Haemophilus somnus

From MicrobeWiki, the student-edited microbiology resource

A Microbial Biorealm page on the genus Haemophilus somnus


Higher order taxa

Haemophilus somnus is a bacteria under the phylum proteobacteria. It is of the class, Gammaproteobacteria, in the order Pasteurellales, which typically live on the mucosal surface of birds and mammals, most notably in the upper respiratory tract. They are also of the family Pasteurellaceae. genus Histophilus

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species somnus Lineage Bacteria; Proteobacteria; Gammaproteobacteria; Pasteurellales; Pasteurellaceae; Histophilus

NCBI: Taxonomy

Genus species

Description and significance

Describe the appearance, habitat, etc. of the organism, and why it is important enough to have its genome sequenced. Describe how and where it was isolated. Include a picture or two (with sources) if you can find them.

Genome Structure

Their genome (seq: RS: NC_008309) consists of a circular chromosome containing 2007700 base pairs and a plasmid(pHS129) is approximately 5178 bp in length. It is made up of roughly 34% GC content and 66% AT and contains genes coding for approximately 1798 different proteins and 65 RNA genes.

Cell structure and metabolism

Haemophilus somnus is a rod-shaped, gram negative bacteria. It is a facultative pathogen that has LOS is its major outer membrane component. It also contains bacterial transferrin receptors, which is a structure that contributes to its virulence (typically in cattle). Haemophilus has no flagella and is catalase negative.


Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.


How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Haemophilus somnus causes a wide variety of systemiatic diseases ranging from penumonia , abortion, arthritis, myocarditis, and septimia. It spreads throughout cattle herds in an elusive matter and become a major issue before it is even detected. There are 3 primary forms that h. somnus is able to assume: reproductive tract,urinary tract, respiratory tract form.

1.Reproductive and urinary tract form

In this form, h. somnus attacks the reproductive tract of pregnant cows, which may lead to the death of a fetus and subsequent abortion. This also causes the infection of the uterus and has been found in the urinary tract and prepuce of bulls which contracted the organism during mating. The excretion of uterine or vaginal discharge and urine of the infected animal also acts to transmit the disease to other unaffected cattle in close proximity, which become exposed to the organism by sniffing or by physically being contacted with the discharge. This can then lead to the respiratory form

2. Respiratory form p> The respiratory form of this infection is able to attack both the upper and lower portions of the respiratory tract. Typically in calves, the upper respiratory tract is infected causing what is known as calf diptheria. The surface tussues of the larynx, also known as the voice box, become infected due to the interuption in blood supply, causing the tissue to die and become degraded, making it extremely difficult to breath. If the disease continues, the windpipe may also become infected as will be the lungs. If the infection occurs in the lungs, pneumonia may be the result, which can cause rapid death. However, although this is typically the primary cause of pnemonia, it is often outgrown by other organisms such as Pasteurella multocida and Pasteurella haemolytica.

3. The septic form

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

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[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Edited by student of Rachel Larsen and Kit Pogliano