Papers by Abhinav Upadhyay
Frontiers in Microbiology, 2016
Escherichia coli O157: H7 (EHEC) is a major foodborne pathogen largely transmitted to humans thro... more Escherichia coli O157: H7 (EHEC) is a major foodborne pathogen largely transmitted to humans through the consumption of undercooked ground beef. This study investigated the efficacy of two food-grade, plant-derived antimicrobials, namely rutin (RT), and resveratrol (RV) with or without chitosan (CH) in enhancing EHEC inactivation in undercooked hamburger patties. Further, the effect of aforementioned treatments on beef color and lipid oxidation was analyzed. Additionally, the deleterious effects of these antimicrobial treatments on EHEC was determined using scanning electron microscopy (SEM). Ground beef was inoculated with a five-strain mixture of EHEC (7.0 log CFU/g), followed by the addition of RT (0.05%, 0.1% w/w) or RV (0.1, 0.2% w/w) with or without CH (0.01% w/w). The meat was formed into patties (25 g) and stored at 4°C for 5 days. On days 1, 3, and 5, the patties were cooked (65°C, medium rare) and surviving EHEC was enumerated. The effect of these treatments on meat color and lipid oxidation during storage was also determined as per American Meat Science Association guidelines. The study was repeated three times with duplicate samples of each treatment. Both RT and RV enhanced the thermal destruction of EHEC, and reduced the pathogen load by at least 3 log CFU/g compared to control (P < 0.05). The combination of RT or RV with CH was found to be more effective, and reduced EHEC by 5 log CFU/g (P < 0.05). EHEC counts in uncooked patties did not decline during storage for 5 days (P > 0.05). Moreover, patties treated with RV plus CH were more color stable with higher a(∗) values (P < 0.05). SEM results revealed that heat treatment with antimicrobials (CH + RV 0.2%) resulted in complete destruction of EHEC cells and extrusion of intracellular contents. Results suggest that the aforementioned antimicrobials could be used for enhancing the thermal inactivation of EHEC in undercooked patties; however, detailed sensory studies are warranted.
LWT - Food Science and Technology, 2015
The efficacy of four phytochemicals, namely trans-cinnamaldehyde (0.1, 0.2%), carvacrol (0.1, 0.2... more The efficacy of four phytochemicals, namely trans-cinnamaldehyde (0.1, 0.2%), carvacrol (0.1, 0.2%), thymol (0.1, 0.2%) and eugenol (0.3, 0.4%) incorporated in a chitosan-based coating for inactivating Listeria monocytogenes (LM) on frankfurters was investigated. Frankfurters were inoculated with a 5-strain LM mixture (~10 6 /frankfurter, either prior to or after coating with phytochemicals), vacuum-packed, and stored at 4 C for 42 days. Representative samples were analyzed on days 0, 1, 3, 7, 14, 28, and 42 for surviving LM. Moreover, the effect of phytochemicals on lipid oxidation, meat pH and expression of LM genes critical for attachment to meat was studied. On day zero, all phytochemical coatings reduced LM counts by >2.5 log CFU/frankfurter compared to controls (P < 0.05). From days 1 to 42, LM counts on phytochemical-coated frankfurters were consistently lower, and on day 42, the coatings reduced LM bỹ 5.0 log CFU/frankfurter. The phytochemical coatings also significantly reduced lipid oxidation and expression of LM meat attachment genes (P < 0.05). No change in pH of frankfurters was observed (P > 0.05). Results suggest that the aforementioned phytochemicals could potentially be used as an effective antilisterial coating, however, follow up studies on the sensory and quality characteristics of phytochemical-coated frankfurters are necessary.
