TY - JOUR
T1 - Incidence and tracking of escherichia coli O157
T2 - H7 in a major produce production region in California
AU - Cooley, Michael
AU - Carychao, Diana
AU - Crawford-Miksza, Leta
AU - Jay-Russell, Michele T
AU - Myers, Carol
AU - Rose, Christopher
AU - Keys, Christine
AU - Farrar, Jeff
AU - Mandrell, Robert E.
PY - 2007/11/14
Y1 - 2007/11/14
N2 - Fresh vegetables have become associated with outbreaks caused by Escherichia coli O157;H7 (EcO157). Between 1995-2006, 22 produce outbreaks were documented in the United States, with nearly half traced to lettuce or spinach grown in California. Outbreaks between 2002 and 2006 induced investigations of possible sources of pre-harvest contamination on implicated farms in the Salinas and San Juan valleys of California, and a survey of the Salinas watershed. EcO157 was isolated at least once from 15 of 22 different watershed sites over a 19 month period. The incidence of EcO157 increased significantly when heavy rain caused an increased, flow rate in the rivers. Approximately, 1000 EcO157 isolates obtained from cultures of> 100 individual samples were typed using Multi-Locus Variable-number-tandem-repeat Analysis (MLVA) to assist in identifying potential fate and transport of EcO157 in this region. A subset of these environmental isolates were typed by Pulse Field Gel Electrophoresis (PFGE) in order to make comparisons with human clinical isolates associated with outbreak and sporadic Illness. Recurrence of identical and closely related EcO157 strains from specific locations in the Salinas and San Juan valleys suggests that transport of the pathogen is usually restricted. In a preliminary study, EcO157 was detected in water at multiple locations in a low-flow creek only within 135 meters of a point source. However, possible transport up to 32 km was detected during periods of higher water flow associated with flooding. During the 2006 baby spinach outbreak investigation, transport was also detected where water was unlikely to be involved. These, results indicate that contamination of the environment is a dynamic process involving multiple sources and methods of transport. Intensive studies of the sources, incidence, fate and transport of EcO157 near produce production are required to determine the mechanisms of pre-harvest contamination and potential risks for human illness.
AB - Fresh vegetables have become associated with outbreaks caused by Escherichia coli O157;H7 (EcO157). Between 1995-2006, 22 produce outbreaks were documented in the United States, with nearly half traced to lettuce or spinach grown in California. Outbreaks between 2002 and 2006 induced investigations of possible sources of pre-harvest contamination on implicated farms in the Salinas and San Juan valleys of California, and a survey of the Salinas watershed. EcO157 was isolated at least once from 15 of 22 different watershed sites over a 19 month period. The incidence of EcO157 increased significantly when heavy rain caused an increased, flow rate in the rivers. Approximately, 1000 EcO157 isolates obtained from cultures of> 100 individual samples were typed using Multi-Locus Variable-number-tandem-repeat Analysis (MLVA) to assist in identifying potential fate and transport of EcO157 in this region. A subset of these environmental isolates were typed by Pulse Field Gel Electrophoresis (PFGE) in order to make comparisons with human clinical isolates associated with outbreak and sporadic Illness. Recurrence of identical and closely related EcO157 strains from specific locations in the Salinas and San Juan valleys suggests that transport of the pathogen is usually restricted. In a preliminary study, EcO157 was detected in water at multiple locations in a low-flow creek only within 135 meters of a point source. However, possible transport up to 32 km was detected during periods of higher water flow associated with flooding. During the 2006 baby spinach outbreak investigation, transport was also detected where water was unlikely to be involved. These, results indicate that contamination of the environment is a dynamic process involving multiple sources and methods of transport. Intensive studies of the sources, incidence, fate and transport of EcO157 near produce production are required to determine the mechanisms of pre-harvest contamination and potential risks for human illness.
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U2 - 10.1371/journal.pone.0001159
DO - 10.1371/journal.pone.0001159
M3 - Article
C2 - 18174909
AN - SCOPUS:37049010237
VL - 2
JO - PLoS One
JF - PLoS One
SN - 1932-6203
IS - 11
M1 - e1159
ER -