Bordetella bronchiseptica é um agente respiratório zoonótico comumente encontrado em diversars espécies animais domésticos como cães, gatos, coelhos, suínos, aves e equinos. As infecções em humanos ocorrem ocasionalmente, sendo descritas com maior freqüência em indivíduos imunocomprometidos, mas relatos de casos de doença em adultos saudáveis e crianças têm aumentado. O presente estudo teve como objetivos determinar o perfil de resistência antimicrobiana de cepas de B. bronchiseptica isoladas de cães, gatos, coelhos e suínos, caracterizar as cepas pela eletroforese em campo pulsado (PFGE), e comparar os resultados obtidos com os dados epidemiológicos. Foram avaliadas 145 cepas e estas apresentaram 100% de resistência a ampicilina, penicilina, espectinomicina, clindamicina, tiamulina e tilosina. Taxas de resistência superiores a 95% das cepas foram observadas frente a tilmicosina, danofloxacina e ceftiofur. Os antimicrobianos com menores taxas de resistência foram enrofloxacina (2,1%) e clortetraciclina (11 %). As cepas isoladas de coelhos apresentaram menores taxas de resistência que as de suínos e de animais de companhia. A caracterização das cepas pela PFGE permitiu a separação de acordo com as espécies de origem em diferentes pulsotipos. A caracterização do agente, principalmente no que se refere à resistência a antimicrobianos, será de grande utilidade para os veterinários no controle das infecções pelo mesmo em suínos, animais de companhia e coelhos, visto que os dados sobre este agente etiológico no Brasil são escassos / Bordefella bronchisepfica is a zoonotic respiratory agent commonly found in domestic animais as dogs, cats, rabbit, swine, birds and horses, Infections in humans occur rarely and have been described more frequently in immunocompromised individuais, but reports of cases of illness in healthy adults and children have increased. This study aims to characterize the resistance profile of B. bronchiseptica strains isolated from dogs, cats, rabbits and pigs and evaluate the strains by pulsed field gel electrophoresis (PFGE), comparing the results with epidemiological data. From 145 strains tested 100% presented resistance to ampicillin, penicillin, spectinomycin, clindamycin, tiamulin and tylosin. Resistance rates higher than 95% were found against tilmicosin, danofloxacin and ceftiofur. The antimicrobials with lower resistance rates were enrofloxacin (2.1 %) and chlortetracycline (11 %). Strains isolated from rabbits presented low resistance rates when compared with swine and pet animais. The PFGE analysis separated the strains according specie of origin in different pulsotypes. The agent characterization, mainly in relation with antimicrobial resistance will be of great help to veterinarians in control of infections in swine, pets and rabbits, since data about this bacteria in Brazil are rare

Os Mollicutes causam doenças em várias espécies animais de importância econômica, inclusive em bovinos. Neste estudo, foi avaliada por concentração inibitória mínima (CIM) e citometria de fluxo, a atividade de oito agentes antibacterianos (enrofloxacina, ciprofloxacina, gentamicina, claritromicina, cloranfenicol, oxitetraclina, tiamulina e tilosina) contra Ureaplasma diversum. Foram analisadas 24 amostras de isolados de campo oriundas da mucosa genital de fêmeas bovinas. As amostras foram confirmadas por crescimento em caldo, placa e por PCR. Os inóculos foram submetidos à analise de suscetibilidade aos antibióticos pelo método da microdiluição em microplaca e posteriormente analisados pelo citômetro de fluxo a fim de avaliar a atividade antimicrobiana nas células. A claritromicina apresentou os maiores índices de inibição in vitro, sendo a gentamicina considerada o antibiótico de menor espectro de ação nesse estudo. De acordo com as análises do citômetro, a gentamicina apresentou o menor número de células viáveis enquanto a tiamulina apresentou o maior número. Embora haja resultados destoantes entre as técnicas utilizadas, o citômetro de fluxo pode ser utilizado como uma boa ferramenta para auxiliar a avaliação da suscetibilidade desses microrganismos a antibióticos. / The Mollicutes cause disease in several economically important species, including cattle. In this study, was evaluated by minimum inhibitory concentration (MIC) and flow cytometry, the activity of eight antibacterial agents (enrofloxacin, ciprofloxacin, gentamicin, clarithromycin, chloramphenicol, oxitetraclina, tiamulin and tylosin) against Ureaplasma diversum. We analyzed 24 samples of field isolates originating from the genital mucosa of cows. The samples were confirmed by growth in broth, plate, and PCR. The inoculations were subjected to analysis of susceptibility to antibiotics by the method of micro-dilution plate and then analyzed by flow cytometry to assess the antimicrobial activity in cells. Clarithromycin showed the highest levels of inhibition in vitro, the antibiotic gentamicin considered lower spectrum of action in this study. According to the analysis of the flow cytometer, gentamicin showed the lowest number of viable cells as tiamulin showed the greatest number. Although there are divergent results between the techniques used, flow cytometry can be used as a good tool even help assess the susceptibility of microorganisms to antibiotics.

