Health care-associated and hospital-acquired infections are two entities associated with increased morbidity and mortality. They are highly costly and constitute a great burden to the health care system. Vitamin D deficiency (< 20 ng/ml) is prevalent and may be a key contributor to both acute and chronic ill health. Vitamin D deficiency is associated with decreased innate immunity and increased risk for infections. Vitamin D can positively influence a wide variety of microbial infections. Herein we discuss hospital-acquired infections, such as pneumonia, bacteremias, urinary tract and surgical site infections, and the potential role vitamin D may play in ameliorating them. We also discuss how vitamin D might positively influence these infections and help contain health care costs. Pending further studies, we think it is prudent to check vitamin D status at hospital admission and to take immediate steps to address existing insufficient 25-hydroxyvitamin D levels.

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This study focused on evaluating the antimicrobial activity of chlorine dioxide (ClO2) and different plant-based antimicrobials (carvacrol, thymol, and eugenol as bioactive compounds and muscadine extract- ME and blueberry extract- BBE as plant extracts) against selected foodborne pathogens under in vitro conditions and on produce (spinach and blueberries). In addition, bacterial microbiota associated with blueberries and blueberry farm environments from three different regions: Cundinamarca, Colombia; Mississippi, United States; and Guadalajara, Mexico, was determined. Under in vitro conditions, carvacrol and thymol were more effective (lower MICs and MBCs) than eugenol against Salmonella spp., Escherichia coli O157:H7 (MIC=MBC=0.2 mg/ml), and Listeria monocytogenes (MIC=MBC=0.4 mg/ml). Both plant extracts had the same MIC and MBC for Salmonella spp. while BBE had stronger bactericidal effect on Escherichia coli O157:H7 (MBC=150 mg/ml) and ME on L. monocytogenes (MBC=100 mg/ml). ClO2 had stronger bacteriostatic effect on L. monocytogenes (MIC=1 ppm) than on the Gram-negative bacteria (MIC=3 ppm). For the produce study, 300 mg/ml ME exerted the highest (P ≤ 0.05) E. coli O157:H7 reduction (4.5 log CFU/g at day 1) on spinach, and 3 ppm ClO2 + 300 mg/ml ME had the highest (P ≤ 0.05) L. monocytogenes reduction on both (4.5-5.6 log CFU/g). There was a similar (P>0.05) E. coli O157:H7 reduction on blueberries, regardless of antimicrobial treatment. For the microbiota study, Proteobacteria was the most abundant phylum in blueberries, soil, and water, with the exception of fruits from Mexico. Blueberries grown on the different regions shared two predominant genera: Heliorestis (10.5-47.4%) and Thiomonas (5.0-9.1%). Nonetheless, alpha and beta diversity revealed that blueberry microbiota structures were distinctive. PCoA plots revealed that within regions the microbial composition distribution was different (P ≤0.05) among fruits, soil, and water. Based on the results, ME combined with ClO2, could represent an antimicrobial alternative against foodborne pathogens for the produce industry. Furthermore, the study of the microbiota provided a good understanding on the bacterial community profile in blueberries and the blueberry farming environment across regions.

