Is Legionella Mycobacterium tuberculosis Gram positive or negative?

Legionella species are fastidious, facultative intracellular Gram-negative bacilli that fail to grow on many standard media routinely used in Clinical Microbiology, but can be isolated on BCYE agar (5).

Is legionella a Gram?

Species of the genus Legionella are Gram-negative, non-spore-forming, rod-shaped, aerobic bacteria. They contain branched-chain fatty acids, have a non-fermentative metabolism, and require L-cysteine and iron salts for growth.

Does Legionella show up on Gram stain?

Legionella stains poorly with Gram stain, stains positive with silver, and is cultured on charcoal yeast extract with iron and cysteine.

What is the Gram stain morphology of Legionella spp?

Legionella cells are thin, somewhat pleomorphic Gram-negative bacilli that measure 2 to 20 μm (Fig. 40-2). Long, filamentous forms may develop, particularly after growth on the surface of agar.

Is Mycoplasma Gram positive or negative?

The signet-ring-shaped cell of Mycoplasma is gram-negative, and the size of the cell is 0.2–0.3 μm and is normally smaller than 1.0 μm. Cells have no cell wall.

Are mycobacteria Gram-positive?

Basic Microbiology Mycobacteria are Gram-positive, catalase positive, non-motile, non-spore forming rod-shaped bacteria (0.2–0.6 μm wide and 1.0–10 μm long).

Is Mycobacterium Gram-negative or Gram-positive?

The phylogenetic position of Mycobacterium tuberculosis relative to other bacteria is controversial. Its cell wall has characteristics of both Gram-positive and Gram-negative bacteria. In the standard reference of bacterial phylogeny based on 16S ribosomal RNA sequence comparison, M.

What bacteria Cannot be Gram stained?

Atypical bacteria are bacteria that do not color with gram-staining but rather remain colorless: they are neither Gram-positive nor Gram-negative. These include the Chlamydiaceae, Legionella and the Mycoplasmataceae (including mycoplasma and ureaplasma); the Rickettsiaceae are also often considered atypical.

Is Legionella gram negative or atypical?

The Legionella bacterium is a small, aerobic, waterborne, gram-negative, unencapsulated bacillus that is nonmotile and oxidase and catalase positive. Legionella bacterium is a fastidious organism and will not grow anaerobically on a standard media.

How many cases of Legionella pneumophila are there?

Legionella pneumophila is the species responsible for ≈90% of human cases of infection. L. pneumophila is divided into 15 serogroups, among which serogroup 1 is the most prevalent disease-causing variant ( 1 ).

What kind of illness is caused by Legionella bacteria?

From Wikipedia, the free encyclopedia Legionella is a genus of pathogenic Gram-negative bacteria that includes the species L. pneumophila, causing legionellosis (all illnesses caused by Legionella) including a pneumonia-type illness called Legionnaires’ disease and a mild flu-like illness called Pontiac fever.

How big does a free living Legionellae get?

Free-living legionellae are rod-shaped, 0.3–0.9µm wide and approximately 1.3µm long. They will grow to 2–6µm in vitro, but can form filaments 20µm or more in length. Although they are Gram- negative, legionellae actually stain poorly in the Gram procedure and by other similar staining methods, particularly in infected tissues.

How long does it take to detect Legionella pneumophila?

Legionella urine antigen test has sensitivity 53-56% and specificity of approximately 99% for detecting infection due to Legionella pneumophila, serotype 1. Rapid detection within 24 hours.