Foodborne Pathogens and Disease, 2015
Salmonella Enteritidis (SE) is a major foodborne pathogen responsible for causing gastrointestina... more Salmonella Enteritidis (SE) is a major foodborne pathogen responsible for causing gastrointestinal infections in humans, predominantly due to the consumption of contaminated eggs. In layer hens, SE colonizes the intestine and migrates to various organs, including the oviduct, thereby leading to egg yolk and shell contamination. This study investigated the efficacy of caprylic acid (CA), a medium-chain fatty acid, in reducing SE colonization and egg contamination in layers. Caprylic acid was supplemented in the feed at 0%, 0.7%, or 1% (vol/wt) from day 1 of the experiment. Birds were challenged with 10 10 log colony-forming units (CFU)/mL of SE by crop gavage on day 10, and re-inoculated (10 10 log CFU/mL) on day 35. After 7 days post first inoculation, eggs were collected daily and tested for SE on the shell and in the yolk separately. The birds were sacrificed on day 66 to determine SE colonization in the ceca, liver, and oviduct. The consumer acceptability of eggs was also determined by triangle test. The experiment was replicated twice. In-feed supplementation of CA (0.7% and 1%) to birds consistently decreased SE on eggshell and in the yolk ( p < 0.05). Supplementation of CA at 1.0% decreased SE population to & 14% on the shell and & 10% in yolk, when compared to control birds, which yielded & 60% positive samples on shell and & 43% in yolk. Additionally, SE populations in the cecum and liver were reduced in treated birds compared to control ( p < 0.05). No significant difference in egg production, body weight, or sensory properties of eggs was observed ( p > 0.05). The results suggest that CA could potentially be used as a feed additive to reduce eggborne transmission of SE.
Poultry science, 2015
This study investigated the efficacy of two GRAS (generally regarded as safe)-status, plant-deriv... more This study investigated the efficacy of two GRAS (generally regarded as safe)-status, plant-derived antimicrobials (PDAs), namely trans-cinnamaldehyde (TC) and eugenol (EUG) applied as a fumigation treatment in reducing SE on embryonated egg shells. Egg shells of day-old embryonated eggs were spot inoculated with a 4-strain mixture of SE (∼6.5 log CFU/egg) and subjected to fumigation with the aforementioned PDAs (0 or 1% concentration) for 20 minutes in a hatching incubator. SE on the shell and embryo was enumerated on days 1, 3, 6, 9, 13, 16 and 18. On day 13, the eggs were re-inoculated, followed by fumigation treatment for 20 minutes. Since the two PDAs were dissolved in ethanol (final concentration 0.04%), eggs fumigated with ethanol were included as a control.Approximately 6 log CFU/egg of SE were recovered from the shell of untreated, inoculated eggs on days 1 and 13. The fumigation of embryonated egg shells with the two PDAs was more effective in reducing SE on the shell and ...
Listeria monocytogenes has emerged as one of the major foodborne pathogens, characterized by high... more Listeria monocytogenes has emerged as one of the major foodborne pathogens, characterized by high hospitalization and case fatality rates in humans. The ubiquitous distribution of L. monocytogenes in the environment along with its ability to form biofilms results in its frequent persistence in food processing and packaging facilities, thereby contaminating a variety of foods, especially ready-to-eat meat products. The drug of choice for the treatment of listeriosis in humans has been antibiotic, however, there have been reports of development of antibiotic resistance in L. monocytogenes, with isolation of multidrug resistant strains from cattle carcasses and meat. This increasing antibiotic resistance in L. monocytogenes and growing concerns over the use of synthetic chemicals in the food industry has ignited an interest in exploring the potential of various natural approaches as an alternative strategy to prevent food contamination and control listeriosis in humans. This chapter di...
