Sandbox hemophillus: Difference between revisions
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===Seeding=== | ===Seeding=== | ||
*The colonizing bacteria invade the mucosa and enter the bloodstream. | *The colonizing bacteria invade the mucosa and enter the bloodstream. | ||
*Eustachian tube dysfunction, antecedent viral upper respiratory tract infection (URTI), foreign bodies, and mucosal irritants, including smoking, can promote infection. | *Eustachian tube dysfunction, antecedent viral upper respiratory tract infection (URTI), foreign bodies, and mucosal irritants, including smoking, can promote infection. | ||
*In patients with underlying chronic obstructive pulmonary disease (COPD) or cystic fibrosis (CF), NTHi frequently colonizes the lower respiratory tract and can exacerbate the disease. | *In patients with underlying chronic obstructive pulmonary disease (COPD) or cystic fibrosis (CF), NTHi frequently colonizes the lower respiratory tract and can exacerbate the disease. | ||
{| class="wikitable" | |||
!Spread of bacterial load | |||
!Type of infection | |||
|- | |||
|Eustachian tube | |||
|Otitis media | |||
|- | |||
|Sinuses | |||
|Sinusitis | |||
|- | |||
|Respiratory tract | |||
|Bronchitis and pneumonia | |||
|} | |||
===Pathogenesis=== | ===Pathogenesis=== | ||
Revision as of 18:00, 17 May 2017
Pathophysiology
Transmission
- Transmission is by direct contact or by inhalation of respiratory tract droplets.
- Neonates can acquire infection by aspiration of amniotic fluid or contact with genital tract secretions containing the bacteria.
Incubation
Incubation period of Hemophilus influenza infection is variable.
Seeding
- The colonizing bacteria invade the mucosa and enter the bloodstream.
- Eustachian tube dysfunction, antecedent viral upper respiratory tract infection (URTI), foreign bodies, and mucosal irritants, including smoking, can promote infection.
- In patients with underlying chronic obstructive pulmonary disease (COPD) or cystic fibrosis (CF), NTHi frequently colonizes the lower respiratory tract and can exacerbate the disease.
| Spread of bacterial load | Type of infection |
|---|---|
| Eustachian tube | Otitis media |
| Sinuses | Sinusitis |
| Respiratory tract | Bronchitis and pneumonia |
Pathogenesis
- The antiphagocytic nature of the Hib capsule and the absence of the anticapsular antibody lead to increasing bacterial proliferation.
- When the bacterial concentration exceeds a critical level, it can disseminate to various sites, including meninges, subcutaneous tissue, joints, pleura, pericardia, and lungs.
- The antibody to the Hib capsule plays the primary role in conferring immunity.
- Newborns have a low risk of infection, likely because of acquired maternal antibodies.
- When these transplacental antibodies to the PRP antigen wane, infants are at high risk of developing invasive H influenzae disease, and their immune responses are low even after the disease.
- Therefore, they are at high risk of repeat infections since prior episodes of H influenzae do not confer immunity. By age 5 years, most children have naturally acquired antibodies.
- The Hib conjugate vaccine induces protection by inducing antibodies against the PRP capsule.
- The Hib conjugate vaccine does not provide protection against NTHi strains. Since the widespread use of the Hib conjugate vaccine, NTHi has become more of a pathogen.