This document discusses Staphylococcus aureus, a gram-positive bacterium commonly found on human skin and in the environment. S. aureus can cause a variety of infections through adherence to skin or mucosa and releasing toxins. It is identified by being catalase-positive, coagulase-positive, and able to grow in 7.5% sodium chloride. S. aureus infections include skin infections like boils and impetigo, deep infections like osteomyelitis and endocarditis, and toxin-mediated diseases like toxic shock syndrome and food poisoning.

1. STAPHYLOCOCCUS AUREUS
Infection
Amjad Khan Afridi
Lecturer,
Department of Health & Biological Sciences
Abasyn University Peshawar
Chapter # 4

3. STAPHYLOCOCCUS AUREUS BASIC CHARACTERISTICS
• Description
• The term ‘aureus’ is derived from Latin, which refers to the color of gold.
• Gram-positive round shape (coccus) in clusters.
• Non-motile.
• Non-spore-forming.
• Catalase: Positive.
• Coagulase: Positive
• Oxidase: Negative.
• Urease: Positive
• Facultatively anaerobic

4. Staphylococcus species
• 61 species
• Important
• S. aureus
• S. epidermidis
• S. saprophyticus
• S. pseudointermedius
• Others
• S. haemolyticus
• S. capitus
• S. hominis
• S. xylosis
• S. warneri

5. Ecology
• Staphylococcus aureus is a gram positive bacterium that is usually
found in the nasal passages, mouth, throat etc.
• And on the skin of 15 to 40% of healthy humans, but can also survive
in a wide variety of locations in the body.
• Commonly found in the environment (air, water & soil).

6. General cultural and biochemical characteristics
• S. aureus is an aerobic and facultative anaerobic organism
that forms fairly large yellow or white colonies on Nutrient
agar media.
• The yellow color of the colonies is reported by carotenoids
produced by the organism.
• The term ‘aureus’ is derived from Latin, which refers to the
color of gold.

7. • The organism is often haemolytic in blood agar due to production of
haemolysins (alpha, beta, gamma). Leukocidin- hemolysis
• Nearly all isolates of S. aureus produce coagulase enzyme, that also helps in
identification of the organism.
• The organism is able to grow in mannitol-salt agar medium containing 7.5%
sodium chloride.

8. Epidemiology
• Normal microbiota
• Direct transmission
• Portal of Entry
• Hair follicle
• Break in skin
• Respiratory
• Complications
• Bacteremia
• Septicemia
• Abscess

9. PATHOGENESIS
1. Adherence
• Attached to the damaged sites ( Skin, mucosa, tissue etc.)
• At these sites, bacteria evade defence mechanisms of the host in the result
colonize and cause tissue damaged.
• S. aureus produced disease by;
• 2. Entry
• 3. Multiplying in tissue
• 4. Releasing toxins

10. Clinical Syndromes
1. Cutaneous Infections
• Folliculitis
• Boils/Furuncles
• Carbuncle
• Impetigo
2. Deep Infections
1. Osteomyelitis
2. Endocarditis
3. Toxin Shock syndrome
4. Staphylococcal food Intoxication

16. 3. Toxic Shock
Syndrome

17. 4. Staphylococcal Food Poisoning

21. Laboratory Diagnosis

25. Thank You
6
th
April,
2022