Spatial and temporal variability of bacterial indicators and pathogens in six California reservoirs during extreme drought

Partyka, Melissa L.; Bond, Ronald F.; Chase, Jennifer; Atwill, Edward R.

doi:10.1016/j.watres.2017.11.038

Cited by 21 publications

(26 citation statements)

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“…Sampling larger volumes has been shown to improve detection of rare pathogens (Jimenez and Chaidez, 2012; Polaczyk et al, 2008). For example, a 2014 monitoring study of six dammed reservoirs of central California found Salmonella , STEC, and O157 in 26, 9, and 1%, respectively, in 20‐L samples (Partyka et al, 2018). Another survey of publicly accessible water of California's central coast by Cooley et al (2014) found Salmonella in 65%, STEC in 11%, and O157 in 8% of Moore swabs exposed to water for >24 h, similar to the high prevalence we found in the California LV samples (Table 2).…”

Section: Discussionmentioning

confidence: 99%

“…The 500‐mL water samples were processed within 8 h of collection using the membrane filtration technique previously described by Partyka et al (2018) for three bacterial indicators, including: E. coli , enterococci, and fecal coliforms. Filtered volumes were adjusted regularly based on prior knowledge of each source (previous bacterial concentrations) and visual inspection for turbidity and/or algae that could clog filters and reduce bacterial growth.…”

Section: Methodsmentioning

confidence: 99%

“…The LV samples were processed using ultrafiltration methods (Partyka et al, 2018) with a final reduced volume (retentate) of approximately 1 L (10:1 concentration). Samples collected in California were received and processed by the laboratory staff within 8 h of collection, while Washington retentates were shipped overnight and processed within 30 h. The SV sample and approximately 500 mL of the retentate were analyzed for presence of Salmonella spp., E. coli O157 (O157), and non-O157 STEC using a membrane-filtration-enrichment (MFE) procedure ( Supplemental Table S3).…”

Section: Indicator Bacteria (E Coli Fecal Coliforms and Enterococci)mentioning

confidence: 99%

“…According to the Centers for Disease Control and Prevention, outbreaks that occurred during 2013 to 2014 from drinking water systems solely supplied by surface water accounted for nearly 80% of reported cases (Allende and Monaghan, 2015; Benedict et al, 2017; Uyttendaele et al, 2015). However, there is a paucity of research capable of linking microbial contamination in irrigation water to foodborne outbreaks in the United States (Pachepsky et al, 2016; Partyka et al, 2018). One possible explanation is that many irrigation water supplies, particularly those in the arid west, are controlled by irrigation districts, semigovernmental agencies, which can lead to reduced access to irrigation water supplies by researchers.…”

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confidence: 99%

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Spatiotemporal Variability in Microbial Quality of Western US Agricultural Water Supplies: A Multistate Study

et al. 2018

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In 2011, the US Congress passed the Food Safety Modernization Act, which tasks the US Food and Drug Administration to establish microbiological standards for agricultural water. However, little data are available for the microbiological quality of surface water irrigation supplies. During the 2015 irrigation season, we conducted a baseline study on the microbial water quality of large irrigation districts in California (n = 2) and Washington (n = 4). Monthly samples (n = 517) were analyzed for bacterial indicators (fecal coliforms, enterococci, and Escherichia coli) and pathogens (Salmonella spp., E. coli O157, and non‐O157 Shiga toxin‐producing E. coli [STEC]). Although there was a high degree of variability (μ ± SD = 59.13 ± 106.0), only 11% of samples (56/517) exceeded 126 colony‐forming units (CFU) 100 mL−1, and only six samples exceeded 410 CFU 100 mL−1. Two volumes of water were collected for pathogen analysis (1 L and 10 L); prevalence of Salmonella in 10‐L samples (68/149) was nearly double of that found in 1‐L samples (132/517). We found STEC during ∼9% of sampling events (58/517); serotypes O26 and O45 were the most common at 31 and 26%, respectively. Pathogens were not associated with exceedance of the regulatory threshold, yet the odds of detecting Salmonella increased approximately threefold (odds ration [O.R.] = 3.14, p < 0.0001) for every log increase in turbidity. Microbiological outcomes were highly district‐specific, suggesting drivers of water quality vary across spatiotemporal scales. The true risk of contamination of produce from irrigation water supplies remains unknown, along with the optimal monitoring strategy to improve food safety. Core Ideas Western US irrigation water supplies rarely exceed FDA agricultural water standards. Indicator bacteria are not predictive of pathogen prevalence or concentration. Prevalence of pathogens in irrigation water is higher than previously reported. Odds of detecting Salmonella improved >270% with an increase in sample volume. More research is needed to provide science‐based guidance to the produce industry.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Indicator Bacteria (E Coli Fecal Coliforms and Enterococci)mentioning

