2. HAEMOPHILUS
• First isolated in 1892 by Robert Pfeiffer – Hence also called Pfeiffer’s bacillus
• Was thought to be the infectious agent for flu
• Was also called Bacillus influenzae
• Common Species
• H. influenzae
• H. parainfluenzae
• H. ducreyi
3. HAEMOPHILUS INFLUENZAE
• Gram negative Rods.
• Range from coccobacillary to long
filamentous forms.
• Non – motile
• Aerobic
• Fastidious organisms
7. CAPSULE
• Polysaccharide in nature
• Six types : a, b, c, d, e and f
• Type b is associated with most severe form of disease
• Hib capsule is Polyribitol Phosphate (PRP)
8. VIRULANCE FACTOR
• Outer membrane protein
• Pili
• Immunoglobulin A1 Protease
• Lipopolysaccharides
• Capsule
• Endotoxin
9. VIRULENCE FACTORS FUNCTIONS
Capsular polysaccharides PRP of the capsule is antiphagocytic. It resists
phagocytosis of the bacteria
Lipopolysaccharides Causes meningococcal inflammation
IgA1 protease Causes breakdown of IgA, facilitate colonization of
H. inflenzae on the basis of mucosal surface
Pilli Helps in adherence of H. influenzae to epithelial
cells
Endotoxin Induces host inflammatory response
10. • Humans are the only natural hosts
• Transmission: respiratory droplet spread
• The incidence of Hib fell by 95% in populations with high rates of vaccination
11. PATHOGENESIS
H.Influenzae enters the human host by respiratory route.
Adhesions of the bacteria mediate colonization in
the nasopharynx and oropharynx
Lipid A lipopolysaccharides impairs ciliary function and IgA1 protease
breakdown IgA1
A large bacterial load or the viral infection potentiate the bacterial
infection that invade mucosa and enter the blood stream.
Cause damage of the respiratory mucosa
12. The presence of antibodies, complement components and phagocytes
cause clearance of bacteremia
The absence of anti PRP antibodies contributes to bacterial infection
High grade bacteremia leads to disseminate to various sites including
meninges, subcutaneous tissue,joints,pleura and pericardium
Responsible for causing Meningitis, Arthritis, pneumonia and endocarditis
Colonization of noncapsulated strains will direct extend to sinuses,
eustachian tube etc cause sinusitis and otitis media
13. HAEMOPHILUS INFLUENZAE
Uncapsulated Capsulated
Responsible for localized infections i.e. Responsible for Invasive disease i.e.
Otitis media Meningitis
Conjuctivitis Septicaemia
Brochitis Epiglottitis
Sinusitis Pneumonia
Septic arthritis
Cellulitis
18. NON TYPEABLE H. INFLUENZAE
• Otitis media
• COPD
• Pneumoniae in adults underlying COPD or AIDS
• Puerperal sepsis and neonatal bacteremia ( NMF)
• Sinusitis in children and adults
• Rarely invasive infections
19. Features Type b strains Nontypeable strains
Capsule Made up of poly ribosyl ribitol phosphate
(PRP)
Non capsulated
Manifestations Invasive – meningitis, epiglottits,
pneumonia, bacterimia, endocarditis
Noninvasive – otitis media
(children) and penumonia
(adult)
Age Affect children Affect adult
Spread Hematogenous spread Contiguous spread
Vaccine Hib vaccine is available Not available
29. PREVENTION AND CONTROL
Vaccination :
• Purified type b capsular polysaccharide vaccine 18-24 months 2 months interval
• Hib PRP vaccine type b capsular polysaccharide covalently coupled to protiens such as
diptheria toxoid, tetanus toxoid and N. meningitidis outer membrane protein.
• Rifampicin 4 days to prevent infection in contacts and also to eradicate carrier state.
30.
31. HACEK GROUP BACTERIA
• Highly Fastidious bacteria, slow growing, capnophilic, G –ve, resident of mouth
• Sometimes cause severe infection like endocarditis.
• Species of this group includes
• Haemophilus species : H. aphorphilus, H. paraphrophilus & H. Parainfluenzae
• Aggregatibacter (formerly Actinobacillus) actinomycetemocomitans
• Cardiobacterium hominis
• Eikenella corrodens
• Kingella kingae
• Blood cultures positive after 7-30 days.
• Highly drug resistant so ASTs are essential.