Recent Articles

General characteristics of Staphylococci

Staphylococci are gram-positive cocci arranged in cluster (grape-like fashion). The genus name, Staphylococcus, is derived from the Greek term staphle, meaning “bunches of grapes.” On gram stained smears, they appear as gram positive spherical cells (0.5 to 1.5 μm) arranged singly, in pairs, and in clusters. Although the Staphylococci can be identified on the basis […]

Methods/Ways/Media that can inhibit swarming of Proteus

There are various methods/ways/media to inhibit swarming of Proteus spp. We can either increase the concentration of agar (2.5-3.0% w/v) or incorporate growth inhibitors like chloral hydrate (1 in 500), sodium azide (1 in 5000), boric acid (1 in 100) and sulphonamide. Use of these chemicals may inhibit the growth of other pathogenic bacteria too […]

Normal flora of skin

Skin provides good examples of various microenvironments. Skin can be compared to geographic regions of earth: the desert of the forearm, the cool woods of the scalp, and the tropical forest of the armpit. The composition of the dermal microflora varies from site to site according to the character of the microenvironment. A different bacterial […]

Normal flora

By Normal flora, we mean the population of microorganisms residing in  the skin and mucous membranes of  healthy normal individuals without causing any harm to them. There are more numbers of bacteria (1014) in human body than the number of cells (1013). These bacterial populations constitute the normal microbial flora of human body. The normal flora is […]

Oxidation Fermentation (OF) test: Principle, Procedure and Result Interpretation

Oxidation Fermentation (OF) test is used to differentiate those organisms that utilize carbohydrates aerobically (Oxidation) such as Pseudomonas aeruginosa, from those that utilize carbohydrates anaerobically (Fermentation) such as members of the Enterobacteriaaceae and those that do not utilize carbohydrates at all (Non fermenters) such as Alcaligenes faecalis  . This test was developed by Hugh and […]

Tween 80 hydrolysis test

Tween 80 hydrolysis test is used mainly to differentiate slow–growing Mycobacterium (Scotochromogens) with similar colony appearance, M. gordonae (positive) and M. scrofulaceum (negative). This test is also useful in identifying M. kansasii (positive results within 24 hours). Those Mycobacterium spp that produce lipase hydrolyse the detergent Tween 80 (polyethylene derivative of sorbitan mono-oleate) with the production of oleic acid and polyoxyethylated […]

Hanging drop test/preparation

Hanging drop test is a confirmatory test to identify if an organism is motile or non motile. It can also be used for the presumptive identification of organism on the basis of its characteristic motility like Vibrio cholerae which has a darting type of motility in stool sample of patients with cholera. This test is prepared […]