Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

BAHG
82711
Clinical Information: 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.
Useful For: Bacterial typing is useful to investigate infection outbreaks by a single species.
Interpretation: Isolates which show identical DNA restriction fragment length polymorphism
patterns are considered to be closely related.
Reference Values:
Reported as isolates from these sources are "indistinguishable" or "different" by pulsed-field gel
electrophoresis. Results will be faxed to the client.
Clinical References: 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
Bahia Grass, IgE
Clinical Information: Clinical manifestations of immediate hypersensitivity (allergic) diseases are
caused by the release of proinflammatory mediators (histamine, leukotrienes, and prostaglandins) from
immunoglobulin E (IgE)-sensitized effector cells (mast cells and basophils) when cell-bound IgE
antibodies interact with allergen. In vitro serum testing for IgE antibodies provides an indication of the
immune response to allergen(s) that may be associated with allergic disease. The allergens chosen for
testing often depend upon the age of the patient, history of allergen exposure, season of the year, and
clinical manifestations. In individuals predisposed to develop allergic disease(s), the sequence of
sensitization and clinical manifestations proceed as follows: eczema and respiratory disease (rhinitis and
bronchospasm) in infants and children less than 5 years due to food sensitivity (milk, egg, soy, and
wheat proteins) followed by respiratory disease (rhinitis and asthma) in older children and adults due to
sensitivity to inhalant allergens (dust mite, mold, and pollen inhalants).
Useful For: Testing for IgE antibodies may be useful to establish the diagnosis of an allergic disease
and to define the allergens responsible for eliciting signs and symptoms. Testing also may be useful to
identify allergens which may be responsible for allergic disease and/or anaphylactic episode, to confirm
sensitization to particular allergens prior to beginning immunotherapy, and to investigate the specificity
of allergic reactions to insect venom allergens, drugs, or chemical allergens.
Interpretation: Detection of IgE antibodies in serum (Class 1 or greater) indicates an increased
likelihood of allergic disease as opposed to other etiologies and defines the allergens that may be
responsible for eliciting signs and symptoms. The level of IgE antibodies in serum varies directly with
the concentration of IgE antibodies expressed as a class score or kU/L.
Reference Values:
Class IgE kU/L Interpretation
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