Transformation and release of micronized Cu used as a wood preservative in treated wood in wetland soil.

Micronized Cu (µ-Cu) is used as a wood preservative, replacing toxic chromated copper arsenate (CCA). Micronized Cu is malachite [Cu2CO3(OH)2] that has been milled to micron/submicron particles, with many particle diameters less than 100 nm, mixed with biocides and then used to treat wood. In addition to concerns about the fate of the Cu from µ-Cu, there is interest in the fate of the nano-Cu (n-Cu) constituents. We examined movement of Cu from µ-Cu-treated wood after placing treated-wood stakes into model wetland ecosystems. Release of Cu into surface and subsurface water was monitored. Surface water Cu reached maximum levels 3 days after stake installation and remained elevated if the systems remained inundated. Subsurface water Cu levels were 10% of surface water levels at day 3 and increased gradually thereafter. Sequential filtering indicated that a large portion of the Cu in solution was associating with soluble organics, but there was no evidence for n-Cu in solution. After 4 months, Cu in thin-sections of treated wood and adjacent soil were characterized with micro X-ray absorption fine structure spectroscopy (µ-XAFS). Localization and speciation of Cu in the wood and adjacent soil using µ-XAFS clearly indicated that Cu concentrations decreased over time in the treated wood and increased in the adjacent soil. However, n-Cu from the treated wood was not found in the adjacent soil or plant roots. The results of this study indicate that Cu in the µ-Cu-treated wood dissolves and migrates into adjacent soil and waters primarily in ionic form (i.e., Cu2+) and not as nano-sized Cu particles. A reduced form of Cu (Cu2S) was identified in deep soil proximal to the treated wood, indicating strong reducing conditions. The formation of the insoluble Cu2S effectively removes some portion of dissolved Cu from solution, reducing movement of Cu2+ to the water column and diminishing exposure.

Medium matters: modeling the impact of solid medium performance on tuberculosis trial sample size requirements.

SETTING: Two-month solid medium culture conversion is a commonly used, if suboptimal, endpoint for phase 2 anti-tuberculosis treatment trials. OBJECTIVE AND DESIGN: To model the effect of the performance characteristics (sensitivity and contamination rate) of solid medium on required sample size for a two-arm clinical trial with 85% true (gold standard) culture conversion in the control and 95% in the experimental arm. RESULTS: Increasing sensitivity and decreasing contamination reduced the sample size from 239 subjects/arm (60% sensitivity, 30% contamination) to 138 subjects/arm (95% sensitivity, 1% contamination). CONCLUSION: Optimizing solid medium has significant potential to reduce sample size and increase the efficiency of tuberculosis clinical trials.

The effects of quantitative fecundity in the haploid stage on reproductive success and diploid fitness in the aquatic peat moss Sphagnum macrophyllum.

A major question in evolutionary biology is how mating patterns affect the fitness of offspring. However, in animals and seed plants it is virtually impossible to investigate the effects of specific gamete genotypes. In bryophytes, haploid gametophytes grow via clonal propagation and produce millions of genetically identical gametes throughout a population. The main goal of this research was to test whether gamete identity has an effect on the fitness of their diploid offspring in a population of the aquatic peat moss Sphagnum macrophyllum. We observed a heavily male-biased sex ratio in gametophyte plants (ramets) and in multilocus microsatellite genotypes (genets). There was a steeper relationship between mating success (number of different haploid mates) and fecundity (number of diploid offspring) for male genets compared with female genets. At the sporophyte level, we observed a weak effect of inbreeding on offspring fitness, but no effect of brood size (number of sporophytes per maternal ramet). Instead, the identities of the haploid male and haploid female parents were significant contributors to variance in fitness of sporophyte offspring in the population. Our results suggest that intrasexual gametophyte/gamete competition may play a role in determining mating success in this population.

Should all patients undergoing treatment with biologic agents be screened annually for latent tuberculosis infection with an interferon gamma release assay?

