[A multi-channel input convolutional neural network for artifact reduction in quantitative susceptibility mapping].

OBJECTIVE: To develop a deep learning-based QSM reconstruction method for reducing artifacts to improve the accuracy of magnetic susceptibility results. METHODS: To eliminate artifacts caused by susceptibility interfaces with gigantic differences, we propose a multi-channel input convolutional neural network for artifact reduction (MAR-CNN) for solving the dipole inversion problem in QSM. In this neural network, the original tissue field was first separated into two components, which were subsequently imported as additional channels into a multi-channel 3D U-Net. MAR-CNN was compared with 3 conventional model-based methods, namely truncated k-space deconvolution (TKD), morphology enabled dipole inversion (MEDI), and improved sparse linear equation and least squares method (iLSQR), and with a deep learning method (QSMnet). High-frequency error norm, peak signal-to-noise ratio, normalized root mean squared error, and structure similarity index were reported for quantitative comparisons. RESULTS: Experiments on healthy volunteers demonstrated that the results obtained using MAR-CNN had superior peak signal-to-noise ratio (43.12±1.19) and normalized root mean squared error (51.98± 3.65) to those of TKD, MEDI, iLSQR and QSMnet. MAR-CNN outperformed QSMnet reconstruction on all the 4 quantitative metrics with significant differences (P < 0.05). Experiment on data of simulated hemorrhagic lesion demonstrated that MAR-CNN produced less shadow artifacts around the bleeding lesion than the other 4 methods. CONCLUSION: The proposed MAR-CNN for artifact reduction is capable of improving the accuracy of deep learning- based QSM reconstruction to effectively reduce artifacts.

Fermionic order by disorder in a van der Waals antiferromagnet.

CeTe3 is a unique platform to investigate the itinerant magnetism in a van der Waals (vdW) coupled metal. Despite chemical pressure being a promising route to boost quantum fluctuation in this system, a systematic study on the chemical pressure effect on Ce3+(4f1) states is absent. Here, we report on the successful growth of a series of Se doped single crystals of CeTe3. We found a fluctuation driven exotic magnetic rotation from the usual easy-axis ordering to an unusual hard-axis ordering. Unlike in localized magnetic systems, near-critical magnetism can increase itinerancy hand-in-hand with enhancing fluctuation of magnetism. Thus, seemingly unstable hard-axis ordering emerges through kinetic energy gain, with the self-consistent observation of enhanced magnetic fluctuation (disorder). As far as we recognize, this order-by-disorder process in fermionic system is observed for the first time within vdW materials. Our finding opens a unique experimental platform for direct visualization of the rich quasiparticle Fermi surface deformation associated with the Fermionic order-by-disorder process. Also, the search for emergent exotic phases by further tuning of quantum fluctuation is suggested as a promising future challenge.

[Comparison study on sensitivity of five ophthalmic antibiotics to common drug-resistant Staphylococci on ocular surface].

Objective: To investigate the in vitro antibacterial sensitivity of levofloxacin, tobramycin, cefazolin sodium, clindamycin and fusidic acid to 67 strains of Staphylococci in ocular surface infection. The purpose of this study is to provide reference for clinical selection of drugs. Methods: Experimental study. Sixth-seven strains of drug-resistant Staphylococci isolated from the Department of Microbiology, Henan Provincial Ophthalmic Hospital during January 2018 and May 2019 were collected. There were 67 strains of Staphylococci including 28 strains of drug-resistant Staphylococcus epidermidi, 17 strains of drug-resistant Staphylococcus aureus, 15 strains of drug-resistant Staphylococcus intermedius and a few other kinds of drug-resistant Staphylococci. The minimum inhibitory concentrations (minimum inhibitory concentration, MIC) of levofloxacin, tobramycin, cefazolin sodium, clindamycin and fusidic acid in 67 strains of drug-resistant Staphylococci were determined by microliquid-based method. The sensitivity was determined according to the American CLSI-M100 standard. The statistical analysis of the data was carried out by using two-dimensional test and Fisher accurate test. Results: Fourteen strains of fusidic acid were sensitive to 17 strains of MRS-Meca-resistant Staphylococcus epidermidis, the difference between fusidic and levofloxacin is statistically significant; 14 strains of cefazolin sodium and 11 strains of fusidic acid were sensitive to 14 strains of ß-Lac enzyme-producing Staphylococcus aureus, and there were significant differences between the two drugs and levofloxacin; 6 strains of cefazolin sodium and 5 strains of fusidic acid were sensitive to 10 strains of MRS-Meca-resistant Staphylococcus intermedius, as compared to levofloxacin, there were significant differences between cefazolin sodium and levofloxacin (P=0.011,0.033). Cefazolin sodium was sensitive to 5 strains of MRS-Meca-positive other drug-resistant Staphylococci, which was significantly different from levofloxacin (P=0.048); 54 and 48 strains of cefazolin sodium and fusidic acid were sensitive to 67 strains of drug-resistant Staphylococci, and the sensitive rates were 80.1% and 71.6%, respectively, which were significantly higher than those of levofloxacin, tobramycin and clindamycin. There were significant statistical differences between drug sensitivity (χ²=18.377,9.940；P=0.000,0.003). Conclusions: The sensitivity of cefazolin sodium and fusidic acid to 67 strains of drug-resistant Staphylococci is better than that of levofloxacin, tobramycin and clindamycin, these findings may provide guidance for the clinical treatment of drug-resistant Staphylococci in ocular infection. (Chin J Ophthalmol, 2020, 56: 621-625).

