This thesis attempts, first, to correlate pigmentation of actinomycetes with the degree of antibiocity; second, to establish the most favorable means of producing a rich luxuriant pigmentation in the individual organism studied by enriching favorable media with specific types of proteins and amino acids.

The present study of the production and properties of an antibiotic was undertaken in the hope that some useful information could be contributed to a long-range investigation program being carried on at North Texas State Teachers College. This program is concerned with the production of a useful antibiotic from a variant of the Penicillium notatum-chysogenum group of molds.

This thesis is an investigation of Antibiotic "S" with the purpose of determining which organisms it has a marked effect on, the amount required to cause inhibition, its action in blood, and its therapeutic effect and toxicity in laboratory animals.

Manure is a commonly used soil fertilizer, but there are concerns that this practice could affect the spread of antibiotic resistance genes (ARGs) from farm to fork. A microcosm-scale study evaluated the effect of prior antibiotic use (manure-based soil amendments generated from dairy and beef cattle with or without antibiotic administration), composting, and soil type on the quantity of ARGs and the microbial community composition of dairy and beef manure applied soil. ARGs were analyzed through novel metagenomic techniques and quantitative polymerase chain reaction of sul1, tet(W), and 16S rRNA gene, while the microbial community composition was determined via 16S rRNA amplicon sequencing. The results indicated that while prior antibiotic administration elevated the relative abundance of ARGs and changed the microbial community of raw manure applied soils, composting reduced this effect. However, compost applied soils still had a higher relative abundance of ARGs than the unamended soils and occasionally soil applied with raw manure of untreated cattle. Soil type may be a mediating factor as there were differences observed between the three soil types (sandy loam, silty clay loam, and silty loam) with sandy loam amended soils often having the least attenuation of ARGs. As the relative abundance of ARGs was still elevated and the microbial community composition still significantly different from the unamended soils after 120 days, these results suggest that 120 days is not a long enough waiting period between biological soil amendments and crop harvest for ARG dissipation. / Master of Science / Antibiotics are lifesaving drugs that kill infection-causing bacteria. However, bacteria are living organisms and can adapt to stresses, such as antibiotics. When antibiotics are used, not all of the targeted bacteria are necessarily killed, and populations of resistant bacteria can survive. Resistant bacteria can not only continue to grow, but can also share their resistance capabilities with other unrelated bacteria through the transfer of antibiotic resistance genes (ARGs). ARGs are segments of DNA encoding mechanisms for the bacteria to survive antibiotic attack, such as pumping antibiotics outside of the cell or strengthening the cell wall so antibiotics cannot enter. The transfer of ARGs to human pathogens is of utmost concern, as it can cause once treatable diseases to turn deadly. Antibiotics are thus a double-edged sword because they can save lives on one hand, while their overuse or misuse can undermine their effectiveness by increasing antibiotic resistance. In the U.S. and many other countries, the biggest user of antibiotics is the livestock industry. Thus, there is growing interest in possible routes by which antibiotic resistance can spread from agriculture to humans. While some previous work has been done on direct contact with animals and meat products, less attention has been paid to the potential role raw produce grown in soils fertilized with manure-based amendments. This study thus sought to determine which factors impact ARG levels in soil. Questions of interest included: What is the effect of composting raw manure prior to soil application? Does prior treatment of cattle with antibiotics matter? Does the soil type influence the levels of ARGs? Do the ARG composition and microbial community composition respond similarly to such factors? These and other questions were evaluated in a controlled environment by simulating amended field conditions in small glass jars (microcosms) containing mixtures of different soils and manure-based amendments. Three different soils were amended with one of the following manure-based amendments: raw manure from antibiotic administered cattle, composted manure of antibiotic administered cattle, raw manure from cattle not given antibiotics, composted manure of untreated cattle, and no amendment. This experimental setup was done in duplicate, one for treatments from dairy cows and one for the beef steer treatments. The experiment lasted 120 days, as that is a current standard for how long organic farmers must wait between manure application and crop harvest. Samples were taken throughout the 120-day experiment, and the quantity of targeted ARGs was determined by analyzing the DNA through qPCR, while the overall ARG profile was studied using a new tool, called metagenomics. To identify the kinds of bacteria present in the samples (microbial community composition), the 16S rRNA gene, which is a universal gene in organisms, was targeted and sequenced via amplicon sequencing. The results of these analyses indicated that administering antibiotics to cattle and then subsequently amending soil with their manure was associated with the highest levels of ARGs compared to the other treatments, but composting reduced the effect of prior antibiotic use. Depending on the ARG, composting decreased ARG levels relative to the other treatments, but in some instances, it increased ARGs compared to soils with raw manure of untreated cattle. Even after composting, there were still higher levels of ARGs in the soil than unamended soils. Different soil types did react differently to the amendments, but more research is needed. All of the treatments resulted in different changes to the microbial community composition and did not return to the unamended soil’s community structure even after 120 days. Overall, based on these results, ARGs and the microbial community do not return to the initial condition within 120 days, which is a recommended wait time between amendment and harvest, while composting and soil type appear to be mediating factors. Additional research is needed to further advance understanding of potential mitigation options and to benchmark them to defined and measureable risk endpoints.

