Beta Lactamase Test – Principle, Procedure, Uses and Interpretation

Beta Lactamase Test

Different bacteria produce an important class of enzymes called beta-lactamases, which may be mediated by genes on plasmids or chromosomes. These enzymes confer resistance to a number of penicillin antibiotics by cleaving the beta-lactam ring of penicillins and cephalosporin antibiotics, resulting in inactivation of these … Read more

Litmus Milk Test – Principle, Procedure, Uses and Interpretation

Litmus Milk Test Results

Milk is an excellent medium for the growth of microorganisms because it contains the milk protein casein, the sugar lactose, vitamins, minerals and water. Litmus milk is a milk-based medium used to distinguish between different species of bacteria. The lactose (milk sugar), litmus (pH indicator), and casein (milk protein) contained within the medium can … Read more

Lysine Iron Agar (LIA) Slants Test – Procedure, Uses and Interpretation

Lysine iron agar (LIA) slants test

Lysine iron agar (LIA) slants tests organisms for the ability to deaminate lysine or decarboxylate lysine. Lysine deamination is an aerobic process which occurs on the slant of the media. Lysine decarboxylation is an anaerobic process which occurs in the butt of the media. Principle Lysine iron agar contains lysine, peptones, a small amount of glucose, ferric … Read more

Kligler’s Iron Agar Test – Procedure, Uses and Interpretation

The Kliglers Iron Agar test

The Kligler’s Iron Agar test employs a medium for the identification of Enterobacteriaceae, based on double sugar fermentation and hydrogen sulphide production. In 1918, Kligler described a medium for detection of H2S and differentiation of Salmonella spp. Bailey and Lacey further modified the medium by … Read more

Hippurate Hydrolysis Test – Procedure, Uses and Interpretation

Hippurate Hydrolysis Test

Hippurate hydrolysis test is used to detect the ability of bacteria to hydrolyse substrate hippurate into glycine and benzoic acid by action of hippuricase enzyme present in bacteria. Hippuricase is a constitutive enzyme that hydrolyzes the substrate hippurate to produce the amino acid glycine. Glycine … Read more

PYR Test- Principle, Uses, Procedure and Result Interpretation

Result Interpretation of PYR Test

PYR (Pyrrolidonyl Aminopeptidase) Test is used for the detection of pyrolidonyl arylamidase (also called pyrrolidonyl aminopeptidase) activity in Streptococcus pyogenes (group A strep), Enterococcus spp., some coagulase-negative staphylococci, and some Enterobacteriaceae. It is also known as PYR (L-pyrrolidonyl-β-naphthylamide) which serve as a substrate for the … Read more

Bile Solubility Test- Principle, Reagents, Procedure and Result Interpretation

Bile Solubility Test

Bile Solubility Test is the test which differentiate Streptococcus pneumoniae (positive- soluble) from alpha-hemolytic streptococci (negative- insoluble). Streptococcus pneumoniae is bile soluble whereas all other alpha-hemolytic streptococci are bile resistant. Principle of Bile Solubility Test S. pneumoniae has an autolytic enzyme which can be demonstrated … Read more

Urease Test- Principle, Media, Procedure and Result

Result Interpretation of Urease Test

Urea Agar was developed by Christensen in 1946 for the differentiation of enteric bacilli. The urease test is used to determine the ability of an organism to split urea, through the production of the enzyme urease. Principle of Urease Test Urea is the product of decarboxylation … Read more

Citrate Utilization Test- Principle, Media, Procedure and Result

Result Interpretation of Citrate Utilization Test

This test is among a suite of IMViC Tests (Indole, Methyl-Red, Vogues-Proskauer, and Citrate) that are used to differentiate among the Gram-Negative bacilli in the family Enterobacteriaceae. Principle of Citrate Utilization Test Citrate agar is used to test an organism’s ability to utilize citrate as a source … Read more

Coagulase Test- Principle, Procedure, Types, Interpretation and Examples

Introduction to Coagulase Test Coagulase test is used to differentiate Staphylococcus aureus (positive) which produce the enzyme coagulase, from S. epidermis and S. saprophyticus (negative) which do not produce coagulase. i.e Coagulase Negative Staphylococcus (CONS). Principle of Coagulase Test Coagulase is an enzyme-like protein and causes plasma to … Read more