Cell-surface anchoring of Listeria adhesion protein on L. monocytogenes is fastened by internalin B for pathogenesis.

Listeria adhesion protein (LAP) is a secreted acetaldehyde alcohol dehydrogenase (AdhE) that anchors to an unknown molecule on the Listeria monocytogenes (Lm) surface, which is critical for its intestinal epithelium crossing. In the present work, immunoprecipitation and mass spectrometry identify internalin B (InlB) as the primary ligand of LAP (KD ∼ 42 nM). InlB-deleted and naturally InlB-deficient Lm strains show reduced LAP-InlB interaction and LAP-mediated pathology in the murine intestine and brain invasion. InlB-overexpressing non-pathogenic Listeria innocua also displays LAP-InlB interplay. In silico predictions reveal that a pocket region in the C-terminal domain of tetrameric LAP is the binding site for InlB. LAP variants containing mutations in negatively charged (E523S, E621S) amino acids in the C terminus confirm altered binding conformations and weaker affinity for InlB. InlB transforms the housekeeping enzyme, AdhE (LAP), into a moonlighting pathogenic factor by fastening on the cell surface.

Receptor-targeted engineered probiotics mitigate lethal Listeria infection.

Probiotic bacteria reduce the intestinal colonization of pathogens. Yet, their use in preventing fatal infection caused by foodborne Listeria monocytogenes (Lm), is inconsistent. Here, we bioengineered Lactobacillus probiotics (BLP) to express the Listeria adhesion protein (LAP) from a non-pathogenic Listeria (L. innocua) and a pathogenic Listeria (Lm) on the surface of Lactobacillus casei. The BLP strains colonize the intestine, reduce Lm mucosal colonization and systemic dissemination, and protect mice from lethal infection. The BLP competitively excludes Lm by occupying the surface presented LAP receptor, heat shock protein 60 and ameliorates the Lm-induced intestinal barrier dysfunction by blocking the nuclear factor-κB and myosin light chain kinase-mediated redistribution of the major epithelial junctional proteins. Additionally, the BLP increases intestinal immunomodulatory functions by recruiting FOXP3+T cells, CD11c+ dendritic cells and natural killer cells. Engineering a probiotic strain with an adhesion protein from a non-pathogenic bacterium provides a new paradigm to exclude pathogens and amplify their inherent health benefits.

Inactivation of Acinetobacter baumannii Biofilms on Polystyrene, Stainless Steel, and Urinary Catheters by Octenidine Dihydrochloride.

Acinetobacter baumannii is a major nosocomial pathogen causing human infections with significant mortality rates. In most cases, infections are acquired through exposure to A. baumannii biofilms that persist on contaminated hospital equipment and surfaces. Thus, it is imperative to develop effective measures for controlling A. baumannii biofilms in nosocomial settings. This study investigated the efficacy of octenidine dihydrochloride (OH), a new generation disinfectant for reducing A. baumannii biofilms on polystyrene, stainless steel and catheters. OH at 0.3% (5 mM), 0.6% (10 mM), and 0.9% (15 mM) was effective in significantly inactivating A. baumannii biofilms on all tested surfaces (P < 0.05). Furthermore, OH was equally effective in inactivating biofilms of multidrug resistant and drug susceptible A. baumannii isolates. In addition, confocal imaging revealed the predominance of dead cells in the OH-treated samples in comparison to the control. Further, scanning electron microscopy of biofilms formed on catheters revealed that OH treatment significantly reduced A. baumannii biofilm populations in corroboration with our antibiofilm assay. These data underscore the efficacy of OH in inactivating A. baumannii biofilms, thereby suggesting its potential use as a disinfectant or a catheter lock solution to control A. baumannii infections.

Anticarcinogenic properties of medium chain fatty acids on human colorectal, skin and breast cancer cells in vitro.

