Universiẗat, Diss., 2005--Würzburg.

Dissertation (Ph.D.)--University of South Florida, 2006. / Title from PDF of title page. Document formatted into pages; contains 90 pages. Includes vita. Includes bibliographical references.

Made available in DSpace on 2014-06-11T19:28:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-03-15Bitstream added on 2014-06-13T19:58:17Z : No. of bitstreams: 1 pinto_gcs_me_arafo.pdf: 899028 bytes, checksum: 57f6b9a787b99be24637541e57cbfc9c (MD5) / A necessidade de superar o desafio criado pelos biofilmes resistentes aos tratamentos antimicrobianos convencionais tem levado à busca por tratamentos alternativos, como terapia fotodinâmica antimicrobiana (aPDT). Este estudo avaliou in vitro a eficácia da aPDT na inativação de biofilmes de Staphylococcus aureus suscetíveis e resistentes à meticilina (MRSA e MSSA), mediado pelos fotossensibilizadores (PSs) Curcumina (Cur) e Photodithazine® (PDZ). Biofilmes foram formados e tratados com diferentes concentrações de Cur (0, 20, 40 e 80 μM) e PDZ (0, 50 e 75 mg/L), e iluminados ou não por fonte de luz LED (Cur 455 ± 3 nm/ 5,28 J/cm2; PDZ 660 ± 3 nm/ 5,28 J/cm2 ou 50 J/cm²). Os grupos Controle Positivo (CP) não receberam nenhum PS e também não foram iluminados. A viabilidade dos micro-organismos após a aPDT foi avaliado pelo número de colônias viáveis, pelo ensaio de XTT e pela utilização do kit LIVE/DEAD® na Microscopia Confocal de Varredura à Laser (MCVL). Os resultados foram avaliados por análises de variância de dois fatores de efeitos fixos (ANOVA) e complementados por comparações múltiplas de médias pelo teste de Tukey. Para ambas as cepas, todas as concentrações de Cur e PDZ testadas reduziram significativamente a atividade metabólica e o UFC/mL para ambos micro-organismos quando comparado com os grupos CN (p0,05). Os resultados foram otimizados para a Cur quando utilizou-se a maior concentração (80 μM), para a PDZ, a maior redução nos micro-organismos foi observada quando associou-se a maior concentração de PDZ (75 mg/L) com a maior dose de luz (50 J/cm²). Os biofilmes submetidos a aPDT demostraram pela MCVL um maior número de células coradas em vermelho, indicando que a aPDT foi eficaz para promover danos ou morte às células bacterianas. Assim, a aPDT pode ser considerada promissora para atuar de forma sinérgica no tratamento de infecções bacterianas / The need to overcome the challenge created by biofilms regarding conventional antimicrobial approaches has lead to search of alternative treatments such as Antimicrobial Photodynamic Therapy (aPDT). This in vitro study evaluated the efficacy of aPDT using the photosensitizer (PS) Curcumin (Cur) and Photodithazine® (PDZ) in the inactivation of biofilms of methicillin susceptible and resistant S. aureus (MSSA and MRSA). Biofilms were treated with different Cur (0, 20, 40 or 80 μM of Cur) and PDZ concentrations (0, 50 or 75 mg/L) and illuminated or not with LED source (Cur 455 ± 3 nm/ 5.28 J/cm2; PDZ 660 ± 3 nm/ 5.28 J/cm2 or 50 J/cm²). Positive control samples were not exposed to PS or light. The microorganisms viability after aPDT were evaluated by counting the number of colonies, the XTT assay and LIVE/DEAD® staining using confocal laser scanning microscopy (CLSM). The results were evaluated by analysis of variance, two-factor fixed effects (ANOVA) and complemented by multiple comparisons by Tukey test. For both strains, all the tested Cur and PDZ concentrations reduced significantly both biofilm metabolic activity and CFU/mL compared to the negative control (p0.05). Moreover, the results were optimized for Cur when the higher concentration was used (80 μM); For PDZ, the best results were obtained when it was associated a higher concentration of PDZ (75 mg/L) with the higher dose of light (50 J/cm²). Biofilms submitted to aPDT showed a large number of red-stained colonies, indicating that this therapy was efficient in disrupting the bacterial membrane. It can be concluded that PS was efficient in reducing viable colonies of both S. aureus strains by damaging cell membrane and causing cell death. Thus, the aPDT is can be considered promising to act synergistically in the treatment of bacterial infections

