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Caracteriza????o gen??tica de isolados cl??nicos e ambientais de Klebsiella pneumoniae

By Patricia Mayer Lima

Abstract

Klebsiella sp. ?? uma bact??ria ub??qua, respons??vel por infec????es nosocomiais oportunistas. Linhagens multirresistentes a antibi??ticos t??m se tornado um problema cada vez mais freq??ente no mundo todo. Estudos objetivando a determina????o do potencial patog??nico dos isolados ambientais s??o escassos. K. pneumoniae de origem ambiental poderia estar atuando como reservat??rio de genes de resist??ncia que eventualmente poderiam ser transferidos e levar ao aparecimento linhagens multirresistentes. Nosso objetivo ?? determinar o perfil de resist??ncia aos antimicrobianos de isolados cl??nicos e ambientais de K. pneumoniae, determinar os gen??tipos circulantes e sua clonalidade e caracterizar a gen??tica da resist??ncia observada. A susceptibilidade a 9 classes de antibi??ticos foi determinada para os 76 isolados cl??nicos e ambientais. De modo geral, os isolados cl??nicos mostraram-se resistentes a maioria das classes de antibi??ticos testadas, enquanto os isolados ambientais mostraram-se suscet??veis ??s diferentes classes. A pesquisa por elementos gen??ticos associados a resist??ncia a antibi??ticos mostrou a presen??a de integron de classe 1 entre os isolados cl??nicos e integron de classe 2 em isolados ambientais. Os principais cassetes identificados no integron de classe 1 foram acetilt- e adenil-transferases ou dihidrofolatoredutase, os cassetes mais frequentemente encontrados nessa classe. No integron de classe 2, foi caracterizado o arranjo sat-aadA. Essa ?? a primeira identifica????o de integron de classe 2 em isolado ambiental de K. pneumoniae. A caracteriza????o da rela????o gen??tica entre os isolados, utilizando MLST, mostrou a exist??ncia de 45 sequencias-tipo(STs), das quais 24 novas. A an??lise por MLST mostrou que existe uma linhagem principal, distribu??da pelo Brasil. Identificamos STs pand??micos: ST11, ST23, ST37, ST423 e ST437 e sua distribui????o mostra a exist??ncia de complexos clonais distribu??dos em diferentes regi??es geogr??ficas do Brasil.Klebsiella sp. Are ubiquitous bacteria associated with opportunistic nosocomial infections. Multiresistant strains to antibiotics have become an increasingly common problem worldwide. Studies focused on determining the pathogenic potential of environmental isolates are scarce. K. pneumoniae environmental strains could be acting as reservoirs of resistance genes that could be transferred and eventually lead to the emergence of multiply antibiotic-resistant strains. Our aim is to determine the antimicrobial resistance profiles of clinical and environmental K. pneumoniae strains, characterize the circulating genotypes and their clonality, and investigate the presence of genetic elements associated with the resistance observed, in Brazil. The susceptibility to nine classes of antibiotics was determined for 76 clinical and environmental isolates. There is a prevalence of the multidrug resistant phenotype (MDR) within the clinical isolates, whilst the environmental isolates are susceptible to different classes of antibiotics. The search for genetic elements associated with antibiotic resistance revealed the presence of class 1 and class 2 integrons among clinical and environmental isolates, respectively. The main gene cassettes present in class 1 integrons were aac and aad (acetylt- and adenyl-transferases) or dfr (dihydrofolateredutase), the most commonly found in class 1 integrons. The class 2 integron harbored the sat-aadA arrangement. This is the first observation of class 2 integrons in environmental K. pneumoniae isolates. Using the MLST approach, the genetic relationship among the strains showed 45 sequence-types (STs), of which 24 have not been described yet. The MLST analysis revealed a major K. pneumoniae lineage distributed throughout Brazil. Pandemic STs were identified among the clinical strains: ST11, ST23, ST37, ST423 and ST437. Their distribution shows the existence of clonal complexes throughout geographic regions of Brazil

Topics: Infec????o Hospitalar /virologia, Anti-Infecciosos /imunologia, Resist??ncia Microbiana a Medicamentos /imunologia, Cross Infection /virology, Anti-Infective Agents /immunology, Drug Resistance, Microbial /immunology, Infec????o Hospitalar /virologia, Anti-Infecciosos /imunologia, Resist??ncia Microbiana a Medicamentos /imunologia
Year: 2011
OAI identifier: oai:agregador.ibict.br.RI_FIOCRUZ:oai:localhost:icict/6440
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