Colorectal cancer, breast cancer and skin cancer are commonly-reported cancer types in the U.S. Although radiation and chemotherapy are routinely used to treat cancer, they produce side effects in patients. Additionally, resistance to chemotherapeutic drugs has been noticed in cancers. Thus, there is a need for effective and safe bioprophylactics and biotherapeutics in cancer therapy. The medicinal value of goat milk has been recognized for centuries and is primarily attributed to three fatty acids, namely capric, caprylic and caproic acids. This research investigates the anticancer property of these fatty acids on human colorectal, skin and mammary gland cancer cells. The cancer cells were treated with various concentrations of fatty acids for 48 h, and cell viability was monitored by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay. Additionally, real-time quantitative PCR (RT-qPCR) was performed to elucidate the potential anti-cancer mechanisms of the three fatty acids under investigation. Capric, caprylic and caproic acids reduced cancer cell viability by 70% to 90% (p < 0.05) compared to controls. RT-qPCR data indicated that these natural molecules produced anticancer effects by down-regulating cell cycle regulatory genes and up-regulating genes involved in apoptosis. Future research will validate the anticancer effect of these fatty acids in an appropriate in vivo model.

Antibiofilm Effect of Octenidine Hydrochloride on Staphylococcus aureus, MRSA and VRSA.

Millions of indwelling devices are implanted in patients every year, and staphylococci (S. aureus, MRSA and vancomycin-resistant S. aureus (VRSA)) are responsible for a majority of infections associated with these devices, thereby leading to treatment failures. Once established, staphylococcal biofilms become resistant to antimicrobial treatment and host response, thereby serving as the etiological agent for recurrent infections. This study investigated the efficacy of octenidine hydrochloride (OH) for inhibiting biofilm synthesis and inactivating fully-formed staphylococcal biofilm on different matrices in the presence and absence of serum protein. Polystyrene plates and stainless steel coupons inoculated with S. aureus, MRSA or VRSA were treated with OH (zero, 0.5, one, 2 mM) at 37 °C for the prevention of biofilm formation. Additionally, the antibiofilm effect of OH (zero, 2.5, five, 10 mM) on fully-formed staphylococcal biofilms on polystyrene plates, stainless steel coupons and urinary catheters was investigated. OH was effective in rapidly inactivating planktonic and biofilm cells of S. aureus, MRSA and VRSA on polystyrene plates, stainless steel coupons and urinary catheters in the presence and absence of serum proteins. The use of two and 10 mM OH completely inactivated S. aureus planktonic cells and biofilm (>6.0 log reduction) on all matrices tested immediately upon exposure. Further, confocal imaging revealed the presence of dead cells and loss in biofilm architecture in the OH-treated samples when compared to intact live biofilm in the control. Results suggest that OH could be applied as an effective antimicrobial to control biofilms of S. aureus, MRSA and VRSA on appropriate hospital surfaces and indwelling devices.

Sub-inhibitory concentrations of trans-cinnamaldehyde attenuate virulence in Cronobacter sakazakii in vitro.

Cronobacter sakazakii is a foodborne pathogen, which causes a life-threatening form of meningitis, necrotizing colitis and meningoencephalitis in neonates and children. Epidemiological studies implicate dried infant formula as the principal source of C. sakazakii. In this study, we investigated the efficacy of sub-inhibitory concentrations (SIC) of trans-cinnamaldehyde (TC), an ingredient in cinnamon, for reducing C. sakazakii virulence in vitro using cell culture, microscopy and gene expression assays. TC significantly (p ≤ 0.05) suppressed C. sakazakii adhesion to and invasion of human and rat intestinal epithelial cells, and human brain microvascular endothelial cells. In addition, TC inhibited C. sakazakii survival and replication in human macrophages. We also observed that TC reduced the ability of C. sakazakii to cause cell death in rat intestinal cells, by inhibiting nitric oxide production. Results from gene expression studies revealed that TC significantly downregulated the virulence genes critical for motility, host tissue adhesion and invasion, macrophage survival, and LPS (Lipopolysaccharide) synthesis in C. sakazakii. The efficacy of TC in attenuating these major virulence factors in C. sakazakii underscores its potential use in the prevention and/or control of infection caused by this pathogen.

