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

Definition

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.

Habitat

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

Morphology

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

Pigmentation

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.

Resistance 

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)

Serotype

There are 30 serotypes based on protein A antigen.

Enzyme and toxins

Toxins

Haemolysin: alpha, beta, gamma

Leucodin

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

Enzymes

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

Phosphatase

DNAse

Staphylokinase

Hyluronidase

Lipase

Prptease

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

References

  1. Bailey & Scott’s Diagnostic Microbiology. Editors: Bettey A. Forbes, Daniel F. Sahm & Alice S. Weissfeld, 12th ed 2007, Publisher Elsevier.
  2. Clinical Microbiology Procedure Hand book , Chief in editor H.D. Isenberg, Albert Einstein College of Medicine, New York, Publisher ASM (American Society for Microbiology), Washington DC.
  3. Colour Atlas and Text book of Diagnostic Microbiology. Editors: Koneman E.W., Allen D.D., Dowell V.R. Jr and Sommers H.M.
  4. Jawetz, Melnick and Adelberg’s Medical Microbiology. Editors: Geo. F. Brook, Janet S. Butel & Stephen A. Morse, 21st ed 1998, Publisher Appleton & Lance, Co Stamford Connecticut.
  5. Mackie and Mc Cartney Practical Medical Microbiology. Editors: J.G. Colle, A.G. Fraser, B.P. Marmion, A. Simmous, 4th ed, Publisher Churchill Living Stone, New York, Melborne, Sans Franscisco 1996.
  6.  Manual of Clinical Microbiology. Editors: P.R. Murray, E. J. Baron, M. A. Pfaller, F. C. Tenover and R. H. Yolken, 7th ed 2005, Publisher ASM, USA
  7.  Text book of Diagnostic Microbiology. Editors: Connie R. Mahon, Donald G. Lehman & George Manuselis, 3rd edition2007, Publisher Elsevier.
  8. District Laboratory Practice in  Tropical Countries  –  Part-2-   Monica Cheesebrough-   2nd Edn Update
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