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Last reviewed: 20.11.2021

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The genus Moraxella includes gram - negative bacteria, usually in the form of very short rounded rods with typical sizes of 1.0-1.5 x 1.5-2.5 μm, often acquiring the form of cocci, located mainly in pairs or short chains. Some cultures remain clear, others are pleomorphic: the size and shape of the cells vary, sometimes they form strands and long chains. Polymorphicity increases with a lack of oxygen and at a temperature above optimal for growth (32-35 ° C). There is no dispute, they do not have flagella. Some strains exhibit "twitching" mobility on a dense surface. Capsules and pili may be absent. Moraxellly - chemo-organotrophs with oxidative metabolism, optimal pH 7.0-7.5. Strict aerobes. Most strains are demanding for nutrient media, but specific growth factors are little known. A small number of organic acids, sterols and amino acids are used as a source of carbon and energy. Carbohydrates do not consume. They have oxidase and usually catalase. Indole, acetoin and H2S do not form. Highly sensitive to penicillin. The content of G + C in DNA is 40-46 mol%.

Moraecelles are parasites of the mucous membranes of humans and warm-blooded animals; perhaps there are saprophytes. The genus Moraxella includes two subgenus: actually Moraxella and Branhamella. The key features of the main Moraxella species are as follows.

  • Do not grow on a mineral medium with acetate and ammonium salts.
  • The folded serum is diluted.
  • Cause hemolysis on the "chocolate" agar.
  • Nitrites are usually formed.
  • Blood hemolysis is not allowed on the blood agar.
    • M. Lacunata.
  • Nitrite does not form. On the blood agar, hemolysis is usually given.
    • M. Bovis.
  • The folded serum is not liquefied. Hemolysis on "chocolate" agar is not given.
  • Phenylalanine deaminase is absent.
    • M. Nonliquefaciens.
  • Phenylalanine deaminase is available.
    • M. Phenylpyruvica.
  • They grow on a mineral medium with acetate and ammonium salts.
    • M. Osloensis.

The Branhamella subgenus includes 4 species, including Moraxella catarrhalis, formerly called Micrococcus catarrhalis. Usually takes the form of Gram-negative cocci, arranged in pairs. The dispute does not form, does not have flagella, forms a capsule, does not ferment carbohydrates, does not form polysaccharides from sucrose. It grows on nutrient agar and on medium containing amino acids, mineral salts, biotin and lactate or succinate as a source of energy and carbon. Does not form urease, H2S and indole. Forms lipase, cytochrome oxidase, catalase and DNase. Nitrates are reduced to nitrites. Aerobic, a temperature optimum of 37 ° C, but grows at 22 ° C. The content of G + C in DNA is 40-45 mol%. It is sensitive to penicillin. It is a parasite of the mucous membranes of humans and mammals. It is often found on the mucous membrane of the cervix and urethra in healthy women. May cause inflammation of the mucous membranes alone or in association with other bacteria. There is a message that may be the cause of meningitis. The pathogenicity of many moraxelles for humans has not been studied enough, but they cause inflammatory diseases of the mucous membranes on which they parasitize. For example, M. Lacunata, M. Bovis often cause conjunctivitis in people living in poor hygienic conditions. Some species, for example M. Osloensis and M. Phenylpyruvica, are potential causative agents of septicemia, meningitis or pyogenic diseases.

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