Characterization of Salmonella isolates from municipal sewage, patients, foods, and animals in Greece using antimicrobial susceptibility testing and pulsed field gel electrophoresis

Research Article

International Journal of One Health, 2: 12-18

https://doi.org/10.14202/IJOH.2016.12-18

Theofilos Papadopoulos^1,2, Antonios Zdragas², Georgia Mandilara¹, Georgios Vafeas², Virginia Giantzi², Evanthia Petridou³, and Alkiviadis Vatopoulos¹

1. National Reference Centre for Salmonella, National School of Public Health & Central Public Health Laboratory, Hellenic Centre of Disease Control and Prevention, 16672 Vari, Greece.
2. Laboratory of Bacterial Diseases, Veterinary Research Institute, National Agricultural Foundation, NAGREF Campus, 57001 Thermi, Greece.
3. Laboratory of Microbiology, School of Veterinary Medicine, Aristotle University, University Campus, 54124 Thessaloniki, Greece.

Background and Aim: We aimed to compare Salmonella isolates from different sources using molecular and phenotypic methods, targeting better possibility of understanding the epidemiology of this organism in the Greek context with emphasis in municipal wastewater.

Materials and Methods: In this study, we used pulsed field gel electrophoresis (PFGE) in combination with antimicrobial susceptibility testing to analyze a total of 88 Salmonella Enterica isolates from municipal sewage (n=25), humans (n=36), animals (n=24), and foods (n=3) in Greece.

Results: The higher resistance rates were found to the following antimicrobials: streptomycin (59.1%), tetracycline (47.7%), nalidixic acid (46.6%), ampicillin (37.5%), and oxolinic acid (35.2%). Resistance to ciprofloxacin was not observed; 22 isolates (25%) were sensitive to all 9 antimicrobials, 36%, 25% and 12% of human, animal and wastewater origin, respectively, showing a significant difference. Salmonella ser. Hadar was the serovar with the highest resistance rates followed by Salmonella ser. Anatum and Salmonella ser. Typhimurium; Salmonella ser. Infantis strains were almost pansusceptible. Cluster analysis did not reveal close genetic relationship between human animal food and wastewater strains belonging to the same serovars. In most of the cases, distinct clusters were observed between human and non-human isolates indicating diversity and no epidemiological connection.

Conclusion: This study indicates that municipal wastewater would be of interest to further monitor the community's prevalence of subclinical or non-reported S. Enterica infections. Keywords: Salmonella, wastewater, sewage, PFGE, antimicrobial resistance.

Keywords: Salmonella, wastewater, sewage, PFGE, antimicrobial resistance.

How to cite this article: Papadopoulos T, Zdragas A, Mandilara G, Vafeas G, Giantzi V, Petridou E, Vatopoulos A. Characterization of Salmonella isolates from municipal sewage, patients, foods, and animals in Greece using antimicrobial susceptibility testing and pulsed field gel electrophoresis. Int J One Health 2016;2: 12-18.

Received: 26-12-2015 Accepted: 18-02-2016 Published online: 24-03-2016

Corresponding author: Theofilos Papadopoulos E-mail: theofilos23@vet.auth.gr

DOI: 10.14202/IJOH.2016.12-18

Copyright: Papadopoulos, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.