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Surveillance for Salmonella subtypes shared by human and bovine hosts Margaret A. Davis, DVM, MPH, PhD

Surveillance for Salmonella subtypes shared by human and bovine hosts Margaret A. Davis, DVM, MPH, PhD. Salmonellosis. Caused by Salmonella enterica infection Illness includes gastroenteritis invasive disease in rare cases Overall incidence in U.S. ~ 15/100,000

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Surveillance for Salmonella subtypes shared by human and bovine hosts Margaret A. Davis, DVM, MPH, PhD

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  1. Surveillance for Salmonella subtypes shared by human and bovine hostsMargaret A. Davis, DVM, MPH, PhD

  2. Salmonellosis • Caused by Salmonella enterica infection • Illness includes gastroenteritis • invasive disease in rare cases • Overall incidence in U.S. ~ 15/100,000 • FoodNet: http://www.cdc.gov/mmwr/preview/mmwrhtml/ • Exposure route • Foodborne • ingestion of contaminated food, water • Environmental exposures • e.g. hand-to-mouth • important in pediatric cases

  3. Jones TF, et al. Pediatrics. 2006 Dec;118(6):2380-7.

  4. Salmonellosis • S. enterica >2,000 serovars • Some serovars are host-specific: • Typhi = human • Dublin = cattle • Gallinarum = poultry • Cholerasuis = swine • Some multiple-host serovars: • Typhimurium • Newport • Enteritidis

  5. Nomenclature Salmonella enterica Typhimurium DT104 Species Genus Serovar Phage type

  6. Methods for studying Salmonella molecular epidemiology • Serotype • Phage type • Antimicrobial resistance • Plasmid profiles • Insertion sequences • Pulsed-field gel electrophoresis (PFGE) • Multi-locus variable number of tandem repeats (VNTR) analysis (MLVA)

  7. Why do genotyping? ?

  8. Why do genotyping? ?

  9. TIME X

  10. similarity Country A Country B Transfer event 50 yrs ago Lots of time for local genetic changes since transfer Gel of isolates collected over, say, 5 year span Isolates from country A are all more closely related to each other than to isolates from country B and vice versa Country A A A A A A A B B B B B B

  11. Salmonella Typhimurium epidemiology • Periodic clonal replacement • Regional, continental or global in scale • Frequently multi-drug resistant • Numerous examples: • DT10 Sens (Khakhria et al., Can J Microbiol1983;29(11):1583-8.) • DT193 ACSSuT+ (Rowe et al. Vet Rec 105:468, 1979) • DT204 ACSSuT+ (Threlfall et al. Vet Rec 103:438, 1978) • DT104 ACSSuT (Threlfall J Antimic Chemo 46:7, 2000)

  12. Khakhria et al. Can J Microbiol1983 Nov;29(11):1583-8.

  13. Threlfall EJ, Ward LR, Rowe B. Epidemic spread of a chloramphenicol-resistant strain of Salmonella typhimurium phage type 204 in bovine animals in Britain. Vet Record 1978;103:438-440

  14. Threlfall et al. Br Med J 1980;280:1210-1

  15. Salmonella Typhimurium DT104 • Best described and characterized • Disseminated globally in the 1990s • Characterized by resistance to ACSSuT • Very clonal (PFGE profiles similar between very distant geographic sources) • Successful expansion not explained by a resistance advantage

  16. Annual isolates of Salmonella Typhimurium at WADDL

  17. % of S. Typhimurium infections that were DT104 - Helms et al. International Salmonella Typhimurium DT104 infections, 1992-2001. EID 2005;11:859-867

  18. Imbrechts et al. Vet Record 2000;147:76-77.

  19. Salmonella surveillance project • Real-time surveillance to detect emerging clones: • Doug Call: “Detection and characterization of phenotypic and genotypic traits for newly emergent zoonotic enteric pathogens” • Funded through NIH FWD-IRN contract

  20. Salmonella surveillance project • Human-source isolates: Washington State DOH PH Lab sends us all Salmonella isolates • Animal-source isolates: Washington Animal Disease Diagnostic Lab (WADDL), Phoenix Central Lab, occasional from DOH, and sampling for research studies • All isolates were processed by the FDIU lab – • Disk-diffusion assay for resistance to 12 antimicrobials • Bank at -80 ºC

  21. Salmonella surveillance project • Human and animal isolates were compared with respect to serovar and resistance pattern • Those that matched were compared further using PFGE • PFGE patterns analyzed in Bionumerics (Applied Maths,Sint-Martens-Latem, Belgium)

  22. DT104

  23. Detection of newly emergent non-typhoid Salmonella Typhimurium • Distinct from DT104 by PFGE • Resistant to 2 – 9 antimicrobials • Washington PulseNet PFGE profile TYP035 • 7% of human Typhimuriums 2004-2005 in Washington

  24. TYP035 TYP187 TYP004

  25. Not TYP035/TYP187

  26. XbaI SpeI TYP035 TYP187

  27. Elementary school students Caused by TYP035 46 primary (5th graders) and 12 secondary (K-4th) cases Source of owl pellets was a company in south central Washington State Owl-pellet associated outbreak, Massachusetts, 2006

  28. First detections of bovine-origin S. Typhimurium TYP035 by location

  29. 1999 2000 2005 2000 2001 2000 2006 2002 2000 2000 2001 2001 1999 2000

  30. First detections of bovine-origin S. Typhimurium TYP187 by location

  31. 2006 2004

  32. TYP035/TYP187 in British Columbia • From 2000 to present • 36 TYP035 • Sixteen were from human cases • The rest were primarily from bovine sources • Other animal sources: duck, wolf, buffalo and porcine. •  1 bovine TYP187 (February, 2006)

  33. TYP035/TYP187 in British Columbia

  34. Conclusions • TYP035/TYP187 may be a newly emerged epidemic clone of MDR Salmonella Typhimurium • Currently not important in human population • Apparently regional (Pacific Northwest) • Primarily bovine reservoir • Further characterization needed • Resistance phenotypes v. genotypes

  35. MLVA • Multi-locus variable number of tandem repeats analysis • Based on polymorphisms at loci where tandem repeats occur

  36. Van Belkum et al. Microbiol. Mol Biol Rev 1998;62:275-293

  37. Multi-locus variable number of tandem repeats analysis (MLVA) • Using published protocols (Lindstedt et al 2004) • Five VNTR loci (STTR3, STTR5, STTR6, STTR9, STTR10pl) • Mulltiplex PCR with dye-labeled primers followed by capillary electrophoresis • Analysis of fragment size data • Bionumerics (Applied Maths) • STTR3 • 190/256 isolates lacked amplicon • Passaging experiment: • 2 isolates X 95 wells X 30 passages • At passage 30, 70/95 wells lacked STTR3 • Analysis using 4 VNTR loci:

  38. MLVA PFGE Boiled lysate PCR reaction Capillary electrophoresis Data 2 days 3 – 5 days

  39. MLVA using 4 loci of S Typhimurium from various sources

  40. FDIU Dale Hancock Katie Baker Russ McClanahan & staff Bijay Adhikari ZRU Tom Besser Doug Call Acknowledgments

  41. WA DOH Kaye Eckmann Kathryn MacDonald David Boyle Cornell Lorin Warnick Martin Wiedmann Yesim Soyer BC CDC Linda Hoang Acknowledgments

  42. Thank you!

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