Systemic biologic therapy has become commonplace for the treatment of a variety of inflammatory dermatologic conditions, particularly psoriasis. Screening for latent tuberculosis infection (LTBI) is recommended prior to initiation of systemic biologic agents, and an interferon gamma release assays (IGRA) is often used as the screening modality. Annual screening for LTBI is also recommended for patients while on systemic biologic therapy, but the literature does not clearly support how often screening should be performed. In addition, serial testing with IGRAs, particularly among low-risk populations without any new tuberculosis (TB) exposures, has proven to be unreliable with frequent reversions and conversions. We propose that in low-incidence TB regions, repeat LTBI screening should only be considered for patients on systemic biologic therapy if any new TB exposures occurred since initial LTBI screening was performed prior to starting biologic therapy. This strategy aims to reduce false-positive LTBI testing that can expose patients to hazardous antibiotics and result in the unnecessary interruption of systemic biologic therapy.

Efficacies of designer biochars in improving biomass and nutrient uptake of winter wheat grown in a hard setting subsoil layer.

In the Coastal Plains region of the United States, the hard setting subsoil layer of Norfolk soils results in low water holding capacity and nutrient retention, which often limits root development. In this region, the Norfolk soils are under intensive crop production that further depletes nutrients and reduces organic carbon (C). Incorporation of pyrolyzed organic residues or "biochars" can provide an alternative recalcitrant C source. However, biochar quality and effect can be inconsistent and different biochars react differently in soils. We hypothesized that addition of different designer biochars will have variable effects on biomass and nutrient uptake of winter wheat. The objective of this study was to investigate the effects of designer biochars on biomass productivity and nutrient uptake of winter wheat (Triticum aestivum L.) in a Norfolk's hard setting subsoil layer. Biochars were added to Norfolk's hard setting subsoil layer at the rate of 40 Mg ha(-1). The different sources of biochars were: plant-based (pine chips, PC); animal-based (poultry litter, PL); 50:50 blend (50% PC:50% PL); 80:20 blend (80% PC:20% PL); and hardwood (HW). Aboveground and belowground biomass and nutrient uptake of winter wheat varied significantly (p⩽0.0001) with the different designer biochar applications. The greatest increase in the belowground biomass of winter wheat over the control was from 80:20 blend of PC:PL (81%) followed by HW (76%), PC (59%) and 50:50 blend of PC:PL (9%). However, application of PL resulted in significant reduction of belowground biomass by about 82% when compared to the control plants. The average uptake of P, K, Ca, Mg, Na, Al, Fe, Cu and Zn in both the aboveground and belowground biomass of winter wheat varied remarkably with biochar treatments. Overall, our results showed promising significance for the treatment of a Norfolk's hard setting subsoil layer since designer biochars did improve both aboveground/belowground biomass and nutrient uptake of winter wheat.

Leachate water quality of soils amended with different swine manure-based amendments.

In the face of the rising level of manure production from concentrated animal feeding operations (CAFOs), management options are being sought that can provide nutrient recycling for plant growth and improved soil conditions with minimal environmental impacts. Alternatives to direct manure application are composting and thermochemical conversion which can destroy pathogens and improve handling and storage. The effect of four forms of swine manure-based soil amendments (raw, compost, hydrochar, and pyrochar) on soil fertility and leachate water quality characteristics of a sandy soil were investigated in soil incubation experiments. All four amendments significantly increased soil carbon, cation exchange capacity and available nutrient contents of the soil. However, hydrochar amended soil leached lower amounts of N, P, and K compared to the other amendments including the control. On the other hand, pyrochar amended soil leached higher concentrations of P and K. Subsequent tests on the hydrochar for K and N adsorption isotherms and surface analysis via XPS suggested that these nutrients were not sorbed directly to the hydrochar surface. Although it is still not clear how these nutrients were retained in the soil amended with hydrochar, it suggests a great potential for hydrochar as an alternative manure management option as the hydrochar can be soil applied while minimizing potential environmental issues from the leaching of high nutrient concentrations to water bodies.

Expanding tuberculosis case notification among marginalized groups in Bangladesh through peer sputum collection.

Case notification rates of tuberculosis (TB) in Bangladesh remain poor despite a high burden of disease. Peer sputum collection among underserved populations was implemented to expand case notification and to provide socially empowering roles in society for often excluded members of marginalized populations. Over the 55 months of the evaluation, 32 587 members of key populations were screened for TB, with 1587 smear-positive TB cases detected. Broadening TB services at human immunodeficiency virus drop-in centers using peer sputum collection to target high-risk populations for TB may be an effective way to increase TB case notification among key populations in Bangladesh.