Localized surface plasmon resonance (LSPR) describes the collective oscillation of conductive electrons in noble metal nanostructures, such as gold, silver and copper; or in selected doped semiconductor nanocrystals. Nanoplasmonics is emerging as a useful and versatile platform that combines the intense and highly tunable optical responses derived from LSPR with the intriguing materials properties at the nanoscale, including high specific surface areas, surface and chemical reactivity, binding affinity, and rigidity. LSPRs in plasmonic nanoparticles (NPs) can provide large optical cross-sections, and can lead to a wide variety of subsequent photophysical responses, such as localization of electric (E-)fields, production of plasmonic hot charge carriers, photothermal heating, etc. Plasmonic NPs can also be combined with other molecular or nanoscale systems into plasmonic heterostructures to further harvest the resonant E-field enhancement or to prolong the lifetime of plasmonic charge carriers. In this dissertation, we study the photophysical properties of plasmonic Ag and Au NPs, particularly E-field localization and hot charge carrier production performances; and illustrate how they can be optimized towards plasmonic photocatalysis, development of nano-antimicrobials, and surface-enhanced Raman spectroscopy (SERS) sensing. We demonstrate that with a lipid-coated noble metal nanoparticle (L-NP) model, the E-field localization properties could be optimized through positioning molecular photosensitizers or photocatalysts within a plasmonic “sweet spot”. This factor renders the plasmonic metal NPs efficient nanoantenna for resonant enhancement of the intramolecular transitions as well as the photocatalytic properties of the molecular photocatalysts. The enhanced photoreactivity have been applied to facilitate fuel cell half reactions for the enhancement of light energy conversion efficiencies; as well as to facilitate the release of broad-band bactericidal compounds that enables plasmonic nano-antimicrobials. Localized E-fields in L-NPs also enhance the inelastic scattering from molecules through SERS. This is utilized to obtain molecular-level information on the configuration of sterol-based, alkyne-containing Raman tags in hybrid lipid membranes, which enables spectroscopic sensing and targeted imaging of biomarker-overexpressing cancer cells at the single-cell level. In contrast to the localized E-field, plasmonic charge carrier generation mechanism relies on non-radiative decay pathways of the excited plasmons that lead to production of ballistic charge carriers. The plasmonic hot charge carriers directly participate in chemical redox processes with degrees of controllability over the nature of the charge carrier produced and direction of their transfers. The implementation and optimization of these mechanisms are explored, and the significances of some relevant applications are discussed.

In recent years, there have been a number of studies looking at inhibition of microorganisms by spices, herbs or their extracts.  Many of these products have been shown to have antimicrobial activity against foodborne pathogens.  The purpose of this research was to evaluate the antimicrobial activity of three essential oil (EO) compounds (thymol, eugenol, and trans-cinnamaldehyde) alone and in combination with three naturally-occurring apple aroma (AA) compounds (hexanal, trans-2-hexenal and 1-hexanol) to identify the minimum inhibitory concentrations necessary to inhibit E. coli O157:H7.  Three commercial apple juice flavoring mixtures (natural apple cinnamon, natural apple spice and natural red apple) were additionally tested alone for antimicrobial activity against E. coli O157:H7. The standard agar dilution method (SAD) and checkerboard assay were used to evaluate the efficacy of the nine compounds, alone and in combination against E. coli O157:H7.  In general, the EO compounds were significantly more effective against E. coli O157:H7 than the AA compounds (P<0.05).  Cinnamaldehye, with an MIC of 0.2 mg/mL, exhibited the highest degree of activity, followed by thymol, eugenol and trans-2-hexenal, which each had individual MIC values of 1.6 mg/mL.  No synergism was found in the combinations of EO compounds with AA compounds. / Master of Science in Life Sciences

