00:00 / 00:00
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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Staphylococcus aureus Characteristics
Staphylococcus aureus Disease
Staphylococcus aureus p. , 133
bacterial endocarditis p. 319
β -hemolytic nature of p. 133
brain abscesses p. 177
cephalosporins p. 186
cystic fibrosis p. 58, 176
dapsone p. 192
exotoxin production p. 131
food poisoning p. 175
immunocompromised patients p. 176
influenza p. 166
IV drug use p. 177
lung abscess p. 706
nosocomial infection p. 176, 182
osteomyelitis and p. 177
penicillins for p. 185
pigment production p. 127
pneumonia p. NaN
postviral infection p. 176
prophylaxis for p. 194
septic arthritis p. 474
skin infections p. 487
Staphylococcus aureus, sometimes called staph aureus, is coccal, or round-shaped, and grows in clusters.
In fact, its name, broken down, means “golden cluster of grapes”.
It sorta starts making sense if you look at it under a microscope - it tends to grow in sticky clusters, and it stains purple when Gram-stained due to its peptidoglycan cell wall, so it’s Gram positive and it resembles grapes.
As for its “golden” color, when it’s grown on blood agar plates, the colonies have a distinctive golden-yellow color.
Staphylococcus aureus are Gram positive and facultative anaerobes, meaning that they can survive in aerobic and anaerobic environments.
They’re non-motile and don’t form spores.
Staphylococci produce an enzyme called catalase which converts hydrogen peroxide to water and oxygen.
Other common cocci, such as streptococci and enterococci, are catalase negative so they don’t have this ability and we can use a few drops of hydrogen peroxide to differentiate them.
Catalase positive bacteria will foam up, while in catalase negative bacteria, nothing happens.
Now, a couple of other staphylococci species, like Staph epidermidis and Staph saprophyticus are also catalase positive, so to distinguish between them we can look for another enzyme that’s made by Staph aureus, called coagulase.
Coagulase converts fibrinogen into fibrin.
So let’s say that we stir up some Staph aureus bacteria in a liquid “emulsion”, and then add a few drops of plasma which contains fibrinogen. The coagulase positive staph aureus will convert the soluble fibrinogen to sticky fibrin, which then visibly clumps up, whereas coagulase negative bacteria won’t.
Staph aureus is extremely common and about a quarter of the population is colonized by it, usually in their nostrils, groin, armpits, and other parts of their skin.
But, most of the time it’s a normal part of our skin flora, and doesn’t cause trouble.
The skin flora is a complex ecosystem of different bacterial species and occasionally, Staph aureus can begin to dominate that ecosystem.
In individuals that have staph aureus colonization, a number of factors like the pH, humidity, sweat levels of the skin, as well as presence of other bacteria on our skin, all affect the amount of staph aureus that’s present.
Staphylococcus aureus, also known as "staph," is a gram-positive, beta-hemolytic, catalase, and coagulase-positive bacteria, which is known to cause a wide range of infections in humans. Staph is normally part of the human normal skin and nasal flora, but if it overgrows or if the skin is damaged, then it can cause disease through direct colonization, toxin production, or both.
Staph is known to cause skin infections, organ abscesses, pneumonia, endocarditis, septic arthritis, and osteomyelitis. Staph infections are typically treated with antibiotics, but in some cases, the bacteria may be resistant to the antibiotics that are commonly used. Methicillin-resistant Staphylococcus aureus (MRSA) is a type of staph that is resistant to many antibiotics and is a significant public health concern.
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