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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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Neisseria species overview
meningococci p. 140
chloramphenicol p. 189
culture requirements p. 124
encapsulation p. 125
Gram-negative algorithm p. 139
immunodeficient patients p. 116
meningitis p. 177
penicillin G/V for p. 184
splenic dysfunction p. 96
Waterhouse-Friderichsen syndrome p. 353
Neisseria meningitidis, also called N. meningitidis or just meningococcus, is a gram-negative round bacterium that causes meningitis in humans, as well as life-threatening conditions like sepsis and disseminated intravascular coagulation.
Now, N. meningitidis has a thin peptidoglycan layer, so it doesn’t retain the crystal violet dye during Gram staining.
Instead, like any other Gram-negative bacteria, it stains pink with safranin dye.
N. meningitidis typically live in pairs called diplococci, stacked side to side, so the pair looks like a coffee bean.
They are also non-motile, non-spore forming, and obligate aerobes, which means that they absolutely need oxygen to grow.
Finally, they’re catalase and oxidase positive - which means they produce both these enzymes.
N. meningitidis grows on a special chocolate medium called Thayer-Martin agar, which mainly consists of sheep’s blood... err, yum?
Some antimicrobials, like vancomycin and nystatin are usually added to the Thayer-Martin agar, to inhibit the possible growth of undesired bacteria or fungi, and maximize the growth of Neisseria species.
However, other Neisseria species, like N gonorrhoeae, also share these properties.
So the maltose fermentation test is done to differentiate the two.
The gist of it is that N. meningitidis can ferment maltose, whereas N. gonorrhoeae cannot.
To check for this, a pure sample from the culture is transferred to a sterile tube containing a mix of phenol red and maltose, which is then incubated at 36 degrees Celsius for 24 hours.
N. meningitidis causes acidic fermentation of maltose, and the resulting byproducts make the solution go yellow.
With N. gonorrhoeae, the solution stays red.
Now, N. meningitidis has a number of virulence factors, that are like assault weaponry that help it attack and destroy the host cells, and evade the immune system.
Neisseria meningitidis also known as meningococcus, is a gram-negative diplococcus, non-spore-forming, both oxidase and catalase positive, which is commonly known to cause meningitis. Meningitis is an infection of the membranes called meninges that surrounds the brain and spinal cord.
When meningococcal bacteria enters the bloodstream, it's referred to as meningococcemia. Meningitis most commonly results from meningococcemia and is associated with outbreaks, especially in unvaccinated people living in crowded settings, like dormitories, military barracks, and schools.
Symptoms of meningococcal meningitis include fever, headache, stiff neck, and a rash. Other symptoms may include nausea, vomiting, sensitivity to light, and altered mental status. Meningitis can progress rapidly and can be fatal if not treated promptly with antibiotics.
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