Rapid sample processing for detection of food-borne pathogens via cross-flow microfiltration.

This paper reports an approach to enable rapid concentration and recovery of bacterial cells from aqueous chicken homogenates as a preanalytical step of detection. This approach includes biochemical pretreatment and prefiltration of food samples and development of an automated cell concentration instrument based on cross-flow microfiltration. A polysulfone hollow-fiber membrane module having a nominal pore size of 0.2 µm constitutes the core of the cell concentration instrument. The aqueous chicken homogenate samples were circulated within the cross-flow system achieving 500- to 1,000-fold concentration of inoculated Salmonella enterica serovar Enteritidis and naturally occurring microbiota with 70% recovery of viable cells as determined by plate counting and quantitative PCR (qPCR) within 35 to 45 min. These steps enabled 10 CFU/ml microorganisms in chicken homogenates or 10(2) CFU/g chicken to be quantified. Cleaning and sterilizing the instrument and membrane module by stepwise hydraulic and chemical cleaning (sodium hydroxide and ethanol) enabled reuse of the membrane 15 times before replacement. This approach begins to address the critical need for the food industry for detecting food pathogens within 6 h or less.

Bioengineered probiotics, a strategic approach to control enteric infections.

Enteric infections account for high morbidity and mortality and are considered to be the fifth leading cause of death at all ages worldwide. Seventy percent of all enteric infections are foodborne. Thus significant efforts have been directed toward the detection, control and prevention of foodborne diseases. Many antimicrobials including antibiotics have been used for their control and prevention. However, probiotics offer a potential alternative intervention strategy owing to their general health beneficial properties and inhibitory effects against foodborne pathogens. Often, antimicrobial probiotic action is non-specific and non-discriminatory or may be ineffective. In such cases, bioengineered probiotics expressing foreign gene products to achieve specific function is highly desirable. In this review we summarize the strategic development of recombinant bioengineered probiotics to control enteric infections, and to examine how scientific advancements in the human microbiome and their immunomodulatory effects help develop such novel and safe bioengineered probiotics.

Modern approaches in probiotics research to control foodborne pathogens.

Foodborne illness is a serious public health concern. There are over 200 known microbial, chemical, and physical agents that are known to cause foodborne illness. Efforts are made for improved detection, control and prevention of foodborne pathogen in food, and pathogen associated diseases in the host. Several commonly used approaches to control foodborne pathogens include antibiotics, natural antimicrobials, bacteriophages, bacteriocins, ionizing radiations, and heat. In addition, probiotics offer a potential intervention strategy for the prevention and control of foodborne infections. This review focuses on the use of probiotics and bioengineered probiotics to control foodborne pathogens, their antimicrobial actions, and their delivery strategies. Although probiotics have been demonstrated to be effective in antagonizing foodborne pathogens, challenges exist in the characterization and elucidation of underlying molecular mechanisms of action and in the development of potential delivery strategies that could maintain the viability and functionality of the probiotic in the target organ.

Plant-derived antimicrobials reduce Listeria monocytogenes virulence factors in vitro, and down-regulate expression of virulence genes.

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 0.50mM, 0.75mM with the MIC of 0.90mM), carvacrol (CR 0.50mM, 0.65mM with the MIC of 0.75mM), and thymol (TY 0.33mM, 0.50mM with the MIC of 0.60mM). All three-plant antimicrobials reduced LM adhesion to and invasion of Caco-2 and HBMEC (p<0.05). The compounds also decreased LM motility, hemolysin production and lecithinase activity (p<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<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.

Recombinant probiotic expressing Listeria adhesion protein attenuates Listeria monocytogenes virulence in vitro.