The Journal of Applied Poultry Research, 2012
ABSTRACT In this study, we investigated the therapeutic efficacy of the plant compounds trans-cin... more ABSTRACT In this study, we investigated the therapeutic efficacy of the plant compounds trans-cinnamaldehyde (TC) and eugenol (EG) on reducing Salmonella enterica serovar Enteritidis (SE) in commercial, market-age broiler chickens. Straight run, day-old commercial broiler chicks (N = 84) were randomly grouped into 6 groups of 14 birds each (n = 14/group): a negative control (no SE, no TC or EG), EG control (no SE, 1% EG), TC control (no SE, 0.75% TC), a positive control (SE, no TC or EG), an EG challenge group (SE, 1% EG), and a TC challenge group (SE, 0.75% TC). Before the start of each experiment, the flock was screened for any inherent Salmonella (n = 12 birds/experiment). Birds were given ad libitum access to Salmonella-free feed and water. On d 30, birds were challenged with a 4-strain mixture of SE (8 log10 cfu/bird). Two birds from each group were killed after 24 h (d 31) to check for colonization of SE in the cecum. Birds were given feed supplemented with TC (0.75%) or EG (1%) for 5 d before slaughter on d 42 (n = 10 birds/group) for determination of SE populations in the cecum and cloaca. The experiment was repeated 2 times. The trans-cinnamaldehyde and EG consistently reduced SE in the samples in both experiments (P &lt; 0.05). Body weights and feed consumption did not differ among the groups (P &gt; 0.05). On the basis of histological analysis, no abnormal changes in the liver were observed because of supplementation of plant compounds. Therefore, TC and EG supplemented through the feed could reduce SE colonization in market-age chickens.
Food Microbiology, 2014
The efficacy of four plant-derived antimicrobials (PDAs), namely carvacrol, thymol, b-resorcylic ... more The efficacy of four plant-derived antimicrobials (PDAs), namely carvacrol, thymol, b-resorcylic acid, and caprylic acid, with or without hydrogen peroxide (HP), as antimicrobial wash and chitosan based coating for reducing Listeria monocytogenes (LM) on cantaloupes was investigated. Cantaloupe rind plugs inoculated with LM (10 7 CFU/cm 2 ) were washed for 3, 6, 10 min at 25 C or 1, 3, 5 min at 55 or 65 C in water, or water containing 2% PDAs with or without 2% HP. Additionally, inoculated cantaloupes (10 8 CFU/fruit) washed with 2% PDA-HP combinations at 55 or 65 C (5 min) were cut into rindless cubical pieces, stored at 4 C for 7 days and sampled for LM. Furthermore, inoculated plugs coated with 2% PDAs were stored for 7 days and sampled for surviving LM. Individual PDA washes reduced LM on rinds by !2.5 log CFU/ cm 2 by 3 min (P < 0.05). PDA-HP combinations decreased LM to undetectable levels by 5 min at 55, 65 C, and 10 min at 25 C (P < 0.05) and reduced LM transfer from cantaloupe surface to interior (P < 0.0001). All PDA coating treatments reduced LM on cantaloupe to undetectable levels by 5 days (P < 0.05). Results indicate that PDAs alone, or with HP could be used to reduce LM on cantaloupes.
International Journal of Molecular Sciences, 2013
Salmonella Enteritidis (SE) is a major foodborne pathogen in the United States and one of the mos... more Salmonella Enteritidis (SE) is a major foodborne pathogen in the United States and one of the most frequently reported Salmonella serotypes globally. Eggs are the most common food product associated with SE infections in humans. The pathogen colonizes the intestinal tract in layers, and migrates to reproductive organs systemically. Since adhesion to and invasion of chicken oviduct epithelial cells (COEC) is critical for SE colonization in reproductive tract, reducing these virulence factors could potentially decrease egg yolk contamination. This study investigated the efficacy of sub-inhibitory concentrations of three plant-derived antimicrobials (PDAs), namely carvacrol, thymol and eugenol in reducing SE adhesion to and invasion of COEC, and survival in chicken macrophages. In addition, the effect of PDAs on SE genes critical for oviduct colonization and macrophage survival was determined using real-time quantitative PCR (RT-qPCR). All PDAs significantly reduced SE adhesion to and invasion of COEC (p < 0.001). The PDAs, except thymol consistently decreased SE survival in macrophages (p < 0.001). RT-qPCR results revealed down-regulation in the expression of genes involved in SE colonization and macrophage survival (p < 0.001). The results indicate that PDAs could potentially be used to control SE colonization in chicken reproductive tract; however, in vivo studies validating these results are warranted.
