Mlt Microbiology (Week 03B)

Front 1

Staphylococcaceae Colonial Morphology

Back 1

Small-medium, white, opaque colonies. Staph aureus is beta, all others are non-hemolytic.

Front 2

Staph Morphology and Gram Stain Reaction

Back 2

GPC, larger than strep, in grape-like clusters.

Front 3

Staph Family Characteristics

Back 3

Staph are non-spore forming, non-motile, catalase positive, salt tolerant bacteria.

Front 4

Occurrence of Staph

Back 4

Occurs basically anywhere that isn't sterile. Nearly any specimen may contain staph, as it's very hardy.

On the body it's commonly found on the anterior nares (nose,) axillae (armpits,) inguinal and perineal areads, toe-webs, face, and uroepithelial tishue (particularly urethra.)

Front 5

Pathogenic Staphylococci

Back 5

Primary

• Staphylococcus aureus

Opportunistic (not normally disease causing, but potential)

• Staphylococcus epidermidis
• Staph saprophyticus
• Staph intermedius
• Staph lugdunesis
• Staph schleiferi

Front 6

Media commonly used for Staph

Back 6

Selective/Differential

• Phenylethyl alcohol agar (PEA)
• Columbia nalidixic acid agar (CNA)
• Mannitol-salt agar (MSA)

Staph is a facultative anaerobe.

Front 7

Staph Toxins & Enzymes

Back 7

Has encapsulation!

Toxins

• Hemolysins (Alpha hemolysins, destroy platelets and cause severe tissue damage.) (Beta hemolysins, acts on sphingomyelin of RBC membrane.) (Gamma hemolysins, less toxic, but effects WBC's as well.)
• Leukocydins (Destroy WBC's.) (PVL - Panton-Valentine Leukocydin, is very potent.)
• Enterotoxins (act on intestines. Most common is enterotoxin A. Food poisoning is preformed toxin, and not an active infection. Staph aureus is the most common cause of food poisoning in the US.)
• Exfoliation (Skin sloughs off. Scalded skin syndrome.)

Enzymes

• Coagulase
• Penicillinase (breaks down penicillin)
• DNAase (DNA thermonuclease, heat stable)
• Phosphatase, lipase, staphylokinase, etc

Protein A (Very important antigen for testing. Causes antigens to bond backwards.)

Adhesins (Allows bacteria to attach to host cells.)

Also causes TSST-1: toxic shock syndrome. Stimulates body's immune system.

Front 8

Predisposing Conditions for Acquiring Staph Infections

Back 8

• Injury to normal skin
• Prior viral infection
• Presence of foreign bodies (implants, etc)
• Leukocyte defects
• Deficiencies in humoral immunity

Front 9

Staph Food Poisoning

Back 9

Ingestion of preformed enterotoxin.

Front 10

Coagulase Negative Staphylococci

Back 10

This includes everything but Staph aureus.

• They are primarily opportunistic
• Alteration of normal skin integrity (implantations, surgery, trauma)
• 40% of prosthetic heart valve endocarditis is due to Staph epidermidis
• Staph saprophyticus is a major cause of UTI in young, sexually active women.

Front 11

Coagulase Test

Back 11

Slide test is for bound coagulase (clumping factor.) Apparently not a very good test.

Tube test for free coagulase - definitive ID of Staph aureus. Clumping at the bottom of the tube is a positive result.

Front 12

Staph Latex Test

Back 12

Latex agglutination tests for clumping factor and protein A, and/or surface antigens. It is coated with anti-protein A antibodies.

Agglutination occurs when there is a presence of Staph aureus.