haempholus

• Haemophilus influenzae was first isolated by Pfeiffer


  1890
• Haemophilus influenzae was erroneously named during the influenza pandemic that ravaged the world from 1889 to 1890
• The basis for this assumption was the frequent isolation of this bacillus from the nasopharynx of patients with influenza and from postmortem lung cultures during those times when viral isolation methods were unavailable
• After viral culture techniques were developed, it became apparent that influenza was caused by a virus and that the actual role of H. influenzae was that of a secondary (opportunistic) invader
• Fastidious


  Requiring special nutrients for isolation and identification
• Growth factors


  Nutrients often supplied by addition of enrichment ingredients to culture media (e.g., blood or blood products)
• Haemophilus species


  • Require Factor X and/or Factor V for optimal growth
  • Bordetella species require niacin, cysteine, and usually methionine
  • Brucella species require thiamine, niacin, and biotin
• Most bacteria included in this group are nonpathogenic or produce opportunistic infections
• Genera of major pathogenic species


  • Haemophilus
  • Brucella
  • Bordetella
  • Francisella
  • Pasteurella
  • Legionella
  • Streptobacillus
• Influenza


  Viral disease characterized by acute inflammation of the upper airways
• Haemophilus influenzae


  • Small, pleomorphic, gram-negative bacilli
  • Nonmotile
  • Facultative anaerobes
  • Growth is enhanced in a 5% to 10% CO2-enriched atmosphere
  • Requires enriched media, usually containing blood or its derivatives, that provide preformed growth factors X and V
• Factor X


  Protoporphyrin IX which acts physiologically as hemin or hematin, an important component of cytochromes, catalase, and peroxidase
• Factor V


  Nicotinamide adenine dinucleotide (NAD) or NAD phosphate (NADP)
• Haemophilus influenzae occurs only in humans and can be found in the upper respiratory tract (oropharynx and nasopharynx) of 20% to 80% of healthy persons
• Haemophilus influenzae is transmitted from person-to-person by respiratory droplets
• Diseases caused by Haemophilus influenzae


  • Meningitis
  • Epiglottitis
  • Bacteremia
  • Otitis media
  • Sinusitis
  • Pneumonia
• Haemophilus influenzae meningitis


  • Until the availability of the Hib vaccine, H. influenzae was the most common cause of meningitis in children between 3 months and 6 years of age
  • Older children, adolescents and adults can less frequently be infected particularly those who are immunocompromised
  • Untreated cases have high fatality (up to 90%) even with prompt diagnosis
• Haemophilus influenzae epiglottitis


  • H. influenzae is the most common cause of this potentially fatal disease in children between the ages of 2 and 4
  • Rapid onset, with sore throat, dysphagia, fever, and swollen, cherry red epiglottis above the larynx at the base of the tongue
  • Acute inflammation and intense edema of the epiglottis may cause complete airway obstruction and suffocation
• Haemophilus influenzae bacteremia


  • Frequently an early manifestation of acute H. influenzae type b meningitis but in some infants, may occur without meningitis
• Haemophilus influenzae otitis media


  • H. influenzae (nontypeable strains) are second to S. pneumoniae as a common cause of otitis media in children, most frequently in children aged 6 months to 5 years with highest incidence among children less than 3 years of age
• Haemophilus influenzae sinusitis


  • Characterized by persistent cold symptoms, purulent nasal or post nasal discharge, cough, fever, headache, and often facial pain
• Haemophilus influenzae pneumonia


  • In adults, H. influenzae causes pneumonia, particularly in individuals with other underlying pulmonary infections
• Haemophilus influenzae virulence factors


  • Capsule (PRP polysaccharide) allows the organism to resist phagocytosis and intracellular killing
  • IgA proteases cleave secretory IgA present on human mucosal surfaces, allowing attachment
  • Pili favor attachment of nontypeable strains to host epithelial cells
  • Outer membrane proteins responsible for invasiveness, attachment, and antiphagocytic function
• Haemophilus influenzae type b (Hib) disease can be prevented by vaccination with Hib vaccines prepared from the purified capsular polysaccharide (polyribosylribitol phosphate, PRP) conjugated to a carrier protein
• Hib conjugate vaccine types

  • PRP-OMPC (Neisseria meningitidis outer membrane protein complex)
  • PRP-T (Tetanus toxoid)
  • PRP-D (Diphtheria toxoid)
  • HbOC (CRM197 mutant Corynebacterium diphtheriae toxin protein)
• Haemophilus aegyptius


  • Etiologic agent of acute, communicable conjunctivitis ("pink eye")
  • Requires Factor X and Factor V for growth
• Haemophilus ducreyi


  • Strictly a human pathogen, infecting the mucosal epithelium, genital and nongenital skin, and regional lymph nodes, and spread by sexual transmission
  • Causes chancroid, a highly communicable sexually transmitted genital ulcer disease
  • Requires X factor alone for growth
• Organisms


  May be inside and outside of polymorphonuclear leukocytes (PMNs)
• Organism


  More fastidious than H. influenzae
• Organism


  Requires X factor for growth
• H. aegyptius was observed by Koch in 1883 in Egyptians in conjunctivitis exudates —hence the species name
• H. aegyptius


  Causes acute conjunctivitis or pink eye
• Haemophilus ducreyi


  Causes penile ulcers that are soft and painful, in contrast to the ulcers of syphilis
• H. ducreyi requires X factor alone
• Haemophilus parainfluenzae


  Member of the normal oral and nasopharyngeal flora
• Haemophilus parainfluenzae


  Involved in infective endocarditis in adults with underlying congenital or rheumatic heart disease, with insidious onset and primarily involving the mitral valve
• Haemophilus parainfluenzae


  Requires V factor for growth
• Haemophilus haemolyticus and Haemophilus parahaemolyticus


  Part of the normal flora of the respiratory tract and are rarely associated with infections
• H. ducreyi


  May be difficult to recover in culture as it requires additional growth factors and special media for cultivation
• Culturing H. ducreyi


  1. Use Müeller–Hinton agar supplemented with 5% chocolatized horse blood plus 1% IsoVitalex enrichment

  2. Use GC agar base supplemented with 2% bovine hemoglobin, 5% fetal calf serum, and 1% IsoVitalex

  3. Add vancomycin (3 µL/mL final concentration) to inhibit contaminating gram-positive bacteria

  4. Incubate at 33°C in 5% to 10% CO2 in a candle jar or CO2 incubator with high humidity