Emergence of a New Multidrug-Resistant Serotype X Variant in an Epidemic Clone of Shigella flexneri

Abstract

, 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.

Sensibilidad antimicrobiana entre los serogrupos de <em>Shigellae</em> aislados en la ciudad de Quito-Ecuador

“…Su identificación se fundamenta en características bioquímicas y antigénicas, en base a ellas se describen cuatro especies: Shigella dysenteriae, serogrupo A; Shigella flexneri, serogrupo B; Shigella boydii, serogrupo C; y, Shigella sonnei, serogrupo D; todos éstos causantes disentería bacilar, aunque con diferente gravedad [1][2][3].…”

“…Su identificación se fundamenta en características bioquímicas y antigénicas, en base a ellas se describen cuatro especies: Shigella dysenteriae, serogrupo A; Shigella flexneri, serogrupo B; Shigella boydii, serogrupo C; y, Shigella sonnei, serogrupo D; todos éstos causantes disentería bacilar, aunque con diferente gravedad [1][2][3]. mente por ruta fecal-oral directa o indirecta en lugares que se caracterizan por una higiene deficiente, como guarderías o centros carcelarios, existiendo también un alto índice de contagio en personas que realizan viajes a países en vías de desarrollo, produciéndose el síndrome diarreico de los viajeros [4].…”

Genomic Portrait of the Evolution and Epidemic Spread of a Recently Emerged Multidrug-Resistant Shigella flexneri Clone in China

“…Serotype Xv first appeared in 2000 in Henan province and subsequently replaced serotype 2a to become the predominant serotype in Henan between 2002 and 2006. Serotype Xv was also the most prevalent serotype in Gansu (67%) and Anhui (54%) in 2007 (9). A novel plasmid (pSFXv_2) carrying the opt gene encoding the O antigen phosphoethanolamine (PEtN) transferase is responsible for serotype conversion from X to Xv (10).…”

“…S. flexneri is divided into at least 19 serotypes (serotypes 1a, 1b, 1c, 1d, 2a, 2b, 3a, 3b, 4a, 4av, 4b, 5a, 5b, X, Xv, Y, Yv, F6, and 7b), based on the combinations of antigenic determinants present on the O antigen of the cell envelope lipopolysaccharide (LPS) (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Serotypes 1c, 4av, 7b, 1d, Yv, and Xv were new serotypes reported in recent years (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14), among which serotypes 1c and Xv have caused epidemic-level disease (5,7,9). Serotype Xv first appeared in 2000 in Henan province and subsequently replaced serotype 2a to become the predominant serotype in Henan between 2002 and 2006.…”

Travel- and Community-Based Transmission of Multidrug-ResistantShigellasonneiLineage among International Orthodox Jewish Communities

“…This cassette contains the aadA1, sat2, and dfrA1 genes that confer resistance to aminoglycosides, streptothricin, and trimethoprim and was chromosomally integrated adjacent to the glmS gene in these isolates (indicating a single acquisition event). This region is identical to a Tn7-like island, also adjacent to the glmS gene, in the newly emerging Xv serotype of S. flexneri (reference strain 2002017 [35]; online Technical Appendix 2 Figure 5). No mutations known to confer quinolone resistance were found in gyrA or parC sequences of isolates in the OJC-associated lineage, and no plasmidencoded quinolone resistance genes were detected (online Technical Appendix 1).…”