[Prevalence of Shiga toxin and Intimine genes in Shiga toxin-producing Escherichia coli isolated from urine samples in Lorestan, Iran]

Shiga toxin-producing Escherichia coli [STEC], as one of the most important food-borne pathogen, in human may lead to deadly syndromes, like hemolytic-uremic syndrome [HUS]. Occurrence of HUS following urinary tract infection [UTI] has been previously reported. The aim of this study was to identify stx1, stx2 and eaeA genes in E. coli strains isolated from urine samples in Alashtar [Lorestan, Iran]. A total number of 144 bacterial isolates were collected from three hospitals in Alashtar during a six-month period. One-hundred E. coli isolates were identified using the standard biochemical tests as well as the selective and differential media. The multiplex PCR method was used to evaluate the presence of stx1, stx2 and eaeA genes. Two out of 100 E. coli isolates carried both stx2 and eaeA genes and one isolate [1%] only sxt1gene. Moreover, the three genes were not found in any of the isolates tested. Detection of Shiga toxin-producing E. coli [e.g. O157:H7 and non-O157:H7 serotypes], which may lead to life-threatening syndromes such as HUS, from urine samples is of great importance. Further research in this field using the fast and precise molecular methods is recommended

Análisis in silico de la capacidad de dos técnicas de PCR para la detección del gen stx / In silico analysis of the capability of two polimerase chain reaction techniques for stx gene detection.

Escherichia coli productor de toxina Shiga es un patógeno emergente cuyo principal factor de virulencia son las toxinas Shiga (Stx), codificadas por los genes stx. Estas toxinas se clasifican en 6 tipos (1, 2, 2c, 2d, 2e y 2f) que agrupan a 22 variantes. En Argentina se validaron dos técnicas de PCR para la detección de los genes stx, PCR-MK y PCR múltiple. Los objetivos del trabajo fueron analizar mediante el uso de herramientas bioinformáticas la capacidad de dichas técnicas para detectar las variantes del gen stx y demostrar experimentalmente la amplificación de 8 variantes stx. Se recopilaron 25 secuencias nucleotídicas de la base de datos GenBank correspondientes a 21 variantes de stx. Se utilizó el programa BLAST 2 sequences para analizar la complementariedad de las bases nucleotídicas entre las secuencias de las variantes y las secuencias de los cebadores utilizados en las PCR estudiadas. La técnica de PCR-MK permite detectar los tipos stx1, stx2, stx2c, stx2d y stx2f, aunque no permite detectar el tipo stx2e y tres variantes del tipo stx2c. La PCR múltiple permite detectar los tipos stx1, stx2, stx2c, stx2d, pero no los tipos stx2e y stx2f. Se demostró experimentalmente que ambas técnicas de PCR son apropiadas para la detección de las variantes que están asociadas a enfermedad grave en el hombre.

Shiga toxin-producing Escherichia coli is an emergent pathogen, being the Shiga toxin (Stx) the main virulence factor. These toxins are classified into 6 types (1, 2, 2c, 2d, 2e and 2f) and 22 variants. In Argentina, two PCR for stx gene detection, PCR-MK and multiplex-PCR, were validated. The aim of this work was to analyze, by using bioinformatic tools, the stx variants that could be amplified by these PCRs, and to experimentally show the amplification of 8 stx variants. Twentyfive nucleotide sequences were collected from GenBank corresponding to 21 stx variants. The BLAST 2 sequences program was used to analyze the complementarities between the nucleotide sequence of the variants and the primers corresponding to the PCR studied. PCR-MK could detect types stx1, stx2, stx2c, stx2d and stx2f, but not type stx2e and three type stx2c variants. On the other hand, the multiplex-PCR could detect types stx1, stx2, stx2c, stx2d, but not stx2e and stx2f types. It was experimentally determined that both PCRs can detect those variants that cause severe disease in humans.

El rol epidemiológico de las mascotas en el ciclo de transmisión urbana de cepas STEC / Epidemiological role of pets in urban transmission cycle of STEC

Escherichia coli is an important constitutional element of both animal's and men's microbiote. Rumiants in general and bovine in particular have been pointed out as reservoirs of shigatoxigenic (STEC) and enterohemorragic strains (EHEC). These strains are rarely reported in pets isolations and are badly documented. Revisions of the pathogenic role of E. coli in small animals, particulary based on intestinal and urogenital isolations, involve in a very low proportion the STEC strains. In dogs, ocasional isolations are reported, from feces coming from both healthy and diarreic dogs. The STEC intestinal strains prevalence in dogs and cats from urban centers, based on the habit of including regular or ocasional raw meat in their diet, should not be understimated.