Neonatal sickness and death is increasingly becoming a public health problem worldwide. The colonization of Group B Streptococcus and Staphylococcus in the rectovaginal area is among the sources of infections in neonates which can result in illness and mortality. The over exposure of humans to antibiotics is the possible cause of resistance in bacteria. These resistant strains can be passed onto offspring, leading to resistant infections and increasing the morbidity of neonates because of treatment failures. Many people, including healthcare personnel are not aware of the effect of these bacteria, and informing clinics and hospitals can help create awareness and monitoring the levels of resistance among bacteria can assist in preventing the transference of the bacteria. In this study we investigated the prevalence of group B Streptococcus (GBS) and Staphylococcus aureus in the anogenital tract of pregnant women in the Eastern Cape Province, South Africa. A total of 49 isolates from 25 (30.5 percent) pregnant women colonized with GBS were isolated from vaginal and rectal swabs of 82 pregnant women at 25-37 gestation who participated in this study. These isolates were obtained using standard microbiological methods and confirmed by polymerase chain reaction (PCR) technique aimed at the ScpB gene. The isolates were further screened for the presence of 9 serogroups (Ia, Ib, II, III, IV, V, VI, VII, VII) and serogroups Ib 2 (4.8 percent), II 20 (40.8 percent) and IV 5 (10.2 percent) and 22 non-typable (44.9 percent) were identified. Susceptibility profiling of the isolates to 12 antibiotics (tetracycline, clindamycin, erythromycin, gentamycin, naladixic acid, norfloxacin, chloramphenicol, cefuroxime, cefotaxime, imipenem, penicillin and vancomycin) was tested in vitro by the standardized disc diffusion method. All the confirmed GBS isolates (49) were resistant to erythromycin, tetracycline and clindamycin. A higher percentage of the isolates were resistant to gentamycin 44 (90 percent), nalidixic acid 41 (84 percent), penicillin 41 (84 percent), chloramphenicol 38 (78 percent), cefuroxime 36 (74 percent), imipenem 36 (74 percent), cefotaxime 35 (71 percent), norfloxacin 32 (65 percent) and vancomycin 31 (78 percent). Multiple antimicrobial resistance patterns ranged from 9‒11 and indices ranged from 0.7‒0.9, respectively. Among the antimicrobial resistance determinants examined, genes encoding for resistance to erythromycin ermB 25 (51 percent), tetracycline tetM 32 (65 percent) and penicillin bla-Z 4 (8 percent) only were identified. On the other hand, screening for S. aureus yielded a total of 7 isolates from 4 study participants as confirmed by PCR based on staphylococcal, nuc gene. The isolates were further screened for the presence of six virulence genes (Hla, Hlb, LUKM, LUKED, PVL, Eta and Etb) and antibiotic susceptibility pattern by the disc diffusion method using 12 (penicillin, vancomycin, tetracycline, rifampicin, imipenem, gentamycin, chloramphenicol, norfloxacin, oxacillin, erythromycin and sulfamethoxazole-trimethoprim) antibiotics that are adopted in the treatment of infections caused by the organism. PVL 6 (85.7 percent) and eta 1 (14.3 percent) were the two virulence genes detected. The following percentages of antibiotics resistance among the isolates were observed; penicillin G 7 (100 percent), clindamycin 7 (100 percent), vancomycin 5 (100 percent), rifampicin 5 (71 percent), oxacillin 5 (71 percent), erythromycin 5 (71 percent) gentamycin 3 (43 percent), norfloxacin 3 (43 percent), sulfamethoxazole-trimethoprim 3 (43 percent), chloramphenicol 2 (29 percent), imipenem 1 (14 percent). Multiple antimicrobial resistance patterns ranged from 7‒8 and indices ranged from 0.6‒0.7, respectively. Genetic profiling of the resistance genes identified erythromycin ermB 5(71.4 percent), tetracycline tetM 5(71.4 percent) and penicillin bla-Z 1(14.3 percent) only. The findings from the study have revealed GBS and S. aureus colonization of pregnant women in the Eastern Cape Province, and these have great public health implications especially for the neonates who are mostly likely to be infected during birth. The unidentifiable multidrug resistant serogroups of GBS as well as resistant S. aureus limit the choice of drugs in the management of infections caused by these pathogens more so if transmitted to infants. Therefore asymptomatic pregnant women needed to be properly educated about the bacteria as well as the precautions that need to be taken.