BACKGROUND: Listeria monocytogenes, an intracellular foodborne pathogen, infects immunocompromised hosts. The primary route of transmission is through contaminated food. In the gastrointestinal tract, it traverses the epithelial barrier through intracellular or paracellular routes. Strategies to prevent L. monocytogenes entry can potentially minimize infection in high-risk populations. Listeria adhesion protein (LAP) aids L. monocytogenes in crossing epithelial barriers via the paracellular route. The use of recombinant probiotic bacteria expressing LAP would aid targeted clearance of Listeria from the gut and protect high-risk populations from infection. METHODOLOGY/PRINCIPAL FINDINGS: The objective was to investigate the ability of probiotic bacteria or LAP-expressing recombinant probiotic Lactobacillus paracasei (Lbp(LAP)) to prevent L. monocytogenes adhesion, invasion, and transwell-based transepithelial translocation in a Caco-2 cell culture model. Several wild type probiotic bacteria showed strong adhesion to Caco-2 cells but none effectively prevented L. monocytogenes infection. Pre-exposure to Lbp(LAP) for 1, 4, 15, or 24 h significantly (P<0.05) reduced adhesion, invasion, and transepithelial translocation of L. monocytogenes in Caco-2 cells, whereas pre-exposure to parental Lb. paracasei had no significant effect. Similarly, Lbp(LAP) pre-exposure reduced L. monocytogenes translocation by as much as 46% after 24 h. Lbp(LAP) also prevented L. monocytogenes-mediated cell damage and compromise of tight junction integrity. Furthermore, Lbp(LAP) cells reduced L. monocytogenes-mediated cell cytotoxicity by 99.8% after 1 h and 79% after 24 h. CONCLUSIONS/SIGNIFICANCE: Wild type probiotic bacteria were unable to prevent L. monocytogenes infection in vitro. In contrast, Lbp(LAP) blocked adhesion, invasion, and translocation of L. monocytogenes by interacting with host cell receptor Hsp60, thereby protecting cells from infection. These data show promise for the use of recombinant probiotics in preventing L. monocytogenes infection in high-risk populations.

N-terminal Gly(224)-Gly(411) domain in Listeria adhesion protein interacts with host receptor Hsp60.

BACKGROUND: Listeria adhesion protein (LAP) is a housekeeping bifunctional enzyme consisting of N-terminal acetaldehyde dehydrogenase (ALDH) and C-terminal alcohol dehydrogenase (ADH). It aids Listeria monocytogenes in crossing the epithelial barrier through a paracellular route by interacting with its host receptor, heat shock protein 60 (Hsp60). To gain insight into the binding interaction between LAP and Hsp60, LAP subdomain(s) participating in the Hsp60 interaction were investigated. METHODS: Using a ModBase structural model, LAP was divided into 4 putative subdomains: the ALDH region contains N1 (Met(1)-Pro(223)) and N2 (Gly(224)-Gly(411)), and the ADH region contains C1 (Gly(412)-Val(648)) and C2 (Pro(649)-Val(866)). Each subdomain was cloned and overexpressed in Escherichia coli and purified. Purified subdomains were used in ligand overlay, immunofluorescence, and bead-based epithelial cell adhesion assays to analyze each domain's affinity toward Hsp60 protein or human ileocecal epithelial HCT-8 cells. RESULTS: The N2 subdomain exhibited the greatest affinity for Hsp60 with a K(D) of 9.50±2.6 nM. The K(D) of full-length LAP (7.2±0.5 nM) to Hsp60 was comparable to the N2 value. Microspheres (1 µm diameter) coated with N2 subdomain showed significantly (P<0.05) higher binding to HCT-8 cells than beads coated with other subdomains and this binding was inhibited when HCT-8 cells were pretreated with anti-Hsp60 antibody to specifically block epithelial Hsp60. Furthermore, HCT-8 cells pretreated with purified N2 subdomain also reduced L. monocytogenes adhesion by about 4 log confirming its involvement in interaction with epithelial cells. CONCLUSION: These data indicate that the N2 subdomain in the LAP ALDH domain is critical in initiating interaction with mammalian cell receptor Hsp60 providing insight into the molecular mechanism of pathogenesis for the development of potential anti-listerial control strategies.