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Harvey Morgan Scott / A randomized controlled field trial was designed to evaluate the effects of two treatment strategies on ceftiofur and tetracycline resistances in feedlot cattle. The two strategies consisted of administering ceftiofur crystalline-free acid administration (CCFA) at either one or else all of the steers within a pen, and subsequent feeding/not feeding of therapeutic doses of chlortetracycline. Both strategies were hypothesized to reduce ceftiofur resistance. The effects of treatment strategies were evaluated via metagenome-based and culture-based assays. In this 26-day study, 176 steers were allocated to 16 pens of 11 steers each. The two strategies were randomly assigned to the pens in a two-way full-factorial manner resulting in four treatment groups. The blaCMY-2, blaCTX-M, tet(A), tet(B), and 16S rRNA gene copies/g feces were quantified using qRT-PCR from fecal community DNA. Antimicrobial susceptibility profiles were determined using microbroth dilution technique from the non-type-specific (NTS) E. coli isolates (n=1,050). The NTS E. coli DNA was screened for the presence of blaCMY-2, tet(A), and tet(B) genes. Pens in which all the steers received CCFA treatment showed an increase in blaCMY-2 and blaCTX-M log10 gene copies/g feces and in the proportion of ceftiofur-resistant and blaCMY-2 positive NTS E. coli. This was in contrast to the pens where only one animal received CCFA treatment. There was a significant decrease in quantities of tetracycline genes in community DNA in pens where all animals received CCFA treatment. In contrast to metagenome-based assay results, culture-based assays indicated an increase in the proportion of tetracycline resistant NTS E. coli upon CCFA treatment. Thereafter, chlortetracycline administration led to rapid expansion both of ceftiofur (blaCMY-2, blaCTX-M) and tetracycline [tet(A) and tet(B)] log10 gene copies/g feces. Chlortetracycline treatment delayed the return of the ceftiofur resistance prevalence to baseline among NTS E. coli and thus did not lead to the hypothesized decrease in ceftiofur resistance. Our data suggest that chlortetracycline use is contraindicated when attempting to avoid expansion of resistance to critically important 3rd generation cephalosporins in feedlot cattle. Further studies are required to better establish the animal-level effects of co-housing antimicrobial-treated and non-treated animals together at varying ratios on the levels of antimicrobial resistance.

Cristais líquidos são sistemas que se apresentam em um estado intermediário entre o estado sólido e líquido. A monoleína é um lipídio polar com capacidade de formar diferentes tipos de cristais líquidos liotrópicos na presença de água, caracterizados como fase lamelar, cúbica e hexagonal. Devido à capacidade de controlar a liberação dos fármacos incorporados e às propriedades mucoadesivas, estes sistemas são considerados potenciais veículos para a liberação controlada de fármacos na mucosa bucal. Sabendo que o desenvolvimento da cárie e doença periodontal está relacionado com a formação do biofilme, é necessário seu controle e prevenção para manutenção da saúde bucal. Dentre os agentes químicos disponíveis para prevenir e/ou diminuir a formação do biofilme, cloreto de cetilpiridínio (CCP), polihexametileno biguanida (PHMB) e Triclosan® têm sido amplamente utilizados. Em vista disso, o objetivo deste estudo foi desenvolver e caracterizar sistemas líquido-cristalinos de fase lamelar e cúbica formados por monoleína e água contendo antimicrobianos com aplicabilidade bucal. Os sistemas foram desenvolvidos usando monoleína e água e os antimicrobianos avaliados foram o CCP, o PHMB e o Triclosan®. A formação das fases líquido-cristalinas com e sem a presença de cada fármaco estudado foi identificada por microscopia de luz polarizada. Além disso, foi avaliado o intumescimento dos sistemas contendo os fármacos estudados após contato com saliva artificial; a atividade antimicrobiana e o perfil de liberação in vitro, bem como o tempo de permanência e a força de mucoadesão ex vivo em mucosa de bochecha de porco. Foi possível obter os sistemas líquido-cristalinos para os fármacos avaliados, e o intumescimento de todos os sistemas foi caracterizado como cinética de segunda ordem. Os resultados do perfil de liberação e da atividade antimicrobiana in vitro para PHMB e Triclosan® foram favoráveis para aplicação bucal, no entanto, o CCP não é adequado para veiculação neste sistema. O perfil de liberação dos fármacos à partir desses sistemas foi influenciado pelas propriedades