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No. of bitstreams: 1 cp076419.pdf: 1045738 bytes, checksum: 5237df70e47139e5fc38d68eed3c013a (MD5) Previous issue date: 2008 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Objetivos: (i) avaliar a distribuição dos tipos de SCCmec e freqüência da leucocidina de Panton-Valentine (PVL) em Staphylococcus aureus resistentes à meticilina (MRSA), coletados como parte de um programa de vigilância em sete centros médicos na Argentina, Brasil e Chile; (ii) avaliar a relação entre os tipos de SCCmec e perfis de sensibilidade a antimicrobianos; (iii) caracterizar os clones de MRSA predominantes nestes centros médicos, utilizando a técnica de eletroforese em campo pulsado (PFGE). Material e Métodos: Foram incluídos todos os isolados MRSA dos sete centros médicos, coletados como parte do Programa SENTRY na América Latina no período 1997-2006. As amostras foram estratificadas em dois subgrupos, de acordo com a sensibilidade in vitro a agentes não β-lactâmicos: multissensível (MS-MRSA) e multirresistente (MR-MRSA). Amostras representativas de cada subgrupo, selecionadas de acordo com o ano e país de isolamento, foram submetidas a testes fenotípicos e genotípicos adicionais. Os tipos de SCCmec foram caracterizados pela reação em cadeia da polimerase (PCR) multiplex, seguidos da pesquisa do complexo ccr e PVL, caso pertinente. Os tipos clonais foram investigados por PFGE. As características demográficas dos pacientes infectados foram analisadas de acordo com cada subgrupo de SCCmec. Resultados: Foram avaliados 56 isolados de MS-MRSA e 141 de MR-MRSA. A maioria de amostras MS-MRSA carreavam SCCmec I (35,7%) ou IV (46,4%); por outro lado, o tipo III predominou no subgrupo MR-MRSA. A maioria de SCCmec I foi detectado na Argentina (n=5) e Chile (n=14). A maioria das 26 amostras tipo IV foram identificadas no Brasil (n=20), apenas cinco foram positivas para PVL, e a média da concentração inibitória mínima (CIM) para oxacilina foi de 45,1 µg/ml. O dendograma obtido pelo perfil de bandas de PFGE classificou as amostras em três grupos distintos: clone brasileiro epidêmico (SCCmec III), clone pediátrico (SCCmec IV), e uma linhagem possivelmente relacionada ao clone Chile/Córdoba (SCCmec I). Conclusões: A coleção de MRSA avaliada continha uma grande diversidade de tipos de SCCmec e linhagens clonais. Os perfis de sensibilidade (MS-MRSA e MR-MRSA) correlacionaram-se bem aos tipos de SCCmec nas diferentes regiões geográficas avaliadas. / Objectives: (i) to evaluate the SCCmec type distribution and the frequency of PantonValentine leukocidin (PVL) gene among methicillin-resistant Staphylococcus aureus (MRSA) collected as part of a surveillance program from seven medical centers in Argentina, Brazil and Chile; (ii) to evaluate the relationship between SCCmec types and antimicrobial susceptibility profiles; (iii) to characterize the predominant MRSA clones in these medical centers, employing the pulsed-field gel electrophoresis (PFGE) technique. Material and Methods: All MRSA isolates from the seven participant centers, collected as part of the SENTRY Latin American Program during 1997-2006 were included. MRSA were stratified into two subgroups: multi-susceptible (MS-MRSA) and multi-resistant (MR-MRSA), according to in vitro susceptibility to selected non-β- lactam agents. Representative isolates of each subgroup, selected by year and country of isolation, were submitted to additional phenotypic and genotypic testing. SCCmec types were characterized by multiplex polymerase chain reaction, followed by ccr complex and PVL assessment if applicable. Clonal types were determined by PFGE. Demographic characteristics of infected patients were analyzed according to each SCCmec subgroup. Results: Overall, a total of 56 MS-MRSA and 141 MR-MRSA were evaluated. Most MS-MRSA harbored either SCCmec I (35,7%) or IV (46,4%); in contrast, SCCmec III prevailed among MR-MRSA. The majority of SCCmec I was detected in Argentina (n=5) and Chile (n=14). Among the 26 type IV isolates, most were identified in Brazil (n=20), only five carried the PVL gene and their mean oxacillin minimal inhibitory concentration (MIC) value was 45,1 µg/ml. The band-based dendogram clustered the Latin American MRSA strains into three distinct PFGE groups: the Brazilian epidemic clone (SCCmec III), the pediatric clone (SCCmec IV), and a lineage possibly related to the Chile/Cordoba clone (SCCmec I). Conclusions: Genetic and geographic diversity of SCCmec and clonal types were identified in the MRSA collection evaluated. Phenotypic susceptibility patterns (MS-MRSA and MR-MRSA) correlated well to specific SCCmec types in the geographic regions evaluated.

