Lecture 22 Haemophilus

بسم الله الرحمن الرحيمبسم الله الرحمن الرحيم

GENUS: GENUS: HAEMOPHILUSHAEMOPHILUS

Prof. Khalifa Sifaw Ghenghesh

• Small, Pleomorphic G-ve Rods

• Require Growth Factors– Two factors > X & V– X = haemin– V = Nicotinamide adenine

dinucleotide (NAD) = NAD phosphate (NADP)

•BA

•Chocolate agar

Species Growth Factor Required

----------------------------------------------H. influenzae X + VH. parainfluenzae VH. ophrophilus XH. ducreyi X----------------------------------------------

Haemophilus influenzae

• Smooth and rough colonies occurSmooth and rough colonies occur

• Capsulated >>Capsulated >>

• Non-capsulated >>Non-capsulated >>

ANTIGENIC STRUCTURE

1. The capsular polysaccharide antigens:

• 6 serotypes: a - f.

• Encapsulated H. influenzae >>Quellung (capsular swelling) reaction.

2. Somatic antigens:

VIRULENCE FACTORS

• i. Capsule:i. Capsule:

• ii. Outer membrane components:ii. Outer membrane components:

• OMP & LOSOMP & LOS

• iii. Adherence:iii. Adherence:

• iv. IgA proteases:iv. IgA proteases:

PATHOGENESIS

• Normal Carriage– H. influenzae > Human parasite– Non-capsulate HI > nasopharynx or throat

of 25-80% of healthy people– Capsulate strains in 5-10% – Immunization with conjugate vaccine >

• Invasive infections

• Non-Invasive Disease

INVASIVE INFECTIONS

H. Influenzae type b

Respiratory portal of entery (Inhalation)

Colonization of nasopharynx

Penetration of submucosaInvasion of Bloodstream

Meningitis, Epiglottitis, Bacteraemia

Pneumonia, Septic arthritis

Non-Capsulate HI:> Meningitis and Septicaemia > the Neonate

NON-INVASIVE DISEASE

• Local Infections:– Physiological or Anatomical Abnormalities– Otitis Media, Sinusitis– Purulent episodes > patients with

exacerbations of chronic obstructive airway disease

– Non-capsulate strains of HI– Viral Infections ?

LABORATORY DIAGNOSIS

1. Direct examination:– Specimen: CSF, middle ear aspirate,

sputum (purulent).

2. Culture:– Chocolate agar + CO2

– Blood culture bottles– Antigenic detection– Molecular Techniques

Blood agar plate culture of Haemophilus influenzae

Haemophilus influenzae satelliting around Staphylococcus aureus

TREATMENT

• - Systemic illness - Systemic illness – 33rdrd Generation cephalosporins Generation cephalosporins– TMP-SMZ, Ciprofloxacin, ClarithromycinTMP-SMZ, Ciprofloxacin, Clarithromycin

• - Otitis media in children- Otitis media in children• - Pneumonia in adults- Pneumonia in adults• - Acute sinusitis- Acute sinusitis

– Amoxicillin, Augmentin, Clarithromycin, Amoxicillin, Augmentin, Clarithromycin,

PREVENTION• VaccinationVaccination

• Haemophilus influenzae biogroup Haemophilus influenzae biogroup aegyptiusaegyptius ((Haemophilus aegyptiusHaemophilus aegyptius))– Epidemic conjunctivitisEpidemic conjunctivitis– Brazillian purpuric feverBrazillian purpuric fever

• Haemophilus ducreyi> Haemophilus ducreyi> ChancroidChancroid

• Haemophilus parainfluenzaeHaemophilus parainfluenzae