Vancomycin is an antibiotic used for the treatment of systemic infections. It is given intravenously usually every twelve or twenty-four hours. This particular drug has a medium level of boundedness, with approximately fty percent of the drug being free and thus physiologically eective. A physiologically-based pharmacokinetic (PBPK) model was used to better understand the absorption, distribution, and elimination of the drug. Using optimal parameters, the model could be used in the future to test how various factors, such as BMI or excretion levels, might aect the concentration of the antibiotic.

Levofloxacin is in a class of antibiotics known as fluoroquinolones, which treat infections by killing the bacteria that cause them. A physiologically-based pharmacokinetic (PBPK) model was developed to investigate the uptake, distribution, and elimination of Levofloxacin after a single dose. PBPK modeling uses parameters such as body weight, blood flow rates, partition coefficients, organ volumes, and several other parameters in order to model the distribution of a particular drug throughout the body. Levofloxacin is only moderately bound in human blood plasma, and, thus, for the purposes of this paper, linear bonding is incorporated into the model because the free or unbound portion of the drug is the only portion that is considered to be medicinally effective. Parameter estimation is then used to estimate the two unknown parameters given clinical data from literature on the total concentration of Levofloxacin in the blood over time. Once an adequate model is generated, the effects of varying Body Mass Index are tested for the absorption and distribution of Levofloxacin throughout the body.

The purpose of this dissertation is threefold: to determine the differences in apparent prevalence and the antimicrobial susceptibility of Campylobacter spp. between antimicrobial-free and conventional swine farms; secondly, to introduce an appropriate statistical model to compare the minimum inhibitory concentration distributions of Escherichia coli and Campylobacter spp. isolated from both farm types; and thirdly, to examine the potential herd level risk factors that may be associated with antimicrobial resistance of Campylobacter spp. and E. coli isolates from finishers on antimicrobial-free and conventional farming systems. In addition, a critical review of studies that have compared the levels and patterns of antimicrobial resistance among animals from antimicrobial-free and conventional farming practices was performed. Fecal samples from 15 pigs were collected from each of 35 antimicrobial-free and 60 conventional farms in the Midwestern U.S. Campylobacter spp. was isolated from 464 of 1,422 fecal samples, and each isolate was tested for susceptibility to 6 antimicrobials. The apparent prevalence of Campylobacter spp. isolates was approximately 33 percent on both conventional and antimicrobial-free farms. The proportion of antimicrobial resistance among Campylobacter was higher for three antimicrobials within conventional compared to antimicrobial-free farms. The susceptibilities of populations of bacteria to antimicrobial drugs were summarized as minimum inhibitory concentration (MIC) frequency distributions. The use of MIC values removed the subjectivity associated with the choice of breakpoints which define an isolate as susceptible or resistant. A discrete-time survival analysis model was introduced as the recommended statistical model when MICs are the outcome. A questionnaire was completed by each farm manager on biosecurity, preventive medication, vaccines, disease history, and production management. Multivariable population-averaged statistical models were used to determine the relationships among antimicrobial susceptibility patterns and potential herd-level risk factors. Controlling for herd type (antimicrobial-free versus conventional), each antimicrobial-bacterial species combination yielded unique combinations of risk factors; however, housing type, history of rhinitis, farm ventilation, and history of swine flu were significant in more than one model. A variety of herd-level practices were associated with the prevalence of antimicrobial resistance on swine farms. Further studies are encouraged when considering interventions for antimicrobial resistance on both antimicrobial-free and conventional farms.