Proteomic analysis of the mode of antibacterial action of trans-cinnamaldehyde against Cronobacter sakazakii 415.

Cronobacter sakazakii is an opportunistic foodborne pathogen that contaminates powdered infant formula, causing a rare but life-threatening infection in neonates and infants. Contaminated powdered infant formula represents the only known source of infection in infants. We previously reported that trans-cinnamaldehyde (TC), an ingredient in cinnamon, inactivated C. sakazakii in powdered infant formula. Although the antimicrobial properties of TC have been well established, only limited information is available on its antimicrobial mechanisms, especially at the molecular level. Therefore, we performed a proteomic analysis of the outer membrane and whole cell proteins from TC-treated C. sakazakii to investigate its potential antimicrobial mechanisms against C. sakazakii. The proteomic data revealed that TC exerts antimicrobial effects by several mechanisms, including disruption of carbohydrate, amino acid, and lipid metabolism. Additionally, TC compromises motility, attachment, and invasion ability and cellular defenses of C. sakazakii against oxidative stress, thereby reducing its virulence. The results of this study suggest that TC could be potentially used for controlling C. sakazakii.

Effect of trans-cinnamaldehyde on inhibition and inactivation of Cronobacter sakazakii biofilm on abiotic surfaces.

The efficacy of trans-cinnamaldehyde (TC), an ingredient in cinnamon oil, for inhibiting biofilm synthesis (560 and 750 µM TC) and inactivating mature biofilms (23 and 38 mM TC) of Cronobacter sakazakii was investigated at 24 and 12 °C in the presence and absence of reconstituted infant formula on polystyrene plates, stainless steel coupons, feeding bottle coupons, and enteral feeding tube coupons. Additionally, TC's effect on the expression of genes critical for biofilm formation in C. sakazakii was determined by reverse transcription quantitative PCR. TC inhibited and inactivated C. sakazakii biofilms on all matrices tested at both temperatures. C. sakazakii was reduced by >4.0 and 3.0 log CFU/ml after 96 h of exposure to 38 mM and 750 µM TC, respectively. Reverse transcription quantitative PCR results revealed that TC significantly (P≤0.05) down-regulated biofilm-associated genes in C. sakazakii. TC could potentially be used to control C. sakazakii biofilms on infant formula feeding equipment and preparatory areas.

Trans-cinnamaldehyde decreases attachment and invasion of uropathogenic Escherichia coli in urinary tract epithelial cells by modulating virulence gene expression.

PURPOSE: Uropathogenic Escherichia coli is the primary bacterium causing urinary tract infection in humans. Attachment and invasion of urinary tract epithelial cells by UPEC is the first critical step in establishing a successful urinary tract infection. We investigated the efficacy of subinhibitory concentrations of trans-cinnamaldehyde to inhibit uropathogenic E. coli attachment and invasion of human uroepithelial cells. We also determined the trans-cinnamaldehyde effect on uropathogenic E. coli genes encoding virulence factors critical for uroepithelial cell bacterial attachment and invasion. MATERIALS AND METHODS: Polystyrene 24-well plates seeded with uroepithelial cells were inoculated with uropathogenic E. coli (about 6.0 log cfu) and subinhibitory concentrations of trans-cinnamaldehyde (0, 325, 560 and 750 µM), and incubated for 60 minutes at 37C. Uroepithelial cells were washed and lysed to enumerate adhered uropathogenic E. coli populations. For the invasion assay uroepithelial cells were treated with gentamicin after incubation and lysed to enumerate invaded uropathogenic E. coli. Also, the trans-cinnamaldehyde effect on uropathogenic E. coli genes encoding attachment and invasion associated virulence factors was determined by real-time quantitative polymerase chain reaction. RESULTS: Trans-cinnamaldehyde significantly decreased uroepithelial cell attachment and invasion by uropathogenic E. coli (p <0.05). Real-time quantitative polymerase chain reaction revealed that trans-cinnamaldehyde significantly decreased the expression of major genes involved in uropathogenic E. coli attachment and invasion of host tissue (p <0.05). The down-regulating effect of trans-cinnamaldehyde on these genes potentially translated into decreased ability of uropathogenic E. coli to attach and invade bladder cells. CONCLUSIONS: Trans-cinnamaldehyde may potentially be used as a safe, effective antimicrobial to control uropathogenic E. coli infection. Followup studies in animal models are warranted.

