EPIDEMIOLOGICAL AND GENETIC CHARACTERIZATION OF MULTIDRUG-RESISTANT SALMONELLA IN THE POULTRY AND THE CLINICAL SECTORS IN ISRAEL
2Government Central Laboratories, Ministry of Health, Jerusalem, Israel
3Department of Clinical Microbiology and Immunology, Tel Aviv University, Tel Aviv, Israel
4Sackler Faculty of Medicine,, Tel Aviv University, Tel Aviv, Israel
Salmonella enterica is a foodborne, zoonotic bacterial pathogen and one of the major causes of gastroenteritis in the world.
Here we analyzed the epidemiology of leading Salmonella enterica serovars associated with the poultry and the clinical sectors in Israel, between the years 2010 and 2017.
We show that 75% and 77% of all Salmonella isolates of the poultry and clinical sector, respectively, belong to only 10 Salmonella enterica serovars (Infantis, Enteritidis, Kentucky, Muenchen, Typhimurium, Hadar, Bredeney, Newport, Java, and Montevideo). Trends in the occurrence of 5/10 serovars (Infantis, Enteritidis, Kentucky, Muenchen, and Newport) in the poultry sector are well correlated with their occurrence in the clinical sector, suggesting a significant contribution of the poultry industry to salmonellosis caused by these serovars. Worrisomely, the vast majority of serovars Kentucky, Infantis and Java were multidrug resistant (MDR).
The whole genomes of 19 MDR isolates from the poultry sector, from 6 different serovars (Blockley, Hadar, Java, Kentucky, Muenchen, Orion), were sequenced and de-novo assembled. Nine out of ten Kentucky isolates have shown the acquisition of SGI1 (Salmonella genomic island; providing resistance to aminoglycosides, beta-lactams, tetracycline and mercury). Two out of two sequenced isolates of serovar Blockley showed integration of the azithromycin island (providing resistance to aminoglycosides, tetracycline and macrolides). In addition to these genomic islands, 11/19 isolates were found to contain plasmids of various sizes (4-245 kb) that encode antibiotic resistance genes. At least three of these plasmids are conjugative and were mobilized into E. coli recipient cells with a frequency of about 0.01conjugation events/ donor.
Our study shows a strong correlation between the epidemiology of dominant Salmonella serovars in the poultry and the clinical sectors in Israel, highlights the prevalence of MDR strains among agricultural isolates and demonstrates the role of important mobile genetic elements in this phenotype.
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