Hemophilus influenzae by Dr. Rakesh Prasad Sah
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This document discusses Haemophilus influenzae, a gram-negative coccobacillary bacteria. It was first isolated in 1892 and thought to cause influenza. There are two main types: unencapsulated and encapsulated strains. Encapsulated type b strains cause more invasive diseases like meningitis while unencapsulated commonly cause localized infections. The document outlines the virulence factors, pathogenesis, clinical manifestations, diagnosis and prevention of H. influenzae infections. It also briefly discusses the HACEK group of bacteria which can cause endocarditis.
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Hemophilus influenzae by Dr. Rakesh Prasad Sah
- 1. HEMOPHILUS By Dr. Rakesh Prasad Sah Assistant Professor, Microbiology
- 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
- 6. HAEMOPHILUS INFLUENZAE • Two main types: • I The uncapsulated (untypable) strains • II The encapsulated strains
- 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
- 15. CELLULITIS CAUSE BY H.INFLUENZAE IN FOOT
- 16. CELLULITIS CAUSED BY H.INFLUENZAE IN CHEEK
- 17. H. INFLUENZAE CAUSING OTITIS MEDIA
- 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
- 20. SPECIMEN • CSF • Throat Swab • Sputum • Pus • Joint Aspirates • Pleural Aspirates • Bronchial Aspirates • Pericardial Aspirates
- 23. DIRECT SMEAR OF H.INFLUENZAE IN CSF IN A CASE OF MENINGITIS
- 24. H.INFLUENZAE IN IMMUNOFLUORESCENCE MICROSCOPY
- 25. CULTURAL CHARACTERISTICS H.Influenzae in Chocolate Agar
- 26. SATELLITISM Satellitism Test for H.Influenzae
- 27. ANTIGEN DETECTION Latex Agglutination Test For H. influenzae
- 28. Blood Culture: • Brain Heart Infusion Broth (BHI Broth) • Biochemical Reactions • Catalase • Oxidase • Nitrate reduction test • Serotyping
- 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.
- 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.