Gram Positive Bacteria + Flashcards by Olivia Hofer

Staphylococcal characteristics

Aerobic cocci, catalase positive violent prolific toxins

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What does it mean to be catalase positive? Catalase negative?

Catalase positive - bubbling with H2O2
Catalase negative - no bubbling with H2O2

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What test determines Staph aureus? And how?

Coagulate test. Staph aureus is coagulate positive. This means there is clumping when mixed with plasma

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Infections/Syndromes caused by Staph aureus (3)

Soft tissue infections
Toxic Shock Syndrome (TSST)
Staph Scalded Skin Syndrome (SSSST)

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What type of toxin is SSSST and what does it cause?

Exfoliative toxin
Generalized peeling of the skin

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What is the toxin of Staph aureus that is a super antigen? And what does it cause?

Enterotoxin
Causes quick onset food poisoning

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What is MRSA and why is it bad?

Methicillin Resistant Staph aureus
It is penicillin resistant - produces beta lactamase which breaks up penicillin

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Resist phagocytes, hard

Capsules

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Attaches to fibrinogen, plastic devices, fibrin; can choke a pathway

Clumping factor

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Coagulase

Produces clots in capillaries; clots fibrinogen

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Enterotoxin

Superantigens causing food poisoning if ingested

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exfoliatoxin

Separates layer of epidermis

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Fibronectin binding protein

Attached to acceptors tissue substances

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Breaks down hyaluronic acid component of tissues

Hyaluronidase

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Kills neutrophils or causes them to release their enzymes

P-V Leucoidin

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Breaks down fats; can break down the whole body if overreacted

Lipase

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Degrade collagen and other tissue proteins

Proteases and nucleases

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Makes holes in host cell membranes; unnecessary substances in, necessary out (messes up homeostasis)

Alpha toxin, beta toxin and delta toxin

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Immunoglobulin binding protein

Protein A

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Causes rash, diarrhea and shock

Toxic shock syndrome toxin

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Converts plasminogen to fibriolytic plasma

Staphylokinase

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Streptococci characteristics

Gram positive, catalase negative, aerobic, M proteins and thick cell wall

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What does being catalase negative mean?

Forms in chains

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What are the most common and most devastating groups of strep? (2)

Group A and Group B

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C5a peptidase

Inhibits attraction of phagocytes by destroying C5a strep virulence factor

Inhibits phagocytosis; aids in penetration of epithelium

Hyaluronic acid capsule

M protein

Interferes with phagocytosis by breakdown of C3b opsonin strep virulence factor

Protein F

Helps with attachment to host cells

Interferes with phagocytosis by binding Fc segment of Ig

Protein G

Superantigen responsible for scarlet fever and flesh eating fasciitis

Strep pyrogenic exotoxins

Streptolysin O and S

Lyse leukocytes and erythrocytes -> cause infection

Enhance spread of bacteria by breaking down DNA, proteins, blood clots, tissue, hyaluronic acid

Tissue degrading enzymes

What is alpha hemolysis?

Partial RBC hemolysis by alpha hemolysin

What are the 2 bacteria that are alpha hemolytic? How do you tell them apart?

S. pneumoniae and S. Viridans Optochin test

What are the results of the optichin test?

S. Pneumoniae - sensitive S. Viridans - resistant

Two bacteria under S. Viridans

S. mutans S. sanguis

What is beta hemolytic mean?

Complete RBC hemolysis

Which bacteria are Beta hemolytic? How do you tell them apart?

S. pyogenes (Group A) and S. agalactiae (Group B) Bacitracin test

What are the results of the bacitracin test?

S. pyogenes (Group A) - sensitive S. agalactiae (Group B) - resistant

What does Gamma hemolytic mean?

No hemolysis of RBC

What two bacteria are gamma hemolytic?

Enterococcus fecalis and Enterococcus faecium

What is present when S. pneumoniae is put through an optichin test? How big should it be?

A zone of inhibition 14 mm or greater from the disk

What type of plates are used for an optochin test

Blood agar plates

Streptococcus pneumoniae characteristics

Gram positive, encapsulated cocci, nonmotile, alpha hemolytic, catalase negative

What is the most common cause of community acquired pneumonia?

