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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #102649
Title: IDENTIFICATION OF DIMINISHED TISSUE CULTURE INVASIVENESS AMONG MULTIPLE ANTIBIOTIC RESISTANT SALMONELLA TYPHIMURIUM DT104

Author
item Carlson, Steven
item BROWNING, M - UNIVERSITY OF IOWA
item FERRIS, K - USDA, APHIS, NVSL, DBL
item JONES, B - UNIVERSITY OF IOWA

Submitted to: Microbial Pathogenesis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Salmonella infections continue to cause gastrointestinal and systemic disease throughout the world. Salmonella typhimurium, a specific "subtype" of Salmonella, further poses a major health concern due to its apparent enhanced ability to exhibit resistance to multiple antibiotics. Currently it is unclear if multiresistant Salmonella typhimurium are more or less able to cause disease than nonresistant counterparts. Using an assay that measures the ability of Salmonella typhimurium to cause disease by infecting intestinal cells, we evaluated this characteristic in over 400 multiresistant Salmonella typhimurium isolates. Our studies identified 12 isolates exhibiting a diminished ability to cause disease relative to controls. These 12 "hypoinfective" strains were found in a variety of Salmonella typhimurium subgroups all possessing a specific antibiotic resistance profile. Further studies revealed that the decreased ability to cause disease was not due to changes in the ability to attach to intestinal cells. Studies exploring animal models of Salmonella typhimurium-induced disease revealed that a representative "hypoinfective" strain had a decreased ability to cause lethality. These results indicate that the quantitative ability to cause disease is attenuated for certain isolates of multiresistant Salmonella typhimurium.

Technical Abstract: Salmonella infections continue to cause gastrointestinal and systemic disease throughout the world. Salmonella typhimurium further poses a major health concern due to its apparent enhanced ability to acquire multiple antibiotic resistance genes. Currently it is unclear if multiresistant S. typhimurium are more or less pathogenic than nonresistant counterparts. Using an in vitro invasion assay, we evaluated the pathogenicity of over 400 multiresistant S. typhimurium isolates. Our studies failed to identify any "hyperinvasive" isolates. However, we identified 12 isolates exhibiting invasive phenotypes that were constrained relative to controls. These "hypoinvasive" strains were found in a variety of phage types all possessing at least a hexaresistant profile. Further studies revealed that the alterations in invasion were not due to changes in adherence. Studies exploring in vivo virulence revealed a decreased ability to cause lethality for the hypoinvasive strain examined. These results indicate that the quantitative ability to cause disease is not increased but rather is mildly attenuated for certain isolates of multiresistant S. typhimurium.