Haemophilus is the name of a group of bacteria. There are several types of Haemophilus. They can cause different types of illnesses involving breathing, bones and joints, and the nervous system. One common type, Hib (Haemophilus influenzae type b), causes serious disease. It usually strikes children under 5 years old

1. Hemophilus
includes a number of species
that cause a wide variety of
infections
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2. Introduction
• It requires blood derived factor during growth
• Hemophilus influenzae is the major pathogen
• Gram positive coccobacilli, H influenzae requires hemin (factor
X) and NAD+ (factor V) for growth
• Other Hemophilus require only NAD+
• Typable H influenzae isolates are classified on the basis of seven
antigenically distinct capsular polysaccharides; isolates lacking
these polysaccharides are called non-typable

3. Introduction
Other Haemophilus species Disease
Haemophilus parainfluenzae sometimes causes pneumonia or bacterial
endocarditis
Haemophilus ducreyi chancroid
Haemophilus aphrophilus member of the normal flora of the mouth and
occasionally causes bacterial endocarditis
Haemophilus aegyptius conjunctivitis and Brazilian purpuric fever, non
typable strains
Haemophilus haemolyticus Example for non typable strains

4. Diseases caused
• Type b H influenzae was the most common cause of meningitis in children between the ages of 6 months and
2 years
• In meningitis: headache is followed rapidly by development of a stiff neck, with progression to coma and, in the
absence of treatment, death
• Treatment reduces the incidence of, but does not eliminate, problems such as deafness and learning
disabilities
• Type b H influenzae also causes cellulitis
• Epiglottitis: a condition in which the epiglottitis becomes inflamed and swells, closing off the upper airway.
(Suffocation can be prevented in some cases only by performing a tracheostomy)
• Nontypable H influenzae strains commonly cause infection of the middle ear (otitis media)

5. Diseases caused
• In adults, these organisms cause bronchitis and pneumonia, especially if some underlying disease of the
bronchi and lungs is present
• Nontypable H influenzae strains also commonly cause acute or chronic sinusitis in patients of all ages
• Chancroid is a venereal disease caused by H ducreyi.
• Lesions that resemble a syphilitic chancre result from sexual contact with an infected individual; they are
usually found on the genitals.
• Unlike syphilitic chancres, the lesions are painful and are associated with a remarkable degree of swelling of
lymph nodes in the inguinal area.

6. Diseases caused
H
influenzae
Meningitis
Cellulitis
Epigloittitis
Otitis media
Bronchitis
Pneumonia
H ducreyi Chancroid

7. Structure
• Gram-negative coccobacilli
• cell walls contain lipooligosaccharide, which resembles the lipopolysaccharide of Gram-negative bacilli but has
shorter side chains
• generally been thought not to make toxins or other extracellular products that account for their ability to
produce infection
• organisms require hemin (factor X) and/or nicotinamide adenine dinucleotide (NAD+) (factor V) for growth.
• Whereas NAD+ is released into the medium by red blood cells and is available to the bacteria in blood agar,
hemin is bound to red blood cells and is not released into the medium unless the cells are broken up as in
chocolate agar

8. Structure
• Haemophilus influenzae requires both factors X and V; accordingly, it grows on chocolate agar but not on blood
agar
• Haemophilus parainfluenzae requires only factor V and therefore is able to grow on blood agar
• All Haemophilus species grow more readily in an atmosphere enriched with CO2
• H ducreyi and some nontypable H influenzae strains will not form visible colonies on culture plates unless
grown in CO2-enriched atmosphere.

9. Structure

10. ClassificationHaemophilusinfluenzae
Typable
Non typable
• they display a capsular polysaccharide antigen
• six generally recognized types: a, b, c, d, e, and f
• They lack a capsule

11. Antigenic types
• polyribosyl ribitol phosphate (PRP) capsule is an important virulence factor
• it renders type b H influenzae resistant to phagocytosis by polymorphonuclear leukocytes
• Type b H influenzae is plainly the most virulent of the Haemophilus species and most common in childrens
• nontypable strains of H influenzae are the most common cause of Haemophilus infection in adults. Why?
• H influenzae also may be classified into six biotypes designated I through VI
• Most type b H influenzae strains fall into biotypes I or II
• whereas most non typable H influenzae strains fall into biotypes II through VI.

