title: Identification of antibiotic-resistant Escherichia coli isolated from a municipal wastewater treatment plant.
abstract: The emergence and diffusion of antibiotic-resistant bacteria has been a major public health problem for many years now. In this study, antibiotic-resistance of coliforms and Escherichia coli were investigated after their isolation from samples collected in a municipal wastewater treatment plant in the Milan area (Italy) along different points of the treatment sequence: inflow to biological treatment; outflow from biological treatment following rapid sand filtration; and outflow from peracetic acid disinfection. The presence of E. coli that showed resistance to ampicillin (AMP) and chloramphenicol (CAF), used as representative antibiotics for the efficacy against Gram-positive and Gram-negative bacteria, was evaluated. After determining E. coli survival using increasing AMP and CAF concentrations, specific single-resistant (AMPRor CAFR) and double-resistant (AMPR/CAFR) strains were identified among E. coli colonies, through amplification of the β-lactamase Tem-1 (bla) and acetyl-transferase catA1 (cat) gene sequences. While a limited number of CAFRbacteria was observed, most AMPRcolonies showed the specific resistance genes to both antibiotics, which was mainly due to the presence of the bla gene sequence. The peracetic acid, used as disinfection agent, showed to be very effective in reducing bacteria at the negligible levels of less than 10 CFU/100 mL, compatible with those admitted for the irrigation use of treated waters.
authors.affiliation: Department of Medical Biotechnologies and Translational Medicine, University of Milan, Via Vanvitelli, 32, 20129, Milan, Italy. Electronic address: carlo.zanotto@unimi.it.
authors.forename: Carlo
authors.initials: C
authors.lastname: Zanotto
authors.affiliation: Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti, 9, 20133, Milan, Italy. Electronic address: massimiliano.bissa@nih.gov.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Bissa
authors.affiliation: Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti, 9, 20133, Milan, Italy. Electronic address: elena.illiano@unimi.it.
authors.forename: Elena
authors.initials: E
authors.lastname: Illiano
authors.affiliation: Department of Earth and Environmental Sciences (DISAT), University of Milan Bicocca, Piazza della Scienza 1, 20126, Milan, Italy. Electronic address: valeria.mezzanotte@unimib.it.
authors.forename: Valeria
authors.initials: V
authors.lastname: Mezzanotte
authors.affiliation: Department of Earth and Environmental Sciences (DISAT), University of Milan Bicocca, Piazza della Scienza 1, 20126, Milan, Italy. Electronic address: francesca.marazzi@unimib.it.
authors.forename: Francesca
authors.initials: F
authors.lastname: Marazzi
authors.affiliation: Politecnico di Milano, Department of Civil and Environmental Engineering (DICA), Environmental Section, Piazza Leonardo da Vinci 32, 20133 Milano, Italy. Electronic address: andrea.turolla@polimi.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Turolla
authors.affiliation: Politecnico di Milano, Department of Civil and Environmental Engineering (DICA), Environmental Section, Piazza Leonardo da Vinci 32, 20133 Milano, Italy. Electronic address: manuela.antonelli@polimi.it.
authors.forename: Manuela
authors.initials: M
authors.lastname: Antonelli
authors.affiliation: Catholic University "Our Lady of Good Counsel", Rr. Dritan Hoxha, Tirana, Albania. Electronic address: carlo.degiulimorghen@unimi.it.
authors.forename: Carlo
authors.initials: C
authors.lastname: De Giuli Morghen
authors.affiliation: Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti, 9, 20133, Milan, Italy; Cellular and Molecular Pharmacology Section, National Research Council (CNR) Institute of Neurosciences, University of Milan, Via Vanvitelli, 32, 20129, Milan, Italy. Electronic address: antonia.radaelli@unimi.it.
authors.forename: Antonia
authors.initials: A
authors.lastname: Radaelli
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis* / Q000633:toxicity; D004352:Drug Resistance, Microbial / Q000187:drug effects* / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D006090:Gram-Negative Bacteria / Q000187:drug effects; D007558:Italy; D008826:Microbial Sensitivity Tests; D062065:Wastewater / Q000737:chemistry / Q000382:microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity; D018508:Water Purification / Q000379:methods*; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D062065:Wastewater; D014874:Water Pollutants, Chemical; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1
keywords: Antibiotic resistance; Escherichia coli; WWTPs; bla and cat genes