Molecular epidemiology of Haemophilus influenzae type B isolates from Uruguay

Little information is available about the molecular epidemiology and genetic relationships of Haemophilus Influenzae serotype b (Hib) recovered from patients living in South America. Forty-three Hib isolates cultured largely from patients with invasive diseases in Uruguay between 1987 and 1992 were characterized for multilocus enzyme genotype and outer membrane protein (OMP) subtype. OMP analysis identified three of the known subtypes, including 3L (70%), 2L (18%), and 18L (2%). Two previously undescribed patterns related to the L and U subtype families were also found, and each represented 5% of the organisms. Four multilocus enzyme electrophoretic types were identified in the sample, including ET 12.5 (67.3%), 12.8 (23.3%), 12.7 (4.7%), and an ET closely related to ET 25.6 (47%). The combination of OMP subtype and ET allowed the recognition of 7 distinct Hib subclones. The ET 12.5/3L subclone accounted for 63% of all isolates, and caused 83% of the meningitis cases but only 55% of the episodes of pneumonia and sepsis. In general, the frequency of occurrence of Hib subclones in Uruguay was similar to that recorded in several European countries.