Antibiotic resistance in wastewater
Year: 2020
Type: dissertation
Abstract: Antibiotic resistance is a characteristic possessed by some bacteria that enables them to\nwithstand the effects of antibiotic treatment. Antibiotic use and abuse may result in\ndevelopment of antibiotic resistant bacteria. After an antibiotic treatment, antibiotics are\npartially excreted in urine and feces, and wastewater is therefore an important source of\nboth bacteria and antibiotics from healthy and sick individuals. Due to the close contact\nbetween large numbers of bacteria and diverse types of antibiotics over prolonged\nperiods, wastewater has the potential to select for and disseminate antibiotic resistance\ninto the environment. Previous studies of hospital wastewater effluents have shown that\nthese outlets discharge more antibiotic resistance factors than the general population.\n\nThis study was initiated to map the occurrence of antibiotic resistance in wastewater\nunder Norwegian conditions to identify whether local treatment of hospital wastewater\ncould contribute to limit the dissemination of antibiotic resistance to the environment.\nSamples of untreated wastewater were collected monthly during one year from a\nhospital, a community, and from the wastewater treatment plant that treats the\nwastewater from the Greater Oslo region. The samples were analyzed for the occurrence\nof antibiotic resistant E. coli, 53 different antibiotics, heavy metals, and 144 bacterial\ngenes encoding antibiotic resistance and mechanisms for the transfer of these genes\nbetween bacteria.\n\nDuring this study, higher levels of antibiotics and antibiotic resistant bacteria were\nfound in wastewater from the hospital than from the general population. Broad-spectrum\nantibiotics were also present at much higher concentrations in the hospital effluents.\nThese results indicate that local treatment of the hospital wastewater system may help\nlimit the spread of resistance to the environment. A cost-benefit analysis should be\nperformed to determine whether localized hospital wastewater treatment may be more\neffective than large-scale implementation at the wastewater treatment plants.\n\nThis study also identified variants of multi-resistant E. coli producing ESBL-enzymes\nthat can degrade broad-spectrum β-lactam antibiotics in the wastewater from the studied\ncommunity. Some of these bacteria were exclusively and repeatedly found in the\ncommunity wastewater. These belonged to two types of highly infectious E. coli (ST131\nand ST648) that have been found all over the world. The finding of these bacterial\nclones in the community wastewater indicates that the dissemination of multi-resistant\nand pathogenic bacteria through wastewater is not exclusively attributable to hospital\neffluents. Hence, it is recommended to investigate additional as well as other types of\noutlets to identify potential high-risk sources for the spread of antibiotic resistance.\n\nHigh abundances of genes encoding mechanisms for lateral transfer of antibiotic\nresistance were found in this study, as well as clinically relevant antibiotic resistance\ngenes like ndm-1 that have only scarcely been reported in association with clinical\ndisease in Norway. These results thus verified a previous study of wastewater from\nEuropean countries, wherein Norway had the highest levels of lateral transfer genes.\nEven though Norway has a relatively low prevalence of antibiotic resistance and a\nmoderate consumption of antibiotics due to strict regulation, these results indicate the\nunderlying potential for a substantial mobilization and dissemination in the future.\n\nThis study has illuminated important aspects of antibiotic resistance that have\npreviously not been described. The results of this study contribute to a broader\nknowledge base for decision-making regarding wastewater management in Norway and\ninternationally.
Author: Erik Paulshus
Language: English
Subfield: Pollution
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W3042728747