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Previous studies on the prevalence of Salmonella in cats have used a variety of culture methods producing a variety of results, but none have been compared to PCR. Using a double enrichment protocol developed at Texas Veterinary Medical Diagnostic Laboratory the prevalence of Salmonella in shelter cat feces was determined in this current study. The culture protocol used included Xylose Lysine Tergitol 4 (XLT4) and MacConkey (MAC) agars with a primary enrichment in Tetrathionate broth (TTH) with iodine and a secondary enrichment in Rappoport-Vassilaidis R10 broth (RV). This study further modified an equine PCR technique and demonstrated its successful use in cats. When comparing the results of the two protocols, PCR and culture, it was found that the procedures are equally adequate at detecting the presence of Salmonella in cat feces. This study further confirmed that Salmonella is a potential hazard for families who adopt shelter cats.

Previous studies on the prevalence of Salmonella in cats have used a variety of culture methods producing a variety of results, but none have been compared to PCR. Using a double enrichment protocol developed at Texas Veterinary Medical Diagnostic Laboratory the prevalence of Salmonella in shelter cat feces was determined in this current study. The culture protocol used included Xylose Lysine Tergitol 4 (XLT4) and MacConkey (MAC) agars with a primary enrichment in Tetrathionate broth (TTH) with iodine and a secondary enrichment in Rappoport-Vassilaidis R10 broth (RV). This study further modified an equine PCR technique and demonstrated its successful use in cats. When comparing the results of the two protocols, PCR and culture, it was found that the procedures are equally adequate at detecting the presence of Salmonella in cat feces. This study further confirmed that Salmonella is a potential hazard for families who adopt shelter cats.

Charles University in Prague Faculty of pharmacy in Hradec Králové Department of Biological and Medical science Candidate: Magdaléna And lová Supervisor: Mgr. Marcela Vejsová, Ph.D. Name of diploma thesis: Evaluation of activity of potentional antibacterial substances throught of the use microdilution broth metod Background Aim of this diploma work was research of activity of potentional antimicrobiotic substances. Research of antibacterial substances is one of the most important factor in pharmaceutic industry. The main reason is being the never stopping growth of bacterial resistence. Methods The microdilution broth metod was used to test the substances. This metod was used because of low difficulty and low cost. All the steps including the final analising was done by hand. Results The substances were divided in groups depending their chemical struction. The most effective was the salicylanilide derivates group. The other groups inhibitated growth of bacteria very little or were non-functional. In case of every bacterial stems were analised all substances which were effective. Conclusion Depending on the results the most sensitive and the most resistant bacterial stem were choosen. The most sensitive reaction on tested substances had bacterial stem Staphylococcus aureus. The Klebsiella pneumoniae...

Philosophiae Doctor - PhD / The emergence of virulent and drug-resistant bacterial strains such as methicillin-resistant Staphylococcus aureus (MRSA) is a global public health burden. The World Health Organization (WHO) has placed MRSA and vancomycin-intermediate-sensitive S. aureus (VISA) and vancomycin-resistant S. aureus (VRSA) on a high global priority pathogens list of antibiotic-resistant bacteria to promote the research and development of novel and effective antibiotic therapeutic rationales. Uncomplicated S. aureus bacteraemia (e.g., mild skin infections) may be treatable with the conventional regimens of antibiotics, but resistance strains of the bacteria (e.g., invasive infections), often persist as a high load of bacterial DNA in blood, and has been linked to increased mortality in world populations, irrespective of country or location. Several lines of evidence imply that combinations of vancomycin (a glycopeptide antibiotic that targets cell wall synthesis) and ß-lactam antibiotics that target the penicillin-binding proteins (PBPs) improve clearance of MRSA bloodstream infections (BSIs).