The polyene macrolide antibiotic natamycin (Antibiotic A-5283) is commonly used to retard the growth of surface molds on various cheese varieties. Natamycin is commonly applied to the surface of cheese by dipping or spraying, using an aqueous dispersion containing 200 to 300 ppm of the additive. The large molecular weight of natamycin, 666 g/mol, and conjugated double bond structure causes it to be extremely insoluble in water and most food grade solvents. The inability to apply natamycin in true solution creates void non-treated areas on the food surface. These non-treated areas promote the growth of fungal organisms. A water soluble N-alkyl semisynthetic derivative of natamycin was synthesized by the Michael addition reaction of the parent with a N-substituted malemide. A comparative study investigating the effectiveness of the semisynthetic derivative of natamycin and the parent antibiotic in suppressing mold growth on one month aged shredded Cheddar cheese modified atmosphere packaged (MAP) was performed. A 20 ppm natamycin treatment effectively suppressed visible mold growth (<104 CFU/g) in MAP samples for up to 30 days after opening. The 20 ppm semisynthetic derivative performed similarly to the 10 ppm natamycin treatment in retarding mold growth. Visible mold growth did not occur for these treatments in MAP samples until 20 days after opening. Analysis of storage conditions revealed that an outgrowth of mold in shredded cheese occurred in MAP packages stored longer than 15 days. This bloom in mold growth was attributed to the degradation of natamycin and the semisynthetic derivative throughout storage. The stability and degradation of natamycin and the derivative were monitored throughout the study. Antibiotic concentration on the cheese surface was quantified by molecular absorption spectrometry. Results from this study showed, heavily contaminated samples caused the rate and loss of natamycin and the derivative to increase. Antibiotic concentration decreased at a similar rate in MAP and open package conditions. Natamycin and derivative were found to have similar degradation properties. / Master of Science

Yes / The photoprotection and isolation of marinomycin A using sporopollenin exine capsules (SpECs) derived from the spores of the plant Lycopodium clavatum is described. The marinomycins have a particularly short half-life in natural light, which severely impacts their potential biological utility given that they display potent antibiotic and anticancer activity. The SpEC encapsulation of the marinomycin A dramatically increases the half-life of the polyene macrodiolide to the direct exposure to UV radiation by several orders of magnitude, thereby making this a potentially useful strategy for other light sensitive bioactive agents. In addition, we report that the SpECs can also be used to selectively extract culture broths that contain the marinomycins, which provides a significantly higher recovery than with conventional XAD resins and provides concomitant photoprotection.

This paper describes the preparation of pyridine derivatives of 2,3-dichloro-5(8?)-nitro-1,4-naphthoquinone. A method for the nitration of 2,3-dichloro-1,4-naphthoquinone is also described. Certain 4-n-alkyl, 3,4-dialkyl, and 4-cycloalkyl pyridine derivatives are caused to undergo condensation reactions with the nitrated naphthoquinone, giving rise to a series of compounds of the preceding type (X). All of the compounds prepared will be tested for anti-tubercular activity by Parke-Davis and Company.

Osteomyelitis or infection of bone is painful and difficult to treat due to limited tissue penetration by antibiotics. A resulting chronic infection has around a 30% chance of never resolving and resulting in amputation of the limb. The current standard of care for osteomyelitis is debridement and systemic antibiotics for two to six months, which can cause systemic toxicity and increase the emergence of antibiotic-resistant bacteria. It is therefore necessary to develop a localized biodegradable treatment that can deliver high concentrations of antimicrobials while minimizing the risk of systemic side effects. The overall objective of this work was to develop, characterize, and challenge locally delivered chitosan-based biomaterials loaded with either antibiotic or alternative antimicrobial agent(s) in either chronic or acute rat osteomyelitis models. The specific aims were to: (i) determine the chemical and biological interactions between chitosan hydrogels and fosfomycin in vitro, (ii) evaluate the antimicrobial efficacy of chitosan hydrogel loaded with fosfomycin antibiotic, either in the gel, in polylactic acid microparticles, or in both gel and microparticles in vitro and in a chronic rat osteomyelitis model, compared to blank chitosan hydrogel, and (iii) evaluate the antimicrobial efficacy of electrospun chitosan membranes loaded with cis-2-decenoic acid and/or bupivacaine in an acute rat osteomyelitis model, compared to current standard Celox™gauze. As hypothesized, chitosan biomaterials loaded with antimicrobial(s) reduced the bacterial burden and disease symptoms when compared to the standard treatment or blank materials. In closing, locally administrated antibiotics with prolonged availability via engineered biomaterials such as chitosan may allow for increased therapeutic efficacy against osteomyelitis.

