Definition and biochemical characteristics
The enterococci are complex, diverse, and important group of bacteria in terms of interaction with humans. Some strains are used for manufacture of food whereas others are the cause of serious human and other animal infections. They are ubiquitous and encountered in nearly every thing we humans come into contact with.
Enterococci are facultative anaerobic Gram positive cocci that appear singly, in pairs and in short chains, they may be coccobacillary in gram-stained films prepared from agar cultures but tend to be ovoids and in chain when prepared from thioglycolate medium.
Enterococci are homofermentative lactic acid bacteria, with an optimum growth temperature of 35°C and a growth range from 10 to 45°C. They are all catalase negative, grow in broth containing 6.5% NaCl, and they hydrolyse esculin in the presence of 40% bile salts. Most of them also hydrolyse pyrrolidonyl-β- naphtylamide (PYR). Other characteristics of enterococci that have made them extremely competitive in many areas are their tolerance against disinfectants and heat as well as a promiscuous lifestyle.
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