Prevalence of antimicrobial resistance in fecal Escherichia coli isolates from feedlot cattle was characterized. Tetracycline resistance in isolates from newly weaned, auction market derived calves on arrival at the feedlot in a clinical trial was 9.8% and resistance to three or more antimicrobials was 2.1% compared to 17.6 % and 5.9% in a cohort study. The prevalence of tetracycline resistance at 78.3% and resistance to three or more antimicrobials at 52.5 % in isolates from spring calves submitted to a regional diagnostic laboratory were higher than those found on arrival at the feedlot. Of isolates from composite feedyard pen samples late in the feeding period, 39.4% were tetracycline resistant and 7.6% were resistant to three or more antimicrobials, somewhat higher than on arrival. Use of oxytetracycline in the feed for disease prophylaxis and the metaphylactic use of long-acting injectable oxytetracycline were associated with increased proportions of cattle with one or more resistant E. coli isolates early in the feeding period, while the use of individual animal treatments was not. The proportion of animals with one or more tetracycline resistant E. coli isolates was not different between the control, metaphylactic treatment and prophylactic treatment groups preslaughter; however, there were significantly more resistant animals in all groups preslaughter than at arrival. There were also no associations found between the total volume of parenteral antimicrobials used for disease treatment in individual animals and antimicrobial resistance in the cohort study. In addition, no strong associations were found between pen-level prevalence of antimicrobial resistance antimicrobial use or other variables. There was no significant difference between the proportion of isolates per pen resistant to tetracycline, one or more, two or more antimicrobials, or three or more antimicrobials when using 20, 15, 10 or 5 isolates from composite pen-level fecal samples. Variance for isolates resistant to three or more antimicrobials was partitioned as 12.7% at the feedyard-level and 28.7% at the pen-level. The use of diagnostic laboratory data for AMR surveillance was also discussed, and alternatives to antimicrobial treatment in the feedlot were also investigated. Overall a significant contribution to our understanding of antimicrobial resistance in feedlot cattle was achieved.

This thesis summarizes an investigation of antimicrobial resistance (AMR) and antimicrobial use (AMU) in cow-calf herds. The specific objectives of this project were to describe common reasons for treatment and the types of antimicrobials used in cow-calf herds, to describe the frequency of AMR in generic fecal Escherichia coli isolated from various age groups commonly found on cow-calf farms, to determine risk factors associated with the occurrence of AMR, and finally to investigate the underlying molecular mechanisms of AMR in cow-calf herds. At least 86% of the herds treated one or more calves or cows during the study period; however, the overall proportion of both calves and cows reported as treated was less than 14% for calves and 3% for cows. The majority of antimicrobials reported as used in cow-calf operations were for individual therapeutic use rather than prophylaxis, metaphylaxis, or growth promotion. Injectable formulations were the most commonly reported method of antimicrobial administration on cow-calf farms. Cow-calf herds in Wetern Canada are not a significant reservoir for resistance to antimicrobials classified as very important to human medicine such as ciprofloxacin and ceftiofur. The three most common resistances detected were to tetracycline, sulphamethoxazole, and streptomycin regardless of age group. Young calves sampled in the spring of the year were more likely to be shedding AMR E. coli than older calves sampled in the fall of the year or than cows sampled in the spring of the year. The cow-calf pair relationship was not an important factor in transfer of AMR from the individual cow to her calf, but the presence of AMR in the general cow herd was associated with AMR in the calf population. The potential importance of co-selection for AMR at the molecular level was demonstrated by both the risk factor analysis and the molecular work. Phenotypic resistance to streptomycin, tetracycline, and sulphamethoxazole were each associated with the presence of resistance genes from all six families of antimicrobials examined in this study. Several statistically significant associations were also detected between the resistance genes considered. No significant associations were detected between any of the AMR phenotypes or genotypes and the STEC virulence factors stx1, stx2 and eae.

Prevalence of antimicrobial resistance in fecal Escherichia coli isolates from feedlot cattle was characterized. Tetracycline resistance in isolates from newly weaned, auction market derived calves on arrival at the feedlot in a clinical trial was 9.8% and resistance to three or more antimicrobials was 2.1% compared to 17.6 % and 5.9% in a cohort study. The prevalence of tetracycline resistance at 78.3% and resistance to three or more antimicrobials at 52.5 % in isolates from spring calves submitted to a regional diagnostic laboratory were higher than those found on arrival at the feedlot. Of isolates from composite feedyard pen samples late in the feeding period, 39.4% were tetracycline resistant and 7.6% were resistant to three or more antimicrobials, somewhat higher than on arrival. Use of oxytetracycline in the feed for disease prophylaxis and the metaphylactic use of long-acting injectable oxytetracycline were associated with increased proportions of cattle with one or more resistant E. coli isolates early in the feeding period, while the use of individual animal treatments was not. The proportion of animals with one or more tetracycline resistant E. coli isolates was not different between the control, metaphylactic treatment and prophylactic treatment groups preslaughter; however, there were significantly more resistant animals in all groups preslaughter than at arrival. There were also no associations found between the total volume of parenteral antimicrobials used for disease treatment in individual animals and antimicrobial resistance in the cohort study. In addition, no strong associations were found between pen-level prevalence of antimicrobial resistance antimicrobial use or other variables. There was no significant difference between the proportion of isolates per pen resistant to tetracycline, one or more, two or more antimicrobials, or three or more antimicrobials when using 20, 15, 10 or 5 isolates from composite pen-level fecal samples. Variance for isolates resistant to three or more antimicrobials was partitioned as 12.7% at the feedyard-level and 28.7% at the pen-level. The use of diagnostic laboratory data for AMR surveillance was also discussed, and alternatives to antimicrobial treatment in the feedlot were also investigated. Overall a significant contribution to our understanding of antimicrobial resistance in feedlot cattle was achieved.

