Avaliação da ocorrência de bactérias resistentes a antibióticos no sistema de drenagem urbana na cidade de Maputo - bacia do Rio Infulene

Abstract

The degradation of water quality in urban centers, due to poor sanitation and the discharge of untreated effluents, constitutes a serious environmental problem, exacerbated by the growing spread of antibiotic-resistant bacteria (ARB). In Mozambique, this issue is intensified by urbanization and the expansion of informal settlements, which lack or have inadequate sanitation systems, increasing the direct discharge of effluents into water bodies. This study assessed the physicochemical and microbiological quality, including ARB, of the urban drainage system, System 3, in the Infulene River Basin, Maputo, characterized by direct effluent discharge in areas with informal settlements. Two sampling campaigns were conducted—during the dry and wet seasons—at 12 points, analyzing physicochemical parameters, indicators of fecal contamination, and Escherichia coli producing extended-spectrum β-lactamases (ESBL). Results revealed that although temperature and pH were within acceptable limits, water quality was compromised by other parameters, with high nutrient levels— phosphates exceeding 44 mg/L and nitrates reaching up to 99 mg/L in Mafalala—and BOD surpassing 73 mg/L and COD reaching 128.9 mg/L in Xipamanine. From a microbiological perspective, the dry season showed total coliforms up to 6.8×10⁸ MPN/100 mL and fecal coliforms up to 1.6×10⁷ MPN/100 mL, extremely high in Mafalala, with all points exceeding the irrigation limit for E. coli. In the wet season, detection of ESBL-producing E. coli reached up to 300,000 CFU/mL and was significant in several neighborhoods, including Mafalala, Maxaquene, and Munhuana. The presence of these ARB in irrigation points raises serious public health concerns. In summary, the drainage system under study constitutes a hotspot of urban pollution, directly contributing to the environmental degradation of the Infulene River Basin and the spread of resistant microorganisms, with serious implications for human health.