We evaluated 52 children with invasive
Haemophilus influenzae infection in Kamikawa subprefucture, Hokkaido, Japan between 1996 and 2005. The most frequent disease was
meningitis, in 30 children (57.7%), followed by
pneumonia in 9 (17.3%),
bacteremia in 8 (15.4%),
epiglottitis in 4 (7.7%), and
cellulitis in 1 (1.9%). Patients ranged in age from 0 days to 8 years. Thirty (57.7%) of the patients were less than 2 years old. Only 6 cases of invasive H. influenzae
infection occurred in children older than 5 years. Between 1996 and 2005 the annual incidence rates of invasive H. influenzae
infection in children aged less than 5 years, and those aged from 5 to 9 years were 4.3/100,000 to 56.8/100,000 and 0/100,000 to 12.4/100,000, respectively. A marked increase of the annual incidence rate in children aged under 5 years was observed in the most recent 2 years (2004 and 2005). No patients with invasive H. influenzae
infection died, but sequelae were seen at discharge in 2 patients with
meningitis, predominantly
epilepsy and developmental delay of varying severity. Two patients with
epiglottitis were treated by endotracheal intubation or
tracheostomy. Of 41 strains isolated from 1999 to 2005, 35 were classified for antimicrobial resistance by the polymerase chain reaction (PCR) method. The number of strains of
beta-lactamase-negative
ampicillin-susceptible, low
beta-lactamase-negative
ampicillin-resistant, beta-lactamase-negative
ampicillin-resistant, beta-lactamase-negative
amoxicillin/clavulanic acid resistant-I, and
beta-lactamase-positive
amoxicillin/clavulanic acid resistant-II, were 22, 3, 5, 2, and 3, respectively. The serotype in 37 (97.4%) of 38 cases demonstrated type b.