Investigação da resistência antimicrobiana em esgoto sanitário e efluente de lagoas de estabilização na região de Belo Horizonte/MG, durante a pandemia da COVID-19

Abstract

Antimicrobial resistance (AR) is one of the main global challenges in public health, and the Wastewater treatment plants (WWTPs) plays a crucial role in the removal, selection and dissemination of antibiotic resistant bacteria (ARBs) and antibiotic resistance genes (ARGs). This study aimed to investigate the occurrence of ARBs and ARGs in the inffluent of three WWTPs in the region of Belo Horizonte during the COVID-19 pandemic, evaluating the impact of pandemic on the increase and dissemination of AR, compared to values reported in prior research and literature. The removal efficiency of ARBs and ARGs was analyzed in an facultative pont system, followed by maturation pond (WWTP 3). Thus, weekly samples of inffluent of three WWTPs, as well as effluent samples of theWWTP 3, during October/2021 and June/2022 were collected. For microbiological and molecular analyzes, the quantification and isolation of total heterotrophic bacteria (THBs) and cultivable ARBs without and with the addition of antibiotics, and some colonies identified by the Maldi-toof technique. Of these, selected strains were characterized as susceptibility and resistance to various antibiotics, in order to determine the multidrug-resistant (MDR) bacterias. The resistance genes sul1, ermB, qnrB, blaTEM, tetA, class 1 integron (int1) e RNAr 16S gene were quantified with Polimerase Chain Reaction in real-time (qPCR). The results showed similar concentrations of THBs and ARBs in the three ETES, except for bacteria resistant to amoxicillin and Meropenem, which presented significant differences. As for ARGs, significant differences were observed between WWTPs, with greater absolute abundances in the specific investigated (WWTP 3). The facultative pond treatment system followed by maturation pond presented removal of ARBs and ARGs, with average reductions of 1.2 to 2.6 log units and average removal values from 0.7 to 3.1 log, respectively. However, the effluent still had considerable levels of ARGs (about 10³ copies/mL). Among the resistant bacteria identified, genres belonging to the list of six priority pathogens defined by the World Health Organization (WHO), both in inffluent (such as Klebsiella pneumoniae, and Staphylococcus, Enterobacter and Acinetobacter) as well as in the effluent (Enterobacter cloacae and Enterobacter asburiae), with multi-resistant phenotype. By comparing the results with previous studies in the metropolitan region of Belo Horizonte/MG, there was an increase in THBs concentrations (0.9 to 1.2 units log), some ARBs (resistant to amoxicilin and sulfamethoxazole and trimethoprim, about 1,0 and 0.7 log higher) and ARGs (ermB and qnrB, about 2.0 and 1.0 log) during the pandemic, suggesting the impact of COVID-19 in the increase of circulation and spread of these agents on sewage. The treatment system used has demonstrated efficiency in reducing these agents, although additional strategies are required to ensure more complete removal. These results contribute to the knowledge of the dissemination of bras and gras in sewage treatment systems and can assist in the implementation of AR control and prevention measures.