Characterization of flagella produced by clinical strains of stenotrophomonas maltophilia

Stenotrophomonas maltophilia is an emerging nosocomial pathogen associated with opportunistic infections in patients with cystic fibrosis, cancer, and HIV. Adherence of this organism to abiotic surfaces such

as medical implants and catheters represents a major risk for hospitalized patients. The adhesive surface factors involved in adherence of these bacteria are largely unknown, and their flagella have not yet been

characterized biochemically and antigenically. We purified and characterized the flagella produced by S. maltophilia clinical strains. The flagella filaments are composed of a 38-kDa subunit, SMFliC, and analysis

of its N-terminal amino acid sequence showed considerable sequence identity to the flagellins of Serratia marcescens (78.6%), Escherichia coli, Proteus mirabilis, Shigella sonnei (71.4%), and Pseudomonas

aeruginosa (57.2%). Ultrastructural analysis by scanning electron microscopy of bacteria adhering to plastic showed flagellalike structures within the bacterial clusters, suggesting that flagella are produced as the

bacteria spread on the abiotic surface.

Estudo da adesäo de Escherichia coli enteroagregativa (EAEC) a superfícies bióticas e abióticas / Study of adhesion of enteroaggregative Escherichia coli (EAEC) the biotic and abiotic surfaces

Escherichia coli enteroagregativa (EAEC) é um emergente agente de diarréia em diversos países e é definida por seu característico padräo de aderência agregativa (AA) a células HEp-2. Tem sido demonstrado que o fenótipo AA em cepas de EAEC está associado com a presença do plasmídio de 65 MDa (plasmídio AA), no qual estäo presentes vários genes relacionados às propriedades de virulência, bem como os genes que codificam para os fatores de aderência melhor estudados em EAEC, as fímbrias de aderência agregativa (AAFs). Até o presente momento, somente duas diferentes AAFs têm sido descritas: AAF I e AAF II. No presente trabalho, nos propusemos a estudar a relaçäo estrutura-funçäo destas fímbrias com o intuito de esclarecer alguns aspectos sobre a adesäo de EAEC a superfícies bióticas e abióticas...

The iron uptake mechanisms of enteroinvasive "Escherichia coli"

Enteroinvasive "Escherichia coli" strains (EIEC) of different serotypes isolated from patients with acute diarrhea were examined for the ability to produce siderophores and iron-regulated outer membrane proteins (IROMP). For iron starvation cultures were grown at 37ºC in LB supplied with 200(micro)M of (alpha)-(alpha)'dypirydil. All strains produced enterobactin and twelve (40(per cent)) produced aerobactin. The strains showed IROMP varying from 67-82 kDa. Proteins were either induced or stimulated by the iron starvation. Differences were observed in the electrophoretic profile among the serotypes, originating 5 electrophoretic profiles. All serotypes expressed proteins of 82kDa (FepA) and 76 kDa (IutA) (except serotype O28ac:H(-) that did not produce the 76 kDa protein). Several strains (O29:H(-), O144:H(-), 0152:H(-), and O167:H(-)) expressed IutA in the outer membrane, in the abscence of aerobactin production. Additionally to well characterized proteins (FepA and IutA), we found two IROMP of unknown function in some serotypes: a 71 kDa protein was detected in three profiles and a 67 kDa protein was present in serotype O152:H(-). Moreover, two bands (39 and 43 kDa) which were not iron-regulated bound specifically to human lactoferrin