CLINICAL MICROBIOLOGY

5) Urea Hydrolysis Test:  
                                  Urea is a common metabolic waste product of protein digestion in most vertebrates that is toxic to most living organisms. The enzyme Urease catalyzes the breakdown of urea into ammonia & carbon dioxide. 
The basic principle of this test is to determine the ability of certain microorganisms to produce the enzyme Urease. It is one of the useful diagnostic tests for  identifying bacteria, particularly Proteus spp  from other Gram negative bacteria. 
Urease test is performed by growing the test organisms on urea agar medium containing the pH indicator, phenol red. During incubation microorganisms capable of producing the enzyme urease will liberate ammonia which cause the rise in pH of the medium. As, the pH increases, the color of the phenol red changes from an orange to deep pink. 
 In the clinical laboratory, members of the genus Proteus can
be distinguished from other enteric nonlactose-fermenting
bacteria (Salmonella, Shigella) by their fast urease activity. P.mirabilis is a major cause of human urinary tract infections.
Please visit these links ;
www.vumicro.com › Home › Reference Books › Biochemical Tests
www.austincc.edu/microbugz/urease_test.php‎
www.hccfl.edu/media/700729/urease%20test.pdf
www.mesacc.edu/~johnson/labtools/Dbiochem/urea.html
www.youtube.com/watch?v=GSTmVJfhpug
amrita.vlab.co.in/?sub=3&brch=76&sim=214&cnt=1‎
www.childrensonlinebooks.com/bi284/.../urease_hydrolysis_test.htm‎
avfaust-biology.blogspot.com/2011/.../lab-report-urea-hydrolysis-test.ht...


Cited By Kamal Singh Khadka
Assistant Professor  in PU, RE-COST, PNC , NA, LA 

Comments

Post a Comment

Popular posts from this blog

Stains/ Dyes

STAINS/ DYES      They are colored organic compounds used for staining microorganisms. Chemically, Stains= Benzene ring+ Chromophore+ Auxochrome According to nature of stain, it can be classified into: 1. Acidic Dyes:   It is dye which has negative charge so they bind to positively charged cell structures like some proteins. Acidic dyes are not very often used in Microbiology lab.except to provide background staining like Capsule staining. Examples: Nigrosine, Picric acid, Eosin, Acid fuschin, India ink etc.  2. Basic Dyes:  This dye have positive charge & bind to negatively charged molecules(nucleic acid, -COOH -OH). Since, surface  of bacterial cells are negatively charged(due to Teichoic acid), basic dyes are most commonly used in bacteriology. Examples: Crystal Violet, Methylene Blue, Safranin , basic fuschin. 3. Neutral Dyes:  They are usually formed from precipitation in which are produced when aqueous acidic & basic stains are combined. Neutral dyes stains nuc
Read more

CLINICAL MICROBIOLOGY

Image
3)   Triple Sugar Iron(TSI) Agar Test:                         The TSI agar test  is used to differentiate among the members of the family Enterobacteriaceae and between Enterobacteriaceae and other intestinal bacteria. The authors have chosen three common bacteria in the family Enterobacteriaceae: Escherichia coli, Proteus vulgaris, and Shigella flexneri .  All three are facultatively anaerobic gram-negative rods. In a TSI tube, E. coli produces an acid butt, an acid or alkaline slant, and no H2S, but does produce gas. P. vulgaris produces an acid butt, an acid or alkaline slant, H2S, and gas. S. flexneri produces an acid butt, an alkaline slant, no H2S, and no gas. For the other intestinal bacteria, the authors have chosen Alcaligenes faecalis and Pseudomonas aeruginosa. Both of these intestinal bacteria are gram-negative aerobic rods. In a TSI tube, A. faecalis produces an alkaline butt, alkaline slant, H2S, and gas; P. aeruginosa, an acid butt, alkaline slant, H2S,
Read more

VIROLOGY

Image
VIRUS IDENTIFICATION:    Identifying viral isolates is not an easy task. For one thing, viruses cannot be seen at all without the use of an electron microscope. Serological methods, such as Western blotting, are the most commonly used means of identification. In these tests, the virus is detected and identified by its reaction with antibodies.  Virologists can identify and characterize viruses by using such modern molecular methods as use of restriction fragment length polymorphisms (RFLPs) and the polymerase chain reaction(PCR).PCR PCR was used to amplify viral RNA to identify the west Nile virus in 1999 in the United States & SARS-associated coronavirus in china in 2002. Viral Multiplication:  The nucleic acid in a virion contains only a few of the genes needed for the synthesis of new viruses. These include genes for the virion structural components, such as the capsid proteins, and genes for a few of the enzymes used in the viral life cycle. These enzymes are
Read more