Widespread antibiotic resistance is a major public health concern, and plants represent an emerging antibiotic exposure route. Recent studies indicate that crop plants fertilized with antibiotic-laden animal manure accumulate antibiotics, however, the molecular mechanisms of antibiotic entry and subcellular partitioning within plant cells remain unknown. Here we report that mutations in the Arabidopsis locus Multiple Antibiotic Resistance (MAR1) confer resistance, while MAR1 overexpression causes hypersensitivity to multiple aminoglycoside antibiotics. Resistance is highly specific for aminoglycosides and does not extend to antibiotics of other classes, including the aminocyclitol, spectinomycin. Yeast expressing MAR1 are hypersensitive to the aminoglycoside, G418, but not to chloramphenicol or cycloheximide. MAR1 encodes a protein with 11 putative transmembrane domains with low similarity to ferroportin1 from Danio rerio. A MAR1:YFP fusion protein localizes to the chloroplast, and chloroplasts from plants overexpressing MAR1 accumulate more of the aminoglycoside, gentamicin, while mar1-1 mutant chloroplasts accumulate less than wild type. MAR1 overexpression lines are slightly chlorotic, and this chlorosis is rescued by application of exogenous iron. MAR1 expression is also downregulated by low iron. Taken together, these data suggest that MAR1 is a plastid transporter that is likely to be involved in cellular iron homeostasis, and allows opportunistic entry of multiple antibiotics into the chloroplast. mar1 mutants represent an interesting example of plant antibiotic resistance that is based on the restriction of antibiotic entry into a subcellular compartment. Knowledge about this process – and other processes of antibiotic entry – could enable the production of crop plants that are incapable of antibiotic accumulation, aid in development of phytoremediation strategies for decontamination of water and soils polluted with antibiotics, and further the development of new plant-based molecular markers. The work described here also contributes to our understanding of how plants interact with the antibiotics they encounter, both in the laboratory (where aminoglycosides such as kanamycin are used heavily to select for transgenics) and in the natural environment. / text

La maitrise de la résistance bactérienne et l’utilisation prudente des antibiotiques à l’hôpital constituent des enjeux majeurs pour les autorités de santé dans tous les pays européens. Toutefois, les connaissances en matière de consommation des antibiotiques et de politique de bon usage des antibiotiques dans les établissements sont limitées. Dans ce contexte, le travail de cette thèse permet de donner une meilleure vision de la consommation des antibiotiques dans les pays européens à partir des données de surveillance disponibles. Il apporte également des cibles d’amélioration de la prescription des antibiotiques et identifie plusieurs indicateurs de qualité pour mener à bien une politique de bon usage des antibiotiques. De plus, ce travail utilise le modèle des hôpitaux français pour identifier des critères d’ajustement de la consommation des antibiotiques facilement disponibles qui sont essentiels à mettre en œuvre pour établir des comparaisons entre les différents hôpitaux. Il s’intéresse également à la relation entre la politique de bon usage des antibiotiques dans les hôpitaux et une moindre consommation des antibiotiques. En conclusion, les données de surveillance de la consommation des antibiotiques ont donc permis de répondre à plusieurs hypothèses de recherche et de dégager de nouveaux axes de réflexions. / The control of bacterial resistance and the prudent use of antibiotics in hospitals are major challenges for health authorities in all European countries. However, little is known regarding antibiotic consumption and antibiotic policies in hospitals. In this context, this thesis provides insight into the antibiotic consumption using available survey databases. It also identifies targets for quality improvement and several quality indicators which are essencial to carry out a prudent use antibiotic policy. Moreover, the model of French hospitals was used to explore easily available adjustment criteria for the antibiotic consumption which are crucial to implement comparisons between different types of hospitals. This work brings light onto the relationship between the antibiotic policy and a low level of antibiotic use in French hospitals. In conclusion, survey databases have enabled us to answer several research assumptions and to generate new horizons of reflection.