4.7 Flashcards
haemophilus commensals of
- Commensals of the human upper respiratory tract but may also cause disease
haemophilus capsules
§ Some strains are encapsulated
□ Polysaccharide capsule
□ Endows virulence
□ Antigenic differences allow classification into serotypes
typability
□ Antigenic differences allow classification into serotypes
□ Encapsulated/typable
□ Strains which don’t use capsules are called
® Nonencapsulated or nontypeable
® Are less virulent
haemophilus antigenic differences
® Antigenic differences in the polysaccharide capsules between strains allow classification into seven serotypes: a,b,c,d,e,f,& g
® Haemophilus influenzae type B
◊ Vaccine available
◊ Significant mortality in unvaccinated communities
HIB causes
meningitidis
epiglottis
HIB ◊ Meningitis
} Leading cause of bacterial meningitis in children <18 mo
} Frequently associated with septicaemia
}
sequelae of HIB meningitidis
} High incidence of sequelae in survivors; mental retardation, deafness
mortality of HIB meningitidis
100% untreated mortality
leading cause of bacterial meningitidis in childrenn <18 mo
HIB
HIB ◊ Epiglottitis
} Invasive infections of the epiglottis in children >18 mo
} Inflammation and swelling of epiglottal tissue
} Rapid progression to laryngeal obstruction, asphyxiation
® Nontypeable haemophilus influenza
◊ Commensal of upper respiratory tract
◊ Cause infectious disease of mucosal surfaces
◊ Otitis media, bronchitis, conjunctivitis, sinusitis, and types of pneumonia
○ Haemophilus parainfluenza commensal of
upper respiratory tract
○ Haemophilus parainfluenza causes
§ Poorly defined cause of upper respiratory tract infection including otitis media
§ Uncommon cause of meningitis in children and endocarditis in adolescents
4 less commonly seen species of haemophilus
aphrophilus
paraphrophilus
ducreyi
aegyptius
○ Haemophilus aphrophilus and paraphrophilus
§ Recently reclassified as Aggregatibacter
§ Normal oral flora
§ Rare causes of infective endocarditis
§ Members of the HACEK group
H
haemophilus aphrophilus and paraphrophilus
A
actinobacillus
C
cardiobacterium hominis
E
eikenella corrodens
K
kingella kingae
○ Haemophilus ducreyi
§ Cause of sexually transmitted disease chancroid
chancroid caused by
○ Haemophilus ducreyi
chancroid
□ Ulcerative genital lesions and enlarged inguinal lymph nodes
□ Can enhance transmission of HIV in those concurrently infected
