RECENT TRENDS IN THE EPIDEMIOLOGY OF SHIGELLA SPECIES IN ISRAEL

Trends in the epidemiology of infections due to Shigella species over a period of 6 years (1986-1991) in Israel were studied by analysis of the results of 51,300 stool cultures, of which 2,987 yielded Shigella species. In a university hospital, the relative prevalence of Shigella sonnei in patients with shigellosis increased over the years from 60% in 1986 to 91% in 1991 (r = 0.93; P = .007); concomitantly, the preva lence of Shigella flexneri decreased from 29% to only 8% (r = -0.80; P < .05). In the community, the increase in prevalence of S. sonnei was more moderate and occurred only from 1989 to 1991. Since 1990, S. son nei has been isolated from more hospitalized patients than has S. flex neri, in contrast to their rates of isolation in the past. The increas e in prevalence of S. sonnei was most prominent among children, in who m it caused 94% of shigella infections in 1991. Shigella boydii and Sh igella dysenteriae remained relatively rare, causing approximately 5% and approximately 1%, respectively, of the cases of shigella infection . Concomitantly, the antimicrobial resistance of S. sonnei has become significantly greater, and it is currently 2.7 and 1.6 times higher th an that of S. flexneri to trimethoprim-sulfamethoxazole and ampicillin , respectively. We conclude that the relative frequency of S. sonnei i s increasing, especially in hospitalized patients, and hypothesize tha t this may be related to its increasing antimicrobial resistance. Thes e trends have clinical implications.