Streptococcal emm types in Hawaii: a region with high incidence of acute rheumatic fever.

BACKGROUND

The clinical epidemiology of group A streptococcal (GAS) infections in Hawaii seems different from that in the continental United States with frequent skin infections and endemically high rates of acute rheumatic fever (ARF).

METHODS

GAS emm types in Hawaii were determined to identify any possible association between the emm types and specific clinical manifestations. A convenience sample of 1482 Hawaii GAS isolates collected between February 2000 and December 2005 was used. All isolates were characterized by emm sequence typing. The distribution of emm types in Hawaii was compared with the published continental US data for pharyngeal and invasive GAS strains, the CDC database from similar time periods, as well as with emm types present in a candidate GAS vaccine.

RESULTS

Ninety-three distinct emm types were recognized among the 1482 GAS isolates. The most frequently identified emm types in order of decreasing frequency were 12, 1, 28, 4, 22, 77, 81, 58, 65/69, 49, 74, 85, 92, 75, 101 and 2. Of this study sample, 27 of the 50 invasive GAS isolates belonged to uncommon continental US emm types (54% in Hawaii cultures vs. 10% reported from the continental US). Of the 1179 pharyngeal isolates, 509 belonged uncommon continental US emm types (43% in Hawaii cultures vs. 27% reported from the continental US).

CONCLUSIONS

The prevalent emm types in Hawaii differ from those in the continental US. The prevalence of these unusual emm types might limit the effectiveness of any proposed multivalent type-specific GAS vaccine in Hawaii.