Hemolysins in S. aureus

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What color do inflammatory cells, background tissue debris, and proteinaceous material generally stain in properly gram stained specimens?

Pink to red

What type of medium is Blood agar medium (BAM)?

Enriched medium

What does Mannitol salt agar (MSA) select for?

Staphylococci

What inhibits the growth of other organisms in Mannitol salt agar (MSA)?

High salt concentration (7.5% NaCl) Signup and view all the answers

What color does Mannitol fermentation result in on Mannitol salt agar (MSA)?

Yellow Signup and view all the answers

What does the high salt concentration in Mannitol salt agar (MSA) selectively allow the growth of?

Halotolerant staphylococci Signup and view all the answers

How are Staphylococcal colonies described in terms of size and color?

Medium to large (1-2 mm in diameter), off-white or gray Signup and view all the answers

What distinguishes some S.aureus colonies?

They produce golden yellow pigments 'lipochrome' Signup and view all the answers

What is the significance of the name 'aureus'?

It means 'golden' Signup and view all the answers

Describe the colonies produced by S.epidermidis.

Small to medium, opaque, gray-white Signup and view all the answers

What distinguishes colonies of S.saprophyticus?

They are large, very glossy, smooth, opaque, butyrous, convex Signup and view all the answers

What do Mannitol-fermenting staphylococci produce on MSA?

Yellow colonies with yellow discoloration of the medium Signup and view all the answers

What is the purpose of colistin and nalidixic acid in Columbia CNA Agar?

To render the medium selective for G+ bacteria by inhibiting G- bacteria. Signup and view all the answers

Why should PEA Agar not be used for determination of hemolytic reactions?

Atypical reactions may be observed. Signup and view all the answers

How is the selectivity of Vogel-Johnson (VJ) Agar achieved?

Through potassium tellurite, lithium chloride, and glycine which inhibit nonstaphylococcal organisms, both G+ and G- bacteria. Signup and view all the answers

What is the indicator of acid production in Vogel-Johnson (VJ) Agar?

Phenol red Signup and view all the answers

How does S.aureus produce distinctive colonies on Vogel-Johnson (VJ) Agar?

By reducing tellurite to metallic tellurium, resulting in black or gray-black colonies. Signup and view all the answers

Why is it important to have the prior written permission of SLU before reproducing or distributing the document?

Because the document is the property of SLU and is for their exclusive use. Signup and view all the answers

What role does δ-Hemolysin play in S.aureus infections?

Acts primarily as a surfactant or a detergent-like molecule that interacts with cell membranes and forms channels resulting in slow leakage of cellular contents. Signup and view all the answers

What is the composition of γ-Hemolysin and how does it affect white blood cells?

Composed of two proteins designated S and F. It lyses white blood cells by causing pore formation in the cellular membranes, increasing cation permeability, leading to degranulation, cell swelling, and lysis. Signup and view all the answers

What is the function of Panton-Valentine Leukocidin (PVL) and how does it affect neutrophils?

PVL is produced by lysogenized strains of S.aureus and is active against neutrophils, causing tissue necrosis. It consists of two components, S and F, that act synergistically on the white blood cell membrane. Signup and view all the answers

What is Toxic Shock Syndrome Toxin (TSST-1) and how does it contribute to toxic shock syndrome?

TSST-1 is a superantigen that promotes the manifestations of toxic shock syndrome. It stimulates T cells non-specifically, resulting in polyclonal T-cell activation. Signup and view all the answers

What is the mechanism of action of superantigens like TSST-1 on T cells?

Superantigens stimulate T cells non-specifically by directly cross-linking T-cell receptor (TCR) to MHC class II molecules on APCs outside of the antigen-binding site. Signup and view all the answers

What cellular effects are observed when γ-Hemolysin affects white blood cells?

Affected cells undergo degranulation of the cytoplasm, cell swelling, and lysis. Signup and view all the answers

What is the purpose of the Oxidation-Fermentation (O-F) test?

To determine whether bacteria can utilize glucose in the presence or absence of oxygen. Signup and view all the answers

How is the O-F test set up?

Two tubes are inoculated by stabbing; one tube is overlaid with sterile mineral oil (closed tube) and the other tube is exposed to oxygen (open tube). Signup and view all the answers

Why does the medium in the open tube turn yellow for Micrococci?

Because Micrococci are oxidative, producing acids from glucose only in the presence of oxygen. Signup and view all the answers

What type of bacteria are Staphylococci in terms of utilizing glucose?

Staphylococci are fermentative, utilizing glucose and producing acids in both presence and absence of oxygen. Signup and view all the answers

How can you differentiate Staphylococci using the O-F test?

Staphylococci can be differentiated by the yellow color change of the medium in both open and closed tubes due to bound coagulase production. Signup and view all the answers