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Gram-positive bacteria are those that are stained dark blue or violet by gram staining, in contrast to gram-negative bacteria, which are not affected by the stain. The stain is caused by a high amount of peptidoglycan in the cell wall, which typically lacks the secondary membrane and lipopolysaccharide layer found in other bacteria. In the original bacterial phyla, the gram-positive forms made up the phylum Firmicutes, a name now used for the largest group. It includes many well-known genera such as Bacillus, Listeria, Staphylococcus, Streptococcus, Enterococcus, and Clostridium. It has also been expanded to include the Mollicutes, bacteria like Mycoplasma that lack cell walls and so do not have gram-positive stains, but are derived from such forms. The granulomas in tuberculosis are called tubercles, or tuberculous nodules. They can be seen in tissues by the naked eye as small white spots 1-2mm in size. This type IV immune response can kill some bacteria. Bacteria can also survive where they live within the macrophagic cells. If the affected patient has a strong immune system and is well nourished, it is likely that the immune response will eliminate bacteria and the tubercle heals by formation of a scar. Usually the immune system is able to halt the multiplication of TB bacilli, preventing further spread in about 90 percent of cases. However if a person has a weak immune system or is poorly nourished bacteria are not eliminated and proliferate. The tubercles enlarge and there is local tissue destruction. Another feature of the granulomas of tuberculosis is the development of cell death, also called necrosis, in the centre of tubercles. To the naked eye this has the texture of soft white cheese and was termed caseous necrosis. Click on following items to see more information: Alcaligenes, Antibiotics, Antibiotic prophylaxis, Bactericidal, Bacillus, Bacillus subtilis, Bacteria, Microbial, Bacteriophage, Bacteroides, Botulism, Candida albicans, Cell suspensions, Clostridia, Culture medium, Escherichia coli, Escherichia coli, Escherichia coli, Escherichia coli, Escherichia coli, Enterobacters, Fermentations, Yeasts, Gram positive, Haemophilus, Leuconostoc, Bacteria, Bacteriological, Microorganisms, Neisseria, Pichia, Pseudomonas aeruginosa, P. putida, S. cerevisiae, S. cerevisiae, Salmonella typhimurium, Sepsis, Staphylococcus aureus, Streptococci, Streptococcal, Thermophile, Yeasts At least 14 different serovars of Legionella pneumophila have been described as well as several other species being subdivided into a number of serovars. Sera have been used both for slide agglutination studies as well as for direct detection of bacteria in tissues using fluorescent-labelled antibody. Specific antibody in patients can be determined by the indirect fluorescent antibody test. ELISA and microagglutination tests have also been successfully applied. Legionella pneumophila is non-acid, fast non-capsulated rods, aerobic and do not hydrolyse gelatin or produce urease. They are non-fermentative. L. pneumophila is neither pigmented nor does it autofluoresce. It is oxidase and catalase positive, produces beta-lactamase. Many bacteria are capable of movement in their environment either by flagella or gliding motility. In the case of flagella, bacteria have a long, flexible, spiral shaped structure, the flagellum, that helps to push the microbe through solution. Flagella also help in the detection of favorable or unfavorable conditions and move the bacterium in an appropriate direction. As a microbe grows it has to synthesize more of itself. Knowing what it is made of and how it is put together is critical to gain an understanding of the growth process.
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