Taxis response is to move towards or away from the stimulus. If the organism moves towards the stimulus the taxis is positive, while if it moves away the taxis is negative. For example, flagellate protozoans of the genus "Euglena" move towards a light source. This reaction or behaviour is called "positive phototaxis", since phototaxis refers to a response to light and the organism is moving towards the stimulus. Many types of taxis have been identified, including: Depending on the type of sensory organs present, a taxis can be classified as a "klinotaxis", where an organism continuously samples the environment to determine
HACEK organisms HACEK organisms The HACEK organisms are a group of fastidious gram-negative bacteria that are an unusual cause of infective endocarditis, which is an inflammation of the heart due to bacterial infection. HACEK is an abbreviation of the initials of the genera of this group of bacteria: "Haemophilus", "Aggregatibacter" (previously "Actinobacillus"), "Cardiobacterium", "Eikenella", "Kingella". The HACEK organisms are a normal part of the human microbiota, living in the oral-pharyngeal region. The bacteria were originally grouped because they were thought to be a significant cause of infective endocarditis, but recent literature has shown that they are rare and only responsible for 1.4–3%