β-lactam antibiotics have long been a reliable course of treatment for bacterial infections. However, with recent increases in resistance and rising populations of immunocompromised patients new β-lactams have been synthesized and tested. The Turos laboratory has recently discovered novel β-lactams that have a mode of action distinct from penicillin and other β-lactam antibiotics as cell lysis is not observed. In the current investigations, these compounds are shown to also have antifungal properties. The rising incidence and prevalence of invasive fungal infections has become an increasing concern. The most common fungal pathogens involved in these infections are species in the genus Candida. In this study antifungal activity is observed for a wide range of N-methylthio β-lactams against C. albicans, C. tropicalis, C. keyfr, C. glabrata, C. lusitinae, C. utilis, and C. parapsilosis. The structure-activity relationship based on studies of β−lactam derivatives leaving different substituents at various positions on the lactam ring are investigated, and the minimum inhibitory concentration values determined using standard methods. In studies towards understanding the mode of action, the products of the interaction between the drug and fungal cells in a suspension were investigated using nuclear magnetic resonance spectroscopy and transmission electron microscopy. The mode of action of these new lactams seems to be similar to that observed in bacteria, involving transfer of the methylthio group to a cellular thiol.

Made available in DSpace on 2016-08-17T18:39:51Z (GMT). No. of bitstreams: 1 6095.pdf: 2718900 bytes, checksum: c4d734a7b2927b9a3c31ecfb042e26bd (MD5) Previous issue date: 2014-04-16 / Many efforts have been dedicated in the searching of natural compounds which are suitable to be applied in food conservation. Among them, the chitosan has presented promising results concerning the antimicrobial activity, structural preservation and delay of fruits senescence. However, the chitosan, as found commercially, is soluble only in acidic medium solutions what is considered a hindrance for fully applications as food conservative. In this sense, chitosan derivations which are able to be solubilized in neutral pH have been developed. The N,N,N Trimethylchitosan (TMC) is one of them, characterized as a hydrosoluble derivative of chitosan, which has been considered as an efficient antimicrobial agent with positive action as fresh food conservative. The aim of the present was the evaluation of the antimicrobial activity of the TMC against Gram-positive and Gram-negative bacteria and filament fungi. The TMC antimicrobial activity was assessed by comparing with the Commercial Chitosan (CC), by means of the determination of the Minimum Inhibitory Concentration (MIC), following the Clinical and Laboratory Standards Institute (CLSI) according to M7-A6 (NCCLS, 2003) and M38-A (NCCLS, 2002) standards, both recognized by the Agência Nacional de Vigilância Sanitária (ANVISA). Additionally, the TMC and CC antifungal activity was carried out by recoding the visual fungi growth and estimated from the percentage of infected samples by the fungy on cut faces of grape-tomatoes (Solanum lycopersicum variety cerasiforme), in coated and non-coated conditions, along seven days of incubation. The results concerning antibacterial activity points to a greater action of the TMC when comparing to some analysis performed on CC coating against four of the six strains analyzed: Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Salmonella enterica. Nevetheless the CC antifungal activity was considerable superior to that observed to TMC for three different fungi tested: Penicillium sp., Aspergillus flavus standard and Aspergillus flavus wild. However, both polymers showed high antibacterial and antifungal activity and are therefore considered as natural agents with relevant antimicrobial potential for the fresh food conservation. / Muitos têm sido os esforços pela procura de substâncias naturais que possam ser aplicadas à conservação de alimentos. Dentre as substâncias em estudo, a quitosana tem apresentado resultados promissores tanto com relação à atividade antimicrobiana quanto na manutenção estrutural de alimentos e redução da senescência em frutos. No entanto, a quitosana, em sua forma comercial, é solúvel apenas em soluções ácidas diluídas, o que dificulta sua plena utilização como conservante alimentício. Dessa forma, derivados de quitosana que apresentem capacidade de solubilização em pH neutro têm sido desenvolvidos. Dentre esses derivados a N,N,N-trimetilquitosana (TMQ), um polímero hidrossolúvel derivado da quitosana, tem sido avaliado como promissor agente antimicrobiano e conservador de alimentos frescos. Assim, o presente projeto teve como objetivo avaliar a atividade antimicrobiana da N,N,N-trimetilquitosana sobre o crescimento de bactérias Gram-positivas e Gram-negativas e de fungos filamentosos. A atividade antimicrobiana da TMQ foi avaliada mediante comparação com a Quitosana Comercial (QC) pela determinação das Concentrações Inibitórias Mínimas (CIM) a partir de testes padronizados pela Clinical and Laboratory Standards Institute (CLSI), segundo suas normas M7-A6 (NCCLS, 2003) e M38-A (NCCLS, 2002), ambas reconhecidas pela Agência Nacional de Vigilância Sanitária (ANVISA). Além disso, a avaliação da atividade antifúngica das substâncias foi realizada mediante leitura visual e estimada a partir do percentual de amostras infectadas pelos fungos sobre fatias de tomatecereja (Solanum lycopersicum variedade cerasiforme) revestidas e não revestidas, ao longo de sete dias de incubação. Os resultados indicaram uma maior atividade antibacteriana da TMQ em relação à QC para quatro das seis cepas bacterianas analisadas: Enterococcus faecalis, Staphylococcus aureus, Escherichia coli e Salmonella enterica. No entanto, a atividade antifúngica da QC superou a da TMQ para os três fungos testados: Penicillium sp., Aspergillus flavus padrão e Aspergillus flavus selvagem. Entretanto, ambos os polímeros avaliados apresentaram atividade antibacteriana e antifúngica satisfatória sendo, portanto, considerados como agentes naturais com potencial antimicrobiano relevante para a conservação de alimentos frescos.