The astrocyte network in the ventral nerve cord neuropil of the Drosophila third-instar larva.

Understanding neuronal function at the local and circuit level requires understanding astrocyte function. We have provided a detailed analysis of astrocyte morphology and territory in the Drosophila third-instar ventral nerve cord where there already exists considerable understanding of the neuronal network. Astrocyte shape varies more than previously reported; many have bilaterally symmetrical partners, many have a high percentage of their arborization in adjacent segments, and many have branches that follow structural features. Taken together, our data are consistent with, but not fully explained by, a model of a developmental growth process dominated by competitive or repulsive interactions between astrocytes. Our data suggest that the model should also include cell-autonomous aspects, as well as the use of structural features for growth. Variation in location of arborization territory for identified astrocytes was great enough that a standardized scheme of neuropil division among the six astrocytes that populate each hemi-segment is not possible at the third instar. The arborizations of the astrocytes can extend across neuronal functional domains. The ventral astrocyte in particular, whose territory can extend well into the proprioceptive region of the neuropil, has no obvious branching pattern that correlates with domains of particular sensory modalities, suggesting that the astrocyte would respond to neuronal activity in any of the sensory modalities, perhaps integrating across them. This study sets the stage for future studies that will generate a robust, functionally oriented connectome that includes both partners in neuronal circuits-the neurons and the glial cells, providing the foundation necessary for studies to elucidate neuron-glia interactions in this neuropil.

Structural analysis and enhanced production of fusaricidin from Paenibacillus kribbensis CU01 isolated from yellow loess.

A bacterial strain showing strong antifungal activity was isolated from yellow loess and was identified as Paenibacillus kribbensis CU01. Insoluble mucoidal polymers were separated from M9 culture medium via low-speed centrifugation. Most antifungal activity was associated with substances in the insoluble precipitate, which was purified by reverse phase high performance liquid chromatography. Purified fractions were analyzed using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry. Two major ion peaks with mass-to-charge ratio values (m/z) at 883.6 and 897.6 were revealed. After alkaline hydrolysis and sequence analysis, two cyclic depsipeptides were identified as, fusaricidin A and fusaricidin B. Their production was significantly increased by the addition of glucose, Fe2+ , and Mn2+ to M9 medium. Maximum concentrations of produced fusaricidin A and fusaricidin B at flask-scale comprised 460 mg L-1 and 118 mg L-1 , respectively: the highest production concentrations yet reported in the literature. This demonstrates that P. kribbensis CU01 has enormous commercial potential for the mass production of fusaricidin.

Effect of exposure routes on the relationships of lethal toxicity to rats from oral, intravenous, intraperitoneal and intramuscular routes.

The lethal toxicity values (log 1/LD(50)) of 527 aliphatic and aromatic compounds in oral, intravenous, intramuscular and intraperitoneal routes were used to investigate the relationships of log 1/LD(50) from different exposure routes. Regression analysis shows that the log 1/LD(50) values are well correlated between intravenous and intraperitoneal or intramuscular injections. However, the correlations between oral and intravenous or intraperitoneal routes are relatively poor. Comparison of the average residuals indicates that intravenous injection is the most sensitive exposure route and oral administration is the least sensitive exposure route. This is attributed to the difference in kinetic process of toxicity testing. The toxic effect of a chemical can be similar or significantly different between exposure routes, depending on the absorption rates of chemicals into blood. Inclusion of hydrophobic parameter and fractions of ionic forms can improve the correlations between intravenous and intraperitoneal or oral routes, but not between intraperitoneal and oral routes. This is due to the differences of absorption rate in different exposure environments from different routes. Several factors, such as experimental uncertainty, metabolism and toxic kinetics, can affect the correlations between intravenous and intraperitoneal or oral routes.

