Use of automated riboprinter and pulsed-field gel electrophoresis for epidemiological studies of invasive Haemophilus influenzae in Taiwan

A total of 87 invasive isolates of Haemophilus influenzae isolated througho ut Taiwan from 1994 to 1998 was collected; 57 were from children <14 years old, In all, 60.9% of isolates were resistant to ampicillin and produced <b eta>-lactamase. Ribotyping revealed six different profiles in 55 isolates o f type b, nine profiles in 10 isolates of non-type b and 12 profiles in 22 isolates of non-typable H. influenzae. Among isolates from 35 cases of meni ngitis, 30 (86%) were in ribogroups 1, 2 and 3 with >90% genetic similarity . Compared with all the other ribogroups, ribogroups 1, 2 and 3, which enco mpassed all H. influenzae type b, were significantly more prevalent as a ca use of meningitis in children <14 years old. Further subtyping of the predo minant ribogroup by pulsed-field gel electrophoresis (PFGE) identified diff erences of 0-6 bands among these isolates of ribogroup 1, which indicated d istant relatedness, Automated ribotyping was found to be a useful method an d was less time-consuming for molecular epidemiology studies of H. influenz ae. PFGE is suggested as an addition to ribotyping to improve discriminatio n if H, influenzae type b is involved. Differentiating ribogroups between t ype b and non-type b H. influenzae by genotyping may help to understand the molecular characteristics of outbreaks, endemicity and value of vaccinatio n. According to the results of ribotyping and PFGE, it seems possible that spread of invasive H. influenzae type b had occurred and ribotyping confirm ed that there was no clonal spread of non-type b H. influenzae in Taiwan.