Changes in Patterns of Antimicrobial Susceptibility and Integron Carriage among Shigella sonnei Isolates from Southwestern Korea during Epidemic Periods

Abstract

Shigella sonnei isolates from southwestern Korea during the epidemic periods of 1998 to 2000 were genetically related. The antimicrobial susceptibilities of the outbreak-related isolates changed annually. All isolates carried class 2 integrons, and the outbreak-related isolates from 1999 also carried class 1 integrons. The antimicrobial susceptibilities of S. sonnei isolates are readily changed by antibiotic selective pressures, and integrons are responsible for resistance to antimicrobial agents commonly used to treat shigellosis.

High prevalence of trimethoprim-resistance cassettes in class 1 and 2 integrons in Senegalese Shigella spp isolates

“…In this study, class 1 integrons were the most prevalent, in keeping with the results of other studies of African Shigella isolates [18]. In contrast, integron prevalence is very low in other parts of the world [20,21,22]. We found class 2 integrons in half the 32 strains studied here.…”

“…[7,19,4,20]. In Senegal, multiple resistance to ampicillin, sulfamethoxazole, trimethoprim and tetracycline is related to the intensive first-line use of these antibiotics to treat diarrhoeal illnesses and other infectious diseases.…”

Prevalence of integrons in Shigella sonnei from Brazil

“…Even if it is considered that the results for Int3 were inconclusive, 92% of the strains were positive for two integrons (Int1 and Int2) and all the strains showing resistance for two or more tested antibiotics had at least one of the integron. The detection rate of Int2 in Shigella in this study (100%) was higher than in other reports, including the frequencies of 86.6% in other studies in Brazil 3 and 76.9% in Japan 11 and was similar to the frequency in Korea 12 and Italy. 13 However, the frequency of Int1 in Shigella in this study (92%) was higher than that of Brazil (6.7%), 3 Korea (14.9%) 12 and Japan (3.8%).…”

“…The detection rate of Int2 in Shigella in this study (100%) was higher than in other reports, including the frequencies of 86.6% in other studies in Brazil 3 and 76.9% in Japan 11 and was similar to the frequency in Korea 12 and Italy. 13 However, the frequency of Int1 in Shigella in this study (92%) was higher than that of Brazil (6.7%), 3 Korea (14.9%) 12 and Japan (3.8%). 11 Gene cassettes conferring resistance to some commonly used antibiotics in the past, such as TT and streptomycin, have been discovered and it is known that resistance genes for new antibiotics used to treat shigellosis have become part of a gene cassette.…”

“…14 Many studies have directly linked the presence of integrons with dissemination of antibiotic resistance genes among the world microbial population, with the consequence that the presence of multiple genes or gene cassettes may cause even the newest effective antibiotics to become ineffective quickly. 7,12,15 From the results obtained, it was possible to conclude that no linkage of drug resistance to specific integrons could be proven, but nearly all strains evaluated did contain Int1 and Int2.…”