Virulence and antimicrobial resistance genes transfer mechanism between salmonella strains by means of Salmonella genomic island 1


Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Gıda Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2018

Öğrenci: ŞAHİN NAMLI

Danışman: YEŞİM SOYER

Özet:

Salmonella, is responsible for significant part of the food borne diseases around the world and isolated abundantly from the food samples. In recent years, with the increasing trend of multidrug-resistance, Salmonella become an important threat for public health. Drug resistance leads inefficiency of antibiotic treatment and it is seemed as a very important problem worldwide as well for Turkey. Drug resistance acceptance mechanism has not been understood yet especially for Salmonella. Salmonella Genomic Island 1 (SGI1) has known to contribute to the dissemination of drug resistance among Salmonella serovars. Also SGI1 was thought to be an important factor for Salmonella serovar Typhimurium DT104 to become the dominant serovar among foodborne pathogens in recent years, by contributing to the drug resistance and pathogenicity. Salmonella serovar Infantis is an emerging serovar and it has been one of the most prevalent serovar in Turkey and Europe. The isolates belonging to this serovar show high rate of multidrug-resistance. In this study, we investigated multidrug resistant Infantis in the contents of drug resistance and pathogenicity. It was hypothesized that SGI1 might have increased the morbidity and drug resistance of Infantis like it did in the case Typhimurium DT104 in 90’s. To check this hypothesis SGI1 was searched in 70 Infantis isolates with SGI1 specific primers. Intactness of SGI1 was controlled and class 1 integrons were checked. Virulotyping of those isolates were done and compared with Typhimurium DT104 and other Salmonella enterica serovars. Findings showed that the none of the Infantis isolates harbored SGI1 and thus multidrug-resistane of these isolates did not caused by SGI1. However, the streptomycin and spectinomycin resistance of those isolates, most probably, due to the one class 1 integron they carry with an aadA1 gene cassette. Class 1 integrons found in Infantis isolates showed the potential of these strains to get more resistant in time with. The effect of SGI1-possession on virulotypes could not be obtained because all of the Infantis isolates were SGI1-negative. However, virulotypes of Infantis isolates were obtained, they can be used in future studies for strain comparisons. This study helped us to enhance our knowledge about the SGI1-possession, class 1 integron profiles and virulotypes of the Infantis strains isolated in Turkey and will give idea about the transfer mechanism of resistance genes and virulence genes.