant Staphylococcus aureus) cases, contrasted by an average annual increase of 3.61% in community-associated MRSA infections.
Staphylococcus aureus is a common bacterium often found on skin and in the respiratory tract, typically causing mild infections. However, when it develops resistance to antibiotics, particularly in the form of MRSA, treatment becomes significantly more challenging. The rise of community-associated MRSA is particularly concerning as it impacts individuals without recent hospitalizations.
The analysis of the 51,532 cases, drawn from a network of over 600 healthcare units, showed a MRSA prevalence of 42.6% among patients with active infections and 37.4% among those colonized with the bacteria – meaning they carried the bacteria without exhibiting symptoms. Children under three years ancient and individuals aged 65 and older were identified as the most affected demographic groups.
Researchers also noted a marked increase in a specific type of community-associated MRSA sensitive to clindamycin, growing at an average annual rate of 8.77%. This finding suggests evolving bacterial strains and potential complexities in treatment protocols. The study also mapped the geographic distribution of cases, identifying areas within the state of São Paulo with MRSA concentrations exceeding 20% in the community.
The shift in the epidemiological profile, from a predominantly hospital-based threat to a community-wide concern, underscores the need for broader public health strategies, according to the study authors. These strategies must address both hospital environments and the general population, emphasizing appropriate antibiotic use and increased awareness of infection signs.
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