Inactivation of Salmonella spp. on tomatoes by plant molecules.

The efficacy of carvacrol (CAR), trans-cinnamaldehyde (TC), eugenol (EUG) and ß-resorcylic acid (BR) as a wash treatment for reducing Salmonella spp. on tomatoes was investigated. Plum tomatoes inoculated with a six-serotype mixture of Salmonella (108CFU) were subjected to washing in sterile deionized water (control) or deionized water containing chlorine (100 ppm), CAR (0.25 and 0.75%), TC (0.5 and 0.75%), EUG (0.25 and 0.75%), or BR (0.75 and 1.0%) for 15 sec, 1 min, and 3 min. The plant molecules were more effective (P<0.05) in reducing Salmonella on tomatoes compared to washing in water and chlorine. Both concentrations of CAR and TC, and 0.75% EUG decreased Salmonella counts on tomatoes by~6.0 log CFU/ml at 1 min. Both concentrations of BR decreased the pathogen on tomatoes to undetectable levels at 3 min of exposure. Washing of tomatoes in deionized water and chlorine for 3 min reduced Salmonella by ca. 2.0 and 4.0 log CFU/ml, respectively. No Salmonella was detected in the wash water containing the plant molecules or chlorine, whereas a substantial population of the pathogen survived in the control wash water. Moreover, none of the dipping treatments had any effect on the red color of tomatoes (P>0.05). Results indicate that CAR, TC, EUG and BR could effectively be used to kill Salmonella on tomatoes, but additional studies on sensory and quality characteristics of tomatoes treated with plant molecules are warranted.

Effect of trans-cinnamaldehyde on reducing resistance to environmental stresses in Cronobacter sakazakii.

Cronobacter sakazakii is an emerging foodborne pathogen transmitted exclusively through contaminated infant formula (IFM), and associated with life-threatening infections in infants. C. sakazakii has the ability to tolerate a variety of environmental stress conditions, including heat stress, acidity, high osmotic pressure, and desiccation. In this study, we investigated the efficacy of a subinhibitory concentration (750 µM) of trans-cinnamaldehyde (TC), an ingredient in cinnamon, for reducing C. sakazakii's tolerance to these environmental stresses. Three strains of TC-treated C. sakazakii were separately subjected to high temperature (50°C, 55°C, and 60°C), acidic pH (3.3), high osmotic pressure (a(w) 0.81), and desiccation. TC (750 µM) substantially (p < 0.05) compromised stress tolerance of C. sakazakii compared to C. sakazakii cells not exposed to TC. Real-time quantitative polymerase chain reaction results revealed that TC significantly (p < 0.05) downregulated C. sakazakii genes critical for stress tolerance and survival, including rpoS, chaperonins, phoP/Q, outer membrane porins, and osmolyte transporter genes. The efficacy of TC in reducing C. sakazakii stress tolerance underscores its potential use for controlling the pathogen by increasing its susceptibility to commonly applied hurdles in food processing.

Enhancing the thermal destruction of Escherichia coli O157:H7 in ground beef patties by trans-cinnamaldehyde.