This thesis summarizes an investigation of antimicrobial resistance (AMR) and antimicrobial use (AMU) in cow-calf herds. The specific objectives of this project were to describe common reasons for treatment and the types of antimicrobials used in cow-calf herds, to describe the frequency of AMR in generic fecal Escherichia coli isolated from various age groups commonly found on cow-calf farms, to determine risk factors associated with the occurrence of AMR, and finally to investigate the underlying molecular mechanisms of AMR in cow-calf herds. At least 86% of the herds treated one or more calves or cows during the study period; however, the overall proportion of both calves and cows reported as treated was less than 14% for calves and 3% for cows. The majority of antimicrobials reported as used in cow-calf operations were for individual therapeutic use rather than prophylaxis, metaphylaxis, or growth promotion. Injectable formulations were the most commonly reported method of antimicrobial administration on cow-calf farms. Cow-calf herds in Wetern Canada are not a significant reservoir for resistance to antimicrobials classified as very important to human medicine such as ciprofloxacin and ceftiofur. The three most common resistances detected were to tetracycline, sulphamethoxazole, and streptomycin regardless of age group. Young calves sampled in the spring of the year were more likely to be shedding AMR E. coli than older calves sampled in the fall of the year or than cows sampled in the spring of the year. The cow-calf pair relationship was not an important factor in transfer of AMR from the individual cow to her calf, but the presence of AMR in the general cow herd was associated with AMR in the calf population. The potential importance of co-selection for AMR at the molecular level was demonstrated by both the risk factor analysis and the molecular work. Phenotypic resistance to streptomycin, tetracycline, and sulphamethoxazole were each associated with the presence of resistance genes from all six families of antimicrobials examined in this study. Several statistically significant associations were also detected between the resistance genes considered. No significant associations were detected between any of the AMR phenotypes or genotypes and the STEC virulence factors stx1, stx2 and eae.

Objectives: To evaluate the influence of pharmacist interventions on drug and dosage prescribing in pediatric settings. Method: Demographic, clinical, and prescribing data and parents’ measurement data were evaluated by pre- and post studies including time series studies and control groups. The data was evaluated against Australian Therapeutic Guidelines. Educational intervention strategies were designed and administered and a post-intervention evaluation was conducted. Group comparisons were made using x2 and Student’s t-test statistics. Time series analysis involved multiple linear regression analysis. Results: The major study involved antibiotics and analgesic drugs and dosages in appendectomy in children. Significant improvements occurred in the selection and dosages of prophylactic antibiotics @<0.001) and in subsequent ward antibiotic treatments @<0.001) also showed marked conformity with the guidelines Other pediatric studies involved liquid medication dosing and prescribing accuracy for paracetamol in a developing country where a simple intervention produced very marked improvements @<0.001). An intervention in severe community-acquired pneumonia showed an improvement in the prescription of appropriate drugs @<0.001) and appropriate dosages of paracetamol (p<O.OOl) according to the guidelines. In drug utilisation evaluation of cefiriaxone, flucloxacillin and Liquigesic COB, there was a significant improvement in the dosage prescribing of ceftriaxone and flucloxacillin and no change in Liquigesic COB following the intervention. O f the total, 38/218 (17%) o f the patients received appropriate post-operative antibiotic dosages. 286/368 (78%) of the analgesic prescriptions and 31/218 (14%) of the patients on postoperative antibiotic choice and dosage that were identified as appropriate in tonsillectomy. / Conclusion: This study has identified deficiencies related to the prescribing of antibiotics and analgesics in children. There was a varied level of improvement in the drug dosage prescribing of pediatricians following the pharmacist educational intervention. Locally developed guidelines are more likely to be accepted and followed than those developed nationally without local input.

La résistance aux antibiotiques est une menace sérieuse pour la santé publique en Europe, entrainant une augmentation des coûts de la santé, des échecs thérapeutiques, et de la mortalité (ECDC, 2011). Le développement de l'antibiorésistance est principalement lié à la consommation d'antibiotiques chez l'Homme et les animaux. Depuis le début des années 2000, les pays européens ont limité cette consommation et en 2006, l'UE a interdit l'utilisation d'antibiotiques comme promoteurs de croissance. Ceci a favorisé le développement de diverses alternatives à l'utilisation d'antibiotiques. L'objectif principal de ce projet de thèse est d'évaluer l'utilisation d'alternatives spécifiques et non spécifiques à l'utilisation d'antibiotiques dans les élevages de porcs européens. L'étude sera organisée en trois parties: i) une évaluation technique, visant à quantifier le lien entre l'utilisation d'antibiotiques et les performances techniques des élevages, ii) une évaluation économique, basée sur une analyse coût-efficacité et coûts-bénéfices des stratégies alternatives aux antibiotiques et iii) une évaluation psychosociologique, décrivant les attitudes et les comportements des éleveurs, vétérinaires et scientifiques vis-à-vis de l'utilisation d'antibiotiques en élevage porcin. Ce projet impliquera à la fois la réalisation de visites d'élevages français, l'utilisation d'outils statistiques variés et de méthodes de recherche qualitative et d'évaluation des risques. Ainsi, ce projet fournira les bases d'une compréhension globale des facteurs techniques, économiques et psychosociologiques qui orientent les décisions des éleveurs et des vétérinaires au sujet de la santé et de la production porcine et qui, par conséquent, définissent les possibles interventions sur l'utilisation d'antibiotiques. Cette étude fait partie du projet de recherche du Consortium MINAPIG financé par le programme Emida Era-Net. Un financement supplémentaire est fourni par l'Office vétérinaire fédéral suisse. / Antimicrobial resistance is a serious threat to public health in Europe, leading to mounting healthcare costs, treatment failure, and deaths (ECDC, 2011). The development of antimicrobial resistance is mainly due to antimicrobial consumption in humans and animals. From early 2000s, European countries have implemented restriction measures and in 2006, EU banned the use of antibiotics as growth promoters in animal feed. This has promoted the development of various alternatives to antimicrobial. The main objective of this PhD project is to assess and evaluate specific and unspecific alternatives to antimicrobials in the European pig industry. The study will be organised in three main parts: i) a technical assessment, quantifying the link between antimicrobial use and technical performances of the pig farms, ii) an economic evaluation, conducting cost-effectiveness and cost-benefit analyses of alternative strategies in comparison with antimicrobial usage, and iii) a psycho-sociological evaluation, describing farmers, veterinarians and pig experts attitudes, beliefs and behaviours regarding the use of antimicrobials in pig farming. The project will involve field work in France, statistical analysis using a range of methods, qualitative research methods, conceptual work and the use of risk assessment methods. We expect this PhD project to provide the foundation for an integrated understanding of technical, economical and psychological factors driving decisions of farmers and veterinarians about pig health and production and the consequential interventions, particularly the use of antimicrobials. This study is part of the MINAPIG Consortium Research project funded by the Era-Net programme Emida. Additional funding is available through the Federal Veterinary Office of Switzerland.

