Dissertation Defense Announcement

School of Public Health announces the Final Dissertation Defense of

Nabanita Mukherjee

for the Degree of Doctor of Philosophy

November 1, 2018 at 10:00 AM in Robison Hall, Room 235

Advisor: Dr. Pratik Banerjee

Source Attribution, Antibiotic Resistance and Virulence Properties of Salmonella Serotypes Isolated from Clinically Diagnosed Human Salmonellosis Cases from Tennessee

ABSTRACT: Non-typhoidal Salmonella (NTS) infection is one of the major causes of diarrheal disease throughout the world. Recently, an increase in the trend of human S. Newport, S. Javiana, and S. Mississippi infection has been observed in TN. The sources of human S. Javiana infection were underwhelmingly reported in the literature. The current study performed a systematic literature review to identify the potential sources of human S. Javiana infection based on available scientific evidence. This systematic review identified the food (such as tomatoes, watermelons, paprika-spice, and cheese), drinking well water, as well as non-foodborne (such as animal contact) exposures are associated with human S. Javiana infection. The current study explored the potential risk factors associated with any of the above mentioned three Salmonella serotypes. A total of 2,757 culture-confirmed salmonellosis cases were included in this analysis. A case-case analysis was performed to identify the potential risk factors for human NTS infections caused by any of the three serotypes. This study identified the risk factors associated with the cases: recreational water [ORadjusted = 1.7 (95% CI 0.9, 3.0) P= 0.08], contact with dog [ORadjusted= 1.6 (95% CI 0.9, 2.7) P= 0.09], exposure with pet treats/chews [ORadjusted = 3.0 (95% CI 1.6, 5.5) P= 0.0005], visit to a farm [ORadjusted = 2.3 (95% CI 0.9, 6.0) P= 0.08], consumption of ice cream [ORadjusted = 1.5 (95% CI 0.9, 2.4) P= 0.10], and consumption of frozen pizza [ORadjusted = 1.5 (95% CI 0.9, 2.5) P= 0.11]. This study also demonstrated that the Salmonella serotypes, tested harbors antibiotic resistance characteristics as well as several virulence genes. In addition to this, the current study identified the association between antibiotic resistance and virulence genes of Salmonella isolates. The virulence gene, ssaQ, was observed to be significantly associated with antibiotic-resistant characteristics of Salmonella [χ2 (df=1) = 12.16, PŠidák adjusted = 0.019]. Further investigation with large sample size is needed to better understand this association. To conclude, this study points out the need for routine surveillance of human NTS infections as well as increased public awareness and practice of hand hygiene to prevent the occurrence of the infection.