Skip to main content
ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Produce Safety and Microbiology Research » Research » Publications at this Location » Publication #315576
Title: Effect of Neem (Azadirachta indica) on the survival of Escherichia coli O157:H7 in dairy manure

Author
item Ravva, Subbarao
item Korn, Anna

Submitted to: International Journal of Environmental Research and Public Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2015
Publication Date: 7/10/2015
Citation: Ravva, S.V., Korn, A.M. 2015. Effect of Neem (Azadirachta indica) on the survival of Escherichia coli O157:H7 in dairy manure. International Journal of Environmental Research and Public Health. 12:7794-7803.

Interpretive Summary: Interpretative Summary: 20-75 CHARACTER LINES Concentrated animal feeding operations generate large amounts of manure waste, thus raising the concerns of foodborne pathogen contamination of fruit and vegetable crops grown in the vicinity. A mid-sized dairy produce more than 12 million kilograms of manure per year and the manure is usually stored on-site. This further increases the risk of pathogen contamination of produce grown nearby. Ruminants are primary reservoirs of many enteric pathogens including Escherichia coli O157:H7 (EcO157) and they shed as high as 107 cells per gram of feces. EcO157 can cause life-threatening hemorrhagic colitis and in very severe cases causes hemolytic uremic syndrome. Nineteen percent of all EcO157 associated outbreaks during 1998 to 2007 were due to the consumption of contaminated produce. Pathogens attached to contaminated ‘ready to eat’ produce are difficult to remove. Therefore, prevention of pre-harvest contamination is critical. Thus, designing effective and inexpensive on-farm control strategies are essential. We evaluated the influence of neem supplements on the survival of pathogenic Escherichia coli O157:H7 in manure and observed that neem leaf and bark were effective in eliminating the pathogen. Neem supplementation to manure piles on dairies and feedlots, and also to produce fields could be a novel strategy for on-site pathogen control.

Technical 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 if 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 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. Ethyl acetate extractable fraction of neem leaves was inhibitory to the growth of EcO157 in nutrient 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 to consider for controlling the foodborne pathogen transfer from farm to fork.