The purpose of this research is to support the California Department of Food & Agriculture (CDFA) with education and outreach about recent changes regarding antimicrobial use in livestock, and to enhance their emergency communications network. This was done by characterizing a population of small-scale livestock owners underserved with regards to educational outreach about animal health issues, such as antimicrobial use rules. The project also seeks to enhance public understanding of the importance of responsible antimicrobial use in animal and human health. To accomplish this, the study used a survey administered in person at local farm supply stores and online to investigate the level of understanding of antimicrobial rules among livestock owners in San Luis Obispo county. The survey gathered information about the livestock owners’ practices, connection to livestock groups, and access to information pertaining to animal health among other things. The results of the survey showed that respondents were largely unaware of new rules pertaining to use of antimicrobials in livestock. Familiarity with California rules of this kind was used as an indicator of access to information about animal health and was found to correlate positively with knowledge about antimicrobial resistance and familiarity with federal rules concerning antimicrobial use in livestock. As predicted, respondents with a connection to 4-H and FFA had greater familiarity with both federal and state rules concerning antimicrobial use in livestock.

Made available in DSpace on 2015-12-06T23:46:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2013 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Introdução: O resfriado comum a uma das sindromes infecciosas mais frequentes na infancia, sendo causado por um grupo numeroso de virus, podendo vir acompanhado de complicacoes e uma significativa morbidade. Constitui uma das principais causas de consultas em servicos de atendimento primario a Saúde e um dos principais motivos para o uso indevido de antibioticos.! OBJETIVOS. Descrever a ocorrencia, etiologia, evolucao clinica, uso de antibioticos e absenteismo no trabalho dos responsaveis dos casos de resfriados comuns dentre as criancas atendidas em um servico de atencao primaria a Saúde na cidade de São Paulo. METODOS. No periodo de mar/2008 a fev/2009, foi selecionada uma amostra de casos de criancas menores de 12 anos com diagnostico de resfriado comun com inicio ate cinco dias, as quais foram acompanhadas ate a resolucao completa do quadro. Foram excluidos casos com suspeita de infeccoes bacterianas secundarias, cardiopatias congenitas, doencas pulmonares cronicas, imunodefiCiências e historico de prematuridade. Os dados clinicos foram anotados em formularios padronizados e as amostras de lavado de nasofaringe (uma por caso) foram submetidas a uma ou mais tecnicas laboratoriais (imunofluorescencia direta, reacao da polimerase em cadeia e reacao da polimerase em cadeia em tempo real) para a deteccao de rinovirus (HRV), virus sincicial respiratorio (RSV), parainfluenza 1, 2 e 3 (PIV1-3), adenovirus (AdV), metapneumovirus (hMPV), bocavirus (HBoV), influenza A e B (IFVA e IFVB), coronavirus (HCoV) e enterovirus (HEV). RESULTADOS. Os resfriados representaram 29,0% de todas as consultas medicas (955/3282). Foi obtida uma amostra de 134 casos, com media de idade de 3,6 anos (med 2,6 a). Em 73,8% (99/134) dos casos foi detectado pelo menos um virus, tendo sido o HRV (41,0%) e o IFVA (17,2%) os mais frequentes. O tempo medio de duracao dos sintomas foi de 8,8 dias, nao tendo havido diferencas nas medias de duracao dos sintomas associados aos diferentes virus. A coriza (91,8%) e a tosse (90,3%) foram as manifestacoes mais frequentes, sendo que o quadro associado aos diferentes virus foi semelhante, exceto pelos casos com HRV que apresentaram menos febre (p=0,025) e com IFVB que apresentaram menos tosse (p=0,001). As coinfeccoes ocorreram em 30,3% dos casos (30/99) e nao apresentaram diferencas com relacao as manifestacoes clinicas, ocorrencia de complicacoes e media de duracao dos sintomas quando comparadas aos casos com monoinfeccoes, O indice de complicacoes foi de 11,9%, porem, os antibioticos foram prescritos em 39,6% dos casos, tendo sido a maior parte das prescricoes consideradas indevidas. Foi verificada uma media de 1,5 consultas e 1,0 dia de absenteismo por caso de resfriado. CONCLUSAO. Apesar de considerados patologias benignas, os resfriados foram responsaveis por um alto indice de uso indevido de antibioticos, consultas medicas e dias de absenteismo no trabalho. A ampliacao das faixas etarias para as vacinas disponiveis no sistema publico de Saúde, a disponibilizacao de testes diagnosticos rapidos para os virus respiratorios e o estimulo a educacao medica continuada poderiam contribuir para melhorar o cenario atual possibilitando uma profilaxia mais ampla, o diagnostico rapido e o uso racional de antibioticos / INTRODUCTION. The common cold are caused by a large group of viruses and is one of the most frequent infectious syndromes in childhood which can be followed by complications and a significant morbidity. They are a major cause of consultations in primary care services and a major reason for the misuse of antibiotics. OBJECTIVES. To describe the occurence, etiology, clinical course, complications, use of antibiotics, number of consultations and days of work absenteeism of