12 plus species including:


Klebsiella aerogenes (UK)
Klebsiella oxytoca
Klebsiella ozaenae
Klebsiella planticola
Klebsiella pneumoniae (USA)
Klebsiella rhinoscleromatis
Klebsiella terrigena


Gram Stain: Negative.
Morphology: Rod-shaped; singly and in pairs or short chains.
Size: 0.3-1.0 micrometers by 0.6-6.0 micrometers.
Motility: Non-motile.
Capsules: Yes.
Spores: None.


Encapsulated. Commonly seen are muccoid colonies with a viscid consistency. The capsular material also diffuses freely into the surrounding liquid medium as extracellular capsular material.



Facultatively anaerobic. Chemoorganotrophic; respiratory and fermentative types of metabolism. Most species ferment all carbohydrates except dulcitol and erythritol.


Klebsiella species are distributed in a wide variety of environments including: the gastrointestinal tract, clinical specimens, soil, water and grain.


Klebsiellae are opportunistic pathogens that can give rise to bacteremia, pneumonia, urinary tract and several other types of human infection. In recent years there has been an increase in Klebsiella infections, particularly in hospitals, due to strains with multiple antibiotic resistance. The gastrointestinal tract is considered to be the main reserve and the hands of the personnel the main factor of transmission. (2) Environmental strains, which grow at 10 degrees C., are probably not pathogenic.


For culture: Tryptic Soy Agar, Brain Heart Infusion (BHI) Agar, Blood Agar 5%.
For selective isolation: Methyl Violet / Double Violet or MacConkey Agar. (2)
For maintenance: Tryptic Soy Agar or Brain Heart Infusion (BHI) Agar. Brucella with 20% Glycerol may be used for long-term storage at -70 degrees C. Lyophilization may also be use for preservation.


Temperature: 35 degrees C. (clinical samples) and 10 degrees C. (environmental samples).
Time: 24-48 hours.
Atmosphere: Aerobic.


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.