4 MU DISCS
PRINCIPLE / DISCUSSION:
When a substrate is bound to 4-MU, the degradation by the
enzyme releases a blue fluorescent end product (4-methylumbelliferone). This
blue fluorescence can be observed under a hand-held long-wave-length UV lamp
(i.e. Wood’s Lamp). The 4 MU tests have
been used many
years in the clinical and industrial labs as screens for various organisms. Key
manufactures several 4mu bound substrates for rapid screening.
MATERIAL SAFETY DATA:
KEY 4mu discs contain the respective 4-methylumbelliferyl
bound substrates in an inert base. The
unused discs are non-hazardous. Uninoculated waste
may be discarded in normal trash.
Inoculated product should be discarded according to normal methods for biohazardous waste.
STORAGE:
Discs are light sensitive.
Store in dark and tightly covered at 0-8 C.
MATERIALS REQUIRED:
Discs are provided 50 per container. Usage requires a pure 24-48 hour culture of
the organism on a non-fluorescing media such as blood agar or TSA. A loop or stick for harvesting the organisms,
a slide, and distilled water, pH 7.0 to 7.2 are needed but not provided.
PROCEDURE:
1) Place a disc onto a slide and moisten slightly.
(2) Smear a paste of the test organism onto the moistened
paper.
(3) Incubate in the dark for 2-5 minutes. Observe
fluorescence under a long wave UV (360nm or greater).
INTERPRETATION:
The appearance of an intense blue/white fluorescence where
the organism was smeared is a positive result.
Negative tests have no fluorescence or may fluoresce
a different color. Look only for the
blue/white fluorescence.
QUALITY CONTROL:
Each lot of discs should be checked with organisms of
known reactivity. The chart shows some
suggestions but these are not to be interpreted as the only organisms
acceptable for QC. If in doubt about
your organism, call us and we will verify reactivity.
LIMITATIONS:
MacConkey, EMB, or similiar media contain substances which can flouresce and make reading the test difficult. Use only a
non-fluorescing type medium.
REFERENCES:
1) Journal of Clinical Microbiology, Sept.,1986, p.368-371, "Comparison of ß-Glucuronidase-Based
Substrate Systems for Identification of Escherichia coli.", Stephen
C. Edberg, and Christine M. Kontnick.
2) Manual of Clinical Microbiology, Fifth Edition, Chapter
28, "Staphylococcus".
3) Bailey and Scott's Diagnostic Microbiology, Seventh
Edition, Chapter 27 "Enterobacteriaceae".
4) Journal of Clinical Microbiology, June 1992,
p.1402-1406, "Fluorogenic Substrates for
Differentiation of Gram-Negative Non fermentative and Oxidase-Positive
Fermentative Bacteria", Peter Kampfer, Isolde Kulies, and Wolfgang Dott.
5) Standard Methods for the Examination of Water and
Wastewater 17th Edition, APHA . AWWA
. WPCF.