The effect of trans-cinnamaldehyde (TC) on the inactivation of Escherichia coli O157:H7 in undercooked ground beef patties was investigated. A five-strain mixture of E. coli O157:H7 was inoculated into ground beef (7.0log CFU/g), followed by addition of TC (0, 0.15, and 0.3%). The meat was formed into patties and stored at 4 degrees C for 5 days or at -18 degrees C for 7 days. The patties were cooked to an internal temperature of 60 or 65 degrees C, and E. coli O157:H7 was enumerated. The numbers of E. coli O157:H7 did not decline during storage of patties. However, cooking of patties containing TC significantly reduced (P<0.05) E. coli O157:H7 counts, by >5.0log CFU/g, relative to the reduction in controls cooked to the same temperatures. The D-values at 60 and 65 degrees C of E. coli O157:H7 in TC-treated patties (1.85 and 0.08min, respectively) were significantly lower (P<0.05) than the corresponding D-values for the organism in control patties (2.70 and 0.29min, respectively). TC-treated patties were more color stable and showed significantly lower lipid oxidation (P<0.05) than control samples. TC enhanced the heat sensitivity of E. coli O157:H7 and could potentially be used as an antimicrobial for ensuring pathogen inactivation in undercooked patties. However detailed sensory studies will be necessary to determine the acceptability to consumers of TC in ground beef patties.

Inactivation of Escherichia coli O157:H7 in apple juice and apple cider by trans-cinnamaldehyde.

This study investigated the antimicrobial effect of low concentrations of trans-cinnamaldehyde (TC) on Escherichia coli O157:H7 in apple juice and apple cider. A five-strain mixture of E. coli O157:H7 was inoculated into apple juice or cider at approximately 6.0 log CFU/ml, followed by the addition of TC (0%v/v, 0.025%v/v, 0.075%v/v and 0.125%v/v). The inoculated apple juice samples were incubated at 23 degrees C and 4 degrees C for 21 days, whereas the cider samples were stored only at 4 degrees C. The pH of apple juice and cider, and E. coli O157:H7 counts were determined on days 0, 1, 3, 5, 7, 14 and 21. TC was effective (P<0.05) in inactivating E. coli O157:H7 in apple juice and apple cider. At 23 degrees C, 0.125 and 0.075%v/v TC completely inactivated E. coli O157:H7 in apple juice (negative by enrichment) on days 1 and 3, respectively. At 4 degrees C, 0.125 and 0.075%v/v TC decreased the pathogen counts in the juice and cider to undetectable levels on days 3 and 5, respectively. Results indicate that low concentrations of TC could be used as an effective antimicrobial to inactivate E. coli O157:H7 in apple juice and apple cider.

Antibiofilm effect of trans-cinnamaldehyde on uropathogenic Escherichia coli.

PURPOSE: Urinary tract infections are the most common hospital acquired infections in humans, caused primarily by uropathogenic Escherichia coli. Indwelling urinary catheters for bladder drainage in humans become encrusted with uropathogenic E. coli biofilms that are resistant to common antibiotics, resulting in chronic infections. We studied the efficacy of the cinnamon ingredient trans-cinnamaldehyde (Sigma) for preventing uropathogenic E. coli biofilm. We also determined the efficacy of trans-cinnamaldehyde as an ingredient in catheter lock solution to inactivate preformed uropathogenic E. coli biofilm. MATERIALS AND METHODS: Polystyrene plates and urinary catheters inoculated with uropathogenic E. coli (5 to 6.0 log cfu) were treated with trans-cinnamaldehyde (0%, 0.1%, 0.25% or 0.5%) at 37C. Catheters with uropathogenic E. coli biofilm were also treated with lock solution containing trans-cinnamaldehyde (0%, 1%, 1.25% or 1.5%). Uropathogenic E. coli biofilm on control and trans-cinnamaldehyde treated plates and catheters was determined on incubation days 0, 1, 3 and 5. Trans-cinnamaldehyde potential cytotoxity, if any, was determined in HTB-4 bladder epithelial cells (ATCC). RESULTS: At all concentrations trans-cinnamaldehyde effectively prevented uropathogenic E. coli biofilm on plates and catheters. As a constituent in catheter lock solution, it inactivated uropathogenic E. coli biofilm on catheters. Trans-cinnamaldehyde produced no cytotoxic effects on human bladder epithelial cells at the tested concentrations. CONCLUSIONS: Results suggest that trans-cinnamaldehyde may be applied as a catheter surface coating or as an ingredient in catheter lock solution to prevent urinary tract infection in humans.