Made available in DSpace on 2015-07-22T20:50:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-03-31 / Objetivo geral: Caracterizacao fenotipica e genotipica de S. aureus resistentes a oxacilina (MRSA), coletados de hemoculturas provenientes de diversos centros participantes do projeto SCOPE - Brasil, no periodo de Junho de 2007 a Julho de 2009. Objetivos especificos: (i) avaliar a distribuicao dos tipos de SCCmec atraves das tecnicas de PCR convencional e PCR multiplex das diferentes instituicoes participantes; (ii) detectar a possivel presenca do gene lukF codificador da toxina PVL (Panton Valentine Leukocidin); (iii) avaliar a similaridade genetica das amostras utilizando as tecnicas de PFGE e MLST e (iv) determinar as concentracoes inibitorias minimas a oxacilina e vancomicina. Material e Metodos: Foram avaliados 62 isolados de MRSA provenientes do primeiro episodio de infeccao de corrente sanguinea (ICS) de pacientes hospitalizados em 11 centros medicos de diferentes regioes do pais. Os isolados resistentes a oxacilina foram submetidos a PCR convencional para a deteccao do gene nuc e lukF e PCR multiplex para identificar os tipos de SCCmec. Foi feito diluicao em agar e EtestR para vancomicina, PFGE e MLST. Resultados: Do total de 62 amostras, 29 amplificaram para o SCCmec tipo III, 16 amplificaram para o SCCmec tipo II, 9 amostras amplificaram para o SCCmec tipo IV, 6 amplificaram para SCCmec tipo I e 2 amostras nao foram identificadas pelas metodologias de PCR multuplex utilizadas. A amostra com SCCmec subtipo IVc apresentou o gene que codifica PVL. As amostras com SCCmec tipo I, II e III apresentaram CIM >256 ƒÊg/ml para oxacilina por EtestR com excecao de uma delas com SCCmec tipo II com CIM igual a 128 ƒÊg/ml. Seis amostras do total de nove com SCCmec tipo IV apresentaram CIM.48 ƒÊg/ml. Observamos CIMs de 1,0, 1,5 e 2,0 ƒÊg/m para vancomicina por EtestR. Quando feito a diluicao em agar, duas amostras tiveram CIM igual a 2,0 ƒÊg/ml, todas as outras apresentaram valores entre 0,5 e 1,0 ƒÊg/ml. Dentre as 8 amostras de MRSA que foram submetidas a tecnica de MLST, verificou-se ST105 em amostras com SCCmec tipo I; ST5 e ST105 para amostras com SCCmec tipo II; ST239 para amostras carreando SCCmec tipo III e ST5 e ST1176 relacionados a amostras apresentando SCCmec tipo IV. Conclusoes: Houve predominio de amostras de MRSA carreadoras de SCCmec tipo III e relacionadas geneticamente ao clone CEB. Foram detectadas amostras portando SCCmec tipo II e IV relacionados aos clones Nova Iorque/Japao e Pediatrico em diferentes hospitais e regioes do pais e ausencia do clone Chile/Cordoba. Apenas uma amostra com SCCmec tipo IV (subtipo IVc) nao relacionada a nenhum clone foi produtora de PVL. Apenas dois ancestrais geneticos comuns (CC5 e CC8) nas amostras estudadas foram observados pela tecnica de MLST, sendo caracterizado um novo ST1176. Nao foram detectadas amostras resistentes a vancomicina. / General objective: Phenotypic and genotypic characterization of methicillin-resistant S. aureus (MRSA) collected from bloodcultures from several centers participants of Brazilian SCOPE Project, from June 2007 to July 2009. Specific Objectives: (i) to assess the different types of SCCmec distribution through conventional and multiplex PCR for the different participant institutions; (ii) to detect the possible presence of lukF gene, which codes for PVL toxin (Panton Valentine Leukocidin); (iii) to assess the genetic similarity