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Bacterial structure and functions
Bacillus anthracis (Anthrax)
Bacillus cereus (Food poisoning)
Corynebacterium diphtheriae (Diphtheria)
Clostridium botulinum (Botulism)
Clostridium difficile (Pseudomembranous colitis)
Clostridium tetani (Tetanus)
Streptococcus agalactiae (Group B Strep)
Streptococcus pyogenes (Group A Strep)
Bartonella henselae (Cat-scratch disease and Bacillary angiomatosis)
Legionella pneumophila (Legionnaires disease and Pontiac fever)
Salmonella typhi (typhoid fever)
Yersinia pestis (Plague)
Vibrio cholerae (Cholera)
Bordetella pertussis (Whooping cough)
Francisella tularensis (Tularemia)
Haemophilus ducreyi (Chancroid)
Mycobacterium tuberculosis (Tuberculosis)
Mycobacterium avium complex (NORD)
Gardnerella vaginalis (Bacterial vaginosis)
Coxiella burnetii (Q fever)
Ehrlichia and Anaplasma
Rickettsia rickettsii (Rocky Mountain spotted fever) and other Rickettsia species
Borrelia burgdorferi (Lyme disease)
Borrelia species (Relapsing fever)
Treponema pallidum (Syphilis)
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Rocky Mountain Spotted Fever
Rickettsia species overview
The Rickettsiae are a genus of Gram-negative coccobacilli, which includes two major groups of bacteria.
First, there’s the spotted-fever group, the main species in this group is Rickettsia rickettsii, which causes a disease called Rocky Mountain spotted fever.
Second, there’s the typhus group of Rickettsia species - which cause different forms of typhus.
This group includes Rickettsia prowazekii, which causes a disease called epidemic typhus, and Rickettsia typhi, which causes murine typhus, also called endemic typhus.
Now, Rickettsiae are small bacteria, measuring only 0.7 to 2 micrometers in diameter.
They have a plasma membrane that’s surrounded by a microcapsule.
And inside the bacteria, there’s cytosol, which contains ribosomes and a single circular chromosome.
Also, these bacteria have a thin wall, that doesn’t retain the crystal violet dye during gram staining, so they’re classically considered Gram-negative bacteria.
However, they are very weak Gram-negative bacteria, so special staining methods are needed to visualize them, such as Giemsa, Gimenez or Machiavello.
So, on Giemsa staining, the bacteria appear bluish-purple, on Gimenez staining they look red, on a bluish-green background and on Machiavello staining they look bright red, on a blue background.
Finally, they’re non-motile and obligate intracellular which means they can survive only inside cells and this is because it can’t make two important energetic compounds, NAD+ and coenzyme A, by itself, and instead it gets them from eukaryotic cells.
Rickettsiae are a genus of Gram-negative coccobacilli, which includes Rickettsia rickettsii known to cause Rocky Mountain spotted fever (RMSF); and Rickettsia prowazekii that causes epidemic typhus; and Rickettsia typhi, which is known to cause endemic typhus. Rickettsia rickettsii is transmitted through ticks; Rickettsia prowazekii through lice; whereas Rickettsia typhi is transmitted through rat fleas. Symptoms of Rickettsiae infections depend on the type but may include fever, headache, malaise, myalgias, arthralgias, and skin rashes. Rickettsiae can be diagnosed with serologic tests such as indirect immunofluorescence or with special stains on a skin biopsy and they can be treated with antibiotics like doxycycline or chloramphenicol.
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