Emergence of Multidrug-Resistant Salmonella enterica Serovar Typhi in Korea

Abstract

A chloramphenicol-resistant strain of Salmonella enterica serovar Typhi was first noted in Korea in 1992, when a resistant isolate was detected in a returned traveler. Continued isolation of multidrug-resistant (MDR) strains thereafter in other settings prompted a retrospective analysis of laboratory records and phenotypic and genotypic analyses of 12 chloramphenicol-resistant isolates. Among these, one isolate was resistant only to chloramphenicol, and the other isolates were also resistant to ampicillin and co-trimoxazole. MDR was transferred by conjugation from 9 of the 11 isolates. PCR showed that all isolates had an incompatible group HI1 plasmid, and oriT was detected in 10 isolates, which included strains with an unsuccessful transfer of resistance. All of the ampicillin-resistant isolates had a ␤-lactamase band of pI 5.4 and bla TEM alleles. A PCR amplicon from an isolate showed that the sequences were identical to those of bla TEM-1 , suggesting that all isolates had a TEM-1 ␤-lactamase. All isolates had class 1 integrons: 10 isolates had integrons of ca. 1.2 kb with dhfr7 gene cassettes, and 1 isolate had an integron of ca. 2.3 kb with aacA4 and bla OXA-1 -like gene cassettes. The pulsed-field gel electrophoresis patterns of 7 of 11 MDR isolates were identical and indistinguishable from those reported for isolates in India and Indonesia. In conclusion, some of the MDR strains in Korea are related to those in other Asian countries. Susceptibility testing became necessary for selection of antimicrobial agents for the optimal treatment of patients with the emergence of MDR Salmonella serovar Typhi in Korea.

Emergence of plasmid-mediated multidrug resistance in epidemic and non-epidemic strains of Salmonella enterica serotype Typhi from Jordan

“…Besides plasmids, mobile elements contribute to the dissemination of antibiotic resistance and integrons represent the major vehicle for spread [33]. In this study, all MDR S. Typhi strains harbored a class 1 integron carrying the dfrA7 gene cassette, conferring resistance to trimethoprim, which is similar to the results of earlier studies on other S. Typhi isolates from different countries of South East Asia [8,15]. The presence of the integron must not be undervalued since two reports have already described multidrug-resistant S. Typhi strains harboring integrons with up to six drug resistance genes [34,35].…”

“…The PFGE pattern of MDR S. Typhi strains investigated was apparently identical to one of the five XbaI-PFGE-patterns identified as circulating MDR S. Typhi strains in Asia and Middle Eastern countries in previous studies [8,26,27,36]. These findings confirm that MDR strains from Jordan are related to those in other countries and could have been introduced possibly about November 2004 or even before.…”

“…However, multiple resistance to these antibiotics, and more recently to fluoroquinolones, has developed among S. Typhi strains [3][4][5][6]. Multidrug resistant (MDR) isolates have been reported as causative agents of numerous outbreaks, dramatically reducing the choice of therapy in many areas of Africa, Southeast Asia and the Indian subcontinent [7][8][9][10] where typhoid fever is endemic.…”

Comparison of Blood Clot Culture with Conventional Blood Culture and Biphasic Blood Culture for the Diagnosis of Enteric Fever

“…(Lee, 2004) In our hospital settings, isolation can be done by conventional blood culture method, clot culture and Biphasic blood culture.…”

Nosocomial Outbreak of Pediatric Gastroenteritis Caused by CTX-M-14-Type Extended-Spectrum β-Lactamase-Producing Strains of Salmonella enterica Serovar London

“…Etest strips and Etest ESBL strips (AB BIODISK, Solna, Sweden) were used to determine MICs of cefotaxime and ceftazidime and to confirm ESBL production, respectively. Isoelectric points (pIs) of the ␤-lactamases were determined as described previously (11). The bla TEM and bla SHV alleles were detected by PCR as described previously (2,10).…”