Le taux de déclaration des cas de tuberculose (TB) au Bangladesh reste médiocre en dépit du lourd fardeau de la maladie. Le recueil de crachats par les pairs au sein des populations vulnérables a été mis en œuvre pour augmenter la déclaration des cas et également fournir des rôles socialement valorisants à des membres des populations marginales souvent exclus. Pendant 55 mois d'évaluation, 32 587 membres de ces populations ont bénéficié d'un dépistage de la TB, qui a permis de détecter 1587 cas de TB à frottis positif. L'expansion des services de TB dans les centres pour le virus d'immunodéficience humaine sans rendez-vous, utilisant le recueil de crachats par les pairs pour cibler les populations à haut risque de TB, peut être une façon efficace d'augmenter la déclaration des cas de TB parmi les populations les plus touchées au Bangladesh.

Las tasas de notificación de la tuberculosis (TB) en Bangladesh siguen siendo bajas pese a la alta carga de morbilidad por esta enfermedad. Se introdujo una medida de recogida de esputo por los pares en las poblaciones desatendidas, con el objeto de aumentar la notificación de casos y al mismo tiempo crear funciones de empoderamiento social en poblaciones marginadas, dirigidas a miembros de la comunidad que con frecuencia están excluidos. Durante los 55 meses de la evaluación, se investigó la TB en 32 587 miembros de poblaciones clave y se detectaron 1587 casos de TB con baciloscopia positiva. Una ampliación de los servicios de atención de la TB a los centros de encuentro y consulta de la infección por el virus de la inmunodeficiencia humana con aplicación de una estrategia de recogida de esputo por los pares y destinada a llegar a las poblaciones de alto riesgo de contraer la TB, sería una medida efectiva en aras de mejorar la notificación de los casos en las poblaciones clave de Bangladesh.

Listeria monocytogenes batch culture growth response to metabolic inhibitors.

In certain environments nutrient and energy sources available to microorganisms can be limited. Foodborne pathogens must efficiently adapt in order to be successfully transmitted through the food chain to their hosts. For the intracellular foodborne pathogen Listeria monocytogenes, little is known regarding its response to nutrient/energy-limiting conditions. The alternative stress responsive sigma factor σ(B) has been reported to contribute to survival under specific stresses. Therefore, the effects of several metabolic inhibitors on growth of L. monocytogenes wild-type and a ΔsigB mutant were examined. In the absence of inhibitors, both strains reached stationary phase after 18 h at 23°C and 10 h at 37°C. All of the metabolic inhibitors slowed growth of either strain, with few differences observed among the different inhibitors.

Carbon mineralization in two ultisols amended with different sources and particle sizes of pyrolyzed biochar.

Biochar produced during pyrolysis has the potential to enhance soil fertility and reduce greenhouse gas emissions. The influence of biochar properties (e.g., particle size) on both short- and long-term carbon (C) mineralization of biochar remains unclear. There is minimal information on the potential effects of biochar particle sizes on their breakdowns by soil microorganism, so it is unknown if the particle size of biochar influences C mineralization rate and/or stability in soils. In order to evaluate the effect of different sources (BS) and particle sizes (BF) of biochar on C loss and/or stability in soils, an incubation study on C mineralization of different biochar sources and particle sizes was established using two soils (ST): Norfolk soil (fine loamy, kaolinitic, thermic, typic Kandiudults) and Coxville soil (fine loamy kaolinitic, thermic, Paleaquults). In separate incubation vessels, these soils were amended with one of two manure-based biochars (poultry litters, PL; swine solids, SS) or one of two lignocellulosic-based biochars (switchgrass, SG; pine chips, PC) which were processed into two particle sizes (dust, <0.42 mm; pellet, >2 mm). The amount of CO2 evolved varied significantly between soils (p≤0.0001); particle sizes (p≤0.0001) and the interactions of biochar source (p≤0.001) and forms of biochars (p≤0.0001) with soil types. Averaged across soils and sources of biochar, CO2-C evolved from dust-sized biochar (281 mg kg(-1)) was significantly higher than pellet-sized biochar (226 mg kg(-1)). Coxville soils with SS biochar produced the greatest average CO2-C of 428 mg kg(-1) and Norfolk soils with PC had the lowest CO2-C production (93 mg kg(-1)). Measured rates of carbon mineralization also varied with soils and sources of biochar (Norfolk: PL>SS>SG≥PC; Coxville: PC>SG>SS>PL). The average net CO2-C evolved from the Coxville soils (385 mg kg(-1)) was about threefold more than the CO2-C evolved from the Norfolk soils (123 mg kg(-1)). Our results suggest different particle sizes and sources of biochar as well as soil type influence biochar stability.