parents in cases of common colds in children attending an outpatient primary health care service in São Paulo city. METHODS. From mar/2008 to Feb/2009, we selected a sample of cases of children under 12 years diagnosed with common colds starting up to five days, which were followed until resolution of symptoms. We excluded cases with suspected secondary bacterial infections, congenital heart disease, chronic lung diseases, immunodeficiencies and history of prematurity. Clinical data were recorded on a standardized form and samples of nasopharyngeal wash (one for each case) were subjected to one or more laboratory techniques (direct immunofluorescence, polymerase chain reaction and real time polymerase chain reaction) for detection of rhinovirus (HRV), respiratory syncytial virus (RSV), parainfluenza virus 1, 2 and 3 (PIV1-3), adenovirus (AdV), metapneumovirus (hMPV) Bocavirus (HBoV), influenza A and B (IFVA and IFVB ), coronavirus (HCoV) and enterovirus (HEV). RESULTS. Colds accounted for 29.0% of all medical consultations (955/3282). We obtained a sample of 134 cases of common cold cases, with a mean age of 3.6 years (med 2.6). At least one virus was detected in 73.8% (99/134) of cases and HRV (41.0%) and IFVA (17.2%) were the most frequent viral agents. The mean time of symptoms was 8.8 days, with no differences among different types of viruses. Coriza (91.8%) and cough (90.3%) were the most frequent symptoms, and the clinical characteristics among different types of viruses were similar, except for the fact that cases with HRV had less fever (p = 0.025) and with IFVB had less cough (p = 0.001). The coinfections occurred in 30.3% of cases (30/99) and were not different with respect to clinical manifestations, rate of complications and duration of symptoms when compared to cases with monoinfections. The complication rate was 11.9%, however, antibiotics were prescribed in 39,6% of cases, with most prescriptions considered improper. The average of doctos visits and lost work days was 1.5 visits and 1.0 days of absenteeism per case of common cold. CONCLUSION. Although considered benign diseases, common colds were responsible for a high rate of antibiotics misuse, doctor visits and days of work absenteeism. A wider coverage for all ages with vaccines available in the Brazilian public health system, the availability of rapid diagnostic tests for respiratory viruses and the continuous medical education could improve the current scenario and promote a broader prevention, rapid diagnosis and rational use of antibiotics. / BV UNIFESP: Teses e dissertações

The general objectives of this thesis were: (i) to determine the etiological and molecular profile of clinical mastitis (CM) in 20 dairy herds of Southeast, Brazil; and (ii) to quantify antimicrobial used for treatment of CM in the study population. To achieve this goals, four studies were performed. In the Study 1, we characterized the pathogen frequency and severity of CM in dairy herds. In addition, we determined the incidence rate of clinical mastitis (IRCM) and its association with the following herd-level descriptors: bulk milk somatic cell count (BMSCC), bulk milk total bacterial count (BMTBC), herd size (number of lactating cows), milk yield, housing system and season. The association between herd-level descriptors and IRCM were determined by two groups of mixed regression models: one based on the overall IRCM, and five based on the following specific-pathogen groups: contagious, other Gram-positive, Gram-negative, other (composed of yeast and Prototheca spp), and negative culture. A total of 5,957 quarter-cases of CM were recorded and the most frequently isolated pathogens were Escherichia coli (6.6% of total cultures), Streptococcus uberis (6.1%), and Streptococcus agalactiae (5.9%). The majority of CM cases were mild (60.3%), while 34.1% were moderate and 5.6% severe. Overall, the IRCM was 9.7 quarter-cases per 10,000 quarter-days at risk (QDAR), and the only herd-level parameter associated with overall IRCM was BMSCC, in which the highest IRCM was observed for herds with BMSCC &gt;600.000 × 103 cells/mL. In the models evaluating the specific-pathogen groups, IRCM with isolation of major contagious pathogens was associated with BMSCC, milk yield and housing system. For the evaluation of other Gram-positive pathogens, the IRCM was higher in the rainy season of 2015 in comparison with the other seasonal categories. In addition, for the model evaluating the Gram-negative group, the IRCM was highest in herds with BMTBC &gt;30 × 103 cfu/mL. The Study 2 aimed to characterize the treatment profile and quantify the antimicrobial consumption for treatment of CM in dairy herds; and to determine the association of antimicrobial use (AMU) and the same herd-level descriptors as described in the Study 1. Data on treatment practices and AMU were obtained from 19 dairy herds for a period of 12 months per herd. The AMU for treatment of CM was quantified monthly in units of defined daily dose (DDD) and expressed as antimicrobial treatment incidence (ATI; number of DDD per 1,000 lactating cows-day). The overall monthly mean ATI was 17.7 DDD per 1,000 lactating cow-days (15.4 for intramammary compounds, and 2.2 for systematically administered antimicrobials). Among intramammary drugs, aminoglycosides had the highest ATI (11.7 DDD per 1,000 lactating cow-days), while for systematically administrated