In Italy, isolation of Shigella sonnei in the last decades has become very infrequent, but since 2001 some epidemic events have occurred in northern and southern Italy. In this study phenotypic and genotypic testing has been performed on 64 isolates collected in Italy in the years 2001-2003 from outbreak and apparently sporadic cases. Class 2 integron carriage has been investigated. Biotype g, class 2 integron positive and PFGE type B profile were largely prevalent among our strains, supporting the hypothesis of the emergence and spread in Italy of an epidemic clone. Bacillary dysentery caused by Shigella species is an important cause of acute diarrhoeal disease in both developing and industrialized countries (8, 12, 15). Several phenotypic and molecular techniques have been used to type S. sonnei (6). Pulsed Field Gel Electrophoresis (PFGE), a broadly applicable typing method with a high degree of intra- and inter-laboratory reproducibility, has been previously applied on this organism in several countries and allowed for identification of epidemiologically relevant strains (3, 6, 14). Mobile genetic elements including plasmids, transposons, and gene cassettes in integrons play an important role in the dissemination of resistance determinants and are frequently reported in Shigella isolates (16). Conjugative plasmids encoding resistance to multiple antibiotics and both class 1 and 2 integrons have been reported in S. sonnei (11). Moreover, recent studies suggest that class 2 integrons predominate in S. sonnei (7). Class 2 integrons seem to be specifically associated with an epidemic strain of S. sonnei biotype g, that has been recently described in Australia, western Ireland and southwestern Korea (3, 7, 11). More recently, a prolonged multistate increase in shigellosis occurring in the years 2001-2003 in the south and mid-Atlantic areas of the USA has been reported, that has been attributed to strains of S. sonnei rhamnose negative, the distinctive biochemical characteristic of biotype g (2). In the years 1991-2000, S. sonnei has been very infrequently isolated in Italy from immigrants or from travellers from endemic areas (Enter-Net Italia, Annual surveillance reports). Moreover, data from the Centre of Enteric Pathogens of southern Italy illustrate as biotype g had been quite infrequent (2 out of 779 isolates in the decade 1971-1980) among strains of S. sonnei identified in this geographic area (9). In the years 2001-2003, four community outbreaks in Lombardy (northern Italy) and one in Palermo, Sicily (southern Italy) prompted us to investigate about the apparent re-emergence of S. sonnei in Italy. We have examined for epidemiological relationships on the basis of biotype, PFGE profile and antibiogram, 64 isolates from a collection of strains identified in the years 2001-2003 from northern and southern Italy. The presence of class 2 integrons as a marker of the epidemic clone of biotype g was also investigated.
|Titolo:||Epidemic strain of Shigella sonnei biotype g, carrying class 2 integron, in Italy, 2001-2003|
PONTELLO, MIRELLA MARIA (Secondo)
|Parole Chiave:||Shigella sonnei ; epidemiology ; biotype g ; class 2 integrons ; Italy|
|Settore Scientifico Disciplinare:||Settore MED/42 - Igiene Generale e Applicata|
|Data di pubblicazione:||mag-2005|
|Digital Object Identifier (DOI):||10.1128/JCM.43.5.2467-2470.2005|
|Appare nelle tipologie:||01 - Articolo su periodico|