Haemophilus

• Pasteurellaceae

  • Genera: Haemophilus, Actinobacillus, Pasteurella, and Aggregatibacter
  • Reside in human oral mucosa; causes endocarditis HACEK

  - Haemophilus

  - Aggregatibacter

  - Cardiobacterium

  - Eikenella

  - Kingella
• Haemophilus spp.

  • derived from the greek word "blood-lover"
  • Requirements:

  X-factor: hemin or hematin (hemoglobin) X for unknown

  V-factor: nicotinamide adenine dinucleotide (NAD) V for vitamins
• Haemophilus spp.

  • Blood Agar Plate (BAP)

  - V factor dependent haemophilus spp. growth (-)

  - RBC are still intact and contains NADase (hydrolyze V factor) then add blood when heat is already tolerable

  • Chocolate Agar Plate (CAP)

  - lysing RBC by heat

  - Add blood even if the mixture is still hot
• Satellitism

  • Phenomenon without helps in the recognition of Haemophilus spp. that require V factor
  • Occurs when Staphylococcus aureus, Streptococcus pneumoniae, or Neisseria spp. produce V factor
• Haemophilus influenzae (Pfieffer’s bacillus)

  1. Capsule

  • capsular polysaccharide plays the most significant role
  • antiphagocytic property and anticomplementary activity
  • serologic groups: a,b,c,d,e and f
  • most invasive: serotype b
• Haemophilus influenzae (Pfieffer’s bacillus)

  2. Immunoglobulin A Proteases

  • Only genus that produces IgA protease: H. influenzae
  • Cleave secretory IgA
• Haemophilus influenzae (Pfieffer’s bacillus)

  3. Adherence Mechanisms

  • NTHi strains: adherent to human epithelial cells
  • Localized infection
  • Serotype B: not adherent to human epithelial cells
  • Systemic infections
• Haemophilus aegyptius

  • Acute conjunctivitis
  • Koch-Weeks bacillus
  • Commonly referred as “pink eye” → sore eyes
  • Counterpart in virology [study of virus]: Adenovirus → pink eye
• Haemophilus influenzae biogroup aegyptius

  • Conjunctivitis in pediatric patients
  • Nonencapsulated
  • Cause systemic disease known as Brazillian purpuric fever (BPF)
• Haemophilus ducreyi

  • Strict human pathogen and smallest pathogenic bacteria
  • Causative agent of chancroid (highly communicable ST genital ulcer disease [GUD])
  • Commonly referred to as soft chancre
  • Hard chancre (syphilis)
  • Not part of microbiota
  • Suppurative, enlarged, draining, inguinal lymph nodes (buboes)
• Haemophilus parainfluenzae

  • Endocarditis
  • Mitral valve as primary site of infection
• LABORATORY DIAGNOSIS OF HAEMOPHILUS SPP.

  SPECIMEN COLLECTION

  • Site of infection is the site of collection
  • Blood, CSF, middle ear exudate, joint fluids, upper and lower rt specimens, swabs from conjunctivae, vaginal swabs, and abscess drainage
  • Lower RT: bronchial washing
  • Genital sites

  - Cleaned with sterile gauze moistened with sterile saline

  - Swab pre-moistened with sterile phosphate- buffered saline at the base of ulcer

  - Aspirate from buboes

  • Direct plating bedside instead of transport medium
• LABORATORY DIAGNOSIS OF HAEMOPHILUS SPP.

  DIRECT MICROSCOPIC EXAMINATION

  • Haemophilus influenzae: intracellular and extracellular gram-negative coccobacilli
• CULTURE

  Haemophilus influenzae

  • CAP incubated between 33°C and 37°C with 5% to 10% CO2 at 18-24 hrs of incubation
  • With 300 ml/L bacitracin
• CULTURE

  Haemophilus ducreyi and Haemophilus aegyptius

  • CAP with 1% IsoVitaleX or Vitox [source of X and V factor]
• CULTURE

  Haemophilus ducreyi (grows best at 33°C)

  Nairobi biplate

  • GC agar base with 2% bovine hemoglobin and 5% fetal calf serum with vancomycin
  • Mueller Hinton agar with 5% chocolatized horse blood with vancomycin
• Pasteurellaceae


  Genera: Haemophilus, Actinobacillus, Pasteurella, and Aggregatibacter

  
• Pasteurellaceae


  • Gram (-), pleomorphic, coccoid to rod-shaped cells
  • Generally bacilli
  • Nonmotile and facultative anaerobic
  • Catalase and nitrate to nitrite reduction (+)
  • Oxidase negative (-)

  
• HACEK

  Reside in human oral mucosa; causes endocarditis
• HACEK

  • Haemophilus
  • Aggregatibacter
  • Cardiobacterium
  • Eikenella
  • Kingella

  
• Haemophilus


  Derived from Greek word meaning, "blood-lover"
• Haemophilus


  • Requirements: X-Factor (hemin or hematin [hemoglobin]) and V-Factor (nicotinamide adenine dinucleotide [NAD])

  
• Blood Agar Plate (BAP)


  V factor dependent Haemophilus spp. growth (-), RBC are still intact and contains NADase (hydrolyze V factor)

  
• Chocolate Agar Plate (CAP)

  Lysing of the red blood cells by heat, releases both the X factor and the V factor, inactivates NADase

  
• Satellitism


  Phenomenon without helps in the recognition of Haemophilus spp. that require V factor
• Haemophilus influenzae


  • Virulence Factors: Capsule, Immunoglobulin A Proteases, Adherence Mechanisms
• Capsule


  Capsular polysaccharide: plays the most significant role, Antiphagocytic property and anticomplementary activity, Serologic groups: a, b, c, d, e, and f, Most invasive: serotype b (Hib), Composed of ribose, ribitol, and phosphate (polyribitol phosphate), Nontypable H. influenzae (NTHi) - Non-encapsulated
• Immunoglobulin A Proteases


  Only genus that produces IgA protease: H. influenzae, Cleave secretory IgA
• Adherence Mechanisms


  NTHi strains: adherent to human epithelial cells, Localized infection, Serotype B: not adherent to human epithelial cells, Systemic infections
• Haemophilus aegyptius


  Acute conjunctivitis, Koch-Weeks bacillus, Commonly referred as "pink eye"
• Haemophilus influenzae biogroup aegyptius


  Conjunctivitis in pediatric patients, Nonencapsulated, Cause systemic disease known as Brazillian purpuric fever (BPF)
• Haemophilus ducreyi


  Strict human pathogen and smallest pathogenic bacteria, Causative agent of chancroid (highly communicable ST genital ulcer disease [GUD]), Commonly referred to as soft chancre, Not part of microbiota, Suppurative, enlarged, draining, inguinal lymph nodes (buboes)

  
• Haemophilus parainfluenzae


  Endocarditis, Mitral valve as primary site of infection
• Site of infection is the site of specimen collection
• Specimen collection sites: blood, CSF, middle ear exudate, joint fluids, upper and lower rt specimens, swabs from conjunctivae, vaginal swabs, and abscess drainage
• Lower RT: bronchial washing
• Genital sites: Cleaned with sterile gauze moistened with sterile saline, Swab pre-moistened with sterile phosphate-buffered saline at the base of ulcer, Aspirate from buboes

  
• Direct plating bedside instead of transport medium
• Haemophilus influenzae in direct microscopic examination


  Intracellular and extracellular gram-negative coccobacilli
• Haemophilus influenzae culture


  CAP incubated between 33°C and 37°C with 5% to 10% CO2 at 18-24 hrs of incubation, With 300 ml/L bacitracin