There are more than 40 recognized species of CoNS. Most of these species have been isolated from humans, usually from the skin and mucous membranes. Certain species are found in very specific sites, such as the head (Staphylococcus capitis) or ear (Staphylococcus auricularis). Others have been isolated from animals and animal products. CoNS are classified into different […]
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 […]
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 […]
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 […]
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 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 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 […]