Gram Positive Bacteria

Question 1

What are some defining characteristics of Staphylococus Aureus? Virulence factors

Answer 1

Normal human microbiota, but opotunistic pathogens.

Gram-positive, nonmotile, cocci. Evades phagocytosis, produces enzymes and toxins.

Question 2

What are the diseases S. Aureus can cause?

Answer 2

1. Food poisoning by enterotoxin production.
2. Colitis if during antibiotic treatment they overgrow and produce enterotoxin B.
3. Impetigo (Furnuncle, Carbuncle).
4. Scalded skin syndrome.
5. Toxic shock syndrome, Bacteremia (blood), endocarditis, pneumonia, Osteomyelitis (bone marrow)

Question 3

What are some defining characteristics of Streptococcus Pyogenes? Virulence factors?

Answer 3

Gram-possitive cocci. White colonies surrounded by zone of beta-hemolysis. Often has a capsule. Depletes normal microbiota, established before antibodies form, and impairs specific immunity.

Question 4

What are some Diseases caused by S. Pyogenes?

Answer 4

Pharyngitis (strep throat), Scarlet fever, Impetigo, Erysipelas, TSS, Necrotizing Fasciitis.

Question 5

What are postreptococcal Sequelae examples?

Answer 5

1. Rheumatic fever linked to GAS pharyngitis. leads to damage of heart valves. Type II HS
2. Glomerulonephritis linked to GAS-pharyngitis or skin infection. Leads to inflammation of glomeruli and nephrons and obstruct blood flow to kidneys. Type II or Type III HS.

Question 6

What are some characteristics of Alpha-Hemolytic Strep (The viridans)? what can they cause?

Answer 6

Can’t be grouped in lancefield system. Produce green discoloration when brown on blood media. Major role in dental caries and plaque.
Can cause Meningitis and Endocarditis.

Question 7

What are some characteristics of S. Pneumoniae? Virulence factors?

Answer 7

Gram-positive cocci. Forms unpigmented colonies when grown on blood agar. Leading cause of death before antibiotics. Large polysaccharide capsule that protects from immune system.

Question 8

What are some diseases caused by S. Pneumoniae?

Answer 8

Pneumococcal pneumonia, Sinusitis and otitis media, Bacteremia and endocarditis, meningitis.

Question 9

What are some characteristics of Enterrococcus? Virulence factors?

Answer 9

Gram-possitive, lack a capsule. Found in colon. Resistant to a lot of treatments.

Question 10

What are some diseases Enterococcus can cause?

Answer 10

UTI, Bateremia, endocarditis, wound infections.

Question 11

What are some characteristics of Bacillus Anthracis? Virulent factor?

Answer 11

Gram-positive bacilli, forms endospores. Virulence due to 3 component toxin and protein capsule.

Question 12

What are some characteristics of Clostridium perfringens?

Answer 12

Gram-possitive, anaerobic, endospore forming. In soil, water, and GI tract of animals and humans. produces 11 toxins.

Question 13

C. Perfringens causes what diseases?

Answer 13

Food poisoning by enterotoxin.

Gas gangrene.

Question 14

What are some characteristics of Clostridium Difficile? Causes what?

Answer 14

Common intestinal microbiota. Opportunistic. Fecal Transplants for treatment. Causes Pseudomembranous Colitis.

Question 15

What are some characteristics of C. Botulinum? Causes?

Answer 15

Forms a preformed toxin that can be ingested or open wound. Causes botulism.

Question 16

What are some characteristics of Clostridium tetani? Causes.

Answer 16

Endospore forming, gram positive rod. Soil, dust, GI tract. Endospores germinate and form tetanus toxin. Causes tetanus.

Question 17

What are some characteristics of Listeria Monocytogenes?

Answer 17

Gram-positive, non spore forming, coccobacillus. found in soil, water, mammals, birds, fish, insects, Enters by contaminated food and drink. Produces no toxins or enzymes, but virulent through its ability to live in cells.
Polymerizes host cell actin to move around quickly.

Question 18

What are some characteristics of Corynebacterium Diphtheriae?

Answer 18

Transmitted thorugh respiratory droplets. Forms a pseudomembrane from dead cells and fluid that can block the respiratory tract.

Question 19

What are some characteristics of Propionibacterium? Causes?

Answer 19

Small, gram-positive rods found on skin. P. Acnes is most common and causes acne.

Question 20

What are some characteristics of Actinomyces?

Answer 20

Anaerobic gram positive filamentous bacilli. Major component of dental plaque and associated with gingivitis and root caries.

Question 21

What are Nocarida?

Answer 21

Soil saprophytes that cause nocardiosis.

Question 22

What are Streptomyces?

Answer 22

Filmamentous branching soil bacilli that make most of our antibiotics.