Capecitabine maintenance therapy in patients with recurrent or metastatic breast cancer.

Our objective was to investigate the efficacy and safety of capecitabine maintenance therapy (CMT) after capecitabine-based combination chemotherapy in patients with metastatic breast cancer. The clinical data of 139 metastatic breast cancer patients treated from March 2008 to May 2012 with capecitabine-based combination chemotherapy were retrospectively analyzed. When initial disease control was achieved by the combination chemotherapy, we used CMT for 50 patients, while 37 patients were treated with a different (non-CMT) maintenance therapy. We compared time to progression (TTP), objective response rate, disease control rate, clinical benefit rate, and safety of the two groups, and a sub-group analysis was performed according to pathological characteristics. Sixty-four percent of the patients received a median of six cycles of a docetaxel+capecitabine combination chemotherapy regimen (range 1-45); the median TTP (MTTP) for the complete treatment was 9.43 months (95%CI=8.38-10.48 months) for the CMT group and 4.5 months (95%CI=4.22-4.78 months; P=0.004) for the non-CMT group. The MTTPs for the maintenance therapies administered after the initial capecitabine combined chemotherapy were 4.11 months (95%CI=3.34-4.87 months) for the CMT group and 2.0 months (95%CI=1.63-2.38 months) for the non-CMT group. Gastrointestinal side effects, decreased white blood cells and palmar-plantar erythrodysesthesia were the main adverse reactions experienced with the combination chemotherapies, CMT and non-CMT treatments. No significant differences in the incidence of adverse reactions were detected in the CMT and non-CMT patients. After initial disease control was achieved with the capecitabine-based combination chemotherapy, CMT can significantly prolong TTP rates with a favorable safety profile.

Capecitabine maintenance therapy in patients with recurrent or metastatic breast cancer

Our objective was to investigate the efficacy and safety of capecitabine maintenance therapy (CMT) after capecitabine-based combination chemotherapy in patients with metastatic breast cancer. The clinical data of 139 metastatic breast cancer patients treated from March 2008 to May 2012 with capecitabine-based combination chemotherapy were retrospectively analyzed. When initial disease control was achieved by the combination chemotherapy, we used CMT for 50 patients, while 37 patients were treated with a different (non-CMT) maintenance therapy. We compared time to progression (TTP), objective response rate, disease control rate, clinical benefit rate, and safety of the two groups, and a sub-group analysis was performed according to pathological characteristics. Sixty-four percent of the patients received a median of six cycles of a docetaxel+capecitabine combination chemotherapy regimen (range 1-45); the median TTP (MTTP) for the complete treatment was 9.43 months (95%CI=8.38-10.48 months) for the CMT group and 4.5 months (95%CI=4.22-4.78 months; P=0.004) for the non-CMT group. The MTTPs for the maintenance therapies administered after the initial capecitabine combined chemotherapy were 4.11 months (95%CI=3.34-4.87 months) for the CMT group and 2.0 months (95%CI=1.63-2.38 months) for the non-CMT group. Gastrointestinal side effects, decreased white blood cells and palmar-plantar erythrodysesthesia were the main adverse reactions experienced with the combination chemotherapies, CMT and non-CMT treatments. No significant differences in the incidence of adverse reactions were detected in the CMT and non-CMT patients. After initial disease control was achieved with the capecitabine-based combination chemotherapy, CMT can significantly prolong TTP rates with a favorable safety profile.

A population-based study of associations between functional gastrointestinal disorders and psychosocial characteristics in Xi'an, China.

