Abstract
Escherichia coli O157:H7 (EcO157) shed in cattle manure can survive for extended periods of time and intervention strategies to control this pathogen at the source are critical as produce crops are often grown in proximity to animal raising operations. This study evaluated whether neem (Azadirachta indica), known for its antimicrobial and insecticidal properties, can be used to amend manure to control EcO157. The influence of neem materials (leaf, bark, and oil) on the survival of an apple juice outbreak strain of EcO157 in dairy manure was monitored. Neem leaf and bark supplements eliminated the pathogen in less than 10 d with a D-value (days for 90% elimination) of 1.3 d. In contrast, nearly 4 log CFU EcO157/g remained after 10 d in neem-free manure control. The ethyl acetate extractable fraction of neem leaves was inhibitory to the growth of EcO157 in LB broth. Azadirachtin, a neem product with insect antifeedant properties, failed to inhibit EcO157. Application of inexpensive neem supplements to control pathogens in manure and possibly in produce fields may be an option for controlling the transfer of foodborne pathogens from farm to fork.
Highlights
Concentrated animal feeding operations generate large amounts of manure waste [1], raising concerns about foodborne pathogen contamination of fruit and vegetable crops grown in the vicinity.A mid-sized dairy produces more than 12 million kilograms of manure per year [2] and the manure is usually stored on-site
We evaluated the survival and fate of an outbreak related strain of Escherichia coli O157:H7 (EcO157) in manure supplemented with neem materials
A 1.5 log reduction in EcO157 populations occurred in a day after inoculation of neem-free manure controls
Summary
A mid-sized dairy produces more than 12 million kilograms of manure per year [2] and the manure is usually stored on-site. This further increases the risk of pathogen contamination of produce grown nearby. (EcO157) [3,4]. EcO157 can cause life-threatening hemorrhagic colitis and in very severe cases causes hemolytic uremic syndrome [5]. Nineteen percent of all EcO157-associated outbreaks during 1998 to 2007 were due to the consumption of contaminated produce [6]. Pathogens attached to contaminated “ready to eat” produce are difficult to remove [7]. Designing effective and inexpensive on-farm control strategies is essential
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