haemophilus and bordetella

• General Characteristics of Haemophilus

  • Gram-negative, pleomorphic coccobacilli or rods
  • Highly pleomorphic, exhibits a variety of shapes
  • Facultative anaerobe and non-motile
  • Ferment carbohydrates
  • Oxidase positive
  • Catalase positive
  • Reduces nitrates to nitrites
  • Obligate parasites on the mucous membranes of the respiratory tract and genital tract
  • Requires X (hemin or hematin) and V (NAD) factors for growth
  • Hemolysis on 5% horse or rabbit blood agar
  • Pleomorphic form/Pleomorphism
• Highly pleomorphic / Pleomorphic


  • Demonstrates many shapes with no definite shape, size, or microscopic morphology associated with a specific species of Haemophilus organism
  • Can vary from coccobacilli/rods morphology to long filaments morphology
• Facultative anaerobe


  • Can grow with or without oxygen
  • Utilize or consume carbohydrates or sugars in the absence of oxygen for nutrition and growth
• Gram-negative organisms

  • Appear pink/red under the gram stain procedure using the Hucker’s method
  • Contain a thin peptidoglycan layer with lipopolysaccharides
  • Cell wall composed of lipids and polysaccharides
• Haemophilus

  Comes from two Greek words: Hemo which means blood, Filos which means friendly. The genus Haemophilus is a blood-loving type of genus (blood-loving organisms)
• Oxygen is responsible for catalase positive result


  Observed with the appearance of gas bubbles in the culture medium and not destroyed by hydrogen peroxide disinfectant
• Oxidase positive


  Organisms that produce the enzyme cytochrome oxidase
• Non-motile organisms do not possess flagella/flagellum
• Utilization of substances in surroundings by organisms


  Organisms consume other substances in their surroundings to grow in that particular environment
• Hemolysis on 5% horse or rabbit blood agar is an ideal culture medium for Haemophilus organisms
• X factor (Hemin, Hematin, Heme, Protoporphyrin IX)

  Heat stable blood growth factor
• Haemophilus organisms must enter the respiratory/genital tract of the human host to survive and thrive
• Utilization of carbohydrates in the absence of oxygen

  Organisms ferment carbohydrates or utilize/consume carbohydrates or sugars for nutrition and to thrive in an environment without oxygen
• Catalase positive


  Organisms that produce the enzyme catalase, similar to the behavior of staphylococci organisms
• Oxidase and Catalase positive organisms


  • They produce the enzyme cytochrome oxidase and catalase
• V factor (NAD)

  Vitamin, heat labile growth factor
• Obligate parasites of specific species of Haemophilus reside in the respiratory and genital tracts
• Haemophilus organisms require X (hemin or hematin) and V (NAD) factors for growth
• Production of culture medium

  1. Melting the trypticase soy agar and placing it in the plate

  2. Adding 5% sheep’s blood or 5% human blood to the melted agar and allowing it to solidify at room temperature, appearing red in color
• Sheep’s blood and human blood contain the enzyme NADases which destroys NAD, limiting them to provide only the X factor
• Haemophilus influenzae became famous during the 1889-1890 influenza pandemic due to its frequent isolation from the nasopharynx of influenza patients when viral culture techniques were not available
• Substitutes for 5% horse or rabbit blood agar

  • 5% sheep blood agar (SBA)
  • Human blood agar
• Pleomorphic forms of Haemophilus organisms include coccobacilli/small rods morphology and long filaments morphology
• Chocolate agar is a lysed blood agar, providing both X and V growth factors, making it a good alternative culture medium for Haemophilus organisms
• Haemophilus influenzae is also known as PFEIFFER’S BACILLUS
• In the 18th century (1889-1890) during the influenza virus pandemic, haemophilus influenzae was frequently isolated from the nasopharynx of influenza patients
• Later on, it was proven that haemophilus influenzae was not the causative agent of influenza, which is caused by the highly pathogenic avian influenza virus type A of subtype H5N1
• Haemophilus influenzae types A, C, D, E, F contain common substances and an additional unique substance unique to each serotype
• Non-encapsulated strains of haemophilus influenzae also cause infection to human hosts, responsible for localized infections
• Haemophilus influenzae is a Gram-negative short rod (coccobacillus) with 6 serotypes or biotypes (a, b, c, d, e, & f)
• Virulence factors of haemophilus influenzae include Capsular polysaccharide, Immunoglobulin (IgA) proteases, Adherence mechanism (by fimbriae), and Outer membrane component
• Capsular polysaccharide of haemophilus influenzae has anti-phagocytosis and anti-complementary virulence factors
• Haemophilus influenzae habitats in the respiratory tract
• Haemophilus influenzae type B is highly pathogenic, especially to unvaccinated children, and is the leading cause of meningitis in children aged 5 months to 5 years old
• Haemophilus influenzae is a secondary/opportunistic invader in the nasopharynx of patients
• At that time, viral culture techniques were not available for detecting viruses
• Immunoglobulin (IgA) proteases are the second line of defense against haemophilus influenzae when phagocytes do not effectively destroy them
• Encapsulated strains of haemophilus influenzae are responsible for invasive/systemic infections
• Mode of transmission of haemophilus influenzae is through aerosol spray
• The 6 biotypes of haemophilus influenzae can be biotyped using the INDOLE TEST, ORNITHINE DECARBOXYLASE TEST, and UREASE TEST