BACKGROUND: Functional gastrointestinal disorders (FGIDs) are disorders with chronic and recurring gastrointestinal symptoms. This study investigated the prevalence of FGIDs, assessed the association between FGIDs and psychosocial factors, and identified potential risk factors for FGIDs in a population in Xi'an, China. METHODS: Of 752 recruited residents in Xi'an, 720 were selected for an epidemiological survey using a cluster sampling method. All subjects were interviewed face-to-face to complete the Chinese version of ROME III FGIDs questionnaire, the Symptom Check-List-90, the Eysenck Personality Questionnaire, a Life Event Scale, and a questionnaire regarding personal childhood adversity. The prevalence of FGIDs and associations between FGIDs and psychosocial factors were determined using EpiData Software. Logistic regression analysis was performed to identify the potential risk factors for FGIDs. KEY RESULTS: The prevalence of FGIDs in this sample population was 14.3% (103/720). There were 13 (1.8%) cases of overlap of different FGIDs. No significant difference in the prevalence of FGIDs was observed between men and women. Alcohol intake and smoking habits were significantly associated with the presence of FGIDs. The presence of FGIDs was significantly associated with psychological factors and influences such as personality type, life events, childhood adversity, and psychopathology. The potential risk factors for contracting FGIDs were certain life events, childhood adversity, somatization, and a hostile affect (P < 0.001). CONCLUSIONS & INFERENCES: The prevalence of FGIDs and overlap syndrome in Xi'an, China was lower than that reported in other countries. There was a strong correlation between specific lifestyle habits and psychosocial characteristics and the presence of FGIDs.

Comparison of the acute toxicities of novel algicides, thiazolidinedione derivatives TD49 and TD53, to various marine organisms.

Acute toxicity assessments of new algicides, thiazolidinedione derivatives TD49 and TD53, to the marine ecological system were conducted. The toxicity assessments were performed using two of the new International Organization for Standardization (ISO) standard methods employing Ulva pertusa Kjellman and three species representative of the marine ecological system, with the results compared by calculating the 50% effective concentration (EC50), 50% lethal concentration (LC50), no-observed-effect concentration (NOEC), and predicted-no-effect concentration (PNEC). In the acute toxicity assessment using the Kjellman, the EC50, NOEC, and PNEC of TD53 were 1.65 µM, 0.08 µM, and 1.65 nM, and those of TD49 were 0.18 µM, 0.63 µM, and 0.18 nM. In the assessments using Skeletonema costatum, Daphnia magna, and Paralichthys olivaceus fry, the EC50 or LC50 of TD53 were 1.53, 0.61, and 2.14 µM, respectively, indicating that D. magna was the most sensitive. The calculated NOEC and PNEC to D. magna were 0.25 µM and 6.10 nM, respectively. The LC50s (or EC50) of TD49 for the three species were 0.34, 0.68, and 0.58 µM. The NOEC and PNEC to S. costatum, the most sensitive species, were 0.2 µM and 3.4 nM, respectively. The slight difference in the chemical structures of the algicides caused significantly different sensitivities and specificities in the toxicities to the employed species. The results of the toxicity assessments showed that application concentrations for algiciding of red tide blooms were higher than the corresponding PNEC values. Therefore, we suggest that a formulization study of the algicides with high specificity should be conducted to reduce the surrounding ecological toxicity.

Birth of piglets from in vitro-produced, zona-intact porcine embryos vitrified in a closed system.

As the importance of swine models in biomedical research increases, it is essential to develop low-cost, high-throughput systems to cryopreserve swine germplasm for maintenance of these models. However, porcine embryos are exceedingly sensitive to low temperature and successful cryopreservation is generally limited to the use of vitrification in open systems that allow direct contact of the embryos with liquid nitrogen (LN(2)). This creates a high risk of pathogen transmission. Therefore, cryopreservation of porcine embryos in a "closed" system is of very high importance. In this study, in vitro-produced (IVP) porcine embryos were used to investigate cryosurvival and developmental potential of embryos cryopreserved in a closed system. Optimal centrifugal forces to completely disassociate intracellular lipids from blastomeres were investigated using Day-4 embryos. Cryosurvival of delipidated embryos was investigated by vitrifying the embryos immediately after centrifugation, or after development to blastocysts. In this study, centrifugation for 30 min at 13,000 g was adequate to completely delipidate the embryos; furthermore, these embryos were able to survive cryopreservation at a rate comparable to those centrifuged for only 12 min. When delipidated embryos were vitrified at the blastocyst stage, there was no difference in survival between embryos vitrified using OPS and 0.25 mL straws. Some embryos vitrified by each method developed to term. These experiments demonstrated that porcine embryos can be cryopreserved in a closed system after externalizing their intracellular lipids. This has important implications for banking swine models of human health and disease.

A single-channel telemetric intramedullary nail for in vivo measurement of fracture healing.