antimicrobials, fluoroquinolones (4.2 DDD per 1,000 lactating cow-days) were the most frequently used antimicrobials. Herd size and BMSCC were positively associated with ATI. In addition, herd-level ATI was higher in freestall herds than in compost bedded-pack barns. In the Study 3, we determined the phylogeny of E. coli strains isolated from CM in dairy cows and the association of most frequent phylogroups with antimicrobial susceptibility. A total of 100 E. coli isolates recovered from CM cases described in the Study 1 were categorized according to their phylogenetic group using a quadruplex PCR method; antimicrobial susceptibility pattern was also evaluated. Most isolates were assigned to phylogenetic group A (52%), followed by B1 (38%), B2 (2%), C (4%), D (3%), and E (1%). Resistant isolates were observed for all evaluated antimicrobials. Overall, more than 96% of E. coli isolates were resistant to ampicillin, and more than 23% were resistant to cephalothin, sulphadimethoxine or tetracycline. High levels of resistance (&gt;70%) were also found to erythromycin, oxacillin, penicillin, penicillin associated with novobiocin, and pirlimycin. In contrary, high susceptibility was observed to ceftiofur (96.8%) among E. coli isolates. Difference in the antimicrobial susceptibility among phylogenetic groups was observed only for cephalothin, in which E. coli strains belonging to the phylogroup A were inhibited at lower antimicrobial concentrations than strains assigned to the phylogroup B1. In Study 4, we evaluated the genotypic diversity among Strep. agalactiae and Strep. uberis isolates recovered from CM in dairy cows; in addition, the study evaluated the association of genotypes clustered by genetic similarity with antimicrobial susceptibility pattern. Isolates were subtyped using randomly amplified polymorphic DNA (RAPD) analysis. A great genotypic diversity was found for both Strep. agalactiae (45 subtypes out of 89 isolates) and Strep. uberis (56 subtypes out of 88 isolates). For evaluation of antimicrobial susceptibility, subtypes of Strep. agalactiae were clustered into three groups (Ia, Ib and II), while Strep. uberis subtypes were clustered into two groups (I and II) according to their genetic similarity. Overall, Strep. agalactiae isolates showed high susceptibility to most antimicrobials, except to tetracycline and erythromycin. Differences in the antimicrobial susceptibility among clusters of Strep. agalactiae were observed for ampicillin, ceftiofur, erythromycin, pirlimycin, sulphadimethoxine and tetracycline. In contrary, Strep. uberis isolates were categorized as resistant to most antimicrobials, except to cephalothin and penicillin+novobiocin. No differences were observed among clusters for all antimicrobials in the analysis of Strep. uberis. In conclusion, the results of this thesis indicated a high IRCM in the evaluated herds, and although environmental pathogens were the most common cause of CM in these herds, contagious pathogens such as Strep. agalactiae and Staph. aureus, are still a concern in some dairy herds of Brazil. Furthermore, high frequencies of AMU and off-label protocols were observed among the evaluated herds. The non-judicious use of antimicrobials can become a risk factor for the development of antimicrobial resistance, which was even observed for isolates belonging to the three most prevalent bacterial species identified from CM cases in our study (E. coli, Strep. agalactiae and Strep. uberis). Finally, because there were some herd-level descriptors associated with the IRCM and AMU in our study, there may be opportunity for management strategies aiming to improve the control of CM in dairy herds of southeastern Brazil. / Os objetivos gerais desta tese foram: (i) determinar o perfil etiológico e molecular da mastite clínica (MC) em 20 rebanhos leiteiros do Sudeste do Brasil; e, (ii) quantificar os antimicrobianos usados para tratamento da MC na população estudada. Para alcançar esses objetivos, quatro estudos foram realizados. No Estudo 1, foi caracterizada a frequência de patógenos causadores de MC e a gravidade das infecções nos rebanhos leiteiros. Além disso, foi determinada a taxa de incidência de mastite clínica (TIMC) e sua associação com as seguintes variáveis em nível de rebanho: contagem de células somáticas em leite de tanque (CCSLT), contagem bacteriana total em leite de tanque (CBTLT), tamanho (número de vacas em lactação), produção de leite, sistema de alojamento e estação do ano. A associação entre as variáveis em nível de rebanho e a TIMC foi determinada por dois grupos de modelos de regressão logística multivariada: um baseado na TIMC geral, e cinco baseados nos seguintes grupos específicos de patógenos: contagiosos, outros Gram-positivos, Gram-negativos, outros patógenos (composto de leveduras e Prototheca spp.), e cultura negativa. Um total de 5.957 casos de MC em nível de quarto mamário foi registrado e os patógenos mais prevalentes foram Escherichia coli (6,6% de todas as culturas), Streptococcus uberis (6,1%), e Streptococcus agalactiae (5,9%). A maioria dos casos de MC foi de gravidade leve (60,3%), enquanto 34,1% dos casos foram moderados e 5,6% foram graves. A TIMC geral foi de 9,7 casos por 10.000 quartos-dia em risco (QDR), e o único parâmetro em nível de rebanho associado com a TIMC geral foi a CCSLT, em que a TIMC mais alta foi observada em rebanhos com CCSLT &gt;600.000 × 103 células/mL. Nos modelos que