Year-round Monitoring of Verotoxin-producing Escherichia coli from Feces of Dairy Cattle

Abstract

A PCR-aided monitoring of verotoxin-producing Escherichia coli (VTEC) was performed over the period of 12 months by using fresh feces collected monthly from 5 dairy cows that had been identified as VTEC carriers. The PCR products were confirmed to be verotoxin genes by Southern hybridization using a gene fragment of verotoxin 2 as a probe. Although seasonal variation of VTEC shedding seemed to depend on each cow, several factors may have influenced the frequency of detection. Shedding of VTEC tended to be reduced during grazing from the middle of May up to the beginning of October. Only one cow was positive for VTEC in August. Dry-off was also suggested to have a depressive effect on VTEC shedding, i.e. 3 of 4 dry cows showed no shedding of VTEC. Contrary to these factors, winter or indoor rearing tended to increase VTEC with only 5/24 samples being negative during the period from November to April. Total VFA concentration was higher (p<0.05) in VTEC-positive feces than in VTEC-negative feces, while fecal pH and VFA proportions were not different. Partial sequences of verotoxin genes from feces of 4 VTEC-positive cows were nearly identical (99-100%), suggesting that gut bacteria sharing the same gene were distributed among the cows. The present results indicate that grazing and dry-off could be factors which reduce VTEC shedding, while winter/indoor rearing may be a factor which increases the shedding, possibly through on-farm interactions.

Sensitivity of Escherichia coli to Seaweed (Ascophyllum nodosum) Phlorotannins and Terrestrial Tannins

“…Clinical symptoms caused by this pathogen include diarrhea (Pai et al, 1988), hemorrhagic colitis (Riley, 1987) and occasionally hemolytic-uremic syndrome and thrombocytopenic purpura Karmali, 1992). Ruminants are the major reservoir of E. coli O157:H7 and their fecal shedding of E. coli O157:H7 is affected by various factors such as animal health conditions, diet, and season (Stanford et al, 2005;Kobayashi and El-Sawy, 2007). A positive correlation between fecal and hide prevalence of E. coli O157:H7 and adulteration of meat has been reported (Wells et al, 1991;Hancock et al, 1994;Elder et al, 2000).…”

Rapid Identification of Bifidobacteria in Dairy Products by Gene-targeted Species-specific PCR Technique and DGGE

“…In recent years several molecular tools have been proposed for bifidobacterial identification without isolation and enumeration. Various polymerase chain reaction (PCR) methods have been developed using species-specific primers designed with wide-spread genes for lactic acid bacteria (Charteris et al, 1997;Tilsala-Timisjärvi and Alatossava, 1997;Ventura and Zink, 2002;Grand et al, 2003;Venema and Maatthiuis, 2003;Kwon et al, 2005;Kobayashi and El-Sawy, 2007). Nowadays, they mostly rely on amplification and comparison of the 16S rDNA derived primers allowed detection of Bifidobacterium spp.…”