[BIO 120.3] Q1: Gram Positive Cocci - Staphylococci

Cocci, Grape-like clusters

What is the morphology of Staphylococcus spp.?

Catalase (+), B-hemolytic (S. aureus), Coagulase (+) ONLY for S. aureus

Describe the metabolism of Staphylococcus spp. (catalase, hemolysis, coagulase)

Staphylococcus spp. are resistant to Penicillin

Why is it important to distinguish between Staph and Strep in a clinical setting?

Gram Staining, Catalase, Cultures

What are 3 diagnostic methods for Staphylococcus spp.?

Golden appearance

Aside from clear zones (beta-hemolysis), what is another indication that the colonies grown in BPA are S. aureus?

Protein A, Protective

[SA] Identify the Virulence Factor and Category: Binds IgG, prevents phagocytosis

Coagulase, Protective

[SA] Identify the Virulence Factor and Category: Induces clots, protection from phagocytosis

Hemolysins, Protective

[SA] Identify the Virulence Factor and Category: Destroys RBCs, neutrophils, macrophages, platelets

Leukocidins, Protective

[SA] Identify the Virulence Factor and Category: Destroys WBCs

Penicillinase, Protective

[SA] Identify the Virulence Factor and Category: Inactivates penicillin

Hyaluronidase, Tissue-destroying

[SA] Identify the Virulence Factor and Category: Breaks down hyaluronic acid

Staphylokinase, Tissue-destroying

[SA] Identify the Virulence Factor and Category: Lyses formed fibrin clots

Protease, Tissue-destroying

[SA] Identify the Virulence Factor and Category: Destroys tissue proteins

Lipase, Tissue-destroying

[SA] Identify the Virulence Factor and Category: Degrades fats and oils on skin

Beta-lactamase enzyme

Penicillinase is what kind of enzyme?

Protective, Tissue-destroying, Toxins

What are the three categories of virulence factors for S. aureus?

Enterotoxin (food poisoning), TSST-1 (superantigen), Exfoliatin

What are three (3) toxins produced by S. aureus as virulence factors?

20%

TSST-1 has been found in how many % of S. aureus isolates?

Scalded skin syndrome

Exfoliatin as an S. aureus toxin causes what?

Gastroenteritis, TSS, Staphylococcal Scalded Skin Syndrome (Ritter Disease)

What are 3 clinical findings due to exotoxins by S. aureus?

Ritter's Disease

Similar in pathogenesis with TSS, but it produces exfoliatin toxins A and B and establishes a localized infection.

Ritter's Disease

Characterized by cleavage of epidermis, with fine sheets of skin peeling off to reveal red moist skin.

Can infect neonates with a local infection of recently severed umbilicus

How are neonates affected by Ritter's Disease?

Pneumonia, Meningitis, Acute Bacterial Endocarditis, UTI

What are 5 examples of diseases caused by direct invasion of S. aureus?

Bacterial endocarditis in S. aureus is acute (sudden onset), no need for prior history of heart valve damage

What distinguishes the bacterial endocarditis in S. aureus to bacterial endocarditis in Viridans?

Cleaning of the wound, 1st gen cephalosporins, Clindamycin

What are 3 treatments for S. aureus

It is the accumulation of the exotoxins that are causing the symptoms, not the microorganism itself

Why are antibiotics prescribed for S. aureus not curative (does not kill microorganism)?

Gram stain, Culture (B-hemolytic, golden yellow pigment), Catalase (+), Coagulase (+)

What are 4 diagnostics measures for S. aureus?