Haemophilus aegyptius

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1. Classification

a. Higher order taxa Bacteria, Proteobacteria, Gamma Proteobacteria, Pasteurellales, Pasteurellacease, Haemophilus (1)

b. Species Haemophilus Influenzae (1)

2. Description and significance

Haemophilus influenzae biogroup aegyptius is a Gram-negative bacterium with an elongated rod shape (2). H. aegyptius is normally found living in human epithelial cell linings (10), where it exhibits colonization and adherence to epithelial cells with large clusters of elongated chains of cells (2). As a biogroup, H. influenzae biogroup aegyptius has traits that differ from Haemophilus influenzae (H. influenzae), including the severity of virulence and lack of genes that encode for a polysaccharide capsule (3) in H. influenzae biogroup aegyptius. For over a century since its first discovery, H. influenzae biogroup aegyptius had only been known to cause conjunctivitis. However, in 1995, the HaeBPF strain of H. influenzae biogroup aegyptius (3) was identified in patients with Brazilian Purpuric Fever (BPF) (4). BPF has symptoms that are similar to that of meningococcal sepsis, which include an infection that results in high fever, vomiting, abdominal pain, and hemorrhagic skin lesions (5). Researchers have spent over two decades learning about the transformation of H. influenzae biogroup aegyptius from causing mild conjunctivitis to deadly BPF. However, much is still unknown about the organism’s virulence factors (6). Because of this, studies have been focused on understanding the mechanism of pathogenesis and developing preventative measures and treatments for BPF.

3. Genome structure

The Haemophilus influenzae biogroup aegyptius genome, or F3031 genome, contains 77% shared sequences with other H. influenzae genomes (4). The Hae accessory genome sequences were delineated and 163 protein-coding genes were characterized as adhesins and fimbrial operons (3). The Haemophilus influenzae biogroup aegyptius genome includes 3031 plasmids, and sequences coding for pilin proteins (6).

Unique genes sequences to the genome of H. influenzae biogroup aegyptius are: the bpf001 and bpf002 genes, which are associated with Brazilian Purpuric Fever (BPF) (4), and the Haemophilus adhesin A gene (HadA) (7). bpf001 and bpf002 code for proteins that enhance epithelial cell entry, correlating with cell invasion of human respiratory epithelial cells during the pathogenesis of BPF (4). The HadA gene codes for an adhesion protein that is associated with adherence to extracellular matrix proteins of human cells during the onset of BPF (7).

There has been evidence of exchange of the Las gene between H. influenzae biogroup aegyptius and Neisseria meningitidis, a bacterium that causes brain and spinal cord inflammation (5).

4. Cell structure

Interesting features of cell structure. Can be combined with “metabolic processes”

5. Metabolic processes

Describe important sources of energy, electrons, and carbon (i.e. trophy) for the organism/organisms you are focusing on, as well as important molecules it/they synthesize(s).

6. Ecology

Habitat; symbiosis; contributions to the environment.

7. Pathology

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

7. Key microorganisms

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8. Current Research

Include information about how this microbe (or related microbes) are currently being studied and for what purpose

9. References

It is required that you add at least five primary research articles (in same format as the sample reference below) that corresponds to the info that you added to this page. [Sample reference] Faller, A., and Schleifer, K. "Modified Oxidase and Benzidine Tests for Separation of Staphylococci from Micrococci". Journal of Clinical Microbiology. 1981. Volume 13. p. 1031-1035.