Virulence Genes and Prevention of Haemophilus Influenzae Infections
Arch Dis Child: first published as 10.1136/adc.60.12.1193 on 1 December 1985. Downloaded from Archives of Disease in Childhood, 1985, 60, 1193-1196 Current topic Virulence genes and prevention of Haemophilus influenzae infections E R MOXON Infectious Disease Unit, Department of Paediatrics, John Radcliffe Hospital, Oxford The bacterium Haemophilus influenzae causes a infections) are encapsulated.3 H influenzae may wide spectrum of important childhood diseases that make any one of six chemically and antigenically includes meningitis, epiglottitis, cellulitis, acute distinct polysaccharide capsules (designated a-f), pneumonitis, septic arthritis, and otitis media. but strains expressing type b antigen account for Meningitis, the commonest of the systemic infec- most serious infections. The second important tions, in addition to being life threatening, is of observation was that serum factors (later identified particular importance to paediatricians because the as antibodies) with specific activity against the type damage it causes to the developing brain is often b antigen are critical in host defence against systemic permanent. H influenzae is a major cause of H influenzae infections.4 Given these facts, it is pyogenic meningitis in childhood throughout the reasonable to ask what is so important about the how does it differ world, and occurs in about one child in every type b capsule of H influenzae, copyright. thousand, usually within three years of birth. from the five other polysaccharide capsules, and to Although the availability of antibiotics has de- what extent other surface antigens, such as outer creased mortality dramatically (from greater than membrane proteins and lipopolysaccharide, modu- 90% to less than 10%), the occurrence of central late H influenzae virulence or serve as targets for the nervous system damage among survivors has not lethal effects of host immune responses.
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