físico-químicas e concentração dos fármacos, bem como pelo intumescimento. Ainda, a fase lamelar apresentou maior tempo de permanência que a fase cúbica e a força de mucoadesão média da fase lamelar foi de 1,02 ± 0,50 N e da fase cúbica foi de 0,45 ± 0,10 N. Logo, os sistemas líquido-cristalinos de monoleína e água são um interessante veículo com potencial para liberação controlada dos antimicrobianos PHMB e Triclosan® na mucosa bucal com o objetivo de otimizar a eficácia destes fármacos. / Liquid crystals are systems which are in an intermediate state between solids and liquids. Monoolein is a polar lipid capable of forming different types of lyotropic liquid crystals in aqueous environment, which can be classified into lamellar, cubic and hexagonal mesophases. Due to its ability to control drug release and its mucoadhesive properties, these systems have been considerated as potential vehicle to control drug release on buccal mucosa. Based on the knowledge that the development of caries and periodontal disease is related to the biofilm formation, it is necessary their control and prevention to maintain the buccal health. Among the available chemical agents to prevent and/or reduce biofilm formation, cetylpyridinium chloride (CPC), polyhexamethylene biguanide (PHMB) and Triclosan® have been widely used. Based on these facts, the objective of this study was to develop and characterize liquid-crystalline systems formed by monoolein and water, containing antimicrobial agents with buccal applicability. The systems were developed using monoolein and water, and the antimicrobial agents evaluated were CCP, PHMB and Triclosan®. The liquid-crystalline phases with and without the presence of each drug was identified by polarized light microscopy. Furthermore, it was evaluated the swelling of the systems containing the drugs studied after contact with artificial saliva; the in vitro antimicrobial activity and its release profile, as well as the residence time and ex vivo mucoadhesion strength on pig cheek mucosa. It was possible to obtain liquid-crystalline phases for all drugs, and the swelling of all systems was characterized according to second-order kinetics. The results of release profile and antimicrobial activity in vitro to PHMB and Triclosan® were favorable for buccal application, however CCP is not suitable to be released from these systems. The drug release profile from these systems was influenced by the physicochemical properties and loading of the drugs, as well as by swelling. Furthermore, the lamellar phase showed greater residence time that the cubic phase and the mucoadhesion strength average of lamellar phase was 1.02 ± 0.50 N and for cubic phase was 0.45 ± 0.10 N. Thus, the liquid crystalline systems forming by monoolein and water are an interesting vehicle with potential to control release of the PHMB and Triclosan® on the buccal mucosa in order to optimize the drug effectiveness.

Neste trabalho, ingredientes naturais antimicrobianos foram adicionados em filme biodegradável (biofilme) à base de fécula de mandioca tendo como plastificantes sacarose e açúcar invertido. A seleção dos ingredientes antimicrobianos (cravo em pó, canela em pó, pimenta vermelha em pó, óleo essencial de laranja, café em pó, mel e extrato de própolis) foi conduzida por meio de um delineamento experimental (fatorial fracionado 27-3) e os biofilmes foram analisados quanto às suas propriedades de barreira (permeabilidade ao vapor de água e taxa de permeabilidade ao vapor de água) e propriedades mecânicas (resistência máxima à tração e porcentagem de alongamento na ruptura). Os biofilmes apresentaram valores inferiores aos apresentados pelo biofilme controle quanto às propriedades mecânicas. Em geral, a taxa de permeabilidade ao vapor de água nos biofilmes antimicrobianos manteve-se estatisticamente igual ao do controle. Na segunda etapa do trabalho, a otimização dos ingredientes selecionados foi realizada através de delineamento experimental, com somente adição de cravo e canela em pó, que apresentaram resultados mais promissores na etapa anterior. Foi constatado que a adição de cravo e canela em pó alterou as propriedades mecânicas, porém as alterações foram menos intensas com a adição da canela em pó do que com o cravo em pó, o que pode ser justificado pela diferença de granulometria entre eles. A taxa de permeabilidade diminuiu até certa concentração dos ingredientes (0,34% para a canela em pó e 0,20% para o cravo em pó). O