Presence of virulence Genes associated with Verocytotoxigenic Escherichia coli (VTEC) and Enteropathogenic Escherichia coli (EPEC) in pigeons from Argentina

PARMA, YANIL R.; KRÜGER, ALEJANDRA; LUCCHESI, PAULA M. A.; PARMA, ALBERTO E.

Buenos Aires

Simposio; 7th INTERNACIONAL SYMPOSIUM ON SHIGA TOXIN (VEROCYTOTOXIN) - PRODUCING Escherichia coli INFECTIONS; 2009

Asociación Argentina de Microbiología y Comité internacional

Previous studies have detected EPEC and VTEC strains in droppings of feral pigeons in different countries. These animals are considered a natural reservoir of strains that carry a verocytotoxin gene (vt) variant designated vt2f, which have been associated with some cases of diarrhea in children. The goal of this study was to investigate the presence of virulence markers such as verocytotoxins (vt) and intimin (eae) genes in samples from feral pigeons in Argentina. The goal of this study was to investigate the presence of virulence markers such as verocytotoxins (vt) and intimin (eae) genes in samples from feral pigeons in Argentina. A total of 140 samples were analyzed. One hundred and eleven pigeon droppings were collected in two cities, from September to November 2008. Specimens were taken from 3 different squares and one University campus and the surrounding area. Fresh droppings were sampled with a sterile cotton swab. The other 29 samples corresponded to cloacal swab samples taken from the same number of racing pigeons. The swab samples were kept in Stuart transport medium at ambient temperature until processed in the laboratory within 24 hs of collection. After an enrichment step in Luria Bertani broth, 10 to 40 ul of each sample were added to 500ul of sterile water and boiled 10 minutes to be used directly as template for PCR. Another aliquot of the culture was transferred to a cryovial with 20% glicerol and stored at -80ºC for future testing. Multiplex and monoplex PCRs were used for the detection of the virulence genes eae, vt1,  vt2 (including vt2EDL933, vt2f  and other vt2 variants) in the stool enrichment cultures. PCR screening showed that  eae, vt1,  vt2 genes were present in 34%, 1.5 and 15% of the samples, respectively. Among eae-positive samples, 69% were vt-negative. The variant vt2f was detected in 9% of the samples, which were predominantly eae-positive. One of these samples corresponded to a cloacal swab sample taken from a racing pigeon. These results suggest that pigeons can be considered possible carriers of EPEC and VTEC and a potencial source of contamination in Argentina.  As far as we know, this is the first report of vt2f variant in this country.