Length frequency distribution, mortality rate and reproductive biology of kawakawa (Euthynnus affinis-Cantor, 1849) in the coastal waters of Tanzania.

This study explored important aspect of the basis for the highly complex population of kawakawa (Euthynnus affinis) within the coastal waters of Tanzania; by investigating length frequency distribution, mortality rate and reproductive characteristics. This information is essential for the sustainable management of the regionally-important recreational and economic E. affinis fishery. Fish were sampled on a monthly basis for two monsoon seasons using a ring net and artisanal fishermen boat. Maximum and minimum total length was 85 and 31 cm, respectively. Nonlinear least square fitting provided a complete set of von Bertalanffy growth estimates: L8 = 89.25 cm total length and K = 0.78. The estimated value of total mortality based on length converted catch curve using these growth parameters is Z = 1.78 year(-1). Natural mortality based on growth parameters and mean environmental temperature (T = 26.9 degrees C) is M = 1.09 year(-1). The estimated annual instantaneous fishing mortality (F = 0.69 year(-1)) was considerably grater than the target (Fopt = 0.43 year(-1)) and limit (Flimit = 0.58 year(-1)) biological reference point indicating that E. affinis is heavily overexploited. Reproductive aspects were assessed whereby female E. affinis was reported to reach maturity earlier than males which is an indication of phenotypic response toward a decline in population. Two peaks was revealed by the use of Gonad-Somatic Index (GSI), however an extended spawning period was noticed in a period between November to February following an increased water temperature. Although, these findings presents a snapshot concerning population structure and reproduction of E. affinis, further studies covering the entire coastal waters of Tanzania are recommended to aid the management and conservation strategies.

A modified Weibull model for growth and survival of Listeria innocua and Salmonella Typhimurium in chicken breasts during refrigerated and frozen storage.

The potential of food-borne pathogens to survive and grow during refrigerated and frozen storage has raised serious concerns over the safety of stored poultry products. In this study, the effect of refrigeration and freezing temperatures (-20, -12, 0, 4, and 8°C) on growth and survival of Listeria innocua and Salmonella enterica serovar Typhimurium in raw chicken breasts for storage times of 3, 7, 10, 14, and 21 d were investigated. A modified Weibull model was also developed to analyze the microbial behavior of both microorganisms in raw chicken breasts under different refrigerated storage conditions over time. The results showed that the bacterial loads of L. innocua at 4 and 8°C and Salmonella Typhimurium at 8°C were significantly different (P < 0.05) from those at other refrigerated and frozen storage temperatures over storage times. The loads of both bacteria at frozen storage temperatures did not change significantly over time. At a storage time of 7 d, the increase in bacterial loads of L. innocua at 4 and 8°C was 2.1 log cfu/g and 3.7 log cfu/g, respectively, and that of Salmonella Typhimurium at 8°C was 1.2 log cfu/g. The root mean square errors, median relative error, mean absolute relative error, and the plot of predicted versus observed bacterial loads showed a good performance of the model. The results from this study provided useful information regarding the behavior of Listeria and Salmonella in raw chicken breast meat during refrigerated and frozen storage, which would be helpful in giving insight over the safety of poultry products storage.

Interploidal hybridization and mating patterns in the Sphagnum subsecundum complex.

