Prevalence ofEscherichia coliO157:H7 in Surface Water Near Cattle Feedlots

Abstract

Between April 2009 and July 2011, 311 surface water samples in 48 cattle feedlots distributed in an area of about 67,000 km(2) were analyzed to examine the environmental dissemination of Escherichia coli O157:H7. Samples were taken inside and outside the pens, exposed and not exposed to runoff from corrals, near the feedlots. Two types of samples were defined: (1) exposed surface waters (ESW; n=251), downstream from cattle pens; and (2) nonexposed surface waters (NESW; n=60), upstream from cattle pens. By multiplex PCR, 177 (70.5%) ESW samples were rfb(O157)-positive, and 62 (24.7%) E. coli O157, and 32 (12.7%) Shiga toxin-producing E. coli (STEC) O157:H7 strains were isolated. In the NESW samples, 36 (60.0%) were rfb(O157)- positive, and 9 (15.0%) E. coli O157, and 6 (10.0%) STEC O157:H7 strains were isolated. These results showed that the environmental surface waters exposed to liquid discharges from intensive livestock operations tended to be contaminated with more STEC O157:H7 than NESW. However, no significant difference was found. This fact emphasizes the relevance of other horizontal routes of transmission, as the persistence of E. coli in the environment resulting from extensive livestock farming. By XbaI-PFGE, some patterns identified are included in the Argentine Database of E. coli O157, corresponding to strains isolated from hemolytic uremic syndrome and diarrhea cases, food, and animals, such as AREXHX01.0022, second prevalent pattern in Argentina, representing 5.5% of the total database. In the study area, characterized by the abundance of waterways, pathogens contained in feedlot runoff could reach recreational waters and also contaminate produce through irrigation, increasing the potential dissemination of STEC O157:H7 and the risk of human infections. The control of runoff systems from intensive livestock is necessary, but other alternatives should be explored to solve the problem of the presence of E. coli O157 in the aquatic rural environment.

Extending the Holding Time for Agricultural Water Testing EPA Method 1603 for Produce Growers

“…For example, studies conducted in the European Union have reported use of ISO methods (commonly used ISO 7899-2 method) as per the requirements of European Drinking Water Directive 98/83/EG. These methods use 24-h sample holding time before the analysis of water samples, which is in agreement with the conclusion of this study [23,24]. Moreover, in Australia their drinking water standards are similar to the United States but hold stricter requirements for frequency and level of E. coli levels using AS/NZS 5667.5:1998 which requires samples held less than 24 h [25].…”

An Environmental Shiga Toxin-Producing Escherichia coli O145 Clonal Population Exhibits High-Level Phenotypic Variation That Includes Virulence Traits

“…Such diverse stx genotypes in environmental STEC O145 strains may suggest the presence of diverse Shiga toxin-encoding phages in this agricultural environment. Infective Shiga toxin-encoding phages have previously been detected in various ecosystems and in fecal samples from animals and humans (54)(55)(56)(57)(58)(59), and transfer of stx genes has been demonstrated in water and food samples (60). These phages persisted better in nonhost environments than in their bacterial hosts and retained their infectious activities in harsh environments (61,62), implying the potential of stx acquisition by phage transduction in natural environments (63,64).…”

Microbial quality of agricultural water in Central Florida

“…coli O157:H7 was found in 100 and 1000 mL of private water supply samples 2.7% of private wells [33]. In Argentina, surface water samples in 48 cattle feedlots yielded 70.5% rfb positive and 12.7% STEC in runoff from corrals exposed surface waters and 60.0% rfb positive and 10.0% STEC in non-exposed surface waters sampled as two liters with Moore swabs [34]. In this study, all six genes were detected in different percentages.…”