title: Emergence of a new multidrug-resistant serotype X variant in an epidemic clone of Shigella flexneri.
abstract: Shigella spp. are the causative agent of shigellosis with Shigella flexneri serotype 2a being the most prevalent in developing countries. Epidemiological surveillance in China found that a new serotype of S. flexneri appeared in 2001 and replaced serotype 2a in 2003 as the most prevalent serotype in Henan Province. The new serotype also became the dominant serotype in 7 of the 10 other provinces under surveillance in China by 2007. The serotype was identified as a variant of serotype X. It differs from serotype X by agglutination to the monovalent anti-IV type antiserum and the group antigen-specific monoclonal antibody MASF IV-I. Genome sequencing of a serotype X variant isolate, 2002017, showed that it acquired a Shigella serotype conversion island, also as an SfX bacteriophage, containing gtr genes for type X-specific glucosylation. Multilocus sequence typing of 15 genes from 37 serotype X variant isolates and 69 isolates of eight other serotypes, 1a, 2a, 2b, 3a, 4a, 5b, X, and Y, found that all belong to a new sequence type (ST), ST91. Pulsed-field gel electrophoresis revealed 154 pulse types with 655 S. flexneri isolates analyzed and identified 57 serotype switching events. The data suggest that S. flexneri epidemics in China have been caused by a single epidemic clone, ST91, with frequent serotype switching to evade infection-induced immunity to serotypes to which the population was exposed previously. The clone has also acquired resistance to multiple antibiotics. These findings underscore the challenges to the current vaccine development and control strategies for shigellosis.
authors: State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, China CDC, P.O. Box 5, Changping, Beijing, China.
authors: Changyun
authors: C
authors: Ye
authors: Ruiting
authors: R
authors: Lan
authors: Shengli
authors: S
authors: Xia
authors: Jin
authors: J
authors: Zhang
authors: Qiangzheng
authors: Q
authors: Sun
authors: Shaomin
authors: S
authors: Zhang
authors: Huaiqi
authors: H
authors: Jing
authors: Lei
authors: L
authors: Wang
authors: Zhenjun
authors: Z
authors: Li
authors: Zhemin
authors: Z
authors: Zhou
authors: Ailan
authors: A
authors: Zhao
authors: Zhigang
authors: Z
authors: Cui
authors: Jingjing
authors: J
authors: Cao
authors: Dong
authors: D
authors: Jin
authors: Lili
authors: L
authors: Huang
authors: Yiting
authors: Y
authors: Wang
authors: Xia
authors: X
authors: Luo
authors: Xuemei
authors: X
authors: Bai
authors: Yan
authors: Y
authors: Wang
authors: Ping
authors: P
authors: Wang
authors: Qiang
authors: Q
authors: Xu
authors: Jianguo
authors: J
authors: Xu
mesh_terms: D015373:Bacterial Typing Techniques; D002681:China / Q000453:epidemiology; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D004405:Dysentery, Bacillary / Q000453:epidemiology* / Q000382:microbiology*; D016521:Electrophoresis, Gel, Pulsed-Field; D016680:Genome, Bacterial; D044404:Genomic Islands; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D039002:Prophages / Q000235:genetics; D017422:Sequence Analysis, DNA; D012703:Serotyping; D012763:Shigella flexneri / Q000145:classification* / Q000187:drug effects / Q000302:isolation & purification*
chemical_list: D004269:DNA, Bacterial