A proprietary technology owned by Texas A

A proprietary technology owned by Texas A

Campylobacter has been known for more than a century and today Campylobacter infection is considered the leading cause of bacterial foodborne disease in the developed world. Consumption of undercooked poultry and/ or handling of raw poultry are seen as the main transmissions of Campylobacterto humans due to high levels (107 and 108 CFUlg) of C.jejunifound in the intestinal tract of raw poultry. Several studies have suggested that by delaying addition of antibiotics for 2 h at 37??C there was a better recovery of Campylobacter in food samples. Rinses from sixty whole carcasses were treated to non-pre-enrichment incubation and preenrichment at 37??C or 42??C for 2, 4 and 6h. Using TECRA?????? CAMVIA immunoassay method, results showed that 100% of the carcasses were positive for Campylobacter when the pre-enrichment techniques was applied compared to just 30-60% positive results from non pre-enrichment techniques. To develop more efficient enrichment methods, thirty carcass rinses were incubated in Bolton, Preston and TECRA??? broth under aerobic and microaerobic atmosphere at 25??C and 42??C. Results' from TECRA??? CAMVIA revealed that recovery of Campylobacter spp. from TECRA??? broth under aerobic conditions and Bolton or Preston broth under microaerobic conditions are not significantly different (p > 0.05). Charcoal based CCDA and Karmali agar were as effective as blood based Campy-Cefex agar in isolating Campylobacter spp. although Karmali was better in suppressing the growth of background microflora. Twenty samples of retail poultry carcasses, offal, portion chicken, mince respectively and ten samples of each fresh chicken sausages and frozen nuggets respectively were enriched in TECRA??? and Preston broths for recovery of Campylobacter. TECRA??? CAMVIA showed that 100% (TECRA??? and Preston) of the portion chicken was Campylobacter positive compared to 80 (TECRA???)-100% (Preston) of liver, 90 (TECRA???)-1 00% (Preston) of minced chicken and 65 (TECRA???)-75% (Preston) of carcasses. The difference between the two broths to recover Campylobacter spp. was not significant.

