H. influenzae: Difference between revisions

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haemophilus influenzae is a bacteria and thus exhibits characteristics of a prokaryotic cell. it was identified as a gram negative bacteria because of its response to Gram staining techniques, as it stains red. the gram negative coccobacillus has important cell wall components that play a role in its survival and its pathogenicity. H. influenzae bacteria consist of various strains based on the presence or absence of an outer covering called capsules. Haemophilus influenzae, the major pathogen, can be separated into encapsulated or typable strains, of which there are seven types (a through f including e') based on the antigenic structure of the capsular polysaccharide, and unencapsulated or nontypable strains (Baron S). by isolating H. influenzae it was observed that some were shown to have pili structures, which aid in attachment to the oropharyngeal epithelial cell of humans. another important feature of the H. influenzae cell structure is the rough lipopolysaccharide(LPS) which extends from the cell surface. there are variations in the LPS from specie to specie and its has been suggested to be important in the life cycle of the Haemophilus influenzae.
haemophilus influenzae is a bacteria and thus exhibits characteristics of a prokaryotic cell. it was identified as a gram negative bacteria because of its response to Gram staining techniques, as it stains red. the gram negative coccobacillus has important cell wall components that play a role in its survival and its pathogenicity. H. influenzae bacteria consist of various strains based on the presence or absence of an outer covering called capsules. Haemophilus influenzae, the major pathogen, can be separated into encapsulated or typable strains, of which there are seven types (a through f including e') based on the antigenic structure of the capsular polysaccharide, and unencapsulated or nontypable strains (Baron S). by isolating H. influenzae it was observed that some were shown to have pili structures, which aid in attachment to the oropharyngeal epithelial cell of humans. another important feature of the H. influenzae cell structure is the rough lipopolysaccharide(LPS) which extends from the cell surface. there are variations in the LPS from specie to specie and its has been suggested to be important in the life cycle of the Haemophilus influenzae.
haemophilus influenzae metabolizes sugar as its source of energy, however there is little known about this metabolic capability of the H. influenzae. it is a facultative anaerobe and thus makes ATP by aerobic respiration when oxygen is present and is also capable of metabolizing its sugar source in the absence of oxygen by fermentation. it was found that over 90% of H. influenzae isolated, breaks down sugars such as maltose glucose, galactose and ribose by fermentation and the remaining percent ferment fructose, mannose,  or  glycerol.


==Ecology and Pathogenesis==
==Ecology and Pathogenesis==

Revision as of 17:53, 18 April 2011

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Classification

Haemophilus influenzae is found along the bacteria lineage: kindgom name:Bacteria, phylum name:Proteobacteria,class name:Gamma Proteobacteria;order:Pasteurellales, family name:Pasteurellaceae; and genus name Haemophilus. the specie name is haemophilus influenzae

hamophilus influenzae has other names by which it can be identifed as it was formely known as the Pfeiffer's bacillus or Bacillus influenzae. it is also known as haemophilus meningitidis,Mycobacterium influenzae,Influenza-bacillus to name a few.

other species that fall under the same genus name are: haemophilus ducreyi and haemophilus influenzae aegyptius


Species

NCBI: Taxonomy

Genus species

Description and Significance

Haemophilus influenzae is a small Gram negative bacillus which grows best at 35-37 degrees Celsius and at a pH of 7.6. the bacteria has specific need required for growth which are hemin(factor X) and nicotinamide adenine dinucleotide (NAD+:factor V). the growth of the bacteria is enhanced by high concentrations of CO2 concentrations. the haemophilus influenzae bacteria

Genome Structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence?

Haemophilus influenzae is a non-motile Gram-negative coccobacillus first identifed by Dr. Robert Pfeiffer in 1892. the genome structure of haemophilus influenzae consist of 1,830,138 nucleotide base pairs and it is estimated to have approximately 1740 genes and was the first genome to be sequenced and assembled in a free living organism (Fleischmann RD et al). It consist of a single circular chromosome replicon which has coding regions for rRNA, tRNA and proteins. They identified that the four nucleotides are not used at equal frequency across the genome as A and T are more common than C and G. there are sequence uncertainties in the genome as other symbols occur in the sequence and corresponds to positions in the sequence that are not clearly one base or another. other bases which are seen in the sequence are Y, R, K, M, S, W and N. (Computational Genomics). because bacteria can transfer DNA from one specie to another by horizontal gene transfer, haemophilus influenzae takes up DNA by recognizing a 9- base pair sequence, 5'-AAGTGCGGT which is carried in multiple copies in its chromosome. there are 1465 copies of the 9-base pair DNA uptake sequence.the aligning of theses 9-base pair sequence sites have shown that there is an extended consensus region within the DNA of 29 base pairs containing the core 9-base pair region and also two 6-base pair A-T rich regions, each spaced one helix turn apart. most of the sites are inverted repeats(IR) located downstream to a gene terminus and are thus capable of forming loop structures in mRNA that signals for termination of transcription.(Smith OH, 1995 Jul 28;269(5223):538-40).

