ARS | Publication request: Quantification of bacterial indicators and zoonotic pathogens in dairy wastewater ponds

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 6, 2012
Publication Date: October 22, 2012
Citation: Dungan, R.S., Klein, M., Leytem, A.B. 2012. Quantification of bacterial indicators and zoonotic pathogens in dairy wastewater ponds. Applied and Environmental Microbiology. 78(22):8089-8095.

Interpretive Summary: Domesticated livestock harbor a variety of zoonotic bacterial, viral and protozoal pathogens. Infectious diseases that are transmissible from animals to humans and vice versa are known as zoonoses. Many pathogens are endemic in commercial livestock and are native inhabitants of their gastrointestinal tract, thus can be found in untreated feces. A common agricultural practice is to use livestock manures as soil conditioners and fertilizers. However, pathogens in untreated manures can become aerosolized during land application or contaminate natural waters when transported in runoff. In this study we quantified bacterial and protozoal pathogens in dairy wastewaters from southern Idaho using a DNA-based approach known as quantitative real-time polymerase chain reaction. Samples tested positive for the following bacterial pathogens: Campylobacter jejuni, Escherichia coli, Listeria monocytogenes, Mycobacterium avium, and Salmonella enterica. The most dominant pathogens were C. jejuni and M. avium, being detected in up to 21 and 29 of 30 wastewater ponds, respectively.

Technical Abstract: Zoonotic pathogens in land-applied dairy wastewaters are a potential health risk. The abundance and occurrence of 10 pathogens and 3 fecal indicators was determined by quantitative real-time PCR (qPCR) in 30 dairy wastewaters from southern Idaho. Samples tested positive for Campylobacter jejuni, stx1- and eaeA-positive Escherichia coli, Listeria monocytogenes, Mycobacterium avium, and Salmonella enterica, with mean recoveries ranging from 1,000 to 10,000 genome copies per mL of wastewater. The most dominant organisms were C. jejuni and M. avium, being detected in up to 21 and 29 of 30 wastewater ponds, respectively. The qPCR detection limits for the putative pathogens in the wastewaters ranged from 16 cells mL for M. avium to 1,689 oocysts mL for Cryptosporidum. Cryptosporidium and Giardia spp., Yersinia pseudotuberculosis, and pathogenic Leptospira spp. were not detected by qPCR.