Polyploidization is thought to result in instant sympatric speciation, but several cases of hybrid zones between one of the parental species and its polyploid derivative have been documented. Previous work showed that diploid Sphagnum lescurii is an allopolyploid derived from the haploids S. lescurii (maternal progenitor) and S. subsecundum (paternal progenitor). Here, we report the results from analyses of a population where allodiploid and haploid S. lescurii co-occur and produce sporophytes. We tested (i) whether haploids and diploids form hybrid triploid sporophytes; (ii) how hybrid and nonhybrid sporophytes compare in fitness; (iii) whether hybrid sporophytes form viable spores; (iv) the ploidy of any viable gametophyte offspring from hybrid sporophytes; (v) the relative viability of sporelings derived from hybrid and nonhybrid sporophytes; and (vi) if interploidal hybridization results in introgression between the allopolyploid and its haploid progenitor. We found that triploid hybrid sporophytes do occur and are larger than nonhybrid sporophytes, but exhibit very low germination percentages and produce sporelings that develop more slowly than those from nonhybrid sporophytes. All sporophytes attached to haploid gametophytes were triploid and were sired by diploid males, but all sporophytes attached to diploid gametophytes were tetraploid. This asymmetric pattern of interploidal hybridization is related to an absence of haploid male gametophytes in the population. Surprisingly, all sporelings from triploid sporophytes were triploid, yet were genetically variable, suggesting some form of aberrant meiosis that warrants further study. There was limited (but some) evidence of introgression between allodiploid and haploid S. lescurii.

Do pre-existing complications affect the failure to rescue quality measures?

BACKGROUND: A project sponsored by the University Health System Consortium has addressed the inaccuracy and high variability across institutions concerning the use of the failure to rescue (FTR) quality indicator defined by the Agency for Healthcare Research and Quality (AHRQ). Results indicated that of the complications identified by the quality indicator, 29.5% were pre-existing upon hospital admission. OBJECTIVE: The purpose of our study was to investigate the possible bias to FTR measures by including cases of complications that were pre-existing at admission. METHODS: Hospital discharges between 1 January 1996 and 30 September 2007 were retrospectively gathered from administrative databases. Using definitions outlined by the AHRQ and the National Quality Forum (NQF), FTR rates were calculated. Using present on admission coding, FTR rates were recalculated to differentiate between the rates of pre-existing and that of acquired cases. RESULTS: Using the AHRQ definition, the overall FTR rate was 11.60%. The FTR rate for patients with pre-existing complications was 8.85%, whereas patients with complications acquired during hospitalisation had an FTR rate of 18.46% (p<0.001). The NQF FTR rate was 9.93%. Pre-existing and acquired FTR rates using the NQF measure were 9.42% and 12.77%, respectively (p<0.001). CONCLUSIONS: Current definitions of FTR measures meant to identify inhospital complications appear biased by the inclusion of problems at admission. Furthermore, many patients with these complications are excluded from the algorithms. When taking into account the timing of the "complications", these measures can be useful for internal quality control. However, it should be stressed that the usefulness of the measures to compare institutions will be dependent on coding practices of institutions. Validation using chart review may be required.

Antilisterial activity and consumer acceptance of irradiated chicken breast meat vacuum-infused with grape seed and green tea extracts and tartaric acid.

Contamination of poultry with pathogenic bacteria contributes to human foodborne disease, causes damage to industry brand names, and has a significant economic impact on the food industry in the form of both damage to industry brand names and losses associated with recalls. Irradiation is a safe and effective means of decontaminating poultry products, but the maximum dose strengths allowed negatively impact poultry sensory quality characteristics. The 1st objective of this study was to investigate the potential interactive inhibitory effects of natural antimicrobials as components of a vacuum-marination in addition to various dose levels of irradiation. Tartaric acid (TA) at 2 levels and grape seed (GS) and green tea (GT) extracts were combined, vacuum-infused into chicken breast fillets, and irradiated at 1, 2, and 3 kGy by electron beam irradiation. The 2nd objective was to use a consumer test group to evaluate TA and plant extract infusion into chicken breast fillets with and without irradiation at 2 kGy on overall impression, flavor, texture, appearance, and tenderness. The results showed that samples vacuum-infused with TA at 37.5 and 75.0 mM and irradiated at 1 kGy significantly reduced Listeria monocytogenes (L.m.) levels by 2 and 3 log CFU/g compared to the control after 12 d of refrigerated storage. Vacuum-infusion of TA at 37.5 and 75.0 mM at 2 and 3 kGy irradiation, reduced L.m. to near nondetectable levels. The addition of TA and GS and GT to chicken breast fillets with and without irradiation did not significantly impact consumer preference, tenderness, appearance, or flavor. The addition of tartaric acid and natural plant extracts to chicken marinades could contribute to the prevention of L.m. contamination.

