Browsing by Author "Hamner, Steve"

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Bile Salts Affect Expression of Escherichia coli O157:H7 Genes for Virulence and IronAcquisition, and Promote Growth under Iron Limiting Conditions
(2013-09) Hamner, Steve; McInnerney, Kathleen; Williamson, Kerry S.; Franklin, Michael J.; Ford, Tim E.
Bile salts exhibit potent antibacterial properties, acting as detergents to disrupt cell membranes and as DNA-damaging agents. Although bacteria inhabiting the intestinal tract are able to resist bile’s antimicrobial effects, relatively little is known about how bile influences virulence of enteric pathogens. Escherichia coli O157:H7 is an important pathogen of humans, capable of causing severe diarrhea and more serious sequelae. In this study, the transcriptome response of E. coli O157:H7 to bile was determined. Bile exposure induced significant changes in mRNA levels of genes related to virulence potential, including a reduction of mRNA for the 41 genes making up the locus of enterocyte effacement (LEE) pathogenicity island. Bile treatment had an unusual effect on mRNA levels for the entire flagella-chemotaxis regulon, resulting in two- to four-fold increases in mRNA levels for genes associated with the flagella hook-basal body structure, but a two-fold decrease for “late” flagella genes associated with the flagella filament, stator motor, and chemotaxis. Bile salts also caused increased mRNA levels for seventeen genes associated with iron scavenging and metabolism, and counteracted the inhibitory effect of the iron chelating agent 2,2’-dipyridyl on growth of E. coli O157:H7. These findings suggest that E. coli O157:H7 may use bile as an environmental signal to adapt to changing conditions associated with the small intestine, including adaptation to an iron-scarce environment.
Community-based participatory research in Indian country: Improving health through water quality research and awareness
(2010-07) Cummins, C.; Doyle, John T.; Kindness, L.; Lefthand, M. J.; Bear Don't Walk, U. J.; Bends, Ada L.; Broadaway, Susan C.; Camper, Anne K.; Fitch, R.; Ford, Tim E.; Hamner, Steve; Morrison, A. R.; Richards, Crystal L.; Young, Sara L.; Eggers, Margaret J.
Water has always been held in high respect by the Apsaalooke (Crow) people of Montana. Tribal members questioned the health of the rivers and well water because of visible water quality deterioration and potential connections to illnesses in the community. Community members initiated collaboration among local organizations, the tribe, and academic partners, resulting in genuine community-based participatory research. The article shares what we have learned as tribal members and researchers about working together to examine surface and groundwater contaminants, assess routes of exposure, and use our data to bring about improved health of our people and our waters.
Detection and source tracking of Escherichia coli, harboring intimin and Shiga toxin genes, isolated from the Little Bighorn River, Montana
(2014-09) Hamner, Steve; Broadaway, Susan C.; Berg, Ethan; Stettner, Sean; Pyle, Barry H.; Big Man, N.; Old Elk, J.; Eggers, Margaret J.; Doyle, John T.; Kindness, L.; Good Luck, B.; Ford, Tim E.; Camper, Anne K.
The Little Bighorn River flows through the Crow Indian Reservation in Montana. In 2008, Escherichia coli concentrations as high as 7,179 MPN/100 ml were detected in the river at the Crow Agency Water Treatment Plant intake site. During 2008, 2009, and 2012, 10 different serotypes of E. coli, including O157:H7, harboring both intimin and Shiga toxin genes were isolated from a popular swim site of the Little Bighorn River in Crow Agency. As part of a microbial source tracking study, E. coli strains were isolated from river samples as well as from manure collected from a large cattle feeding operation in the upper Little Bighorn River watershed; 23% of 167 isolates of E. coli obtained from the manure tested positive for the intimin gene. Among these manure isolates, 19 were identified as O156:H8, matching the serotype of an isolate collected from a river sampling site close to the cattle feeding area.
Expression of ras and metastatic behavior in panel of cell lines derived from infection of NIH 3T3 cells with Kirsten murine sarcoma virus
(Montana State University - Bozeman, College of Agriculture, 1991) Hamner, Steve
Isolation of potentially pathogenic Escherichia coli O157:h7 from the Ganges River
(2007-02) Hamner, Steve; Broadaway, Susan C.; Mishra, Veer B.; Tripathi, Anshuman; Mishra, Rajesh K.; Pulcini, Elinor D.; Pyle, Barry H.; Ford, Tim E.
Escherichia coli serotype O157:H7 was detected among bacteria collected from the Ganges River. O157:H7 isolates tested positive for stx1, stx2, and eae gene sequences. Identification of potentially pathogenic isolates from extensively used source water indicates that O157:H7 may be a significant but as yet underacknowledged public health concern in India.
Metagenomic Profiling of Microbial Pathogens in the Little Bighorn River, Montana
(2019-03) Hamner, Steve; Brown, Bonnie L.; Hasan, Nur A.; Franklin, Michael J.; Doyle, John T.; Eggers, Margaret J.; Colwell, Rita R.; Ford, Tim E.
The Little Bighorn River is the primary source of water for water treatment plants serving the local Crow Agency population, and has special significance in the spiritual and ceremonial life of the Crow tribe. Unfortunately, the watershed suffers from impaired water quality, with high counts of fecal coliform bacteria routinely measured during run-off events. A metagenomic analysis was carried out to identify potential pathogens in the river water. The Oxford Nanopore MinION platform was used to sequence DNA in near real time to identify both uncultured and a coliform-enriched culture of microbes collected from a popular summer swimming area of the Little Bighorn River. Sequences were analyzed using CosmosID bioinformatics and, in agreement with previous studies, enterohemorrhagic and enteropathogenic Escherichia coli and other E. coli pathotypes were identified. Noteworthy was detection and identification of enteroaggregative E. coli O104:H4 and Vibrio cholerae serotype O1 El Tor, however, cholera toxin genes were not identified. Other pathogenic microbes, as well as virulence genes and antimicrobial resistance markers, were also identified and characterized by metagenomic analyses. It is concluded that metagenomics provides a useful and potentially routine tool for identifying in an in-depth manner microbial contamination of waterways and, thereby, protecting public health.
Microbial Source Tracking of Escherichia coli in the Little Big Horn River, Montana
(2013-03) Berg, Ethan; Stettner, Sean; Hamner, Steve
The method of microbial source tracking was used to determine the source of the gram-negative bacterium Escherichia coli. When E. coli is isolated from a water source, it indicates a possible public health risk due to fecal contamination of the water. Knowing the source of the E. coli can aid in elimination of the contamination. This project was a continuation of an ongoing project that examined E. coli isolates from various cattle ranches at various points along the Little Big Horn River and its tributaries in southeast Montana. This experiment used polymerase chain reaction (PCR) coupled with gel electrophoresis to create a database of DNA fingerprints. Multiple primers were to be used originally, however the BOXA1R and (GTG)5 primers displayed far too complex fingerprints for accurate analysis, therefore the ERIC primer set was used as a basis for creating the fingerprint database. That database was created using the GelCompar II software by Applied Maths. Using this software, all fingerprints were compared using a similarity matrix to create a list of possible matches of E. coli obtained from the various ranches, the river, and its tributaries. Preliminary results suggest possible matches between some of the manure lots on the largest ranch and various drainage sites into the river. Current work is being done using the BOXA1R and (GTG)5 primers to confirm validity of the matches found by the ERIC primer set.