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Microbiology
Micrococci + Catalase Streptococci
(clumps, clusters) (chains)
Differentiation of micrococci
Micrococcns S. aureus Coag-Staph
Catalase + + +
Hemolysis ~ +(-) .(+)
Pigment Yellow, Pink (Golden) Yellow, white
Lysostaphin Resistant + _
Bacitracin Resistant + _
Coagulase/Clumping Factor + _
Mannitol-salt + _
Virulence Factors staphylococcal infections, flesh eating bacteria
Factor Location Action Pathophysiology
Cell Wall:
Capsule Cell wall Protect from
Protein A Cell wall Binds IgG Protect from phagocytosis
Clumping factor Cell wall Binds Fibrin Large clumps
Enzymes:
Coagulase Soluble Clots plasma Abscess wall
Leukocidin Soluble Destroys PMMs Protects from phagocytosis
Hemolysins Soluble Cytotoxic Tissue damage
Lipase Soluble Lipolysis Skin infection
Beta-lactamase Soluble Penase Pen G resistance
Toxins:
Enterotoxin A-E Soluble Vagal stimulator Food poisoning
Exfoliatin A-B Soluble -cell layer cleavage Scalded Skin Syndrome
TSST- 1 Soluble /. TNF, IL-1 stimulator TSS
Epidemiology
A. Normal Flora - Anterior nares, skin, vagina
B. Strain Differential (Examples)
Group Phage Type Disease
I 80/81 Severe Newborn Infection
29/52/52A/79/80 TS S
II 3A/3C Scalded Skin Syndrome
*Strain cycles occur every 5 - 10 years
C. Predisposing conditions:
Neutophil Abnormalities (Job's Syndrome, CGD)
Skin injury (burn, wounds, foreign body, indwelling lines)
Underlying Diseases (Malignancy, Diabetes)
Antimicrobial use
Clinical Syndromes
Invasive Food Poisoning Scalded Skin Toxic Shock
Virulence Factors Capsule Enterotoxins Exfoliatins TSST -1
Clumping Factor Enterotoxins
Coagulase
Protein A
Leukocidin
Hemolysins
Clinical Findings Cellulitis Vomiting Painful Shock
Abscess Diarrhea Erythroderma Erythroderma
Pneumonia + Nikolsly sign Organ failure
Arthritis Bullous Impetigo
Osteomyelitis
Diagnosis Culture Food Clinical Clinical
Focus Culture Culture (focus, vagina)
Treatment Drain Fluids Antibiotics Drain Focus
Antibiotics Patience Antibiotics
Fluids
(Steroids)
TSS Definition
Major Criteria (all required)
Acute fever
Hypotension (orthostatic or shock)
Rash (late desquamation)
Minor Criteria (any 3)
Mucous membrane inflammation Liver abnormalities Renal abnormalities Muscle abnormalities CNS abnormalities Low platelet count
Exclusionary Criteria
Absence of other explanation
Negative blood cultures (except for S. aureus)
B. TSS Model Reproduced with permission from
Infection
Vagina (no menses)Focal Infection
Osteomyelitis