Production and characterization of a monoclonal antibody to Campylobacter jejuni.

Campylobacter species are a group of spiral-shaped bacteria that can cause disease in humans and animals. We developed a high-affinity monoclonal antibody (MAb) probe that recognizes Campylobacter jejuni cells. Cell suspensions grown under microaerobic conditions at 42 degrees C for 20 h on Bolton agar plates with lysed horse blood were used as live and heat-killed preparations, centrifuged at 8,000 x g for 20 min, and resuspended in carbonate buffer (pH 9.6) for coating on the enzyme-linked immunosorbent assay plates. BALB/c mice were immunized with C. jejuni sonicated cells at 10(7) CFU/ml to generate MAb-producing hybridoma clones. Of about 500 initial hybridoma clones, MAb 33D2, which reacted with C. jejuni and Campylobacter coli, was selected for further evaluation. MAb 33D2 is in the immunoglobulin subclass G2a and had relatively weaker reactivity with the C. coli strains tested. MAb 33D2 did not show any cross-reactions with the nine non-Campylobacter bacteria tested in the enzyme-linked immunosorbent assay and had a stronger affinity for C. jejuni as live versus heat-killed cells. In Western blot assays, MAb 33D2 recognized two major antigens of 62 and 43 kDa in extracts from C. jejuni cells but only one antigen of 62 kDa in extracts from C. coli cells.

Organ-specific inhibition of metastatic colon carcinoma by CXCR3 antagonism.

Liver and lung metastases are the predominant cause of colorectal cancer (CRC)-related mortality. Recent research has indicated that CXCR3/chemokines interactions that orchestrate haematopoetic cell movement are implicated in the metastatic process of malignant tumours, including that of CRC cells to lymph nodes. To date, however, the contribution of CXCR3 to liver and lung metastasis in CRC has not been addressed. To determine whether CXCR3 receptors regulate malignancy-related properties of CRC cells, we have used CXCR3-expressing CRC cell lines of human (HT29 cells) and murine (C26 cells) origins that enable the development of liver and lung metastases when injected into immunodeficient and immunocompetent mice, respectively, and assessed the effect of CXCR3 blockade using AMG487, a small molecular weight antagonist. In vitro, activation of CXCR3 on human and mouse CRC cells by its cognate ligands induced migratory and growth responses, both activities being abrogated by AMG487. In vivo, systemic CXCR3 antagonism by preventive or curative treatments with AMG487 markedly inhibited the implantation and the growth of human and mouse CRC cells within lung without affecting that in the liver. In addition, we measured increased levels of CXCR3 and ligands expression within lung nodules compared with liver tumours. Altogether, our findings indicate that activation of CXCR3 receptors by its cognate ligands facilitates the implantation and the progression of CRC cells within lung tissues and that inhibition of this axis decreases pulmonary metastasis of CRC in two murine tumour models.

Effect of organic acids and plant extracts on Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Typhimurium in broth culture model and chicken meat systems.

Foodborne illness due to consumption of products contaminated with Salmonella Typhimurium (S.T.), Listeria monocytogenes (L.m.), and Escherichia coli O157:H7 (E.c.) results in many deaths and significant economic losses each year. In this study, acetic (AA), citric acid (CA), lactic acid (LA), malic acid (MA), and tartaric acid (TA) and grape seed (GS), green tea (GT), bitter melon seed (BMS), rasum, and fenugreek (FG) extracts were investigated as inhibitors against S.T., L.m., and E.c. in both broth-culture and meat systems. Brain Heart Infusion solutions containing 18.7, 37.5, and 75.0 mM organic acids and 5, 10, 20, and 40 mg/mL extracts were challenged with approximately log 6 CFU/mL S.T., L.m., and E.c. A pH-adjusted control was included to determine pH effect on exhibited antibacterial activity. For the meat system, 1 to 2 g chicken breast pieces were vacuum-infused with CA/MA/TA acid at 75 and 150 mM and GS and GT at 3000, 6000, and 9000 ppm in a partial factorial arrangement. GT and GS showed considerable activity in broth-culture. All organic acids were effective in broth-culture at 75 mM after 24 h (P < 0.05). CA and TA were effective at 37.5 mM. CA/MA/TA at 150.0 mM were the most effective in the meat system, reducing E.c., L.m. and S.T. by >5, >2, and 4-6 log CFU/g, respectively, although all organic acids showed some antibacterial activity at 75.0 and 150.0 mM. These findings demonstrate the effectiveness of organic acids and plant extracts in the control of S.T., L.m., and E.c. O157:H7.

