Clonal lines of Salmonella enterica serotype Enteritidis documented by IS200-, ribo-, pulsed-field gel electrophoresis and RFLP typing

Abstract

Summary. Sixty-two selected strains of Salmonella serotype Enteritidis of 33 phage types (PTs), and one strain classified as RDNC, were characterised by four different chromosomally based typing methods to elucidate genetic relationships among strains of different phage types. Based on IS200-hybridisation patterns, two major groups, containing strains of the most commonly encountered phage types, and six minor groups (seven with the RDNC strain included) were observed. IS200 pattern was a stable epidemiological marker in strains of all phage types except PT 6a and 14b. Ribotyping separated strains of the phage types into one major and five minor groups; the pattern of the RDNC strain was not seen with other strains. More than one ribotype was observed among strains of Enteritidis PTs 6, 7, 14b and 21. By pulsed-field gel electrophoresis, strains of 21 of the 33 phage types formed one large cluster when bands > 125 kb were used as the criterion for separation. Among strains belonging to PTs 1,6,7 and 14b, more than one pattern was observed by this method. By probing with five random cloned fragments of the Enteritidis chromosome, strains from 27 of 31 phage types examined showed the same hybridisation pattern. With the combined use of four genotypic methods, two groups of strains, representing eight and seven of 33 Enteritidis phage types, were formed; these two groups may be considered as the main evolutionary lines of Enteritidis. Strains of the remaining phage types, and the RDNC strain, belonged to separate groups.

Host adapted serotypes of Salmonella enterica

“…Dublin strains showed the same RFLP-patterns when hybridized with the insertion sequence IS200 while restriction polymorphism can be demonstrated by ribotyping [41]. The clonal nature of Dublin has been confirmed by analysis of molecular variation in the serotype specific plasmid of this host-adapted serotype [42] and also showed that the geographically restricted clone (Du3) harboured a serotype specific plasmid more closely related to that of the UR serotypes.…”

“…This has been further corroborated by incompatibility studies of the plasmids in both Du3 and the widespread clone Du1 (D. J. Platt, unpublished). Finally, Dublin, as well as Gallinarum, is closely related to certain strains of Enteritidis, a polyphyletic serotype that is pathogenic for a variety of host species [32,41].…”

Molecular tools for the characterisation of antibiotic-resistant bacteria

“…These are mobile DNA elements that are able to integrate within the bacterial genome. As their position and number can vary from strain to strain, this diversity has been used for typing purposes such as with IS6110 typing of Mycobacterium tuberculosis [69] or IS200 fingerprinting of Salmonella enterica [46,47].…”

Fenotipos bioquímicos y fagotipos de cepas de Salmonella enteritidis aisladas en Antofagasta, 1997-2000

“…Las cepas dominantes fueron aisladas de huevos (7), carnes de pollo (1) y clínicas (5), sugiriendo una estrecha relación y un origen clonal común. Esto concuerda con lo descrito por otros autores [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] , en el sentido, que la vía de la transmisión de S enteritidis a los humanos en la zona norte de Chile, puede ser a través del consumo de productos avícolas contaminados con los mismos tipos de S enteritidis. También, la combinación de los fenotipos bioquímicos y fagotipos indicaron que solamente 8/14 del FT1 estaba presente en un mismo FB (C1).…”

“…Algunos investigadores sostienen que los métodos genéti-co-moleculares son altamente efectivos, confirmando su enorme potencial para el diagnóstico de estos agentes infecciosos; como es el caso de la electroforesis de campo pulsado (PFGE) 10,11 , la reacción en cadena de la polimerasa (PCR) 12,13 , amplificación randómica de ADN polimórfico (RAPD PCR) 14 y la ribotipificación [15][16][17] . Todas estas técnicas presentan diferencias en el grado de discriminación de las cepas y los resultados han sido un poco variables; además, la poca accesibilidad a los laboratorios de hospitales por su elevado costo y manejo de las técnicas, hacen difícil su uso rutinario.…”