12. Pathogenesis
Haemophilus species do not produce substances that obviously damage
mammalian tissues, bacterial replication is probably the usual pathway for
disease production, with triggering of the complement cascade by classic and
alternative pathways, followed by accumulation of inflammatory cells.

13. Pathogenesis
• Organisms colonize the nasopharynx
• Spread from one human to another by direct contact or via secretions and/or aerosol
• They penetrate epithelial layers and capillary endothelium by unknown mechanisms, reaching the meninges
either directly via lymphatic drainage from the nasopharynx or indirectly by causing bacteremia
• meningitis in adults are due to nontypable strains
• they gain entry to the central nervous system by direct extension, often associated with infection of the
sinuses or middle ear and/or with trauma involving the sinuses or skull
Meningitis

14. Pathogenesis
• Cellulitis and epiglottitis are discussed together because their pathogenesis is probably quite similar
• Both are due to type b H influenzae, are likely to cause associated bacteremia, and occur more frequently in
children than adults
• Epiglottitis can be regarded as a cellulitis of the relatively loose submucosal connective tissues of the
epiglottis.
• A sore throat rapidly progresses to difficulty in breathing, stridor, obstruction of the air ways, and respiratory
arrest.
Cellulitis and Epiglottitis

15. Pathogenesis
• Cellulitis often involves the face or neck
• It sometimes seems to start at the buccal mucosa and
extend outward, supporting the idea that it also
results from local extension
Cellulitis and Epiglottitis

16. Pathogenesis
• Nontypable H influenzae is a major pathogen that colonizes the human respiratory tract
• Adherence of bacteria to mammalian tissues, which is mediated by pili (fimbriae)
• Respiratory infections caused by these organisms include sinusitis, otitis media, acute tracheobronchitis, and
pneumonia.
• Repeated bouts of otitis media are thought to be due to different strains; each infection may be associated
with emergence of antibody to distinctive surface proteins
• Haemophilus influenzae received its name because it was first isolated from the lungs of individuals who died
during an epidemic of influenza virus infection in 1890
Respiratory disease

17. Pathogenesis
• characterized by nausea, vomiting, hemorrhagic skin lesions, fever, weakness, and shock
• Haemophilus influenzae biogroup aegyptius can be cultured from the blood of affected patients.
• Many have had a history of conjunctivitis in the weeks preceding onset of the disease.
Brazilian Purpuric Fever

18. Diagnosis
• Cannot be distinguished on the basis of clinical presentation, physical examination, or cerebrospinal fluid
abnormalities from meningitis due to other common bacterial pathogens
• Detection of capsular material in the cerebrospinal fluid by counter immunoelectrophoresis is helpful in pre
treated patients
• Gram staining of CSF
• Blood culture is preferable for endocarditis

19. Control
• Type b H influenzae can be prevented by vaccination or prophylactic therapy
• The use of rifampin prophylaxis to prevent or eradicate nasopharyngeal colonization has been recommended
• The mainstay of therapy for H influenzae infection used to be ampicillin, since isolates were uniformly
susceptible to 0.5 μg/ml – but H influenzae isolates have produced β-lactamase
• Treatment with a combination of amoxicillin and clavulanic acid (a substance that covalently binds β-
lactamase) is effective against β-lactamase-producing strains, but has not been recommended for treating
meningitis
• Chloramphenicol - the drug of choice for meningitis caused by a penicillin-resistant H influenzae strain
• Third-generation cephalosporins, such as ceftriaxone or cefotaxime (meningitis)
• The addition of corticosteroids may reduce the incidence of complications such as deafness.

20. Control
• sulfa drugs are effective in treating upper and lower respiratory infections caused by
Haemophilus.
• Erythromycin should not generally be used to treat H influenzae infections
• The spread of soft chancre due to H ducreyi is best prevented by use of a condom
during sexual intercourse.
• Two-thirds of H ducreyi isolates produce β-lactamase.
• All isolates are susceptible in vitro to erythromycin