STAPHYLOCOCCUS

50 plus species including:

SPECIES

MICROSCOPIC APPEARANCE

Gram Stain: Positive.
Morphology: Spherical cocci; often forming regular and "grape-like" clusters. They occur singly, in pairs, tetrads, and short chains.
Size: 0.5 by 1.5 micrometers.
Motility: Non-motile.
Capsules: Usually encapsulated, however, limited capsule formation has been noted on some species.
Spores: None.
Other: Some uncommon strains of staphylococci may require the presence of CO 2 or other metabolites (hemin, menadione, etc.) or a hypertonic medium for growth.

MACROSCOPIC APPEARANCE

Some unusual strains produce dwarf colonies. Most colonies appear relatively smooth, glossy, butyrous, and sometimes appearing wet. Colonies of most strains are usually opaque and may be pigmented white or cream and sometimes yellow to orange.

METABOLIC PROPERTIES

Facultatively anaerobic. Chemoorganotrophic, having both a fermentative and respiratory type metabolism.

KEY BIOCHEMICAL REACTIONS

HABITAT

Mainly associated with skin, glands and mucous membranes of mammals and birds. Often found in the mouth, blood, mammary glands, intestinal and respiratory tracts of humans and warm-blooded animals. Frequently, non-human primates carry large populations of S . aureus in the nares and on the skin. Species have been isolated from food products, dust, and water.

PATHOGENICITY

Some species produce extracellular toxins. S. aureus is a potential pathogen causing a wide range of infections. Some of the major infections involve the skin and include furuncles or boils, cellulitis, impetigo, toxic epidermal necrolysis, scalded skin syndrome, and postoperative wound infections or of various sites. Other major infections produced by S. aureus include bacteremia, pneumonia, osteomyelitis, acute endocarditis, myocarditis, cervicitis, cerebritis, meningitis, and abscesses of the muscle, urogenital tract, central nervous system, and various intra-abdominal organs. Food poisoning is often attributed to staphylococcal enterotoxin.

RECOMMENDED MEDIA

For culture: Tryptic Soy Agar, Brain Heart Infusion Agar (BHI), Blood Agar 5%.
For selective isolation: Columbia CNA Agar, Rose Agar, PNBA Agar, Mannitol Salt Agar and Baird-Parker Agar.
For maintenance: Tryptic Soy Agar, Blood Agar for routine maintenance. Brucella with 20% Glycerol or Skim Milk for long-term storage at -70 degrees C. Lyophilization may be used for preservation.

INCUBATION

Temperature: 30-37 degrees C.
(Optimal growth occurs in most species in 10% CO 2 ).
Time: 18-48 hours.
Atmosphere: Aerobic.

REFERENCES

1. Holt, J.G., et al. 1994. Bergey's Manual of Determinative Bacteriology , 9th ed. Williams & Wilkins, Baltimore, MD.

2. Holt, J.G., et al. 1986. Bergey's Manual of Systemic Bacteriology , Vol. I & II. Williams & Wilkins, Baltimore, MD.

3. The Oxoid Vade-Mecum of Microbiology . 1993. Unipath Ltd., Basingstoke, UK.

4. Murray, P.R., et al. 1995. Manual of Clinical Microbiology , 6th ed. American Society for Microbiology, Washington, D.C.

5. Internet: www.hardlink.com /Bacterial Database Search, February, 1998.

6. Hensyl, B.R., et al. 1990. Stedman's Medical Dictionary , 25th ed. Williams & Wilkins, Baltimore, MD.

7. Koneman, et al. 1997. Color Atlas and Textbook of Diagnostic Microbiology , 5th ed. Lippincott, Philadelphia, PA.


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