Bordetella bronchiseptica é um agente respiratório zoonótico comumente encontrado em diversars espécies animais domésticos como cães, gatos, coelhos, suínos, aves e equinos. As infecções em humanos ocorrem ocasionalmente, sendo descritas com maior freqüência em indivíduos imunocomprometidos, mas relatos de casos de doença em adultos saudáveis e crianças têm aumentado. O presente estudo teve como objetivos determinar o perfil de resistência antimicrobiana de cepas de B. bronchiseptica isoladas de cães, gatos, coelhos e suínos, caracterizar as cepas pela eletroforese em campo pulsado (PFGE), e comparar os resultados obtidos com os dados epidemiológicos. Foram avaliadas 145 cepas e estas apresentaram 100% de resistência a ampicilina, penicilina, espectinomicina, clindamicina, tiamulina e tilosina. Taxas de resistência superiores a 95% das cepas foram observadas frente a tilmicosina, danofloxacina e ceftiofur. Os antimicrobianos com menores taxas de resistência foram enrofloxacina (2,1%) e clortetraciclina (11 %). As cepas isoladas de coelhos apresentaram menores taxas de resistência que as de suínos e de animais de companhia. A caracterização das cepas pela PFGE permitiu a separação de acordo com as espécies de origem em diferentes pulsotipos. A caracterização do agente, principalmente no que se refere à resistência a antimicrobianos, será de grande utilidade para os veterinários no controle das infecções pelo mesmo em suínos, animais de companhia e coelhos, visto que os dados sobre este agente etiológico no Brasil são escassos / Bordefella bronchisepfica is a zoonotic respiratory agent commonly found in domestic animais as dogs, cats, rabbit, swine, birds and horses, Infections in humans occur rarely and have been described more frequently in immunocompromised individuais, but reports of cases of illness in healthy adults and children have increased. This study aims to characterize the resistance profile of B. bronchiseptica strains isolated from dogs, cats, rabbits and pigs and evaluate the strains by pulsed field gel electrophoresis (PFGE), comparing the results with epidemiological data. From 145 strains tested 100% presented resistance to ampicillin, penicillin, spectinomycin, clindamycin, tiamulin and tylosin. Resistance rates higher than 95% were found against tilmicosin, danofloxacin and ceftiofur. The antimicrobials with lower resistance rates were enrofloxacin (2.1 %) and chlortetracycline (11 %). Strains isolated from rabbits presented low resistance rates when compared with swine and pet animais. The PFGE analysis separated the strains according specie of origin in different pulsotypes. The agent characterization, mainly in relation with antimicrobial resistance will be of great help to veterinarians in control of infections in swine, pets and rabbits, since data about this bacteria in Brazil are rare

