Detección y caracterización de Escherichia coli productor de toxina Shiga en ninos atendidos en un hospital pediátrico interzonal de la ciudad de La Plata / Detection and characterization of Shiga toxin-producing Escherichia coli in children treated at an inter-zonal pediatric hospital in the city of La Plata

Escherichia coli productor de toxina Shiga (STEC) es un patógeno transmitido por alimentos que puede causar diarrea acuosa, diarrea sanguinolenta (DS) y síndrome urémico hemolítico (SUH). El objetivo de este estudio fue determinar las características fenotípicas y genotípicas de cepas STEC aisladas de niños con DS y SUH atendidos en un hospital pediátrico de la ciudad de La Plata en el período 2006-2012 y establecer la relación clonal de los aislamientos O157: H7 mediante electroforesis de campo pulsado. El porcentaje de muestras positivas fue de 4,9 y 39,2% en los pacientes que presentaron DS y SUH, respectivamente. Se aislaron 77 cepas STEC de 10 serotipos distintos, con el 100% de recuperación de colonias. El serotipo más frecuente fue O157: H7 (71,4%), seguido por O145: NM (15,6%). El 98,2% de los aislamientos O157: H7 correspondió al biotipo C y fue sensible a los antibióticos ensayados. Todos esos aislamientos presentaron el genotipo stx2, eae, fliC H7, ehxA, iha, efa, toxB, lpfA1-3 y lpfA2-2.Al estudiar la relación clonal de las cepas O157: H7, se identificaron un total de 42 patrones con al menos un 88% de similitud y se establecieron 6 clústeres que agruparon cepas con perfiles idénticos. Los aislamientos eae negativos pertenecieron a los serotipos O59: H19, O102: H6, O174: NM y O174: H21. Las cepas O59: H19 y O174: H21 fueron positivas para el gen aggR. Este estudio muestra que en la ciudad de La Plata y alrededores circulan STEC de diferentes serotipos y genotipos. A pesar de la diversidad genética observada entre los aislamientos O157: H7, algunos fueron indistinguibles por las técnicas de subtipificación utilizadas.

Shiga toxin-producing Escherichia coli (STEC) is a foodborne pathogen that can cause watery diarrhea, bloody diarrhea (BD), and hemolytic uremic syndrome (HUS). The objective of this study was to determine the phenotypic and genotypic profiles of STEC strains isolated from children with BD and HUS treated at a pediatric hospital in the city of La Plata in the period 2006-2012, and to establish the clonal relationship of O157: H7 isolates by pulsed field electrophoresis. The percentage of positive samples was 4.9% and 39.2% in patients with BD and HUS, respectively. Seventy-seven STEC strains from 10 different serotypes were isolated, with 100% colony recovery, O157: H7 being the most frequent (71.4%) serotype, followed by O145: NM (15.6%). An average of 98.2% of O157: H7 isolates belonged to biotype C and were sensitive to all the antibiotics tested. All of them (100%) carried genotype stx2, eae, fliC H7, ehxA, iha, efa, toxB, lpfA1-3 and lpfA2-2. When the clonal relationship of the O157: H7 strains was studied, a total of 42 patterns with at least 88% similarity were identified, and 6 clusters with identical profiles were established. The eae-negative isolates belonged to serotypes O59: H19, O102: H6, O174: NM and O174: H21. The strains O59: H19 and O174: H21 were positive for the aggR gene. This study shows that STEC of different serotypes and genotypes circulate in the city of La Plata and surroundings. Despite the genetic diversity observed between the O157: H7 isolates, some were indistinguishable by the subtyping techniques used.

Shigatoxigenic and atypical enteropathogenic Escherichia coli in fish for human consumption

ABSTRACT Shigatoxigenic and enteropathogenic Escherichia coli with virulence and multidrug resistance profile were isolated from Nile tilapia. This study finding is of great importance to public health because they help understand this pathogen epidemiology in fish and demonstrate how these animals can transmit E. coli related diseases to humans.

Captive wild birds as reservoirs of enteropathogenic E. coli (EPEC) and Shiga-toxin producing E. coli (STEC)

ABSTRACT Psittacine birds have been identified as reservoirs of diarrheagenic Escherichia coli, a subset of pathogens associated with mortality of children in tropical countries. The role of other orders of birds as source of infection is unclear. The aim of this study was to perform the molecular diagnosis of infection with diarrheagenic E. coli in 10 different orders of captive wild birds in the state of São Paulo, Brazil. Fecal samples were analyzed from 516 birds belonging to 10 orders: Accipitriformes, Anseriformes, Columbiformes, Falconiformes, Galliformes, Passeriformes, Pelecaniformes, Piciformes, Psittaciformes and Strigiformes. After isolation, 401 E. coli strains were subjected to multiplex PCR system with amplification of genes eae and bfp (EPEC), stx1 and stx2 for STEC. The results of these tests revealed 23/401 (5.74%) positive strains for eae gene, 16/401 positive strains for the bfp gene (3.99%) and 3/401 positive for stx2 gene (0.75%) distributed among the orders of Psittaciformes, Strigiformes and Columbiformes. None of strains were positive for stx1 gene. These data reveal the infection by STEC, typical and atypical EPEC in captive birds. The frequency of these pathotypes is low and restricted to few orders, but the data suggest the potential public health risk that these birds represent as reservoirs of diarrheagenic E. coli.

Virulence profiles of Shiga toxin-producing Escherichia coli and other potentially diarrheagenic E.coli of bovine origin, in Mendoza, Argentina

This study described a group of strains obtained from a slaughter house in Mendoza, in terms of their pathogenic factors, serotype, antibiotype and molecular profile. Ninety one rectal swabs and one hundred eight plating samples taken from carcasses of healthy cattle intended for meat consumption were analyzed. Both the swab and the plate samples were processed to analyze the samples for the presence of virulence genes by PCR: stx1, stx2, eae and astA. The Stx positive strains were confirmed by citotoxicity assay in Vero cells. The isolates were subsequently investigated for their O:H serotype, antimicrobial susceptibility and molecular profile by Random Amplification of Polymorphic DNA (RAPD). Twelve E.coli strains were identified by their pathogenicity. Nine were from fecal origin and three from carcasses. Three strains carried the stx1 gene, three the stx2 gene, two carried eae and four the astA gene. The detected serotypes were: O172:H-; O150:H8; O91:H21; O178:H19 and O2:H5. The strains showed a similarity around 70% by RAPD. Some of the E.coli strains belonged to serogroups known for certain life-threatening diseases in humans. Their presence in carcasses indicates the high probability of bacterial spread during slaughter and processing.