Seasonal assessment of microbial indicators, antibiotic resistance, and heavy metal tolerance in water, sediment, and edible fish from an urban tropical coastal lagoon (Jansen Lagoon, São Luís, Brazil)

Luciano de Souza Rodrigues Júnior¹Adenilde Ribeiro Mouchereck²Marco Valério Jansen Cutrim^3,4Andrea Christina Gomes de Azevedo-Cutrim⁴Pâmela Thays da Silva Baima⁵Amanda Mara Teles³Walter José Martinez Burgos^6*Roberta Pozzan⁷Ceci Sales-Campos⁸Josilene Lima Serra Pereira^9*

• ¹Food Technology Department, Federal Institute of Education, Science and Technology of Maranhão - Campus Barreirinhas, Barreirinhas, MA, 65590-000, Brazil., Maranhão, Brazil
• ²Department of Industrial Chemistry, PPG Health and Enviroment - Federal University of Maranhão, Cidade Universitária Dom Delgado, Portugueses Road, N◦1966, 65080-805, São Luís, Maranhão, Brazil., Maranhão, Brazil
• ³Department of Industrial Chemistry, PPG Health and Enviroment - Federal University of Maranhão, Cidade Universitária Dom Delgado, Portugueses Road, N◦1966, 65080-805, São Luís, Maranhão, Brazil, Maranhão, Brazil
• ⁴Water Resources Management and Regulation - ProfAgua - UEMA - State University of Maranhão, Brazil., Maranhão, Brazil
• ⁵Department of Chemistry – Federal University of São Paulo, São Paulo, Brazil, São Paulo, Brazil
• ⁶Bioprocess Engineering and Biotechnology Department, Federal University of Paraná (UFPR), Curitiba, PR, 81531-990, Brazil, Curitiba, Brazil
• ⁷Cell Toxicology Laboratory, Department of Cell Biology, Biological Sciences Sector, Federal University of Paraná - Curitiba, PR, Brazil, Curitiba, Brazil
• ⁸National Institute of Amazonian Research (INPA), Laboratory of Mushrooms and Edible Fungi, Aleixo I Campus, Av. André Araújo, 2936, Aleixo, 69060-001, Manaus, Amazonas, Brazi, Manaus, Brazil
• ⁹Food Technology Department – PPGCTM and PPGBionorte, Federal Institute of Education, Science and Technology of Maranhão - Campus Maracanã, São Luís, MA, 65095-460, Brazil, Maranhão, Brazil

Urban coastal lagoons often receive untreated sewage and stormwater, creating conditions for fecal contamination and the selection of antibiotic-resistant bacteria. Objectives: We performed a seasonal assessment of microbial indicators, antibiotic resistance, and heavy metal tolerance in water, sediment, and edible fish in Jansen Lagoon (São Luís, Brazil) to examine environmental health risks and potential co-selection drivers. Methods: During five campaigns in 2018 (rainy: February–April; dry: July– November), we sampled surface water (n = 25), surface sediment (n = 15) and fish (n = 10) at five sites. Thermotolerant coliforms and Pseudomonas spp. were enumerated by MPN; presumptive Clostridium perfringens was detected on SPS agar under anaerobiosis; and Enterobacterales were identified by biochemical tests (conventional + Bactray). Disk diffusion susceptibility to cephalothin, tetracycline, chloramphenicol, gentamicin, penicillin G and sulfamethoxazole–trimethoprim followed the CLSI criteria. Basic physicochemical parameters were measured in situ. Results: Physicochemical parameters exhibited seasonal variability, notably with increased median TDS during the rainy season, while pH remained alkaline (8.4–8.7). The number of thermotolerant coliforms was highest in the water samples collected during the rainy season (up to 1,600 MPN/100 mL), whereas the sediment samples presented consistently higher counts than did the water and fish samples collected during the dry season. We isolated 130 gram-negative strains (19 species), with Escherichia coli prevailing across matrices. Enterobacterales displayed high resistance to cephalothin (70%) and tetracycline (41%) and high susceptibility to chloramphenicol (91%); five species met the MDR criteria. Pseudomonas spp. counts were generally greater in fish (often 2,400 MPN/25 g) and were mostly susceptible to gentamicin (92.5%). Presumptive C. perfringens occurred only in the dry season in the water and sediment. Regarding heavy metals, nearly all isolates tolerated lead (Pb) at high concentrations (3500 ppm), while copper (Cu) tolerance was widespread but dose-dependent. Conclusions: Jansen Lagoon exhibits recurrent fecal contamination and relevant levels of antibiotic resistance in gram-negative bacteria across compartments, with season-dependent patterns. Enhanced monitoring and mitigation of sewage inputs are warranted to reduce human exposure risks in an urban One Health context.