confidence: 99%

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Spatiotemporal Variability in Microbial Quality of Western US Agricultural Water Supplies: A Multistate Study

et al. 2018

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“…Research studies have been conducted to estimate the prevalence of pathogens in irrigation water supplies (Falardeau et al 2017;Gorski et al 2014;Partyka et al 2018b;Ssemanda et al 2018), survival kinetics of these pathogens in agricultural water (Steele & Odumeru 2004;Wang et al 2018), and how well pathogens survive once transferred onto crops via irrigation (Atwill et al 2015;Chase et al 2017;Moyne et al 2011;Van Der Linden et al 2014;Weller et al 2017b). For example, numerous studies have shown the occurrence of bacterial pathogens in US agricultural water supplies, especially for surface water sources (Falardeau et al 2017;Partyka et al 2018a;Partyka et al 2018b;Partyka et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Peer Review #2 of "Environmental inactivation and irrigation-mediated regrowth of Escherichia coli O157:H7 on romaine lettuce when inoculated in a fecal slurry matrix (v0.1)"

2019

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Field trials were conducted in July-August and October 2012 to quantify the inactivation rate of Escherichia coli O157:H7 when mixed with fecal slurry and applied to romaine lettuce leaves. Lettuce was grown under commercial conditions in Salinas Valley, California. One-half milliliter of rabbit, chicken, or pig fecal slurry, containing an average of 4.05×10 7 CFU E. coli O157:H7 (C 0), was inoculated onto the upper (adaxial) surface of a lower leaf on 288 heads of lettuce per trial immediately following a 2.5 h irrigation event. To estimate the bacterial inactivation rate as a function of time, fecal matrix, irrigation, and seasonal climate effects, sets of lettuce heads (n=28) were sampled each day over 10 days and the concentration of E. coli O157:H7 (C t) determined. E. coli O157:H7 was detected on 100% of heads during the 10-day duration, with concentrations ranging from ≤340 MPN/head (~5-log reduction) to >3.45×10 12 MPN/head (~5-log growth). Relative to C 0 , on day 10 (C t=12) we observed an overall 2.6-log and 3.2-log mean reduction of E. coli O157:H7 in July and October, respectively. However, we observed relative maximum concentrations due to bacterial growth on day 6 (maximum C t=8) apparently stimulated by foliar irrigation on day 5. From this maximum there was a mean 5.3-log and 5.1-log reduction by day 10 (C t=12) for the July and October trials, respectively. This study provides insight into the inactivation and growth kinetics of E. coli O157:H7 on romaine lettuce leaves under natural field conditions. This study provides evidence that harvesting within 24 hours post irrigation has the potential to increase the concentration of E. coli O157:H7 contamination, if present on heads of romaine lettuce; foliar irrigation can temporarily stimulate substantial regrowth of E. coli O157:H7.

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Persistent Patterns of E. coli Concentrations in Two Irrigation Ponds from 3 Years of Monitoring

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Pachepsky

Smith

et al. 2021

Water Air Soil Pollut

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quality parameters exist and correlate with persistent patterns of E. coli concentrations. Sampling was conducted fortnightly during the summer months in 2016 to 2018 and consisted of taking water quality measurements at 23 and 34 locations in ponds P1 and P2, respectively. Interannual variability of E. coli was observed in both ponds as was substantial spatial variability of E. coli concentrations within each year. The mean relative difference (MRD) analysis was used to identify temporally stable patterns of E. coli concentrations within the ponds. These patterns found for individual years showed significant positive correlations with each other and with the overall pattern derived from the 3-year dataset. Correlation coefficients of patterns varied from 0.487 to 0.842 in P1 and from 0.467 to 0.789 in P2 (p < 0.05). MRD patterns of water quality parameters and of E. coli concentrations were also significantly correlated. Within the 3-year dataset, the highest positive correlations were observed for chlorophyll-a and turbidity while the dissolved oxygen concentrations demonstrated the greatest negative correlations. Results of the present study emphasize the advisability and feasibility of finding temporally stable spatial patterns in microbial water quality within irrigation ponds.

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Spatial and temporal variability of bacterial indicators and pathogens in six California reservoirs during extreme drought

Cited by 21 publications

References 31 publications

Spatiotemporal Variability in Microbial Quality of Western US Agricultural Water Supplies: A Multistate Study

Spatiotemporal Variability in Microbial Quality of Western US Agricultural Water Supplies: A Multistate Study

Peer Review #2 of "Environmental inactivation and irrigation-mediated regrowth of Escherichia coli O157:H7 on romaine lettuce when inoculated in a fecal slurry matrix (v0.1)"

Persistent Patterns of E. coli Concentrations in Two Irrigation Ponds from 3 Years of Monitoring

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