Haemophilus

1. Haemophilus By Dr. Emad AbdElhameed Morad Lecturer of Medical Microbiology and Immunology

2. Species Members of this genus require certain growth factors present in blood (haemophilic). Species are: Haemophilus influenzae Haemophilus aegyptius Haemophilus ducreyi

3. Haemophilus influenzae

4. Morphology Gram negative, pleomorphic small cocco-bacilli. Many strains are capsulated.

5. Cultural characters Facultative anaerobe and require 5% CO2. Grow on chocolate agar because it provides X factor (hematin) and V factor (NAD) that are essential for growth. Colonies are small and translucent. Satellitism: Around staph. aureus colonies, the colonies of haemophilus grow much well because staphylococci produce V factor.

8. Serological characters Non capsulated strains are found in normal throats. Smooth capsulated strains can be classified into 6 types (a-f) depending on the capsular polysaccharide. Haemophilus influenzae type b (Hib) is the most pathogenic.

9. Fimbriae Virulence factors Capsule IgA protease

10. Pathogenesis The organism enters the upper respiratory tract by inhalation. The organism attaches to the respiratory mucosa by the fimbriae. The polysaccharide capsule makes the bacteria resist phagocytosis and facilitates invasion. The organism also produces IgA protease that degrades IgA at the respiratory mucosa.

11. Diseases Capsulated strains mainly Hib cause invasive diseases in children below 5 years: Meningitis Epiglottitis Pneumonia Septic arthritis Non capsulated strains non invasive diseases like: Otitis media upper respiratory tract infections

12. Laboratory diagnosis Specimen: CSF, sputum, pus Direct Gram smear examination: Pus cells + Gram negative bacilli. Culture: Culture on chocolate agar at 37 degree in 5% CO2. Colonies are identified by: Morphology. Inability to grow in absence of X-V factors. Specific antibodies.

13. Direct detection of the bacteria in specimen: Detection of the capsule by Quellung reaction. Detection of the capsular polysaccharide in CSF by latex agglutination kit. Immunofluoresence PCR

14. Treatment Cefotaxime or ceftriaxone are the drugs of choice for Hib meningitis.

15. Prophylaxis Haemophilus conjugated (Hib) vaccine containing the capsular polysaccharide conjugated to a carrier protein is given to children at 2, 4, 6 months and at 12-15 months. Meningitis could be prevented by giving rifampicin to children in close contact with the patient.

16. Haemophilus aegyptius

17. It is similar to H. influenzae. • It causes acute purulent conjunctivitis.

18. Haemophilus ducreyi

19. It causes chancroid or soft sore which is a sexually transmitted disease. • This organism grows with difficulty on chocolate agar. • PCR is used to detect the organism directly in the specimen.

20. Gardnerella vaginalis

21. It is normal vaginal flora. • However, In association with anaerobic bacteria, it causes bacterial vaginosis. • Bacterial vaginosis is characterized by: • Foul smelling vaginal discharge. • Detection of cluecellsin vaginal swabs. Clue cells are epithelial cells coated with the bacteria. • Whifftestwhich consists of treating the vaginal discharge with 10%KOH. Smelling fishyodouris positive. • VaginalpHis more than 4.5.

22. Clue cells

23. GOOD LUCK