Strep. pneumoniae

Pneumococcal pneumonia is a

Facultative anaerobe

4 diseases/conditions that S. pneumoniae causes

Adult bacterial meningitis Otitis media sinusitis Mastoiditis

What is most common S. Pneumoniae condition in children when they are growing?

Otitis media (middle ear)

Strep. pyogenes A characteristics

Beta hemolytic, cocci, catalase negative, gram positive, bacitracin sensitive

What does Strep. pyogenes A cause? (5)

Strep throat Necrotizing fasciitis (flesh eating disease) Scarlet fever (strawberry tongue) Strep. Toxic Shock Syndrome Glomerulonephritis

Why is flesh eating disease dangerous?

You can get infections in the open air due to exposure of skin IF it is very severe

Strep. agalactiae B characteristics

Beta hemolytic, gram positive, bacitracin resistant, catalase negative

The leading cause of meningitis and septicemia in neonates

Strep. agalactiae B

What can cause skin infections in people with compromised immune systems?

Micrococcus

Micrococcus characteristics

Gram positive cocci M. Lutes oxidizes carbohydrates to CO2 and water

C. tetani characteristics

Gram positive bacilli, spore forming, anaerobic, do not grow in aerobic, transported by retrograde neuronal flow or blood

C. tetani toxin and what type of toxin

Tetanospasmin (exotoxin)

What does C. tetani cause?

Tetanus (muscle tone loss) and Lockjaw

C. botulinum toxin and what type

botulinum toxin Exotoxin

What does C. botulinum cause?

Botulism (muscular paralysis and blurred vision) Botulism food poisoning

C. botulinum characteristics

Gram positive Bacilli, spore forming (spores can be airborne), found in soil, fish, meat)

What is added to can foods to prevent situation of botulism?

Nitrates/nitrites

What does C. perfringens cause?

Gas gangrene/myonecrosis

What happens if intestinal tissues necrotize due to C. perfringens?

Enterotoxin is released -> severe diarrhea

How does C. perfringens spread?

Food borne

Gas production from C. perfringens leads to

Bubbly deformation of infected tissue

C. difficile characteristics

GI microflora, in GI tract of children, can cause watery diarrhea

Clostridium characteristics

Motile, strictly anaerobic, prolific producers of exotoxins and enterotoxins

What is a good stain for Clostridium and why?

Gram stain Spore does not stain, good to identify

Actinomycetes characteristics

Fungus like filamentous bacteria, forms branches, pleomorphic, high G and C content, anaerobe

Who has mycolic acid in their cell walls?

Actinomycetes

Infections/diseases caused by Actinomycetes

Pulmonary infections (nocarditis), actinomycosis, forms abscesses and swelling at the site of infection

Propionibacterium characteristics

Gram positive, anaerobes (can grow in aerobic), propanoic acid

Cutaneous group and dairy group used in cheese

Propinoic acid

What is Propionibacterium linked to? (3)

Certain cases of endocarditis, wound infections, and abscesses

What does P. granulosium and S. epidermidis cause?

Acne vulgaris (pimples)

Bacillus anthracis characteristics

Gram positive, endospore forming, rod with unique capsule, two plasmid coded exotoxins, strict aerobes

Other than humans, Anthrax can be in

Cows, sheep, goats and horses

Humans contract anthrax via animal products/contaminated dusts and get (most common to very rare, 3)

Cutaneous infection, inhalation pulmonary anthrax or GI anthrax

What does Bacillus cereus cause?

Rice eating related food poisoning

What is used for polymyxin production?

Bacillus polymyxa

What does Corynebacterium diptheriae cause?

life threatening diseases diptheriae- URI

Corynebacterium characteristics

Anaerobic, nonmotile, rod shaped, normally saprophytic (expect for C. diptheriae)

Listeria monocytogenes characteristics

Motile, no spores, facultative anaerobe, normal inhabitant of GI tract

What does L. monocytogenes cause?

Listeriosis (inflammation of the brain) and severe food poisoning

Who is most vulnerable to L. monocytogenes? (4)

Pregnant woman (1/3 cases), newborns, elderly, and immunocompromised patients

Lactobacillus characteristics

gram pos, Aerotolerant anaerobes, common in the dairy industry, normal in GI and vagina, derives lactic acid from glucose

How does lactobacillus lead to infection?

It creates an acidic environment, inhibits growth of other bacteria, and then causes urogenital infections

Gram Positive Bacteria + Flashcards

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