Golden yellow pigment of Staphylococcus aureus: Introduction and pathogenecity

Golden yellow pigment of Staphylococcus aureus

Pigment of Staphylococcus

Golden yellow pigment of Staphylococcus  aureus which is ATCC strain 25923 as shown above picture.

Staphylococcus aureus


Spherical, non motile, gram positive, cluster forming. On nutrient agar , growth is opaque and golden yellow or white color. Catalase test positive, coagulase test positive, oxidase negative , aerobic or facultative anaerobe. Parasite of human and animal.


Normal flora of skin, upper respiratory tract  and feces of human, animal and birds too.


Round or spherical arranged in clusters.

0.8-1.0 μm

Non motile, non sporing, usually non encapsulate while some strains are encapsulate. Capsule is of two types

Micro capsule <200 nm

Macro capsule >200 nm and is responsible for slime layer

Cultural characteristics

On nutrient agar

  • Smooth, circular, often yellow pigmented colonies and non diffusible.
  • 1-2 mm in diameter
  • Butyrous in consistency

On blood agar

Beta haemolytic


Golden yellow and increased in the presence of CO2 and also at room temperature. Pigmentation can be induced by culturing bacteria into 30% milk agar, potato and 1% glycerol monoacetate or phosphate agar.

Selective media for Staphylococcus

  1. 7-10% salt agar
  2. Mannitol salt agar
  3. Tellurite glycine agar
  4. Phenolphthalien phosphate agar
  5. Polymyxin B agar (75 μg/ml)

Note: Staphylococcus aureus grow well on this medium but coagulase negative Staphylococci (CoNS) can not grow.


Thermal death point of Staphylococcus aureus  is 60°C for 30 minutes.

It can survive in dried pus for 2-3 months.

Cell wall

Protein -A: It has specific affinity for Fc portion of the IgG molecule (except Ig3) leaving the Fab region free to combine with its specific antigen resulting in agglutination known as coagglutination. Peptidoglycan of cell  activates complement and induces release of inflammatory cytokines. Similarly teichoic acid of cell wall facilitates  adhesion of the cocci to the host cell surface.

Phage types

With the use of 28 phages, several hundred phage types have been identified among them important phage types are-

Group 1: 8052A/79 (Hospital strains)

Group 2: 3B/3C/55 (Impetigo / Staphyococcal Scalded Syndrome)

Group 3: 6/47 (Enterotoxin producer)


There are 30 serotypes based on protein A antigen.

Enzyme and toxins


Haemolysin: alpha, beta, gamma


Enterotoxin A-F

Type A and B are responsible for food poisoning.

25 µg of toxin B can cause food poisoning.

Epidermolytic  toxin: It is responsible for Staphylococcal Scalded Syndrome (SSS) or Ritter’s disease.

Toxic Shock Syndrome Toxin (TSST): Type -F


Coagulase : It is of two types bound and free coagulase.







Pathogenecity of  Staphylococcus aureus

Staphylococcus aureus can cause following diseases-

  1. Abscess
  2. Conjunctivitis
  3. Corneal ulcer
  4. Septicemia
  5. Endocarditis
  6. Pneumonia
  7. Mastitis: It is an inflammation of breast.
  8. Empyemia : It is accumulation  of pus in the body cavity.
  9. Food poisoning
  10. Staphylococcal Scalded Syndrome
  11. Toxic Shock Syndrome (TSS)-enterotoxin F
  12. Septic arthritis
  13. Meningitis
  14. Osteomyelitis


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