Multiple Geographic Origins of Commensalism and Complex Dispersal History of Black Rats

The Black Rat (Rattus rattus) spread out of Asia to become one of the world's worst agricultural and urban pests, and a reservoir or vector of numerous zoonotic diseases, including the devastating plague. Despite the global scale and inestimable cost of their impacts on both human livelihoods and natural ecosystems, little is known of the global genetic diversity of Black Rats, the timing and directions of their historical dispersals, and the risks associated with contemporary movements. We surveyed mitochondrial DNA of Black Rats collected across their global range as a first step towards obtaining an historical genetic perspective on this socioeconomically important group of rodents. We found a strong phylogeographic pattern with well-differentiated lineages of Black Rats native to South Asia, the Himalayan region, southern Indochina, and northern Indochina to East Asia, and a diversification that probably commenced in the early Middle Pleistocene. We also identified two other currently recognised species of Rattus as potential derivatives of a paraphyletic R. rattus. Three of the four phylogenetic lineage units within R. rattus show clear genetic signatures of major population expansion in prehistoric times, and the distribution of particular haplogroups mirrors archaeologically and historically documented patterns of human dispersal and trade. Commensalism clearly arose multiple times in R. rattus and in widely separated geographic regions, and this may account for apparent regionalism in their associated pathogens. Our findings represent an important step towards deeper understanding the complex and influential relationship that has developed between Black Rats and humans, and invite a thorough re-examination of host-pathogen associations among Black Rats

Aislamiento y caracterización de Escherichia coli O157 en productos cárnicos bovinos y medias reses en la provincia de Tucumán

Escherichia coli O157 es un patógeno emergente asociado a diarrea, colitis hemorrágica y síndrome urémico hemolítico. Los productos cárnicos constituyen una importante fuente de contaminación con este microorganismo. Los objetivos de este estudio fueron establecer la frecuencia de detección de E. coli O157 en productos cárnicos y media res en la provincia de Tucumán, caracterizar los factores de virulencia de los aislamientos obtenidos, establecer la relación clonal entre cepas regionales mediante electroforesis de campo pulsado y comparar con lo consignado en la base de datos nacional. Desde 2004 hasta 2013 se analizaron 169 muestras de carne picada, 35 embutidos y 216 esponjados de media res. Se identificaron 13 aislamientos de E. coli O157; 6 de ellos fueron O157:H7 productores de toxina Shiga y se caracterizaron como stx2c(vh-a)/eae/ehxA (n = 5) y stx2/eae/ehxA (n = 1); los 7 aislamientos de E. coli O157 no toxigénicos fueron O157:NT(n = 4),O157:NM (n = 1),O157:ND (n = 1) y O157:H16 (n = 1). Los patrones de PFGE fueron diferentes entre sí y de los registrados en la base de datos nacional. Se concluye que existe gran diversidad genética en los aislamientos de E. coli O157 circulantes en nuestra región

An Stx-EAEC O59:NM[H19] strain isolated from a hemolytic uremic syndrome case in Argentina

Fil: Carbonari, Claudia C. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento bacteriología. Servicio Fisiopatogenia; Argentina.Fil: Ricciardi, Miriam. Hospital Zonal de Puerto Madryn "Dr. Andrés Ísola"; Chubut, Argentina.Fil: Calvo, Ana Rodríguez. Hospital Zonal de Puerto Madryn "Dr. Andrés Ísola"; Chubut, Argentina.Fil: Montes, Alejandro. Hospital Zonal de Puerto Madryn "Dr. Andrés Ísola"; Chubut, Argentina.Fil: Deza, Natalia L. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento bacteriología. Servicio Fisiopatogenia; Argentina.Fil: Conde Valentino, María A. Hospital Zonal de Puerto Madryn "Dr. Andrés Ísola"; Chubut, Argentina.Fil: Zolezzi, Gisela. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento bacteriología. Servicio Fisiopatogenia; Argentina.Fil: Baschkier, Ariela. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento bacteriología. Servicio Fisiopatogenia; Argentina.Fil: Vago, Mariano. Hospital Zonal de Puerto Madryn "Dr. Andrés Ísola"; Chubut, Argentina.Fil: Acosta, Denise. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento bacteriología. Servicio Fisiopatogenia; Argentina.Fil: Manfredi, Eduardo A. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento bacteriología. Servicio Fisiopatogenia; Argentina.Fil: Miliwebsky, Elizabeth. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento bacteriología. Servicio Fisiopatogenia; Argentina.Fil: Chinen, Isabel. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento bacteriología. Servicio Fisiopatogenia; Argentina.Fil: Rivas, Marta. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento bacteriología. Servicio Fisiopatogenia; Argentina.Shiga toxin-producing Escherichia coli (STEC) are a heterogeneous group of foodborne pathogens causing a broad spectrum of human disease, from uncomplicated diarrhea to hemolytic uremic syndrome (HUS). In this study, we report an HUS case associated with an O59:NM[H19] strain, harboring stx2a, iha, lpfAO26, lpfAO113 genes associated with STEC, and aatA, aap, pic, sigA, agg4A genes associated with enteroaggregative E. coli (EAEC), named Stx-EAEC. The strain showed low toxicity on Vero cells, and was resistant to streptomycin and trimethoprim/sulfonamides. The child carried the bacteria for more than 100 days. Since the large outbreak associated with Stx-EAEC O104:H4, many strains with similar profiles have been described. In Germany, an O59:NM[H19] strain, with comparable characteristics to the Argentine strain, was isolated from a bloody diarrhea case. In Argentina, this is the first report of an HUS case associated with a Stx-EAEC infection, and represents a new challenge for the surveillance system