Fecal Matter Identification

What methods can be used to examine fecal matter?

Microscopic examination, fecal bacterial identification, thin-layer chromatography (coprostanol), and detection of immunoglobins, alkaline phosphatase, and amylase

Microscopic examination

uses fluorescence to highlight chlorophyl content/undigested food materials (first documented 1860)

Fecal Bacterial Identification

looks for key microbiota species in human microbiota (E. coli and Enterococci spp.)

What are the tests used for detecting urobilinoids?

Bilirubin oxidation, Schlesinger test, Edelman test, and spectrometric measurement of fluorescence

What does bilirubin oxidize with? What color is the product?

It oxidizes with HgCl2 and creates a pink/red product (most effective test)

Schlesinger Test

mix feces with saturated zinc acetate in ethanol to form an aurobilinoid-zinc chelation complex (fluorescent)

What chemicals are used in the Endelman Test?

Mercuric chloride and zinc chloride

What are the two phases of the Endelman Test?

1. urobilinogen and mercuric chloride react to form urobilin
2. urobilin and zinc chloride react to form a zinc-urobilin complex

What does a positive result for the Endelman Test look like?

The sample will fluoresce green when viewed under UV light

What are the limitations of the Endelman Test?

The extract must be as strong as possible, fresher stains work more effectively, has a low species specificity, urobilin can be found in other biological material (urine and sometimes blood (hepatitis and liver disorders)), and color can be obscured

What can obscure the green color from a positive result of the Endelman Test?

Fats, lipids, chlorophylls (creates pink color), and some types of glass

What are the components of fecal matter?

Water (75%), solid matter (25%; dead bacteria (30%), indigestible food (cellulose; 30%), cholesterol and fats (10-20%), inorganic substances (10-20%), and protein (2-3%)), and cell debris & bile pigments

How is urobilinogen and stercobilinogen created in the digestive system?

1. Hemolysis of erythrocytes/red blood cells in spleen
2.Release of hemoglobin
3. Heme is reduced to bilirubin
4. Bilirubin is converted to urobilinogen
5. Urobilinogen can be further reduced into stercobilinogen

Stercobilin

Brown pigment created from oxidized stercobilinogen

How many phases does the Endelman Test involve?

It is a 2-phase test

What types of cases can fecal matter be used/appear in?

prison, vandalism, breaking & entering, sexual assault, and blood

Feces/excrement

solid waste discharged from the large intestine through the anus

How much fecal matter is excreted daily?

100 - 250 g around 1-2 times a day

What determines the color of feces?

the action of bacteria on bilirubin

What determines the odor of feces?

different chemicals (indole, skatole, hydrogen sulfide, and mercaptins)

When is feces formed?

in the last stage of digestion in the intestine before entering the colon

Urobilinoids

group of pigments in feces

Urobilin

Yellow pigment created from oxidized urobilinogen