avaliaram os grupos específicos de patógenos, a TIMC de patógenos contagiosos foi associada com a CCSLT, produção de leite e sistema de alojamento. Na avaliação de outros patógenos Gram-positivos, a TIMC foi maior na estação chuvosa de 2015 em comparação com as outras categorias referentes à estação do ano. Adicionalmente, para o modelo avaliando o grupo de patógenos Gram-negativos, a TIMC foi mais alta em rebanhos com CBTLT &gt;30.000 × 103 ufc/mL. O Estudo 2 teve como objetivo caracterizar o perfil de tratamento e o consumo de antimicrobianos em rebanhos leiteiros; e determinar a associação de uso de antimicrobianos (UAM) e as mesmas variáveis em nível de rebanho descritas no Estudo 1. Dados sobre as práticas terapêuticas e UAM foram obtidos de 19 rebanhos leiteiros durante um período de 12 meses por rebanho. A frequência de UAM para tratamento da MC foi quantificada mensalmente em unidades de doses definidas diárias (DDD) e expressa como incidência de tratamento antimicrobiano (ITA: número de DDD por 1.000 vacas em lactação-dia). A média de ITA mensal foi de 17,7 DDD por 1.000 vacas em lactação-dia (15,4 para compostos intramamários, e 2,2 para compostos sistêmicos). Entre os produtos intramamários, os aminoglicosídeos tiveram a ITA mais alta (11,7 DDD por 1.000 vacas em lactação-dia), enquanto que para os compostos administrados pela via sistêmica, as fluoroquinolonas (4,2 DDD por 1.000 vacas em lactação-dia) foram os antimicrobianos mais frequentemente usados. O tamanho do rebanho e CCSLT foram positivamente associados com a ITA. Além disso, a ITA foi mais alta em rebanhos com freestall do que em rebanhos com sistema tipo compost barn. No Estudo 3, determinou-se a filogenia de cepas de E. coli isoladas de casos de MC em vacas leiteiras, e a associação dos filogrupos mais frequentes com a susceptibilidade aos antimicrobianos. Um total de 100 isolados de E. coli identificados nos casos de MC descritos no Estudo 1 foram categorizados de acordo com os grupos filogenéticos por meio de um método de PCR quadruplex; o perfil de susceptibilidade aos antimicrobianos também foi avaliado. A maioria dos isolados pertenceram ao grupo A (52%), seguido dos grupos B1 (38%), B2 (2%), C (4%), D (3%), e E (1%). Foram encontrados isolados resistentes para todos os antimicrobianos avaliados. De forma geral, mais de 96% dos isolados de E. coli foram resistentes a ampicilina, e mais de 23% foram resistentes a cefalotina, sulfadimetoxina ou tetraciclina. Altos níveis de resistência (&gt;70%) foram encontrados também para eritromicina, oxacilina, penicilina e penicilina associada a novobiocina. Ao contrário, foi observado alta susceptibilidade ao ceftiofur (96.8%) entre os isolados de E. coli. Diferenças na susceptibilidade entre os grupos filogenéticos foi observada apenas para a cefalotina, em que os isolados de E. coli pertencentes ao filogrupo A foram inibidos em concentrações de antimicrobianas mais baixas que isolados pertencentes ao filogrupo B1. No Estudo 4, avaliou-se a diversidade genotípica entre isolados de Strep. agalactiae e Strep. uberis identificados em casos de MC em vacas leiteiras; adicionalmente, o estudo avaliou a associação dos genótipos agrupados de acordo com a similaridade genética com o perfil de susceptibilidade aos antimicrobianos. Os isolados foram genotipados por meio do método de amplificação randômica de DNA polimórfico (RAPD). Grande diversidade genotípica foi observada tanto para o Strep. agalactiae (45 subtipos de 89 isolados) quanto para Strep. uberis (56 subtipos de 89 isolados). Para a avaliação de susceptibilidade aos antimicrobianos, os subtipos de Strep. agalactiae foram agrupados em três clusters (Ia, Ib e II), enquanto que os subtipos de Strep. uberis foram agrupados em dois clusters (I e II) de acordo com a similaridade genética. De forma geral, os isolados de Strep. agalactiae apresentaram alta susceptibilidade à maioria dos antimicrobianos, exceto para tetraciclina e eritromicina. Diferenças na susceptibilidade aos antimicrobianos entre os clusters de Strep. agalactiae foram observadas para ampicilina, ceftiofur, eritromicina, pirlimicina, sulfadimetoxina e tetraciclina. Por outro lado, os isolados de Strep. uberis foram resistentes à maioria dos antimicrobianos, exceto para cefalotina e penicilina + novobiocina. Não foram encontradas diferenças entre os clusters para todos os antimicrobianos na análise de Strep. uberis. Em conclusão, os resultados desta tese indicaram alta TIMC nos rebanhos avaliados, e apesar de os patógenos ambientais serem a causa mais comum de MC nestes rebanhos, patógenos contagiosos como Strep. agalactiae e Staph. aureus, ainda são uma preocupação em alguns rebanhos do Brasil. Além disso, observaram-se altas frequências de UAM e de terapias não recomendadas em bula entre os rebanhos avaliados. O uso não judicioso de antimicrobianos pode se tornar um fator de risco para o desenvolvimento da resistência bacteriana aos antimicrobianos, o que foi inclusive observado para isolados pertencentes as três espécies bacterianas mais prevalentes nos casos de MC no nosso estudo (E. coli, Strep. agalactiae e Strep. uberis). Finalmente, pelo fato de algumas variáveis em nível de rebanho terem sido associadas com a TIMC e com o UAM em nosso estudo, é possível que hajam oportunidades para implementação de estratégias de manejo com o objetivo de melhorar o controle da MC em rebanhos leiteiros do sudeste do Brasil.