of these samples through PFGE and MLST and (iv) to determine the oxacillin and vancomycin minimal inhibitory concentration (MIC). Material and Methods: Sixty two MRSA isolated from the first episode of bloodstream infection (BSI) were evaluated. These samples came from patients hospitalized at the 11 medical centers from different regions of the country. The oxacillin-resistant isolated were submitted to conventional PCR to detect nuc and lukF genes and to multiplex PCR to identify SCCmec types. Agar dilution and E-test for vancomycin were performed. The strains were molecular typed by PFGE and MLST. Results: From the total of 62 samples, 29 amplified SCCmec type III, 16 SCCmec type II, 9 SCCmec type IV, 6 SCCmec type I and 2 could not be identified. A sample with SCCmec subtype IVc carried the gene which codifies for PVL. Samples with SCCmec types I, II and III showed MIC > 256 ƒÊg/ml for oxalicin by EtestR. Just one of them, with SCCmec type II, presented MIC = 128 ƒÊg/ml. From the nine samples with SCCmec type IV, six presented MIC . 48 ƒÊg/ml. MICs of 1.0, 1.5 e 2.0 ƒÊg/ml were also observed for vancomycin by EtestR. Regarding the agar dilution, two samples presented MICs of 2.0 ƒÊg/ml and all the others showed values between 0.5 e 1.0 ƒÊg/ml. From the 8 MRSA samples typed by MLST, it was observed ST105 in a sample with SCCmec type I; ST5 and ST105 in samples with SCCmec type II, ST239 with SCCmec type III and ST5 and ST1176 with SCCmec type IV. Conclusion: The majority of samples were MRSA carrying SCCmec type III and genetically related to CEB clone. Also were detected samples SCCmec type II and IV, related to New York/Japan and Pediatric clones in different hospitals at different regions of the country. Only one sample SCCmec type IV (subtype IVc) not related to any clone was positive for PVL. Only two common genetic ancestral (CC5 and CC8) were observed through MLST and a new ST1176 was characterized. No vancomycin-resistant isolate was detected. / TEDE / BV UNIFESP: Teses e dissertações

The purpose of this study was to evaluate the antimicrobial potential of the propolis extract, natural substance known for its therapeutic properties, against to 67 microbial isolates of canine otitis. The Minimum Bactericidal Concentration (MBC) of the propolis extract against the isolates of coagulase-positive Staphylococcus and the Minimum Fungicide Concentration (CFM) for Malassezia sp. isolates were determined using the broth microdilution technique. The MBC was 15.1mg mL-1, while the MFC was 2.4mg mL-1. Thus was shown the antimicrobial potential of the propolis extract tested against these two agents and the lower bactericidal and fungicidal concentration needed for the inhibition of them. / O objetivo do presente estudo foi avaliar o potencial antimicrobiano do extrato de própolis, substância natural conhecida pelas suas propriedades terapêuticas, frente a 67 isolados microbianos da otite canina. A Concentração Bactericida Mínima (CBM), do extrato de própolis, frente a isolados de Staphylococcus coagulase positiva e a Concentração Fungicida Mínima (CFM) para isolados de Malassezia pachydermatis foram determinadas utilizando-se a técnica de microdiluição em caldo. A CBM foi de 15,1mg mL-1, enquanto a CFM foi de 2,4mg mL-1.Dessa forma foi demonstrado o potencial antimicrobiano do extrato de própolis testado contra esses dois agentes e a menor concentração bactericida e fungicida necessária para a inibição dos mesmos.