<p>Fokus ove doktorske disertacije je razvijanje modela<br />zasnovanog na konceptu ve&scaron;tačkih neuronskih mreža<br />za predviđanje i projektovanje mikrofiltracije<br />kultivacionih tečnosti preko ispitivanja mogućnosti<br />primene ovog koncepta za modelovanje fluksa<br />permeata pri različitim uslovim a mikrofiltracij e, u<br />sistemima sa i bez primene hidrodinamičkih metoda<br />pobolj&scaron;anja fluksa permeata i njihove kombinacije,<br />kao i razvoj modela kojim će se objediniti<br />eksperimentalni rezultati u cilju dobijanja jedne<br />jedinstvene neuronske mreže za simulaciju svih<br />metoda pobolj&scaron;anja fluksa. Dodatan cilj predstavlja<br />razvoj modela za procenu pobolj&scaron;anja fluksa u<br />stacionarnim uslovim a usled primene metoda<br />pobolj&scaron;anja fluksa permeata čija će se adekvatnost<br />proveriti sa energetskog stanovi&scaron;ta.<br />Eksperimentalna ispitivanja su obuhvatila razvoj i<br />validaciju deset različitih modela neuronskih mreža<br />kod kojih su nezavisne ulazne promenljive i njihovi<br />rasponi (transmembranski pritisak, protok suspenzije<br />i protok vazduha) utvrđeni Box-Behnken-ovim<br />eksperimentalnim planom uz dodatne parametre<br />vreme trajanja mikrofiltracije i temperature koji su<br />varirani u zavisnosti od uslova izvođenja postupka<br />mikrofiltracije. Nasuprot tome, za razvoj dinamičkog<br />modela u svojstvu zavisno promenljive veličine<br />razmatran je pad fluksa permeata sa vremenom, dok<br />je za razvoj modela procene efikasnosti primenjenih<br />metoda pobolj&scaron;anja fluksa permeata razmatran fluks i<br />specifična potro&scaron;nja energije u stacionarnim<br />uslovima.<br />Normalizacijom eksperimentalnih podataka izbegla<br />se velika razlika u specifičnim težinskim<br />koeficijentim a pojedinih ulaznih promenljivih i predupredila opasnost da te promenljive pokažu veći<br />uticaj nego &scaron;to ga imaju u realnosti, a balansiranje<br />efekata nekontrolisanih faktora na izlaznu<br />promenljivu izvedeno je randomizacijom na grupu za<br />obučavanje (70% podataka), grupu za validaciju<br />(15% podataka) i grupu za testiranje (15% podataka).<br />Nestacionarnosti koje utiču na efikasnost algoritma<br />obuke i arhitekture neuronskih mreža izbegnute su<br />ispitivanjem m odela sa pet algoritama obuke<br />(Levenberg-M arkuardt-ov algoritam obuke<br />(trainlm), Bayes-ova regularizacija (trainbr), model<br />rezilientnog povratnog prostiranja (trainrp), model<br />skaliranog konjugovanog gradijenta (trainscg) i<br />model jednostepenog sekantnog povratnog<br />prostiranja gre&scaron;ke unazad (trainoss)) i dve<br />sigmoidalne aktivacione funkcije u skrivenom sloju<br />(logistička i hiperbolična tangensna), dok je u<br />izlaznom sloju kori&scaron;ćena linearna aktivaciona<br />funkcija. Svi modeli su optimizovani primenom<br />metode probe i gre&scaron;ke sa osnovnim ciljem dobiti &scaron;to<br />jednostavniju mrežu, odnosno mrežu sa minimalnim<br />brojem skrivenih neurona koja pokazuje najbolju<br />sposobnost generalizacije. Kao indikatori nivoa<br />generalizacije i parametara učinka obuke neuronske<br />mreže ispitivani su koeficijent determinacije (R2) i<br />srednja kvadratna gre&scaron;ka (MSE), a koeficijent<br />korelacije (r) je odabran kao dodatni parametar<br />adekvatnosti fitovanja vrednosti utvrđenog i<br />neuronskom mrežom procenjenog fluksa permeata.<br />Najbolju sposobnost generalizacije i predikcije<br />pokazao je model neuronske mreže obučavan<br />Levenberg-M arkuardt-ovim algoritmom. Optimalan<br />broj neurona u skrivenom sloju se kretao od 7 do 13<br />&scaron;to ukazuje na znatnu kom pleksnost mehanizama<br />koji utiču na fluks permeata kako je i procenjeno<br />postavljanjem hipoteze ove doktorske disertacije.<br />Analiza apsolutne relativne gre&scaron;ke pokazala je veoma<br />dobro predviđanje po&scaron;to je u rasponu od 81% do<br />100 % podataka imalo gre&scaron;ku manju od 10%, a<br />koeficijent determinacije u rasponu od 0,98091 do<br />0,99976 ukazuje da mreža ne može da objasni manje<br />od 2% varijacija u sistemu. Vrednosti koeficijenta<br />korelacije se kreću u rasponu od 0,99041 do 0,99988<br />&scaron;to sugeri&scaron;e na dobru linearnu korelaciju između<br />eksperimentalnih podataka i podataka predviđenih<br />neuronskom mrežom. Pored primene koncepta<br />fitovanja podataka ispitana je i mogućnost procene<br />uticaja pojedinih eksperimentalnih promenljivih na<br />fluks permeata primenom jednačine Garsona, a<br />komparativnom analizom dobijenih simulacionih rezultata na eksperimentalim podacima koji nisu bili predstavljeni neuronskoj mreži potvrđen je<br />generalizacijski kapacitet modela neuronske mreže.</p> / <p>Focus of this doctoral dissertation is to develop<br />a model based on the artificial neural networks<br />concept for predicting and designing cultivation<br />broth microfiltration by examining the<br />feasibility of this concept for modeling<br />permeate flux under different microfiltration<br />conditions, in systems with and without<br />hydrodynamic im provem ent methods, as well<br />the development of a model that will combine<br />the experimental results in order to obtain a<br />single neural network to simulate all methods of<br />flux improvement. An additional goal is the<br />development of a model in quasi steady state in<br />term so fadequacy of flux enhancement methods<br />application, which will be checked from the<br />energy point of view.<br />Experimental tests included the development<br />and validation of ten different models оf neural<br />networks in which the independent input<br />variables and their ranges (transmembrane<br />pressure, suspension flow and air flow) were<br />determined by Box-Behnken&#39;s experimental<br />plan with added microfiltration parameters time<br />and temperature, varied depending on the<br />conditions of the microfiltration procedure. In<br />contrast, for the development оf a dynamic<br />model as a dependent variable, the decrease in<br />permeate flux with time was considered, while<br />for the development of a model for evaluating<br />the efficiency оf applied permeate flux<br />im provement methods, flux and specific energy<br />consumption in quasi steady state conditions<br />were considered.<br />Normalization of experimental data avoided a<br />large difference in specific weight coefficients of individual input variables and prevented the<br />danger that these variables show a greater<br />impact than they have in reality, and balancing<br />the effects of uncontrolled factors on the output<br />variable was performed by randomization on the<br />training group (70% o f data), a validation group<br />(15% of data) and a testing group (15% of data).<br />Non-stationarities affecting the efficiency of the<br />training algorithm and neural network<br />architecture were avoided by testing the model<br />with five diferent training algorithms<br />(Levenberg-M arquardt training algorithm<br />(trainlm), Bayesian regularization (trainbr),<br />resilient backpropagation algorithm (trainrp),<br />scaled conjugate gradient method (trainscg) and<br />a one-step secant m ethod (trainoss)) and two<br />sigmoid activation functions in the hidden layer<br />(logistic and hyperbolic tangent), while a linear<br />activation function was used in the output layer.<br />All models are optimized by applying the trial<br />and error method with the basic goal of having<br />the simplest possible network, ie a network with<br />a minimum num ber o f hidden neurons that<br />shows the best ability to generalize.<br />Determ ination coefficient (R2) and mean square<br />error (MSE) were examined as indicators of<br />generalization level and neural network training<br />performance parameters, and correlation<br />coefficient (r) was selected as an additional<br />param eter o f adequacy оf fitting the value of<br />determined and neural network estimated<br />permeate flux.<br />The best ability to generalize and predict was<br />shown by a model of a neural network trained<br />by the Levenberg-M arquardt algorithm. The<br />optimal num ber of neurons in the hidden layer<br />ranged from 7 to 13, which indicates a<br />significant complexity of the mechanisms that<br />affect the permeate flux, as assessed by the<br />hypothesis of this doctoral dissertation.<br />Absolute relative error analysis showed very<br />good prediction as in the range of 81% to 100 %<br />of the data had an error of less than 10 %, and<br />the coefficient of determination in the range of<br />0.98091 to 0.99976 indicates that the network<br />cannot explain less than 2 % variation in the<br />system. The values оf the correlation coefficient<br />range from 0.99041 to 0.99988 suggests a good<br />linear correlation between the experimental data<br />and the data predicted by the neural network. In addition to the application of the concept of data<br />fitting, the relative importance of input variables<br />was also investigated by applying the Garson<br />equation. Comparative analysis of the obtained<br />simulation results on experimental data that<br />were not presented to the neural network<br />confirmed the generalization capacity of the<br />neural network model.</p>

