1. Staph Infection and MRSA Staphylococcus aureus
Emily Jewell

2. Facultative Anaerobes
Cocci
Catalase positive
Gram positive
Facultative Anaerobes

3. Reservoirs Humans (Healthy) Humans (Infected) Contaminated food
Skin –armpits, under breasts, groin
Nose –mucosa
Humans (Infected)
Skin lesions, blood
Respiratory mucosa
Contaminated food
Animals
Fur, skin
Athletic equiptment
Fomites
Staph infections turn deadly if the bacteria invade deeper –into the bloodstream, joints, bones, lungs, or heart

4. Transmission Auto-infection –infecting oneself
Person to person –spread via skin-to-skin contact, or sharing towels, sports equiptment, swimming pools, etc
Pets –S. aureus may be found on skin, hair, nostrils or saliva of animals
Food poisoning –food contaminated with staphylococci released from an infected worker
The bacteria enter the body through the skin and respiratory tract.

5. Mode of Action
Enzymes
Coagulase –clots plasma, coats bacterial cell to prevent phagocytosis
Hyaluronidase –breaks down hyaluronic acid to aid spread of bacteria
Deoxyribonuclease
Lipase
Staphylokinase –dissolves fibrin, aids spread
Betalactamase –drug resistance

6. Mode of Action Continued
Toxins
Exotoxins
Protein A
Anchored in bacterial cell wall
IgG-binding protein
Staphyloxanthin
Golden carotenoid pigment
Virulence factor
Bacterial antioxidant, helps evade the ROS (reactive oxygen species) that host uses to kill pathogens

7. Biological Effects –vary widely
Boils –pus pockets develop in follicles or oil glands
Impetigo –rash, oozing blisters
Cellulitis –infection of deeper layers of skin, redness and swelling
Staphylococcal scalded skin syndrome –from toxins  fever, rash, blisters
Blood poisoning
Food poisoning –typical symptoms, onset within hours
Toxic shock syndrome
Septic arthritis

9. Treatment Antibiotics Penicillin
Many bacteria are resistant to penicillin, other antibiotics include: oxacillin or flucloxacillin

10. MRSA Methycillin Resistant Staphylococcus aureus
Caused by inc. use of antibiotics
Penicillinase (a form of ß-lactamase) –cleaves the ß-lactam ring of penicillin
Hospitals
Strain that is resistant to ß-lactam antibiotics
Vancomycin is used to combat
Glycopeptide antibiotic
Inhibits synthesis of peptidoglycan by targeting and binding to amino acids in the bacterial cell wall –preventing cross-linkages from forming