The purpose of this study was to inactivate Escherichia coli O157:H7, SalmonellaTyphimurium, and Listeria monocytogenes by continuous-type pulsed ohmic heatingin buffered peptone water (BPW) and tomato juice. First, BPW inoculated with the three pathogens were treated at different flow rates (0.2–0.4 LPM) and treatment voltages (9.43–12.14 Vrms/cm). Both heating rate of BPW and reduction rates of pathogens increased corresponding to decreased flow rate. Accordingly, higher numbers of pathogens survived at a higher flow rate (0.4 LPM). Increasing treatment voltage was an effective way to inactivate pathogens at 0.4 LPM, but the heating rate overly accelerated with increasing voltage adversely affecting food quality. Alternatively, increasing initial temperature by preheating can help inactivate pathogens in the early treatment stage without affecting heating rate. From the BPW experiments, we identified that treatment conditions such as flow rate, voltage, and initial temperature are important factors determining pathogen inactivation performance of continuous-type ohmic heating. When applied to tomato juice, 5 log reductions of all three pathogens were achieved by applying 12.14Vrms/cm ohmic heating with 0.2 LPM flow rate after preheating sample to 50 °C with a water bath. Quality aspects of color and lycopene content were observed, and a∗ and b∗ values decreased after treatment. Because preheating with additional equipment is inconvenient and occupies valuable space, we developed sequential three cylinder type ohmic heating. By applying the developed sequential ohmic heating, 5 log reductions were achieved for all three pathogens without preheating under the same treatment conditions. Therefore, we concluded that sequential continuous-type ohmic heating can be used utizied effectively to control foodborne pathogensby the juice industry.
Posted in E.coli, E.coli O157, E.coli O157:H7, food contamination, Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology Blog, Food Pathogen, Food Safety, Food Technology, Food Testing, Pathogen, pathogenic, Salmonella, Uncategorized
RASFF – shigatoxin-producing Escherichia coli (O157:H7, O26:H11) in frozen beef minced meat with raw material from Spain in France
RASFF – shigatoxin-producing Escherichia coli (stx2+) in chilled beef from Argentina in Italy
Posted in E.coli, E.coli O157, E.coli O157:H7, E.coli O26, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Pathogen, Food Poisoning, food recall, Food Safety, Food Safety Alert, Food Testing, Food Toxin, RASFF, STEC, STX 1, STX 2, Uncategorized
Food Safety Tech
Following last year’s widespread E.coli O157 outbreak involving romaine lettuce linked to the Yuma, Arizona growing region (Spring 2018), FDA launched a sampling assignment to test romaine lettuce for pathogenic Shiga toxin-producing Escherichia coli (STEC) and Salmonella spp. The microbiological surveillance samplingbegan on December 18, 2018 in the Yuma region and focused on 26 commercial coolers and cold storage facilities to allow FDA to sample multiple farms from several locations at once. The agency collected and tested a total of 188 samples for both pathogens. It did not detect Salmonella in any sample; STEC was detected in one sample, but additional analysis found that the bacteria was not pathogenic.
“The findings of this assignment suggest that there was no widespread Salmonella or STEC contamination of romaine lettuce from the Yuma growing region during the period when sampling occurred. As a next step, the FDA is working with leafy green stakeholders in the Yuma region to consider a longer-term environmental study to identify and control risks that will prevent future outbreaks, with the ultimate goal of protecting consumers. – FDA
The point of the sampling assignment was to determine whether target pathogens were present, and if so, to respond quickly before contaminated products reached consumers.
Posted in E.coli, E.coli O157, E.coli O157:H7, food contamination, food handler, Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Pathogen, Food Poisoning, food recall, Food Safety, Food Safety Alert, Food Testing, Food Toxin, Salmonella, Uncategorized
Journal of Food Protection
Leafy greens are leading vehicles for Escherichia coli O157:H7 foodborne illness. Pest flies can harbor this pathogen and may disseminate it to produce. We determined the occurrence of E. coli O157:H7–positive flies in leafy greens planted up to 180 m from a cattle feedlot and assessed their relative risk to transmit this pathogen to leafy greens. The primary fly groups captured on sticky traps at the feedlot and leafy greens plots included house flies (Musca domestica L.), face flies (Musca autumnalisL.), stable flies (Stomoxys calcitrans L.), flesh flies (family Sarcophagidae), and blow flies (family Calliphoridae). E. coliO157:H7 carriage rates of house, face, flesh, and blow flies were similar (P > 0.05), ranging from 22.3 to 29.0 flies per 1,000 flies. In contrast, the carriage rate of stable flies was lower at 1.1 flies per 1,000 flies (P < 0.05). Differences in carriage rates are likely due to the uses of fresh bovine feces and manure by these different pest fly groups. E. coli O157:H7 carriage rates of total flies did not differ (P > 0.05) by distance (ranging from 0 to 180 m) from the feedlot. Most fly isolates were the same predominant pulsed-field gel electrophoresis types found in feedlot surface manure and leafy greens, suggesting a possible role for flies in transmitting E. coli O157:H7 to the leafy greens. However, further research is needed to clarify this role and to determine set-back distances between cattle production facilities and produce crops that will reduce the risk for pathogen contamination by challenging mechanisms like flies.
E. coli O157:H7 was common in flies captured in leafy greens plots near a feedlot.
E. coli O157:H7 carriage rates of house, face, flesh, and blow flies were similar.
Stable flies had lower E. coli O157:H7 carriage than the other four fly groups.
E. coli O157:H7 carriage of total flies was not affected by distance up to 180 m.
Research is needed to determine risk for leafy green contamination by pest flies.
Posted in E.coli, E.coli O157, E.coli O157:H7, Food Illness, Food Micro Blog, Food Microbiology Blog, Foodborne Illness, Illness, microbial contamination, Microbiology, Uncategorized
Journal of Food Protection
Shiga toxin–producing Escherichia coli (STEC) strains are often found in food and cause human infections. Although STEC O157:H7 is most often responsible for human disease, various non-O157 subtypes have caused individual human infections or outbreaks. The importance of STEC serogroup typing is decreasing while detection of virulence gene patterns has become more relevant. Whole genome sequencing (WGS) reveals the entire spectrum of pathogen information, such as toxin variant, serotype, sequence type, and virulence factors. Flour has not been considered as a vector for STEC; however, this product has been associated with several STEC outbreaks in the last decade. Flour is a natural product, and milling does not include a germ-reducing step. Flour is rarely eaten raw, but the risks associated with the consumption of unbaked dough are probably underestimated. The aim of this study was to determine the prevalence of STEC in flour samples (n = 93) collected from Swiss markets and to fully characterize the isolates by PCR assay and WGS. The prevalence of STEC in these flour samples was 10.8% as indicated by PCR, and a total of 10 STEC strains were isolated (two flour samples were positive for two STEC subtypes). We found one stx2-positve STEC isolate belonging to the classic serogroups frequently associated with outbreaks that could potentially cause severe disease. However, we also found several other common or less common STEC subtypes with diverse virulence patterns. Our results reveal the benefits of WGS as a characterization tool and that flour is a potentially and probably underestimated source for STEC infections in humans.
Several STEC serotypes, including O26, were isolated from 8 (8.6%) of 93 flour samples.
STEC isolates from flour had a variety of virulence patterns.
Flour is a probably underestimated source of STEC infections in humans.
WGS for STEC characterization is more comprehensive than common serotyping.
Posted in E.coli, E.coli O157, E.coli O157:H7, E.coli O26, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Poisoning, Food Safety, Food Technology, Food Testing, Food Toxin, STEC, STX 1, STX 2, Uncategorized