BioMed Research International, 2014
The emergence of antibiotic resistance in pathogenic bacteria has led to renewed interest in expl... more The emergence of antibiotic resistance in pathogenic bacteria has led to renewed interest in exploring the potential of plantderived antimicrobials (PDAs) as an alternative therapeutic strategy to combat microbial infections. Historically, plant extracts have been used as a safe, effective, and natural remedy for ailments and diseases in traditional medicine. Extensive research in the last two decades has identified a plethora of PDAs with a wide spectrum of activity against a variety of fungal and bacterial pathogens causing infections in humans and animals. Active components of many plant extracts have been characterized and are commercially available; however, research delineating the mechanistic basis of their antimicrobial action is scanty. This review highlights the potential of various plant-derived compounds to control pathogenic bacteria, especially the diverse effects exerted by plant compounds on various virulence factors that are critical for pathogenicity inside the host. In addition, the potential effect of PDAs on gut microbiota is discussed.
Applied and environmental microbiology, Jan 20, 2015
Salmonella Enteritidis (SE) is a major foodborne pathogen in the United States, causing gastroent... more Salmonella Enteritidis (SE) is a major foodborne pathogen in the United States, causing gastroenteritis in humans, primarily through consumption of contaminated eggs. Chickens are the reservoir host of SE. In layer hens, SE colonizes the intestine and migrates to various organs including the oviduct, leading to egg contamination. This study investigated the efficacy of in-feed supplementation of trans-cinnamaldehyde (TC), a GRAS (Generally Recognized as Safe)-status, plant compound obtained from cinnamon, in reducing SE cecal colonization and systemic spread in layers. Additionally, the effect of TC on SE virulence factors critical for macrophage survival and oviduct colonization was investigated in vitro. The consumer acceptability of eggs was also determined by a triangle test. Supplementation of TC in feed for 66 days at 1 or 1.5% (vol/wt) to 40-week or 25-week-old layer chickens decreased SE on the eggshell and in the yolk (P<0.001). Additionally, SE persistence in the cecum,...
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International Journal of Molecular Sciences, 2014
Clostridium difficile is a nosocomial pathogen that causes a serious toxin-mediated enteric disea... more Clostridium difficile is a nosocomial pathogen that causes a serious toxin-mediated enteric disease in humans. Reducing C. difficile toxin production could significantly minimize its pathogenicity and improve disease outcomes in humans. This study investigated the efficacy of two, food-grade, plant-derived compounds, namely trans-cinnamaldehyde (TC) and carvacrol (CR) in reducing C. difficile toxin production and cytotoxicity in vitro. Three hypervirulent C. difficile isolates were grown with or without the sub-inhibitory concentrations of TC or CR, and the culture supernatant and the bacterial pellet were collected for total toxin quantitation, Vero cell cytotoxicity assay and RT-qPCR analysis of toxin-encoding genes. The effect of CR and TC on a codY mutant and wild type C. difficile was also investigated. Carvacrol and TC substantially reduced C. difficile toxin production and cytotoxicity on Vero cells. The plant compounds also significantly down-regulated toxin production genes. Carvacrol and TC did not inhibit toxin production in the codY mutant of C. difficile, suggesting a potential codY-mediated anti-toxigenic mechanism of the plant compounds. The antitoxigenic concentrations of CR and TC did not inhibit the growth of beneficial gut bacteria. Our results suggest that CR and TC could potentially be used to control C. difficile, and warrant future studies in vivo.
