Browsing by Author "Duarte, Isabel M."
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- Antibiotic resistance in wastewater: Occurrence and fate ofEnterobacteriaceaeproducers of Class A and Class C β-lactamasesPublication . Amador, Paula P.; Fernandes, Rúben; Prudêncio, Cristina; Barreto, Mário P.; Duarte, Isabel M.Antibiotics have been intensively used over the last decades in human and animal therapy and livestock, resulting in serious environmental and public health problems, namely due to the antibiotic residues concentration in wastewaters and to the development of antibiotic-resistant bacteria. This study aimed to access the contribution of some anthropological activities, namely urban household, hospital and a wastewater treatment plant, to the spread of antibiotic resistances in the treated wastewater released into the Mondego River, Coimbra, Portugal. Six sampling sites were selected in the wastewater network and in the river. The ampicillin-resistant Enterobacteriaceae of the water samples were enumerated, isolated and phenotypically characterized in relation to their resistance profile to 13 antibiotics. Some isolates were identified into species level and investigated for the presence of class A and class C -lactamases. Results revealed high frequency of resistance to the -lactam group, cefoxitin (53.5%), amoxicillin/clavulanic acid combination (43.5%), cefotaxime (22.7%), aztreonam (21.3) cefpirome (19.2%), ceftazidime (16.2%) and to the non--lactam group, trimethoprim/sulfamethoxazol (21.1%), tetracycline (18.2%), followed by ciprofloxacin (14.1%). The hospital effluent showed the higher rates of resistance to all antibiotic, except two (chloramphenicol and gentamicin). Similarly, higher resistance rates were detected in the wastewater treatment plant (WWTP) effluent compared with the untreated affluent. Regarding the multidrug resistance, the highest incidence was recorded in the hospital sewage and the lowest in the urban waste. The majority of the isolates altogether are potentially extended-spectrum -lactamases positive (ESBL(+)) (51.9%), followed by AmpC(+) (44.4%) and ESBL(+)/AmpC(+) (35.2%). The most prevalent genes among the potential ESBL producers were blaOXA (33.3%), blaTEM (24.1%) and blaCTX-M (5.6%) and among the AmpC producers were blaEBC (38.9%), blaFOX (1.9%) and blaCIT (1.9%). In conclusion, the hospital and the WWTP activities revealed to have the highest contribution to the spread of multidrug resistant bacteria in the study area. Such data is important for future management of the environmental and public health risk of these contaminants. This is the first embracing study in the water network of Coimbra region on the dissemination of antibiotic resistance determinants. Moreover, it is also the first report with the simultaneous detection of multiresistant bacteria producers of AmpC and ESBLs -lactamases in aquatic systems in Portugal.
- Characterization of antibiotic resistance in enterobacteriaceae from agricultural manure and soil in PortugalPublication . Amador, Paula; Duarte, Isabel M.; Costa, R.P. Roberto da; Fernandes, Rúben; Prudêncio, CristinaIntensive livestock production uses antibiotics to treat and prevent infectious diseases. Antibiotics are expelled unaltered in animal manure, which is often used as a fertilizer. This practice spreads antibiotic residues and antibiotic-resistant bacteria and their genes into the soil. These resistance determinants affect soil microbial communities, raising concerns about the potential environmental and public health risks. This study aims to characterize soil contaminated with antibiotic resistant bacteria and the putative role played by manure as a vector for these resistance determinants. Six poultry and dairy cattle farms in the central region of Portugal were sampled. Ampicillin-resistant Enterobacteriaceae isolates from manure and manured-soil samples were tested for their resistance profile to 13 antibiotics and the presence of tetracycline and sulfonamide resistance genes. High multidrug resistance rates (>70%) were observed in both manure and soil samples. This resistance was higher in the poultry samples; manured-soil isolates were more resistant to cefoxitin (91.7%), sulfamethoxazole/trimethoprim (79.2%), chloramphenicol (79.2%), and to a lesser extent tetracycline (12.5%). Manure isolates have high resistance frequency to tetracycline (73.9%), amoxicillin with clavulanic acid (66.0%), chloramphenicol (65.3%), and sulfamethoxazole with trimethoprim (36.5%). Manure isolates revealed high frequency of tet(A), sul1, and sul3 genes. The multiple antibiotic resistance index reveals a putative risk of soil contamination due to antibiotic exposure. The results obtained are important for soil management regarding resistance determinants spread through agricultural practices. To our knowledge, this is the first study of tetracycline and sulfonamide resistance in Portuguese manure and soil.