efeito antimicrobiano dos biofilmes foi investigado como embalagem de fatias de pão tipo forma e foi constatado que a atividade de água dos biofilmes aumentou após 7 dias de contato. É provável que os biofilmes tenham se tornado meios propícios para o desenvolvimento de bolores e leveduras visto que estes microrganismos cresceram de forma similar ou mais intensa nas fatias de pão na presença do que na ausência dos biofilmes. A partir dos resultados obtidos, não é possível avaliar de forma clara, o efeito antimicrobiano dos ingredientes incorporados na matriz dos biofilmes contra o crescimento de bolores e leveduras em fatias de pão tipo forma. / In this work, natural antimicrobial ingredients were added to biodegradable film (biofilm) based on cassava starch with sucrose and inverted sugar as plasticizers. The selection of the antimicrobial ingredients (clove powder, cinnamon powder, red pepper powder, orange essencial oil, coffee powder, honey and propolis extract) was carried out applying an experimental design (incomplete factorial 27-3) and the barrier properties (water vapour permeability and water vapour permeability rate) and mechanical properties (tensile strength and elongation at break) of the biofilms were determined. The biofilms presented lower data regarding mechanical properties when compared to biofilm control. In general, the water vapour permeability rate of the antimicrobial biofilms was statistically equal to the control. In the second phase of the work, the optimization of the selected ingredients was carried out applying an experimental design, with the addition of only clove and cinnamon powder due to the fact that they showed the most promissing results at the previous phase. The addition of clove and cinnamon powder modified the mechanical properties but the modifications resulted by the addition of cinnamon powder were less intense tha n the ones resulted by the addition of clove powder, which can be justified by the particle size differences between them. The water vapour permeability rate decreased by specific ingredients concentration (0.34% for the cinnamon in powder and 0.20% for the clove in powder). The biofilms antimicrobial effect was investigated as packaging of pan bread slices and it was verified that the biofilms water activity increased after 7 days of contact. Probably, the biofilms became suitable substrates for yeast and mold development due to the fact that these microorganisms grew equally or more intensely in the pan bread slices when the biofilms were present in comparison to the cases of its absence. According to the results, it is not possible to evaluate clearly the antimicrobial effect of the added ingredients to the biofilm matrix against yeast and mold development in pan bread slices.

Os antimicrobianos promotores de crescimento na alimentação animal tem proporcionado melhora considerável no desempenho. Porém, seu uso vem sendo proibido em diversos países e, face a esta restrição, tem-se buscado alternativas aos antimicrobianos promotores de crescimento. Assim, o objetivo deste trabalho foi avaliar aditivos fitogênicos, butirato de sódio, assim como a colistina sobre o desempenho, histologia intestinal, pH, morfometria de órgãos, digestibilidade dos nutrientes e freqüência de diarréia de leitões recém-desmamados. Um experimento em blocos casualizados, com 34 dias de duração foi realizado para testar cinco tratamentos: controle (T1) - ração basal; antimicrobiano (T2) basal com 40 ppm de sulfato de colistina; fitogênico (T3) dieta basal com 500 ppm de aditivos fitogênicos; butirato de sódio (T4) dieta basal com 1500 ppm de butirato de sódio; fitogênico+butirato de sódio (T5) dieta basal com 500 ppm de aditivos fitogênicos + 1500 ppm de butirato de sódio. Para o desempenho e frequência de diarréia foram utilizados 120 leitões, com idade de 24 dias e peso inicial de 6,10 ± 1,21 kg, oito repetições por tratamento e três leitões por unidade experimental. No ensaio de digestibilidade (quatro primeiras repetições), utilizou-se o método da coleta parcial de fezes e o óxido de cromo como marcador. Ao final do experimento, um animal de cada baia, das quatro primeiras repetições, foi abatido para análise de histologia, pH e morfometria dos órgãos. Foram testados contrastes específicos de interesse. O desempenho, a frequência de diarréia e o pH da digesta não foram influenciados pelos tratamentos (P>0,05). Os leitões dos tratamentos fitogênico e butirato apresentaram