Journal of Food Science, 2013
This study investigated the efficacy of 3 GRAS-status, plant-derived antimicrobials (PDAs), trans... more This study investigated the efficacy of 3 GRAS-status, plant-derived antimicrobials (PDAs), transcinnamaldehyde (TC), carvacrol (CR), and β-resorcylic acid (BR) applied as an antimicrobial wash for killing Escherichia coli O157:H7 on apples. "Red delicious" apples inoculated with a 5 strain mixture of E. coli O157:H7 were subjected to washing in sterile deionized water containing 0% PDA (control), 0.15% TC, 0.35% TC, 0.15% CR, 0.30% CR, 0.5% BR, or 1% BR for 1, 3, and 5 min at 23 • C in the presence and absence of 1% soil, and surviving pathogen populations on apples were enumerated at each specified time. All PDAs were more effective in reducing E. coli O157:H7 compared to the water wash treatment (P < 0.05) and reduced the pathogen by 4-to 5-log CFU/apple in 5 min. Chlorine (1%) was the most effective treatment reducing the pathogen on apples to undetectable levels in 1 min (P < 0.05). Moreover, the antimicrobial effect of CR and BR was not affected by the presence of soil, whereas the efficacy of TC and BR was decreased in the presence of soil. Further, no bacteria were detected in the wash solution containing CR and BR; however, E. coli O157:H7 was recovered in the control wash water and treatment solutions containing TC and chlorine, in the presence of 1% soil (P < 0.05). Results suggest that the aforementioned PDAs, especially CR and BR could be used effectively to kill E. coli O157:H7 on apples when used as a wash treatment. Studies on the sensory and quality characteristics of apples treated with PDAs are needed before recommending their usage.
Journal of Food Protection, 2013
Two naturally occurring, generally recognized as safe compounds, namely, caprylic acid (CA) (1%) ... more Two naturally occurring, generally recognized as safe compounds, namely, caprylic acid (CA) (1%) and b-resorcylic acid (BR) (1%), and their combination, applied at 23 and 60uC were evaluated for their antimicrobial effects against Escherichia coli O157:H7 on cattle hides in the presence and absence of bovine feces. Fresh cleaned cattle hides were cut into pieces (5 cm 2 ), air dried, and inoculated with a five-strain mixture of nalidixic acid-resistant (50 mg/ml) E. coli O157:H7 (,8.0 log CFU). The hide samples were air dried under a biosafety hood for 2 h and sprayed with 95% ethanol, 1% CA, 1% BR, or a mixture of 1% CA and 1% BR at 23 or 60uC. The hide samples were kept at 23uC, and E. coli O157:H7 populations were determined at 2 and 5 min after treatment. Both CA and BR were effective in decreasing E. coli O157:H7 populations on hides by 3 to 4 log CFU/cm 2 (P , 0.05). Sterile bovine feces had no effect on the decontaminating property of CA and BR on cattle hides (P . 0.05). Results of this study indicate that CA and BR could potentially be used to decontaminate cattle hides, but follow-up research under slaughterhouse conditions is warranted.
International Journal of Food Microbiology, 2013
Listeria monocytogenes is a significant foodborne pathogen associated with outbreaks involving co... more Listeria monocytogenes is a significant foodborne pathogen associated with outbreaks involving contaminated ready-to-eat (RTE) products, including frankfurters. The USDA-FSIS has established a zero tolerance policy for L. monocytogenes in RTE products, thereby warranting effective post-processing interventions to control the pathogen on these foods. In the present study, the antilisterial activity of GRAS (generally recognized as safe)-status plant-derived antimicrobials (PDAs), namely β-resorcylic acid (BR), carvacrol (CR), and trans-cinnamaldehyde (TC) either alone or in combination with hydrogen peroxide (HP) as post-processing dip treatments on frankfurters was investigated. Frankfurters were surface inoculated with a five-strain mixture of L. monocytogenes (~6.0 log CFU per frankfurter), followed by dip treatment at 55°C for 60 s or 65°C for 30 s in sterile deionized water, or water containing BR (1.5%), CR (0.75%), or TC (0.75%) either alone or in combination with HP (0.1%). Treated frankfurters were vacuum-packaged, and stored at 4°C for 70 days. Representative samples were analyzed on days 0, 1, 3, 7, 14, 28, 42, 56, and 70 of refrigerated storage for enumerating surviving L. monocytogenes on frankfurters. Six frankfurters were sampled at each time point for each treatment. On day zero, all PDAs reduced L. monocytogenes counts by > 2 log CFU/frankfurter at both temperatures (P b 0.05), compared to controls. From days 1 to 70, L. monocytogenes counts on PDA-treated frankfurters were consistently lower (P b 0.05) and after 70 days of storage, the pathogen counts were reduced to undetectable levels on frankfurters treated with PDA-HP combinations at 65°C, and by combinations of BR and TC with HP at 55°C. Results suggest that PDAs alone, or in combination with HP could be effectively used as post-processing dips to reduce L. monocytogenes on frankfurters, although follow-up studies on sensory and quality characteristics of PDA-treated frankfurters are necessary.
