Short report: analysis of clonal relationship among Shigella sonnei isolates circulating in Argentina

Fil: Pichel, Mariana. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriología; Argentina.Fil: González Fraga, Soledad. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriología; Argentina.Fil: Terragno, R. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriología; Argentina.Fil: Mulki, Jorgelina. Servicio Microbiología, Hospital del Niño Jesús de Praga, Salta; Argentina.Fil: Gentile, Angela. Coordinación de Gestión Epidemiológica de Salta, Ministerio de Salud Pública, Salta, ArgentinaFil: Kremer, C. Laboratorio de Microbiología, Hospital Provincial Neuquén ‘Dr. Eduardo Castro Rendón’, Neuquén; ArgentinaFil: Mola, A M. Laboratorio de Microbiología, Hospital Zonal Materno Infantil ‘Argentina Diego’, Azul; ArgentinaFil: Noseda, R. Laboratorio Azul, Azul; ArgentinaFil: Binsztein, N. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriología; Argentina.Thirty-five isolates of Shigella sonnei from patients with diarrhoea in three geographic regions of Argentina were examined for genetic diversity by pulsed-field gel electrophoresis (PFGE) and plasmid profile. PFGE of XbaI and BlnI DNA digests confirmed the occurrence of outbreaks in two regions caused by two separate predominant clones of S. sonnei. The third region was characterized by three circulating clones, one of which was possibly associated with an outbreak. Similar plasmids were found in distinct clones and in one outbreak clone five different plasmid profiles were identified. Antimicrobial resistance of the isolates varied from fully susceptible to the agents tested, to resistance to cotrimoxazole, ampicillin and ciprofloxacin. Antibiotic resistance did not correlate with plasmid content. This information will form the basis for active surveillance of shigellosis in Argentina and elsewhere in the region through the PulseNet International Network

Beyond Serotypes and Virulence-Associated Factors: Detection of Genetic Diversity among O153:H45 CFA/I Heat-Stable Enterotoxigenic Escherichia coli Strains

Characterization of enterotoxigenic Escherichia coli (ETEC) has been based almost exclusively on the detection of phenotypic traits such as serotypes and virulence-associated factors: heat-labile (LT) and heat-stable (ST) toxins and colonization factors (CFs). In the present work we show that the analysis of band patterns generated by randomly amplified polymorphic DNA (RAPD) analysis and pulsed-field gel electrophoresis (PFGE) of digested chromosomal DNA can be used to detect genetic diversity among ETEC strains expressing identical phenotypic traits. The study included 29 ETEC isolates from Latin America and Spain expressing the phenotype O153:H45 CFA/I ST plus 1 rough derivative, 2 nonmotile derivatives, and 1 O78:H12 CFA/I ST isolate, and a representative of a genetically distinct ETEC group. The results showed that the O153:H45 CFA/I ST ETEC isolates belong to a single clonal cluster whose isolates share on average, 84% of the RAPD bands and 77% of the PFGE restriction fragments, while the O78:H12 isolate shared only 44 and 4% of the RAPD bands and PFGE fragments, respectively, with the isolates of the O153:H45 group. More relevantly, RAPD and PFGE fingerprints disclosed the presence of different clonal lineages among the isolates of the O153:H45 cluster. Some of the genetic variants were isolated from defined geographic areas, while places like São Paulo City in Brazil and the middle-eastern part of Argentina were populated by several genetic variants of related, but not identical, ETEC strains. These results show that molecular biology-based typing methods can disclose strain diversity, which is usually missed in studies restricted to phenotypic typing of ETEC