Not to be confused with Haemophilia

Haemophilia

Haemophilia is a group of hereditary genetic disorders that impair the body's ability to control blood clotting or coagulation, which is used to stop bleeding when a blood vessel is broken. Haemophilia A is the most common form of the disorder, present in about 1 in 5,000–10,000 male births...

.

Haemophilus is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of Gram-negative

Gram-negative

Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...

, pleomorphic, coccobacilli

Coccobacillus

A coccobacillus is a type of rod-shaped bacteria. The word coccobacillus reflects an intermediate shape between coccus and bacillus . Coccobacilli rods are so short and wide that they resemble cocci. Haemophilus influenzae and Chlamydia trachomatis are coccobacilli...

 bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 belonging to the Pasteurellaceae

Pasteurellaceae

Pasteurellaceae comprise a large and diverse family of Gram-negative Proteobacteria with members ranging from important pathogens such as Haemophilus influenzae to commensals of the animal and human mucosa. Most members live as commensals on mucosal surfaces of birds and mammals, especially in the...

family. While Haemophilus bacteria are typically small coccobacilli, they are categorized as pleomorphic bacteria because of the wide range of shapes they occasionally assume. The genus includes commensal

Commensalism

In ecology, commensalism is a class of relationship between two organisms where one organism benefits but the other is neutral...

 organisms along with some significant pathogenic species such as H. influenzae

Haemophilus influenzae

Haemophilus influenzae, formerly called Pfeiffer's bacillus or Bacillus influenzae, Gram-negative, rod-shaped bacterium first described in 1892 by Richard Pfeiffer during an influenza pandemic. A member of the Pasteurellaceae family, it is generally aerobic, but can grow as a facultative anaerobe. H...

—a cause of sepsis and bacterial meningitis in young children—and H. ducreyi

Haemophilus ducreyi

Haemophilus ducreyi is a fastidious gram-negative coccobacillus causing the sexually transmitted disease chancroid, a major cause of genital ulceration in developing countries characterized by painful sores on the genitalia. Another early symptom is dark or light green shears in excrement...

, the causative agent of chancroid

Chancroid

Chancroid is a sexually transmitted infection characterized by painful sores on the genitalia...

. All members are either aerobic

Aerobic organism

An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment.Faculitative anaerobes grow and survive in an oxygenated environment and so do aerotolerant anaerobes.-Glucose:...

 or facultatively

Facultative anaerobic organism

A facultative anaerobic organism is an organism, usually a bacterium, that makes ATP by aerobic respiration if oxygen is present but is also capable of switching to fermentation...

 anaerobic

Anaerobic organism

An anaerobic organism or anaerobe is any organism that does not require oxygen for growth. It could possibly react negatively and may even die if oxygen is present...

.

Metabolism

Members of the Haemophilus genus are typically cultured on blood agar plates as all species require at least one of the following blood factors for growth: hemin (factor X) and/or nicotinamide adenine dinucleotide (factor V). Chocolate agar

Chocolate agar

Chocolate agar - is a non-selective, enriched growth medium. It is a variant of the blood agar plate. It contains red blood cells, which have been lysed by heating very slowly to 56 °C. Chocolate agar is used for growing fastidious respiratory bacteria, such as Haemophilus influenzae...

 is an excellent Haemophilus growth medium as it allows for increased accessibility to these factors. Alternatively, Haemophilus is sometimes cultured using the "Staph streak" technique: both Staphylococcus and Haemophilus organisms are cultured together on a single blood agar plate. In this case, Haemophilus colonies will frequently grow in small "satellite" colonies around the larger Staphylococcus colonies because the metabolism of Staphylococcus produces the necessary blood factor by-products required for Haemophilus growth.

External links

• Haemophilus chapter in Baron's Medical Microbiology (online at the NCBI
  National Center for Biotechnology Information
  The National Center for Biotechnology Information is part of the United States National Library of Medicine , a branch of the National Institutes of Health. The NCBI is located in Bethesda, Maryland and was founded in 1988 through legislation sponsored by Senator Claude Pepper...
  
  bookshelf).