International Journal of Food Microbiology, 2012
Listeria monocytogenes (LM) is a major foodborne pathogen causing septicemia, meningitis and deat... more Listeria monocytogenes (LM) is a major foodborne pathogen causing septicemia, meningitis and death in humans. LM infection is preceded by its attachment to and invasion of human intestinal epithelium followed by systemic spread. The major virulence factors in LM include motility, hemolysin and lecithinase production. Reducing LM attachment to and invasion of host tissue and production of virulence factors could potentially control listeriosis in humans. This study investigated the efficacy of sub-inhibitory concentrations (SICs, concentrations not inhibiting bacterial growth) of three, generally regarded as safe (GRAS)-status, plant-derived antimicrobial compounds in reducing LM attachment to and invasion of human colon adenocarcinoma (Caco-2) and human brain microvascular endothelial cells (HBMEC). Additionally, the effect of these compounds on the aforementioned LM virulence factors was studied. The compounds and their respective SICs used relative to their MICs were trans-cinnamaldehyde (TC 0.50 mM, 0.75 mM with the MIC of 0.90 mM), carvacrol (CR 0.50 mM, 0.65 mM with the MIC of 0.75 mM), and thymol (TY 0.33 mM, 0.50 mM with the MIC of 0.60 mM). All three-plant antimicrobials reduced LM adhesion to and invasion of Caco-2 and HBMEC (p b 0.05). The compounds also decreased LM motility, hemolysin production and lecithinase activity (p b 0.05). Real-time PCR data revealed that TC, CR, and TY down-regulated the expression of LM virulence genes by > 3.0 folds compared to controls (p b 0.05). Results suggest that TC, CR, and TY could potentially be used to control LM infection; however, in vivo studies are necessary to validate these results.
Food Microbiology, 2013
Please cite this article as: Upadhyay, A., Upadhyaya, I., Kollanoor-Johny, A., Venkitanarayanan, ... more Please cite this article as: Upadhyay, A., Upadhyaya, I., Kollanoor-Johny, A., Venkitanarayanan, K., Antibiofilm effect of plant derived antimicrobials on Listeria monocytogenes, Food Microbiology (2013), Abstract 1 The present study investigated the efficacy of sub-inhibitory concentrations (SICs, 2 concentrations not inhibiting bacterial growth) and bactericidal concentrations (MBCs) of four, 3 generally recognized as safe (GRAS), plant-derived antimicrobials (PDAs) in inhibiting Listeria 4 monocytogenes (LM) biofilm formation and inactivating mature LM biofilms, at 37, 25 and 4°C 5 on polystyrene plates and stainless-steel coupons. In addition, the effect of SICs of PDAs on the 6 expression of LM genes critical for biofilm synthesis was determined by real-time quantitative 7 PCR. The PDAs and their SICs used for inhibition of biofilm were trans-cinnamaldehyde (TC 8 0.50, 0.75 mM), carvacrol (CR 0.50, 0.65 mM), thymol (TY 0.33, 0.50 mM), and eugenol (EG 9 1.8, 2.5 mM), whereas the PDA concentrations used for inactivating mature biofilms were 5.0 10 and 10.0 mM (TC, CR), 3.3 and 5.0 mM (TY), 18.5 and 25.0 mM (EG). All PDAs inhibited 11 biofilm synthesis and inactivated fully formed LM biofilms on both matrices at three 12 temperatures tested (P<0.05). Real-time quantitative PCR data revealed that all PDAs down-13 regulated critical LM biofilm-associated genes (P<0.05). Results suggest that TC, CR, TY, and 14 EG could potentially be used to control LM biofilms in food processing environments, although 15 further studies under commercial settings are necessary.
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Papers by Abhinav Upadhyay