A case control study was performed in the conservancy area of the Kruger National Park (KNP), South Africa to find out whether the faeces of impala (Aepyceros melampus) were more likely to contain tetracycline resistant Escherichia coli (TREC) when they drank from rivers that contained these bacteria, compared to rivers that were uncontaminated with TREC. Five perennial rivers (Crocodile, Letaba, Olifants, Sabie and Sand) were selected. A total of 11 points in these rivers were sampled on three separate occasions and cultured for E. coli. Impala herds within 5 kilometres of each water collection site were identified and between 5 and 10 fresh faeces were collected for each collection period (n=209 faecal specimens). Selective culturing of E. coli was done and the resulting colonies were screened for tetracycline resistance by using the Lederberg Replica Plating (LRP) method. Resistant colonies were those that grew in the presence of 4 mg/L of tetracycline. Both a resistant and/or a susceptible isolate were then selected from each specimen, and subjected to the minimum inhibitory concentration (MIC) micro-broth dilution test for tetracyclines. The breakpoint for the MIC method was considered ≥ 8 mg/L (which is higher than for the LRP method). Twenty one of the 33 water specimens examined were found to be contaminated by E. coli. Among them (n=21), 76.19% (n=16) were resistant to tetracycline using the LRP method, although using the MIC method only 19.05% (n=4) were resistant. All of the resistant strains originated from the Letaba, Olifants and Crocodile rivers (TRECpos rivers). Among the 209 impala faeces sampled, 191 were positive for the presence of E. coli (91.38%). Within these (n=191), 36.64% (n=70) showed TREC using the RPL method, while using the MIC, 9.95% (n=19) were found to be TREC. The RPL and MIC methods showed a concordance of only 48%. Resistant isolates screened by PCR for tet(A) and tet(B) genes were found to be negative and it was concluded that other resistant genes were responsible. The odds ratios (OR) showed that impala drinking from TRECpos rivers were 19.3 (2. 63-141.68) times more likely to be infected with TREC than unexposed impala / Dissertation (MSc)--University of Pretoria, 2007. / Paraclinical Sciences / unrestricted

The thermophilic Campylobacters, Campylobacter jejuni and Campylobacter coli are found as commensals in the intestinal tract of healthy mammals and birds. Campylobacter jejuni is one of the leading causes of sporadic food-borne bacterial disease in humans which is predominantly contracted from poultry products. Although the vast majority of these infections are mild, life-threatening complications should be treated with antimicrobials. Patients are usually treated with either macrolides of fluoroquinolones. However, globally there is an increased trend in the development of resistance to these antibiotics. This trend has also been observed in infection of poultry and pigs. The aim of this investigation was to determine antimicrobial sensitivity of thermophilic Campylobacters isolated from pigs and poultry by broth microdilution minimum inhibitory concentration testing. A total of 482 samples of the small intestinal content from poultry and pigs from the Western Cape and Gauteng Provinces were collected and analysed. Thirty-eight Campylobacter isolates were obtained. Statistical analyses included percentage resistance, minimum inhibitory concentrations (MIC50 and MIC90) as well as the distribution percentages of the MICs. The non-parametric Mann-Whitney U test was used to establish any significant differences at an interspecies, interhost and interprovincial level. Analyses of the data obtained revealed indications of decreasing susceptibility to several antibiotic groups including the tetracyclines, macrolides, erythromycin and tylosin, as well as the lincoasamides, and fluoroquinolones. It was found that isolates from the Western Cape were more likely to be resistant to the fluoroquinolones (p = 0.0392), macrolides (p = 0.0262), and lincoasmides (p = 0.0001) and, as well as to a certain extent the pleuromutulins (p = 0.0985), whereas isolates from Gauteng were more resistant to the tetracycyclines (p = <.0001). Poultry Campylobacter spp. were more prone to be resistant to enrofloxacin (p = 0.0021). Campylobacter jejuni, mainly isolated from poultry, was more liable to be resistant to the tetracyclines (chlrotetracycline p= 0.0307), whereas C. coli, predominatly isolated from pigs was more likely to be resistant to the macrolides (tylosin p= 0.063). Four of the bacteria isolated from the Western Cape were resistant to three or more antibiotic classes, namely; tetracyclines, macrolides, lincosamides, pleuromutulins and fluoroquinolones. No multi-resistant Campylobacter spp. were isolated from the flocks in Gauteng. With the exception of tiamulin, the bacterial populations could clearly be divided into resistant and susceptible populations. As consequence of the increased resistance to the antimicrobial classes used for human therapy and the geographical differences in antimicrobial susceptibility, it is recommended that an antimicrobial resistance monitoring system for the thermophilic Campylobacter spp. be initiated in the South Africa National Veterinary Surveillance and Monitoring Programme for Resistance to Antimicorbial Drugs (SANVAD) Copyright / Dissertation (MSc)--University of Pretoria, 2009. / Veterinary Tropical Diseases / unrestricted