Laboratory Test

ORTHO-NITROPHENYL-Β-D-GALACTOPYRANOSIDE / ONPG TEST Description Specimen Requirements Procedure Interpretation Description This test is primarily used to detect late lactose fermenters. These LLF bacteria lack the enzyme β-galactoside permease which allows the lactose to enter the bacterial cell wall. ONPG is structurally similar to lactose, but ONPG is more readily transported through the bacterial plasma membrane …

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NORTHERN BLOT Description Specimen Requirements Procedure Interpretation Description Northern blot is a modification of the Southern Blot technique which are used to detect RNA molecules, most of the time in a form of transcripts. this can also be used to investigate RNA structural abnormalities such as splicing abnormalities which are responsible for various diseases. Like …

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NITRATE REDUCTION TEST Description Specimen Requirements Procedure Interpretation Description This determines whether an organism has the ability to reduce nitrate to nitrite further to nitrogen gas. This test is useful in differentiating the members of Enterobacteriaceae and Neisseria. Specimen Requirements Test organism incubated in broth medium containing nitrogen source (i.e. Nutrient Broth). Procedure 1. Incubate …

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MUG TEST Description Specimen Requirements Procedure Interpretation Description Escherichia coli produces the enzyme beta-D-glucoronidase, which hydrolyzes beta-D-glucopyranosid-uronicderivatives to aglycons and D-glucoronic acid. The substrate 4-methylumbelliferyl-beta-D-glucoronide is impregnated inthe disk and is hydrolyzed by the said enzyme to yield methylumbelliferyl which fluoresces blue color in UV light.   Specimen Requirements Bacterial suspension of test organism from …

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MR (METHYL RED) AND VP (VOGUES-PROSKAUER) TESTS Description Specimen Requirements Procedure Interpretation Description Both tests detect the end products of glucose fermentation. Some bacteria metabolize glucose via the Emden Meyerhof pathway which produces several intermediate products such as pyruvic acid and its further degradation products, mixed acids. However, species under Enterobacteriaceae take two separate pathways …

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MPN TEST Description Specimen Requirements Procedure Interpretation Description Most Probable Number (MPN) is a method used to estimate the concentration of viable bacteria from a sample, usually water, by means of inoculating the broth in 10-fold dilutions. Aside from water bacteriology, MPN is also used in estimating the viable numbers of bacteria in food and …

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MOTILITY TEST Description Specimen Requirements Procedure Interpretation Description This test is used to know if the organism if motile. The organism must possess a flagellum in order to be motile. The media agar concentrations must be at 0.4% or less to allow the spread of the microorganism.   Specimen Requirements Isolated colonies Procedure 1. Using …

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MALDI TOF MS Description Specimen Requirements Procedure Interpretation Description Matrix-associated laser desorption-ionization time of flight mass spectrophotometry (MALDI TOF MS) is one of the new inventions that aids in identifying microorganisms in microbiology and in chemistry, analyze molecular molar masses. The MALDI TOF MS is a two-phase process – ionization and time of flight phase. …

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LYSINE IRON AGAR (LIA) Description Specimen Requirements Procedure Interpretation Description This measures the three parameters useful in the identification of Enterobacteriaceae – lysine decarboxylation, lysine deamination and H2S production. This medium contains amino acid (lysine), carbohydrate source (glucose), proteins, bromcrescol purple which serves as the pH indicator, and sodium thiosulfate and ferric ammonium citrate as …

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LEUKOCYTE ALKALINE PHOSPHATASE/LAP TEST Description Specimen Requirements Procedure Interpretation Description LAP is also known as Neutrophil Alkaline Phosphatase Test (NAP). This stain is primarily used to differentiate chronic granulocytic leukemia and leukemoid reactions.   Specimen Requirements Blood smear Procedure • Stain: LAP stain• Reagents: Fixative, substrate solution (naphthol-AS-BI-phosphate + dimethylformamide), working solution (fast blue BBN), …

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