Co-infection of market-age turkeys with Escherichia coli and Listeria monocytogenes in two stress models.

We have hypothesized that stress-induced subclinical infection of turkeys with Listeria monocytogenes may be an overlooked source of processing plant contamination, and we have shown that concurrent Escherichia coli challenge can increase L. monocytogenes colonization. The objective of this study was to determine the effects of dexamethasone (Dex) immunosuppressive treatment and transport stress on the isolation of L. monocytogenes in an E. coli-L. monocytogenes challenge model. Thirteen-week-old male turkeys housed in floor pens were either nonchallenged (NCH) or challenged (CH) by environmental exposure to E. coli and L. monocytogenes Scott A, using both a coarse spray and feed inclusion. One group of both NCH and CH birds was not stressed (NCH-Con and CH-Con, respectively), a second group was treated with Dex during challenge (NCH-Dex and CH-Dex, respectively), and a third group was subjected to a 12-hour transport (Trans) stress protocol at 15 wk of age (NCH-Trans and CH-Trans, respectively). All birds were bled and necropsied the morning after transport. Dexamethasone treatment increased mortality and disease incidence. The CH-Con, CH-Trans, and CH-Dex birds, as well as the NCH-Dex birds, had lowered body weights compared to the NCH-Con. The relative liver and heart weights were increased, and the relative bursal weights were decreased by both NCH-Dex and CH-Dex treatments. The heterophil:lymphocyte ratio, a measure of the stress response, was increased by CH-Trans, NCH-Dex, and CH-Dex. Total erythrocyte counts and hematocrit were decreased by NCH-Trans, CH-Trans, NCH-Dex and CH-Dex. The challenge strain of E. coli was isolated from the organs of a significant number of CH-Dex birds using direct plating and occasionally from CH-Trans birds. Listeria monocytogenes was not isolated from significant numbers of birds using direct plating, but was isolated from the knee or hip synovial tissues of a significant percentage of CH-Dex birds using pre-enrichment cultural methods, and from CH-Trans and CH-Dex birds using real-time PCR detection. These data suggest that L. monocytogenes colonization of processing-age turkeys can be increased by stress, and the organism may be harbored within inapparent infections of turkey synovial tissue.

Ciprofloxacin-sensitive and ciprofloxacin-resistant Campylobacter jejuni are equally susceptible to natural orange oil-based antimicrobials.

A total of 10 ciprofloxacin-sensitive (ciprofloxacin minimum inhibitory concentration, MIC < 0.5 micro g/ml) and 10 ciprofloxacin-resistant (MIC 16 to 32 micro g/ml) presumptive C. jejuni were further characterized and evaluated for their inhibition by natural orange oil fractions. Partial species identification was performed by using a hippuricase gene-based polymerase chain reaction (PCR) assay. One of the isolates appeared to be atypical and failed to hydrolyze hippurate. Of the ciprofloxacin-resistant C. jejuni isolates tested, six were found to have their quinolone resistance determined by a C --> T mutation in codon 86 of gyrA. Both groups of ciprofloxacin-sensitive and -resistant C. jejuni isolates were most susceptible to cold-pressed terpeneless Valencia orange oil (C4) which yielded inhibition zones from 44.0 +/- 1.4 to 80 +/- 0.0 mm. Less inhibitory responses were recorded for 5-fold concentrated Valencia orange oil (C3) and distilled d-limonene (C7) which exerted similar effects on both ciprofloxacin-sensitive and -resistant C. jejuni isolates. In general, ciprofloxacin-resistant and -sensitive C. jejuni isolates were equally susceptible to the respective orange oil fractions.