P3-226 Correlation of Salmonella spp. to Generic Escherichia coli in Irrigation Water

Wednesday, July 12, 2017
Exhibit Hall (Tampa Convention Center)
Mohammed Alhejaili , Louisiana State University AgCenter , Baton Rouge , LA
Dorra Djebbi-Simmons , Louisiana State University , Baton Rouge , LA
Achyut Adhikari , Louisiana State University AgCenter , Baton Rouge , LA
Marlene Janes , Louisiana State University AgCenter , Baton Rouge , LA
Introduction: Salmonella is one of the most causative foodborne disease outbreaks in the U.S.A. Salmonella has been detected in surface water used in irrigation and can survive for weeks to years in water. 
Purpose: The purpose of this study was to detect low levels of Salmonella spp. by comparing surfactant modified zeolite (SMZ) filtration with the Environmental Protection Agency (EPA) method 1200 and determine if there was a direct correlation between Salmonella and generic Escherichia coli in irrigation water.

Methods: Irrigation water was collected monthly from May to October, 2016. Water samples (300 ml) were filtered through 3 g of SMZ. After filtration the SMZ was mixed with 10 ml of BPW to detach organisms. The presence of Salmonella spp. was examined using standard plating techniques for isolation and latex agglutination and RT-PCR for confirmation. The EPA 1603 method was used to determine generic E.coli counts.

Results: Salmonella was detected in water samples during four months using the EPA 1200 method, whereas it was only detected one month with the SMZ method. Generic E.coli counts ranged from 1.89 to 2.75 log CFU/100 ml of water. During June and July, Salmonella was not detected in the irrigation water, but the generic E. coli counts were 2.47 and 2.75 log CFU/100 ml water, respectively. In August and September, Salmonella was detected in irrigation water and the generic E. coli counts were 1.99 and 1.89 log CFU/100 ml, respectively. 

Significance: The EPA method detected Salmonella at lower levels than the SMZ method. This study found no correlation between generic E.coli and presence or absence of Salmonella in irrigation water.