OBJECTIVE: The objective of this study was to develop a single-channel telemetric intramedullary nail that measures anterior-posterior bending strains and determine whether these forces decrease sigmoidally when normalized to the ground reaction force during fracture healing. METHODS: A transverse midshaft femoral osteotomy (1 mm) was stabilized using a customized TriGen intramedullary nail incorporating a strain gauge in the anterior-posterior plane. Fourteen skeletally mature sheep (2-3 years old) were treated in two pilot studies (n = 3/pilot) and a pivotal study (n = 8). Three animals were excluded as a result of welfare issues. Static strain measurements were acquired at approximately 130 Hz during leg stance. In vivo gait analysis was carried out weekly to assess ground reaction forces and biweekly x-rays to assess stability and fracture healing. Animals were euthanized 12 weeks postoperatively. Callus formation was assessed by microcomputed tomography and histomorphometry. The degree of load share between bone and the nail was determined postmortem by three-point bending. RESULTS: A significant preload was generated during implantation, most notably during placement of the four interlocking screws and by the action of attached soft tissues. Eight animals showed evidence of bone healing by x-ray, microcomputed tomography, and histology. However, a reduction in implant load was only observed with two of the eight. The degree of load sharing observed in vivo in these animals (50%-75%) compared favorably with the in vitro observations (approximately 50%). In the nonhealing ambulating animals, nail forces did not change over time. Three-point bend tests carried out on "healed" femurs suggested that load sharing between the bone and nail could be detected more easily in the absence of soft tissues. CONCLUSION: No clear correlation between implant strain and fracture healing was observed using the single-channel system when subjected to one external loading regime (leg stance phase). However, ex vivo biomechanical testing demonstrated that load share changes could be detected when loads were directly applied to the bone in the absence of muscle and ligament forces. These data emphasize the need to fully characterize the complex biomechanical environment of the limb to determine the load changes resulting from fracture healing.

Transcriptional profiling analysis of host response to Clostridium perfringens infection in broilers.

Necrotic enteritis is a disease caused by Clostridium perfringens, which threatens poultry production in the absence of dietary antibiotics. A total number of 600 Ross broilers were reared in 12 pens with each hosting 50 birds. Each 6 pens of birds were fed medicated (bacitracin at 55 mg/kg) or nonmedicated starter diets immediately after the chicks were placed. At d 18, birds were challenged with C. perfringens (10(7) cfu/mL mixed with feed). Spleens were collected from 12 birds of each group (2 birds per pen randomly) at d 18 (before infection), 19, 20, and 22. A low-density chicken immune microarray was used to study gene expression profiling of host response to C. perfringens infection. Six biological replicates (2 birds per biological replicate) for each treatment group were labeled with either Cy5 or Cy3 with dye swap. A total of 24 arrays were used for this study. Gene signal intensity was globally normalized by locally weighted regression and smoothing scatter plots and expressed on a natural log scale. A mixed model including treatment, time, array, subgrid (random effect), dye, and all interactions among treatment and time was used to identify differentially expressed genes between postinfection vs. preinfection, among postinfections, and between medication treatments, at the 5% significance level. The results indicated subtle medication effects on gene expression of these immune-related genes compared with bacterial infection effect. Our findings strongly suggest that both cell-mediated and antibody-mediated immune responses via MHC class I and II systems were actively involved in the host defense against C. perfringens infection in broilers. The unique cytokine signaling pathway and apoptosis cascade found in the study provide a new insight of molecular regulation of host immune response. Collectively, the findings of the present study will shed light on the molecular mechanisms underlying C. perfringens infection in broilers.

Antimicrobial activity of essential oils and structurally related synthetic food additives towards Clostridium perfringens.

AIMS: To assess the potential of essential oils and structurally related synthetic food additives in inhibiting the growth of Clostridium perfringens for the control of necrotic enteritis in chickens. METHODS AND RESULTS: The antimicrobial activity of essential oils/compounds was measured by determining the inhibition of bacterial growth. Thirty-three of 66 oils/compounds exhibited > or =80% inhibition. Seven with the highest potency were further studied. The oils/compounds had MIC(95) values between 167 and 425 microg ml(-1). Most of them were tolerant to low pH (2.0) and exhibited minor or no inhibition of Lactobacillus isolates from the chicken intestine. When mixed with chicken ileal digesta, the oils/compounds retained their efficacy against C. perfringens, but had little effect on the total number of lactobacilli and anaerobic bacteria in the digesta. CONCLUSIONS: Some essential oils/compounds demonstrated good potential in controlling C. perfringens. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has identified candidates of essential oils/compounds for in vivo studies for the control of necrotic enteritis in chickens.

In vitro assessment of antimicrobial activity of carvacrol, thymol and cinnamaldehyde towards Salmonella serotype Typhimurium DT104: effects of pig diets and emulsification in hydrocolloids.