a média de digestibilidade da energia superior (P=0,07) a dos leitões do tratamento fitogênico+butirato de sódio. Para a morfometria dos órgãos, a média dos tratamentos T2, T3, T4 e T5 para a relação peso:comprimento do intestino delgado foi menor (P=0,02) que a do tratamento controle. Para o peso relativo do ceco, a média dos tratamentos fitogênico e butirato de sódio foi menor (P=0,09) do que a do tratamento fitogênico+butirato de sódio. Em relação à histologia intestinal, no duodeno, a média da densidade de vilosidades (DV) dos leitões dos tratamentos fitogênico e butirato de sódio foi maior (P=0,06) do que a dos leitões do tratamento fitogênico+butirato de sódio. Foi observado, também, maior DV (P=0,02) para os animais do tratamento fitogênico em relação aos animais do tratamento butirato de sódio. No jejuno, a média da DV dos leitões dos tratamentos T2, T3, T4 e T5 foi maior (P=0,03) do que a dos leitões do tratamento controle. Os animais do tratamento butirato apresentaram maior DV do que os animais do tratamento fitogênico (P=0,08). Assim, em condições de creche experimental, não ficou evidenciado efeito dos aditivos fitogênicos e do butirato de sódio como promotores de crescimento de leitões recém-desmamados, alimentados com dietas complexas e altamente digestíveis. Há, também, indicações de que os aditivos fitogênicos e o butirato de sódio, individualmente adicionados às dietas dos leitões, podem melhorar a digestibilidade e algumas características histológicas e morfométricas. / The antimicrobials growth promoters in the animal feed have been related to an increase on animal performance. However, due to the restriction of many countries to the use of antimicrobial as growth promoters, alternatives are being studied. So, the purpose of this work was to evaluate the effect of phytobiotic additives, sodium butyrate and even colistina on performance, intestinal histology, digesta pH, organs morphometry, nutrients digestibility and diarrhea incidence of weanling pigs. A 34-d randomized complete block design experiment was carried out to compare five treatments: control (T1) basal diet; antimicrobial (T2) basal diet with 40 ppm of colistin sulfate; phytobiotic (T3) basal diet with 500 ppm of natural phytobiotics; sodium butyrate (T4) basal diet with 1500 ppm of sodium butyrate; and phytobiotic+sodium butyrate (T5) basal diet with 500 ppm of natural ptytobiotics + 1500 ppm of sodium butyrate. One hundred and twenty piglets (average age around 24 d and initial live weight of 6.10 ± 1.21 kg), eight replications per treatment, and three animals per experimental unit were used for performance data and diarrhea incidence. For digestibility assay, 60 piglets of first four replications were considered, using chromium oxide as fed marker. At the end of experimental period, an animal of each pen of first four replications was slaughtered for histology analysis, digesta pH and organs morphometry. Specific contrasts of practical importance were tested. No differences were found in performance data (P>.05). The treatments did not show any effect (P>.05) on diarrhea incidence and on digesta pH. Energy digestibility coefficient average of phytobiotic additives and sodium butyrate was higher (P=.07) than that of phytobiotic+sodium butyrate. Organs morphometry showed that the average of treatments T2, T3, T4 e T5 for weight:length ratio of small intestine was lower (P=.02) than that of control treatment. The average of phytobiotic and sodium butyrate treatments for caecum relative weight was lower (P=.09) than that of the phytobiotic+sodium butyrate treatment. For intestinal histology of duodenum, the average of villous density (DV) of phytobiotic and sodium butyrate treatments was higher (P=.06) than that of phytobiotic+sodium butyrate treatment. Piglets of phytobiotic treatment showed higher DV (P=.02) than those of sodium butyrate treatment. Jejunum DV average of treatments T2, T3, T4 e T5 was higher (P=.03) than that of control treatment. Piglets of sodium butyrate treatment showed higher DV than those of phytobiotic treatment (P=.08). Therefore, there was no evidence of natural phytobiotic and sodium butyrate as growth promoters of weanling pigs fed complex diet with high digestibility raised in experimental nursery. However, there are some indications that both phytobiotic and sodium butyrate added individually to weanling pig diets, may improve energy digestibility and some histology and morphometry traits.