Bacterial Typing by Pulsed-Field Gel Electrophoresis (PFGE)
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Bacterial typing is useful to investigate infection outbreaks by a single species.
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Pulsed-Field Gel Electrophoresis of DNA Fragments
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
PFGE (Pulsed-Field Gel Electrophoresis)
Pulsed-Field Gel Electrophorsis (PFGE)
Pulsed-Field Gel Electrophorsis (PFGE)
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube: Agar slant
Specimen Volume: Isolates on separate agar slants
1. Individually bag each pulsed-field gel electrophoresis (PFGE) specimen, then place all PFGE specimens (all patients and/or sites to be compared) together in a large bag, and send in the same shipping container. This is necessary for comparison of isolates by this method.
2. Label specimen as an etiologic agent.
1. Specimen source and organism identification are required.
2. Each slant must be submitted under a separate order.
3. Original isolates should be saved at the client site if additional PFGE testing may be needed.
4. See Infectious Specimen Shipping Guidelines in Special Instructions for shipping information.
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Bacterial-typing techniques are useful for determining strain relatedness in the setting of nosocomial outbreaks or apparent outbreaks. Serial isolates obtained from the same patient can be typed to determine whether they are the same or different. Typing often allows the physician to discriminate between 2 species, recognize an outbreak, or identify the source of infection.
In the past, strain typing was accomplished by testing for different biochemical, phage, or antibiotic resistance patterns. Antibiograms are often unreliable because they are easy to over-interpret or under-interpret. Other strain-typing methods are often organism-specific and each requires a unique set of reagents and procedures. The availability of classical strain-typing techniques has been limited.
An excellent example of the power of the technique was in the analysis of a large number of clustered isolates of methicillin-resistant Staphylococcus aureus obtained from patients and staff at a Mayo Rochester hospital during September and October, 1992. Although the high frequency with which this organism was isolated suggested a nosocomial outbreak, molecular typing of the isolates showed: only 3 of the 14 were identical; the remaining isolates were most likely the result of a surge in the number of random isolates of this organism. Thus, the 14 isolates were not part of a nosocomial epidemic due to a single strain, and radical measures for control of a nosocomial outbreak were unnecessary.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Reported as isolates from these sources are "indistinguishable" or "different" by pulsed-field gel electrophoresis. Results will be faxed to the client.
Isolates which show identical DNA restriction fragment length polymorphism patterns are considered to be closely related.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
The fact that 2 strains share the same pattern does not prove that they are epidemiologically related. Establishment of an epidemiologic relationship depends on: the frequency with which the "indistinguishable" pattern is seen among epidemiologically unrelated isolates and correlation with clinical and epidemiological information.
Obviously, if common contact between 2 patients with strains with the same pulsed-field gel electrophoresis (PFGE) type can be established, the chances are greater that an epidemiologic link can be ascribed. Thus, the greatest power of PFGE typing is in showing strain dissimilarity, not in proving similarity or relatedness.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Arbeit RD, Arthur M, Dunn R, et al: Resolution of recent evolutionary divergence among Escherichia coli from related lineages: the application of pulsed field electrophoresis to molecular epidemiology. J Infect Dis 1990;161:230-235
2. Arbeit RD: Laboratory procedures for the epidemiologic analysis of microorganisms. In Manual of Clinical Microbiology, Seventh edition. Edited by PR Murray, ASM Press, Washington, DC. 1999 pp 116-137
Method Description Describes how the test is performed and provides a method-specific reference
Typing of bacterial isolates is accomplished by comparing the DNA restriction fragment length polymorphism (RFLP) patterns of large DNA fragments separated by pulsed-field gel electrophoresis (PFGE) of 2 or more bacterial isolates. Identical RFLP patterns indicate similarity of the isolates. The test is performed by isolating the DNA from the organism, cutting the DNA with a restriction enzyme which recognize 10 to 20 sites on the genome, and separating the fragments using PFGE. The size pattern of DNA fragments in the electrophoresis gel of different isolates is then compared.(Tenover FC, Arbeit RD, Goering RV, et al: Interpreting chromosomal DNA restriction patterns produced by pulsed-field gel electrophoresis: criteria for bacterial strain typing. J Clin Microbiol 1995;33:2233-2239)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday; Continuously
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
13 days ( Testing may take longer if a large number of isolates are submitted)
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
This test uses a standard method. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
|Result ID||Reporting Name||LOINC Code|
|PFGE||Bacterial Typing||In Process|