Cell Structure, Metabolism and Life Cycle

Interesting features of cell structure; how it gains energy; what important molecules it produces.

haemophilus influenzae is a bacteria and thus exhibits characteristics of a prokaryotic cell. it was identified as a gram negative bacteria because of its response to Gram staining techniques, as it stains red. the gram negative coccobacillus has important cell wall components that play a role in its survival and its pathogenicity. H. influenzae bacteria consist of various strains based on the presence or absence of an outer covering called capsules. Haemophilus influenzae, the major pathogen, can be separated into encapsulated or typable strains, of which there are seven types (a through f including e') based on the antigenic structure of the capsular polysaccharide, and unencapsulated or nontypable strains (Baron S). by isolating H. influenzae it was observed that some were shown to have pili structures, which aid in attachment to the oropharyngeal epithelial cell of humans. another important feature of the H. influenzae cell structure is the rough lipopolysaccharide(LPS) which extends from the cell surface. there are variations in the LPS from specie to specie and its has been suggested to be important in the life cycle of the Haemophilus influenzae.

haemophilus influenzae metabolizes sugar as its source of energy, however there is little known about this metabolic capability of the H. influenzae. it is a facultative anaerobe and thus makes ATP by aerobic respiration when oxygen is present and is also capable of metabolizing its sugar source in the absence of oxygen by fermentation. it was found that over 90% of H. influenzae isolated, breaks down sugars such as maltose glucose, galactose and ribose by fermentation and the remaining percent ferment fructose, mannose, or glycerol.

Ecology and Pathogenesis

Habitat; symbiosis; biogeochemical significance; contributions to environment.
If relevant, how does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

References

Computational Genomics: Example of sequence statistics and gene finding with MATLAB http://www.computational-genomics.net/case_studies/haemophilus_demo.html


Whole-genome random sequencing and assembly of Haemophilus influenzae Rd. Fleischmann RD, Adams MD, White O, Clayton RA, Kirkness EF, Kerlavage AR, Bult CJ, Tomb JF, Dougherty BA, Merrick JM. Science. 1995 Jul 28; 269(5223):496-512.

Frequency and distribution of DNA uptake signal sequences in the Haemophilus influenzae Rd genome. Smith HO, Tomb JF, Dougherty BA, Fleischmann RD, Venter JC. Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA. Science.1995 Jul 28;269(5223):538-40.

Haemophilus influenzae pili are composite structures assembled via the HifB chaperone JOSEPH W. ST. GEME III*tt, JEROME S. PINKNERt, GRAHAM P. KRASAN*, JOHN HEUSER§, ESTHER BULLITTr, ARNOLD L. SMITHII, AND Scorr J. HULTGRENt

  • Edward Mallinckrodt Department of Pediatrics, and Departments of tMolecular Microbiology and §Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110; 1Department of Biophysics, Boston University School of Medicine, Boston, MA 02118; and IlDepartment of Molecular Microbiology and Immunology, University of Missouri, Columbia, MO 65203

Proc. Natl. Acad. Sci. USA Vol. 93, pp. 11913-11918, October 1996 Microbiology


Relationship between Colony Morphology and the Life Cycle of Haemophilus influenzae: The Contribution of Lipopolysaccharide Phase Variation to Pathogenesis Jeffrey N. Weiser The Journal of Infectious Diseases Vol. 168, No. 3 (Sep., 1993), pp. 672-680 http://www.jstor.org/stable/30113433

Haemophilus Species. Musher DM. In: Baron S, editor. Medical Microbiology. 4th edition. Galveston (TX): University of Texas Medical Branch at Galveston; 1996. Chapter 30.

Author

Page authored by _____, student of Prof. Doreen Cunningham at Saint Augustine's College.