Marine Sponge Aplysina fulva as a Reservoir of Opportunistic and Methicillin-Resistant Staphylococcus saprophyticus in Brazil.

The marine environment is increasingly impacted by anthropogenic activities. The use of bioindicator organisms, such as sponges, allows for the rapid detection of these impacts on marine environmental quality. This study aimed to isolate, identify, and characterize cultivable bacterial strains associated with the sponge Aplysina fulva, whose individuals were healthy or diseased. Eight individuals of A. fulva were collected in Arraial do Cabo, Rio de Janeiro, Brazil. A total of 165 bacterial strains were isolated, of which 142 were identified by MALDI-TOF mass spectrometry. Notably, Staphylococcus saprophyticus (n = 14; 8.5% of all isolates) was exclusively isolated from diseased sponges. Phenotypic and molecular tests revealed S. saprophyticus strains resistant to a variety of antimicrobials, being three strains considered multidrug-resistant. Additionally, the mecA-gene, encoding penicillin-binding protein 2a, was detected in three strains. Thirteen S. saprophyticus strains harbored virulence genes including uafA, aas, ssp., sssF, dsdA, and ureC. Genetic relatedness analyses suggested the presence of diverse S. saprophyticus strains associated with A. fulva. These findings highlight the opportunistic potential and possible ecological consequences of S. saprophyticus in marine hosts and emphasize the relationship of natural environments, humans, and animals in the dissemination of virulent and resistant bacteria. Impact Statement.