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Outbreak of Ciprofloxacin-ResistantShigella sonnei Associated withTravel to Vietnam, Republic of KoreaJin Seok Kim, Jae Joon Kim, Soo Jin Kim,Se-Eun Jeon, Ki Yeon Seo, Jun-Kil Choi,Nan-Ok Kim, Sahyun Hong, Gyung Tae Chung,Cheon-Kwon Yoo, Young-Taek Kim,Hyeng Il Cheun, Geun-Ryang Bae,Yeong-Hee Yeo, Gang-Ja Ha, Mi-Suk Choi,Shin-Jung Kang, Junyoung KimWe investigated an October 2014 outbreak of illness causedby Shigella sonnei in a daycare center in the Republic ofKorea (South Korea). The outbreak strain was resistant toextended-spectrum cephalosporins and fluoroquinolonesand was traced to a child who had traveled to Vietnam. Improvedhygiene and infection control practices are neededfor prevention of shigellosis.Shigella spp. are etiologic agents of gastrointestinal diseaseworldwide and are frequently associated with outbreaksbecause of their low infectious doses and personto-persontransmission (1,2). For the treatment of personswho have severe infections, fluoroquinolones are amongthe first-line agents for adults; additionally, oral extendedspectrumcephalosporins are used to treat young children.However, the current emergence and spread of drug resistancein Shigella strains could hinder empirical antimicrobialtherapy, leading to treatment failure. S. sonnei is the mostfrequently isolated species among all cases of Shigella infectionin industrialized countries (3), and it has become increasinglyprevalent across Southeast Asia in recent decades(4). Recently, international travel to areas where the diseaseis highly endemic has accelerated the global spread of drugresistantS. sonnei to nonendemic regions. Here, we describea travel-associated outbreak of illness caused by a S. sonneistrain that was resistant to extended-spectrum cephalosporinsand fluoroquinolones.Author affiliations: Korea National Institute of Health, Cheongju-si,South Korea (J.S. Kim, S.J. Kim, S.E. Jeon, N.-O. Kim, S. Hong,G.T. Chung, C.-K. Yoo, S.-J. Kang, J. Kim); Gyeongsangnam-doProvincial Government, Changwon-si (J.J. Kim); Korea Centersfor Disease Control and Prevention, Cheongju-si (K.Y. Seo,J.-K. Choi, Y.T. Kim, H.I. Cheun, G.-R. Bae); Gyeongsangnam-doPublic Health and Environmental Research Institute,Changwon-si (Y.-H. Yeo, G.-J. Ha); Changnyeong Preservationof Health, Changnyeong-gun, South Korea (M.-S. Choi)DOI: http://dx.doi.org/10.3201/eid2107.150363The StudyIn the beginning of October 2014, six children who werevomiting and experiencing abdominal cramping and diarrheawere admitted to the local hospital in Gyeongsangnamdo,Repulic of Korea (South Korea). All patients attendedthe same daycare center that provided care and food tochildren from low-income families. Fecal specimens from6 patients were submitted to the local public health laboratoryand were processed according to a standard bacterialculture method. On October 6, Korea Centers for DiseaseControl and Prevention was notified that S. sonnei phase IIwere identified from all fecal samples. An epidemiologicinvestigation was conducted to determine the extent of theoutbreak and to identify the mode of transmission. A confirmedcase was identified by passive and active case-findingon the basis of laboratory-identified S. sonnei isolates inthe fecal specimens of center attendees and staff members,families of the children, and persons in the community. Aprobable case was defined as a person with any shigellosissymptoms and an epidemiologic link to infected patientswhose cultures were negative. The children’s guardianswere interviewed by using a standardized questionnaire thatrequested information on symptoms, food consumption, recenttravel history, and contact persons. This investigationwas part of a public health emergency response and was accordinglyexempt from institutional review board approval.The investigation revealed that an 8-year-old boy (theindex case-patient in this outbreak) had recently returnedafter visiting family in Vietnam, where S. sonnei infectionis highly endemic. He had experienced sustained diarrhealepisodes since his return, and after returning tothe daycare center, children in the daycare center beganhaving similar symptoms. Cases of shigellosis were alsoidentified among the grandparents of the index case-patientand a person the family visited in a geographicallydistant location on September 27. No isolates were obtainedfrom the environmental samples collected, includingfoods, drinking water, and surface swab specimens ofthe daycare facility.Eleven laboratory confirmed and 4 probable caseswere identified during this outbreak. The median age ofthe patients in the daycare center was 7.8 (range 4–13)years. Overall, the reported symptoms were diarrhea (≥3loose stools during 24 hours) and abdominal cramping; 4patients were asymptomatic but their stool samples wereEmerging Infectious Diseases • www.cdc.gov/eid • Vol. 21, No. 7, July 2015 1247