Methicillin-resistant Staphylococcus aureus is a leading cause of hospital infections world-wide. Consecutive S. aureus wound isolates (n=561) were collected from PHW Microbiology ABM Laboratory, Swansea (PHW-ABM); 137 (24.4%) were mecA-positive; 424 (75.6%) were mecA-negative using real-time PCR. Audit revealed that 15 (10.9%) mecA-positive strains were not reported as MRSA. Genotyping was performed using pulsed-field gel electrophoresis (PFGE), spa typing and SCCmec typing. MRSA predominantly belonged to EMRSA-15 (89.1% >) and EMRSA-16 (5.8%) clones. All S. aureus strains were included in an evaluation of three SCCmec-orfX PCR assays. The assays had high diagnostic sensitivity (>95%) and specificity (> 94% >) but false negative and false positive results were obtained. A deletion at the SCCmec-orfX right junction was proposed as the probable cause of false negative results. SCCmec-associated loci ccrAB1, ccrAB4, ccrC, and dcs were detected in four false positive MSSA, respectively. MALDI Biotyper mass spectrometry was evaluated for identification of S. aureus. Nineteen (3.4%) of the PHW-ABM wound isolates were Panton Valentine-Leukocidin (PVL)-positive S. aureus. The molecular epidemiology of these and PVL-positive S. aureus (n=61) from Specialist Antimicrobial Chemotherapy Unit, Cardiff (SACU) was investigated using mecA and arginine catabolic mobile element PCRs, PFGE, spa and SCCmec typing. The PHW-ABM strains were predominantly MSSA belonging to the CC159 (n=5; 26.3%), CC275 (n=4; 21.1%) and CC005 (n=2; 10.5%) spa-BURP clusters, affiliated to the ST121, ST30 and ST22 lineages. Within the SACU cohort the USA300 clone (n=16; 26.2%) was predominant, other genotypes included: t044- MRSA-IVc (n=5; 8.2%); t002-MRSA-IVc (n=3; 4.9%) and t127-MRSA-IVa (n=2; 3.3%), affiliated to the European (ST80), USA800 (ST5) and USA400 (ST1) clones. Susceptibility testing demonstrated statistically significant differences between the SACU and PHW-ABM cohorts for oxacillin 57%/5% >, gentamicin 2%/16%, and tetracycline 10% >/42% resistance (p < 0.05). These observed differences highlight the importance of including unselected strains in addition to referred reference laboratory isolates in epidemiological investigations.

Synthesis of polysaccharide intercellular adhesin (PIA), accumulation associated protein (Aap) and extracellular matrix binding protein (Embp) are major mechanisms used by Staphylococcus epidermidisto evade immunity through biofilm formation. These evasion strategies are particularly suited for colonisation of medical devices such as heart valves, joint prostheses and central venous catheters resulting in significant patient morbidity. Two biological activities of PIA, Aap and Embp contribute to their role as an evasion molecules. Firstly their ‘barrier’ function limiting penetration of immune cells and antibiotics. Secondly, their ‘immunomodulatory’ properties which influence cytokine responses. At present little is known about these functional activities in physiological media and biological fluids. This thesis uses a cell biology approach to study the environment necessary for PLA production. Specifically in vitromodelling of biofilm formation, PIA production and S. epidermidisleukocyte co-culture experiments have been used to assess conditions that are conducive for PIA production. This thesis has identified that:• Specific cell culture media cause unique profiles of biofilm accumulation with differential production of PIA, Aap and Embp. • Fetal bovine serum and pooled human serum support S. epidermidisgrowth but differentially affect biofilm formation by PIA, Aap and Embp. • Large scale production of PIA (~20mg) can be achieved by culturing in Iscove's Modified Dulbecco's Media which has allowed streamlining of current isolation procedures. • PIA induction of cytokines, including IL-8 and TNF is dependent on being tethered to the bacterial membrane. • Macrophages can penetrate into a S. epidermidisproduced PIA ‘barrier’. • Immunosuppression of whole blood with dexamethasone unmasks the pathogenic advantage of PIA in S. epidermidis expressing PIA compared to negative controls. • Whole blood killing of S. epidermidisis dependent on CD1 lb/CD 18. • PIA induces whole blood killing dysfunction which is likely related to C5a production. • PIA can be produced in a whole blood environment.• Inocula of -1 0 colony forming unit of S. epidermidisare required to form biofilms in whole blood. This study suggests the importance of studying clinically important biofilm production mechanisms under conditions that closely resemble those in human disease.

