MOLECULAR EPIDEMIOLOGY LABORATORY

Microbiologist                     Wanda Manley        (307) 777-8680

 

Pulsed Field Gel Electrophoresis             Salmonella Serotyping             Foodborne Disease Investigation

 

The Molecular Epidemiology Laboratory provides analytical information about specific isolates to Wyoming Department of Health epidemiologists and CDC - Atlanta epidemiologists. This information is used to detect and track foodborne and waterborne bacteria involved with outbreaks.  This information is used to determine possible exposures and trace the source of the pathogen.  Normally, this laboratory is not involved in the diagnosis of a disease or condition.  WPHL is a part of PulseNet, but we also have capabilities to analyze organisms that CDC does not maintain national databases for.  We routinely process samples to determine if a cluster is an outbreak or just a series of random illnesses within the state of Wyoming.

 

 

Pulsed Field Gel Electrophoresis (PFGE)

Pulsed Field Gel Electrophoresis (PFGE) is a molecular fingerprinting technique to determine genetic relatedness within a single bacterial species.  PFGE is used by the Wyoming Public Health Laboratory (WPHL) to evaluate bacterial isolates suspected of being part of an outbreak or cluster of disease in the state or in a facility.  Used primarily with foodborne bacterial pathogens, PFGE is also useful in nosocomial outbreak situations to determine if isolates from different patients are related.  Isolates submitted to WPHL as part of the Reportable Disease program will be tested.  Patterns from the PFGE analysis will be entered into PulseNet, the national database that contains DNA fingerprints of similar strains recovered from across the nation.

PulseNet PFGE is available for:

  •    Campylobacter species
  •    E. coli O157 and E. coli non O157
  •    Listeria species
  •    Salmonella species
  •    Shigella species
  •    MRSA (by facility, compared to other Wyoming isolates only)

PFGE can be performed on most bacterial isolates, but only PulseNet organisms have a large, national database to determine if a Wyoming resident is involved in a national outbreak.  WPHL partners with the Wyoming State Veterinary Laboratory (WSVL) and the Wyoming Department of Agriculture Analytical Services Laboratory to detect and track foodborne outbreaks.

 

 

Salmonella Serotyping

Salmonella serotyping is performed on all Salmonella isolates received at WPHL and WSVL.  Serotyping is useful for surveillance purposes to determine trends occurring in food manufacturing and handling processes, as well as in outbreak investigations.  WPHL normally reports Salmonella species and Salmonella O (somatic antigen) Groups to submitters.  However, PFGE and serotyping information is available from Wyoming Department of Health Infectious Disease Epidemiologists.

 

 

Foodborne Disease Investigation

Suspected foodborne disease outbreaks shoud be referred to your local public health department and the Wyoming Public Health Epidemiology Unit (307-888-9104).  An outbreak is considered to be three or more people from different households that develop the same illness after experiencing a similar exposure.  Only foods implicated in a foodborne outbreak will be tested for pathogens.  Clinical samples should accompany food samples when possible.  All food sample collection and submission must be coordinated between the local health department and/or sanitarian and WPHL.  After the initial investigation is completed, testing will be determined based on symptoms and incubation times for suspected food pathogens.

For specific information on diagnosis and treatment of foodborne illness, the Moribidity and Mortality Weekly Report (MMWR) from April 16, 2004  53 (RR-4) is an excellent resource.  A chart of symptomology and onset time frames for a variety of pathogenic agents is included on page 7 of the publication.

 

Food Testing

TYPE OF TEST

Culture, RPLA, PCR, 16s rDNA sequencing, PFGE.

SPECIMEN REQUIREMENTS

Submit at least 50 grams of each suspected food and food components in a labeled, sterile, leak proof container.

SHIPPING REQUIREMENTS

Food should be shipped with cold packs, not ice.  Frozen food should remain frozen.  Ship for overnight delivery.  Complete and enclose WPHL test request form.

DAYS TEST PERFORMED

Monday – Friday

RESULTS AVAILABLE

Upon completion of identification.

REPORTING & INTERPRETATION

Entertoxin production will be reported for Clostridium perfringens, Staphylococcus aureus, and Bacillus cereus.  Presence or absence of Campylobacter, E. coli (STX positive), Listeria, Salmonella, Shigella, and Vibrio will be noted.

ADDITIONAL COMMENTS

Additional testing to determined serotype and PFGE pattern will be done.  Outbreak isolates may be submitted to CDC-Atlanta for MLVA testing also.
 

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