AIMS: To determine the effect of pig diets in vitro on the antimicrobial activity of carvacrol, thymol and cinnamaldehyde, and to identify an emulsifier/stabilizer that can stabilize the essential oil (EO) components in aqueous solution and retain their antimicrobial activity in the presence of the diets. METHODS AND RESULTS: Emulsification of essential oil components with hydrocolloid solution was achieved by blending with a Polytron. Antimicrobial activity was measured through in vitro assays to determine the inhibition of bacterial growth by measuring the optical density at 600 nm or plating on nutrition agar after incubation of the mixtures of an EO component with the culture of Salmonella serotype Typhimurium DT104 in the presence or absence of pig diets. The results generated through the in vitro assays indicated that pig diets were able to abolish the antimicrobial activity of EOs. Xanthan, fenugreek and yellow mustard gums were the best in forming stable emulsions of five different EO components among ten different plant polysaccharides and surfactants examined. Emulsification of all the EO components in the fenugreek gum solution did not alter their antimicrobial activity. However, the antimicrobial activity of geraniol was significantly reduced when emulsified with other polysaccharides and surfactants. Both fenugreek and xanthan gum solutions were unable to protect the antimicrobial activity of carvacrol and thymol when mixed with the diets. Although cinnamaldehyde required no emulsification, but a high concentration (equivalent to at least three times of minimum bactericidal concentration for cinnamon oil) to inhibit Salmonella growth significantly in the presence of the diets, emulsification in fenugreek gum appeared to be essential for cinnamaldehyde solution to retain its antimicrobial activity during storage. CONCLUSIONS: The diets for newly weaned pigs were a significant factor limiting the antimicrobial activity of EOs and their components. Cinnamaldehyde required a high concentration to retain its antimicrobial activity in the diets, in addition to its requirement for emulsification to stabilize its activity during the storage. SIGNIFICANCE AND IMPACT OF THE STUDY: The assay with the diets used in this study for measuring the antimicrobial activity can be used in vitro for rapid and effective screening of potential antimicrobials for swine production. This study has identified polysaccharides that are able to stabilize EO component solutions. It has also identified cinnamaldehyde for further in vivo studies that may have potential in future application in controlling Salmonella and possibly other enteric pathogens in swine production.

Efficacy of radio frequency cooking in the reduction of Escherichia coli and shelf stability of ground beef.

The effectiveness of radio frequency (RF) cooking on the inactivation of Escherichia coli in ground beef and its effect on the shelf stability of ground beef were investigated with a comparison to hot water-bath cooking. E. coli K12 was used as a target bacterium instead of E. coli O157:H7. The ground beef samples inoculated with E. coli K12 (ampr) were heated until the centre temperature of each sample reached 72 degrees C. These samples were then stored at 4 degrees C for up to 30 days. The enumeration of E. coli K12, background E. coli and coliform counts in ground beef samples was carried out for shelf-life study. Although both methods significantly reduced E. coli K12 (ampr), E. coli and coliform counts and extended the shelf-life, RF cooking had a shorter cooking time, and more uniform heating. Thus, RF cooking of meat has a high potential as a substitute for the hot water-bath cooking.

Antimicrobial activity of essential oils and structurally related synthetic food additives towards selected pathogenic and beneficial gut bacteria.

AIMS: To assess the potential of essential oils and structurally related synthetic food additives in reducing bacterial pathogens in swine intestinal tract. METHODS AND RESULTS: The antimicrobial activity of essential oils/compounds was measured by determining the inhibition of bacterial growth. Among 66 essential oils/compounds that exhibited > or =80% inhibition towards Salmonellatyphimurium DT104 and Escherichia coli O157:H7, nine were further studied. Most of the oils/compounds demonstrated high efficacy against S. typhimurium DT104, E. coli O157:H7, and E. coli with K88 pili with little inhibition towards lactobacilli and bifidobacteria. They were also tolerant to the low pH. When mixed with pig cecal digesta, these oils/compounds retained their efficacy against E. coli O157:H7. In addition, they significantly inhibited E. coli and coliform bacteria in the digesta, but had little effect on the total number of lactobacilli and anaerobic bacteria. CONCLUSIONS: Some essential oils/compounds demonstrated good potential, including efficacy, tolerance to low pH, and selectivity towards bacterial pathogens, in reducing human and animal bacterial pathogens in swine intestinal tract. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has identified candidates of essential oils/compounds for in vivo studies to develop antibiotic substitutes for the reduction of human and animal bacterial pathogens in swine intestinal tract.