title: Changes in the distribution of Haemophilus influenzae type b clones associated with widespread infant vaccination in Finland.
abstract: Isolates from 646 consecutive Finnish Haemophilus influenzae type b (Hib) patients with systemic disease, collected before and during large-scale vaccinations with Hib conjugate vaccines, were analyzed by major outer membrane protein (OMP) subtyping, lipopolysaccharide (LPS) serotyping, and biotyping (BT). Strains with OMP-BT-LPS combinations (clones) 1-I-1 and 1c-I-1 disappeared at the same rate as the disease they were associated with. A preferential decrease in the number of isolates of clone 1-II-1 was recorded, whereas the reduction in disease caused by strains of clone 1-II-9 occurred at a lower rate than expected. The latter clone occurred mainly in the most densely populated area of Finland. Strains belonging to all the common Hib clones were isolated from the 16 infants who acquired Hib disease despite being (partially) vaccinated. Thus, Hib clones disappeared during mass vaccination with conjugate vaccines, although at different rates.
authors.affiliation: Department of Medical Microbiology, University of Amsterdam, Netherlands.
authors.forename: L
authors.initials: L
authors.lastname: van Alphen
authors.forename: A K
authors.initials: AK
authors.lastname: Takala
authors.forename: L
authors.initials: L
authors.lastname: Geelen-van den Broek
authors.forename: J
authors.initials: J
authors.lastname: Dankert
authors.forename: J
authors.initials: J
authors.lastname: Eskola
mesh_terms: D000293:Adolescent; D000367:Age Factors; D016667:Bacterial Capsules; D015373:Bacterial Typing Techniques; D001428:Bacterial Vaccines; D002648:Child; D002675:Child, Preschool; D004826:Epiglottitis / Q000453:epidemiology / Q000382:microbiology / Q000517:prevention & control; D005387:Finland / Q000453:epidemiology; D006192:Haemophilus Infections / Q000453:epidemiology / Q000382:microbiology* / Q000517:prevention & control; D018073:Haemophilus Vaccines; D006193:Haemophilus influenzae / Q000145:classification* / Q000302:isolation & purification; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008583:Meningitis, Haemophilus / Q000453:epidemiology / Q000382:microbiology / Q000517:prevention & control; D011135:Polysaccharides, Bacterial; D012703:Serotyping; D014611:Vaccination
chemical_list: D001428:Bacterial Vaccines; D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine; D011135:Polysaccharides, Bacterial