Η χρήση αντιμικροβιακών παραγόντων συνολικά καθώς και ειδικές κατηγορίες αντιμικροβιακών έχουν ενοχοποιηθεί ως παράγοντες κινδύνου για νοσοκομειακές λοιμώξεις (ΝΛ) από ανθεκτικό στη μεθικιλλίνη χρυσίζοντα σταφυλόκοκκο (methicillin-sensitive Staphylococcus aureus, MRSA). Οι στόχοι της μελέτης ήταν: 1. η διερεύνηση προβλεπτικών παραγόντων για νοσοκομειακή λοίμωξη από MRSA, 2. η σε βάθος αξιολόγηση του ρόλου της πρόσφατης χρήσης αντιμικροβιακών από ποιοτική και ποσοτική άποψη. Υλικό και μέθοδοι. Η χρονική περίοδος της μελέτης ήταν από Οκτώβριο1997 έως και τον Σεπτέμβριο του 2001. Οι ασθενείς με ΝΛ από MRSA σε κρατικό νοσοκομείο φροντίδας βετεράνων πολέμου των ΗΠΑ συγκρίθηκαν με αντίστοιχη ομάδα με ΝΛ από ευαίσθητο στη μεθικιλλίνη Staphylococcus aureus (MSSA). Οι λοιμώξεις στις 2 ομάδες καταγράφηκαν και τεκμηριώθηκαν μα βάση αυστηρά κριτήρια. Καταγράφηκαν δεδομένα σχετικά με παράγοντες κινδύνου (συμπεριλαμβανομένης της ποιοτικής και ποσοτικής χρήσης αντιμικροβιακών) για λοίμωξη από MRSA και ελήφθησαν υπόψη γεγονότα μέχρι 30 ημέρες πριν την ημερομηνία της θετικής καλλιέργειας. Αποτελέσματα. Εκατόν είκοσι επτά ασθενείς (127) με ΝΛ από MRSA και 70 ασθενείς με ΝΛ από MSSA αναλύθηκαν περαιτέρω. Σε μονοπαραγοντική ανάλυση, οι 2 ομάδες διέφεραν σημαντικά στην ηλικία, ιστορικό αιμοκάθαρσης και χρονίων ελκών, είδος κλινικής όπου ελήφθη το δείγμα, διάρκεια προηγούμενης νοσηλείας και παραμονής σε γενική ή καρδιολογική ΜΕΘ, πρόσφατη χειρουργική επέμβαση, άλλες επεμβατικές πράξεις, διασωλήνωση και παρουσία καθετήρα κύστεως για πάνω από 24 ώρες. Επίσης διέφεραν σημαντικά στη χρήση ή όχι τουλάχιστον 1,2 ή 3 αντιμικροβιακών, στο μέσο αριθμό αντιμικροβιακών που είχαν χρησιμοποιηθεί, μέσο αριθμό αντιμικροβιακών-ημερών για κάθε ασθενή, καθώς και ποιοτική και ποσοτική χρήση συγκεκριμένων κατηγοριών αντιμικροβιακών. Σε 2 μοντέλα πολυπαραγοντικής ανάλυσης, εξετάζοντας είτε την ποιοτική (μοντέλο Ι) είτε την ποσοτική (μοντέλο ΙΙ) χρήση αντιμικροβιακών, η διάρκεια παραμονής στο νοσοκομείο τον τελευταίο μήνα αναδείχθηκε ο ισχυρότερος προβλεπτικός παράγοντας λοίμωξης από MRSA (p 0.000), ενώ ιστορικό διασωλήνωσης έδειξε σημαντικότητα στο μοντέλο Ι και οριακή σημαντικότητα στο ΙΙ. Η χρήση αμινογλυκοσιδών και η παρουσία χρονίων ελκών έδειξαν τάση για σημαντικότητα στο μοντέλο Ι. Δεν παρατηρήθηκαν σημαντικές διαφορές στην έκβαση. Συμπεράσματα. Καταλήγουμε στο συμπέρασμα ότι η διάρκεια παραμονής στο νοσοκομείο τις τελευταίες 30 ημέρες αποτέλεσε τον ισχυρότερο προγνωστικό παράγοντα μεταγενέστερης ΝΛ από MRSA στον πληθυσμό των ασθενών μας. Παρά τη σαφώς μεγαλύτερη χρήση αντιμικροβιακών στην ομάδα MRSA, η χρήση αντιμικροβιακών δεν αποτέλεσε ανεξάρτητο προγνωστικό παράγοντα κινδύνου. Όσον αφορά την υπομελέτη, σκοπός ήταν η χρήση αντιμικροβιακών παραγόντων συνολικά καθώς και ειδικές κατηγορίες αντιμικροβιακών έχουν ενοχοποιηθεί ως παράγοντες κινδύνου για νοσοκομειακή βακτηριαιμία (ΝΒ) από ανθεκτικό στη μεθικιλλίνη χρυσίζοντα σταφυλόκοκκο (methicillin-resistant Staphylococcus aureus, MRSA). Από τα δεδομένα της κύριας μελέτης, που ήδη έχει περιγραφεί περιληπτικά παραπάνω, απομονώθηκαν και αναλύθηκαν σε ξεχωριστή υπομελέτη αυτά που αφορούσαν σε ασθενείς που ανέπτυξαν νοσοκομειακή βακτηριαιμία. Οι στόχοι της υπομελέτης ήταν: 1. η διερεύνηση προβλεπτικών παραγόντων για νοσοκομειακή βακτηριαιμία από MRSA, 2. η σε βάθος αξιολόγηση του ρόλου της πρόσφατης χρήσης αντιμικροβιακών από ποιοτική και ποσοτική άποψη. Υλικό και μέθοδοι. Η χρονική περίοδος της μελέτης ήταν από Οκτώβριο1997 έως και τον Σεπτέμβριο του 2001. Οι ασθενείς με ΝΒ από MRSA σε κρατικό νοσοκομείο φροντίδας βετεράνων πολέμου των ΗΠΑ συγκρίθηκαν με αντίστοιχη ομάδα με ΝΒ από ευαίσθητο στη μεθικιλλίνη Staphylococcus aureus (MSSA). Καταγράφηκαν δεδομένα σχετικά με παράγοντες κινδύνου (συμπεριλαμβανομένης της ποιοτικής και ποσοτικής χρήσης αντιμικροβιακών) για λοίμωξη από MRSA και ελήφθησαν υπόψη γεγονότα μέχρι 30 ημέρες πριν την ημερομηνία της θετικής καλλιέργειας Αποτελέσματα. Είκοσι οκτώ ασθενείς (28) με ΝΒ από MRSA και 32 ασθενείς με ΝΒ από MSSA αναλύθηκαν περαιτέρω. Σε μονοπαραγοντική ανάλυση, οι 2 ομάδες διέφεραν σημαντικά στην ηλικία, ιστορικό αιμοκάθαρσης και χρονίων ελκών, διάρκεια προηγούμενης νοσηλείας, ιστορικό και διάρκεια παραμονής σε γενική ή καρδιολογική ΜΕΘ, πρόσφατη χειρουργική