Carrier flies of multidrug-resistant Escherichia coli as potential dissemination agent in dairy farm environment

• Author(s): Alves, Taila Dos Santos ; Lara, Gustavo Henrique Batista ; Maluta, Renato Pariz ; Ribeiro, Márcio Garcia ; Leite, Domingos da Silva
• Date: 2018
• Persistent ID: http://hdl.handle.net/11449/177163
• Origin: Oasisbr
• Subject(s): Antibiotic resistance; Commensal E. coli; dfrA7; Integron; Mechanical vector; Public health
• Document Type: Journal article
• Language: English

Description

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The life cycle of synanthropic flies and their behavior, allows them to serve as mechanical vectors of several pathogens. Given that flies can carry multidrug-resistant (MDR) bacteria, this study aimed to investigate the spread of genes of antimicrobial resistance in Escherichia coli isolated from flies collected in two dairy farms in Brazil. Besides antimicrobial resistance determinants, the presence of virulence genes related to bovine colibacillosis was also assessed. Of 94 flies collected, Musca domestica was the most frequently found in the two farms. We isolated 198 E. coli strains (farm A=135 and farm B=63), and >30% were MDR E. coli. We found an association between blaTEM and phenotypical resistance to ampicillin, or chloramphenicol, or tetracycline; and blaCTX-M and resistance to cefoperazone. A high frequency (86%) of phylogenetic group B1 among MDR strains and the lack of association between multidrug resistance and virulence factors suggest that antimicrobial resistance possibly is associated with the commensal bacteria. Clonal relatedness of MDR E. coli performed by Pulsed-Field Gel Electrophoresis showed wide genomic diversity. Different flies can carry clones, but with distinct antimicrobial resistance pattern. Sanger sequencing showed that the same class 1 integron arrangement is displayed by apparently unrelated strains, carried by different flies. Our conjugation results indicate class 1 integron transfer associated with tetracycline resistance. We report for the first time, in Brazil, that MDR E. coli is carried by flies in the milking environment. Therefore, flies can act as carriers for MDR strains and contribute to dissemination routes of antimicrobial resistance.

Departamento de Genética, Evolução, Microbiologia e Imunologia, Instituto de Biologia, Universidade Estadual de Campinas - UNICAMP, Postal address 6109, CEP 13083-862 Campinas, São Paulo, Brazil

Departamento de Higiene Veterinária e Saúde Pública, Faculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista - UNESP, Postal address 560, CEP 18618-681 Botucatu, São Paulo, Brazil

Departamento de Genética, Evolução, Microbiologia e Imunologia, Instituto de Biologia, Universidade Estadual de Campinas - UNICAMP, Postal address 6109, CEP 13083-862 Campinas, São Paulo, Brazil. Electronic address: [e-mail]