Made available in DSpace on 2014-06-11T19:27:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-03-14Bitstream added on 2014-06-13T19:35:16Z : No. of bitstreams: 1 miranda_es_me_botib.pdf: 341881 bytes, checksum: 0398d195977255821cd91dc539be7ad7 (MD5) / A mastite é uma inflamação da glândula mamária, geralmente causada por infecção bacteriana, causando as maiores perdas econômicas na bovinocultura leiteira, devido à redução na produção de leite e de sua qualidade, aumento do uso de medicamentos e morte dos animais. Existem muitos micro-organismos responsáveis pela mastite bovina, mas Staphylococcus sp permanecem como os mais comumente isolados, em casos de mastites clínicas e subclínicas. São vários os fatores de virulência envolvidos nessa patogênese, principalmente a produção de biofilmes, o que explicaria a cronicicidade da infecção e a produção de toxinas. A presença constante desses micro-organismos pode ocasionar a seleção de cepas resistentes, além de ser um perigo no momento da ordenha, pois o leite contaminado pode causar intoxicações, devido à ingestão de enterotoxinas pré formadas. Assim, o objetivo do trabalho foi identificar os Staphylococcus sp isolados a partir de 279 amostras de leite de vacas saudáveis e 293 de vacas com mastite (clínica ou subclínica), quanto à formação de biofilmes, além da resistência a determinadas drogas. Foram isolados 63 (22,6%) cepas de Staphylococcus sp, entre as amostras de leite de animais hígidos e 80 (27,3%), entre os doentes. A espécie mais frequentemente isolada entre os animais doentes foi S. warneri (27,5%), mas S. aureus (17,5%) foi a única espécie onde ocorreu diferença estatisticamente significativa (p-valor 0,001) entre ambos os grupos, comprovando sua maior ocorrência em animais doentes. Em relação à produção de biofilme, foram testadas duas metodologias e a técnica da microplaca (p-valor 0,47) foi melhor que a do vermelho congo (p-valor 0,29). O gene mecA foi encontrado em 14 (9,8%) das 143 cepas analisadas,ocorrendo somente em estafilococos coagulase negativa (ECN). S. aureus ocorreu predominantemente em vacas doentes, enquanto... / Mastitis is an inflammation of breast tissue, by bacterial infection. It causes economic losses to dairy cattle, because mastitis results in decrease of production and in low quality of milk, increasing antimicrobial treatment and cows mortality. Several microorganisms are associated to bovine mastitis, but Staphylococcus spp. remain as the most commonly isolated bacteria from clinical and subclinical mastitis. Several virulence factors are involved in mastitis pathogenesis; one of the most important of them is the biofilm production that can explain the infection persistency. The persistency of these microorganisms can select antimicrobial resistant strains, besides, can contaminate the milk during collection, resulting in foodborne for the consumers, if pre formed enterotoxins were present. The aim of this study was to identify the species of Staphylococcus, to detect the biofilm formation and to characterize the antimicrobial susceptibility patterns in strains isolated from milk of 279 healthy and 293 mastitic cows. Sixty-three strains of Staphylococcus spp. were isolated from milk of healthy cow (22.6%), and 80 from mastitic cow milk samples (27.3%). The most common species isolated from sick cows were S. warneri (27.5%), but S. aureus was the only species that was significantly (P value 0.001) more associated with mastitic cows group. Regarding to biofilm production, two methodologies were carried out. The microtiter plate assay detected more biofilm producer strains (47%) than the congo red agar technique (29%). In relation to mecA gene, that confers resistance to all beta-lactam antimicrobial agents, it was detected in 14 (9.8%) out of 143 analyzed strains, all of them occurring in coagulase-negative staphylococci. In summary, we observed that S. aureus occurred mainly in mastitic cows, while coagulase-negative staphylococci occurred equally between the healthy and sick (Complete abstract click electronic access below)