Multiresistens hos gramnegativa bakterier är ett stort problem i stora delar av världen. Avsaknaden av nya preparat har resulterat i återintroduktion av ett tidigare stoppat antibiotikum, kolistin, men dessvärre kantas resistensbestämningen av flertalet problem. Kolistin är en positivt laddad molekyl som binder till lipid A i yttermembranet, vilket destabiliseras och resulterar i celldöd. Flertalet resistensmekanismer mot kolistin finns beskrivna och majoriteten resulterar i förändrad lipid A-struktur, vilket leder till försämrad kolistininbindning. Syftet med examensarbetet var att utvärdera fyra potentiella screeningmetoder för att upptäcka kolistinresistens och jämföra resultaten mot buljongspädning som referensmetod. De fyra screeningmetoderna var buljongeluering och diskdiffusion samt de kommersiellt tillgängliga screeningtesterna Superpolymyxin och Rapid polymyxin NP. Totalt analyserades 57 helgenomsekvenserade Enterobacterales, varav 28 Escherichia coli och 29 Klebsiella pneumoniae, där aktuella resistensmekanismer var kända. Samtliga isolat analyserades en gång per metod och utöver detta analyserades även tre kontrollstammar. Vid buljongspädning erhölls värde för minsta inhiberande koncentration (MIC) kolistin, vilket användes för klassificering som känslig (MIC ≤ 2 mg/l) eller resistent (MIC &gt; 2 mg/l). De fyra screeningtesterna var designade för att upptäcka resistenta isolat och innehöll 2–4 mg/l kolistin. Resultaten från screeningtesterna var kvalitativa och känslighetskategoriserade isolaten. Sensitivitet och specificitet beräknades för metoderna. Högst sensitivitet (100 %) noterades för Superpolymyxin och Rapid polymyxin NP, och lägst specificitet (76 %) för buljongeluering. Med hänsyn till resultat, prevalens, hållbarhets-, tids- och kostnadseffektivitet drogs slutsatsen att Rapid polymyxin NP är bästa alternativet som screeningmetod av utvärderade metoder. / Infections due to multidrug resistant Gram-negative bacteria are a major problem in large parts of the world. Due to lack of treatment options, a previously banned antibiotic, colistin, has been reintroduced. Unfortunately, susceptibility testing of colistin is problematic and currently the only recommended method is broth microdilution (BMD). Colistin is a positively charged molecule that binds to lipid A at the negatively charged outer cell membrane, which leads to cell disruption. Several mutations causing colistin resistance have been identified, most of them cause alterations of lipid A, resulting in impaired colistin outer cell membrane interaction. The aim of this study was to evaluate four potential screening methods for colistin resistance and compare the results with BMD (reference method). The four screening methods were broth disk elution, disk diffusion and the commercially available tests Superpolymyxin and Rapid polymyxin NP. A collection of 57 whole genome sequenced Enterobacterales consisting of 28 Escherichia coli and 29 Klebsiella pneumoniae were included in the study. Reference results were obtained by BMD, where the estimated minimum inhibitory concentration (MIC) values were used for classification of the isolates as sensitive (MIC ≤ 2 mg/l) or resistant (MIC &gt; 2 mg/l). Sensitivity and specificity were calculated for the methods. The highest sensitivity (100 %) was noted for Superpolymyxin and Rapid polymyxin NP, and the lowest specificity (76 %) for broth disk elution. Considering the results, prevalence, durability, time and cost efficiency, it was concluded that Rapid polymyxin NP is the best alternative as a screening method of evaluated methods.