επέμβαση, διασωλήνωση και παρουσία καθετήρα κύστεως για πάνω από 24 ώρες. Επίσης διέφεραν σημαντικά στη χρήση ή όχι τουλάχιστον 1,2 ή 3 αντιμικροβιακών, το μέσο αριθμό αντιμικροβιακών που είχαν χρησιμοποιηθεί, μέσο αριθμό αντιμικροβιακών-ημερών για κάθε ασθενή, καθώς και ποιοτική και ποσοτική χρήση συγκεκριμένων κατηγοριών αντιμικροβιακών. Στο μοντέλο πολυπαραγοντικής ανάλυσης Ι (ποιοτική χρήση αντιμικροβιακών), παρατηρήθηκε τάση (trend) για τη διάρκεια της προηγούμενης παραμονή στο νοσοκομείο ως προβλεπτικού παράγοντα (p 0,088), ενώ, από το μοντέλο ΙΙ (ποσοτική χρήση αντιμικροβιακών), ο μέσος αριθμός αντιμικροβιακών-ημερών ανά ασθενή αναδείχθηκε ως ο μόνος ανεξάρτητος προγνωστικός δείκτης ΝΒ από MRSA (p 0,03). Δεν παρατηρήθηκαν σημαντικές διαφορές στην έκβαση. Συμπεράσματα. Καταλήγουμε στο συμπέρασμα ότι η ποσοτική χρήση αντιμικροβιακών, υπό τη μορφή του μέσου αριθμού αντιμικροβιακών-ημερών ανά ασθενή κατά τη διάρκεια του περασμένου μήνα, ήταν ο ισχυρότερος προγνωστικός δείκτης της μεταγενέστερης ΝΒ από MRSA στον πληθυσμό των ασθενών μας, περισσότερο από άλλους παραδοσιακούς παράγοντες κινδύνου. / Both total antimicrobial use and specific antimicrobials have been implicated as risk factors for healthcare-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) infection. Aims. The aims of the study were: 1.to explore predictors of a new HA-MRSA infection in comparison with a new healthcare-associated methicillin-sensitive Staphylococcus aureus (HA-MSSA), 2. to thoroughly assess the role of recent antibiotic use qualitatively and quantitatively. Methods. The time-period for our study was from October 1997 through September 2001. Applying strict criteria, we identified two groups of inpatients, one with a new HA-MRSA infection and one with a new HA-MSSA infection. We recorded demographic, clinical and antibiotic use – related data up to 30 days before the positive culture date. Results.We identified 127 and 70 patients for each group respectively. Two logistic regression models were carried out to assess the role of antimicrobial use (qualitatively and qualitatively). In model I, duration of hospital stay, presence of chronic wounds, aminoglycoside and fluoroquinolone use retained statistical significance. In model II, duration of hospital stay and history of intubation during the last month stood out as the only significant predictors of a subsequent HA-MRSA infection. No siginificant differences in outcome were noted. Conclusions. The length of exposure to the hospital environment may be the best predictor of a new HA-MRSA infection. Use of aminoglycosides and fluoroquinolones may also stand independently along with presence of chronic ulcers and exposure to surgical procedures. No independent association between quantitative antibiotic use and subsequent HA-MRSA infection was documented. As for the substudy, the antimicrobial use has been implicated as risk factor for healthcare-associated methicilin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI). The aims of the study were: 1. to explore predictors of a new MRSA BSI, 2. to thoroughly assess recent antibiotic use qualitatively and quantitatively. Methods. Patients in contact with the healthcare system and MRSA BSI were compared with a methicillin-sensitive BSI group, considering events and risk factors up to 30 days before the positive culture date. Results. Twenty eight patients with MRSA BSI and 32 patients with MSSA BSI were further analyzed. In univariate analysis, significant differences were noted in specific demographic, comorbidity and hospital event-related parameters and also in mean number of antibiotics used, mean number of antibiotic-days per patient, and qualitative and quantitative use of specific classes of antibiotics. From logistic regression model I (qualitative antibiotic use), a trend was noted for duration of prior hospital stay, while, from model II (quantitative antibiotic use), mean antibiotic-days per patient emerged as the single independent predictor of HA-BSI by MRSA (p 0.03). No significant differences in outcome were noted. Conclusion. We conclude that the mean number of antibiotic-days per patient during the last month was the strongest predictor of a subsequent MRSA BSI in our patient population, more than other traditional risk factors.