Title : Food microbes influenced horizontal transfer of ?-lactam resistance genes in the mouse gut

Abstract:

Ingestion of antibiotic-resistant (AR) bacteria may lead to transmission of AR genes in the gut microbiota and cause AR bacterial infection, a significant public health concern. However, it is not clear if and how microbes from the food matrix (food microbes) may influence resistance transmission. Thus, we assessed the colonization of a β-lactam resistant Salmonella Heidelberg strain (donor) and a β-lactam susceptible S.

Typhimurium strain (recipient) and the transfer of the resistance genes in the mouse gut in the presence or absence of food microbes that were derived from washing freshly-harvested carrots. Mice were pre-treated with streptomycin and then inoculated with both donor and recipient bacteria in the presence or absence of food microbes. Donor, recipient and potential transconjugant bacteria were enumerated in fecal samples using selective culture techniques.

Transfer of AR genes was confirmed by whole genome sequencing. Gut microbial composition was determined by 16s rRNA amplicon sequencing. Significantly lower numbers of donor and recipient were shed from mice that were inoculated with food microbes compared to those without food microbe inoculation. S. Typhimurium transconjugants were only recovered from mice without inoculation of food microbes. However, non-Salmonella transconjugatns, including Escherichia coli, Enterobacter, Citrobacter and Proteus were detected from mice with inoculation of food microbes. The results suggest that the food microbes may modulate AR gene transfer through changing the gut microbiome compositions.

Biography:

Jiewen Guan received her Bachelor (1994) and Master (1997) degree in Biochemical Engineering, in the South China University of Technology in Guangdong, China, and her PhD (2002) in Food Microbiology, in the University of Massachusetts – Amherst in Massachusetts, the United States of America. She joined the Canadian Food Inspection Agency (CFIA) in 2002 and since then she has been working as a research scientist in the CFIA at the Ottawa Laboratory (Fallowfield) in Ottawa, Canada. Her early career focused on safe disposal of animal carcasses and disinfection of animal premises for control of infectious animal disease outbreaks. Later on, she developed research interest in airborne transmission of avian influenza viruses. More recently, her research interest expands to understanding the mechanisms of horizontal transfer of antimicrobial resistance in the gut microbiome.