Ygnacio Martínez-Laguna

Learn More
Expression of bfpA, the gene coding for the structural subunit of the bundle-forming pili (BFP) in enteropathogenic Escherichia coli (EPEC), requires the product of bfpT (also called perA), a member of the AraC family of transcriptional regulators. Here, we show that bfpT-cat fusions were not expressed in a bfpT - or in a non-EPEC strain, unless a(More)
The ability of Escherichia coli O157:H7 to colonize the intestinal epithelia is dependent on the expression of intimin and other adhesins. The chromosome of E. coli O157:H7 carries two loci encoding long polar fimbriae (LPF). These fimbriae mediate adherence to epithelial cells and are associated with colonization of the intestine. In order to increase our(More)
Pathogenic Escherichia coli that colonize the small intestine primarily cause gastrointestinal illness in infants and travelers. The main categories of pathogenic E. coli that colonize the epithelial lining of the small intestine are enterotoxigenic E. coli, enteropathogenic E. coli, and enteroaggregative E. coli. These organisms accomplish their pathogenic(More)
Long polar fimbriae 1 (Lpf1) of Escherichia coli O157:H7 is a tightly regulated adhesin, with H-NS silencing the transcriptional expression of the lpf1 operon while Ler (locus of enterocyte effacement-encoded regulator) acts as an antisilencer. We mapped the minimal regulatory region of lpf1 required for H-NS- and Ler-mediated regulation and found that it(More)
PerA is a key regulator of virulence genes in enteropathogenic E. coli. PerA is a member of the AraC/XylS family of transcriptional regulators that directly regulates the expression of the bfp and per operons in response to different environmental cues. Here, we characterized mutants in both the amino (NTD) and carboxy (CTD) terminal domains of PerA that(More)
Worldwide, 130 million persons are estimated to be infected with HCV. Puebla is the Mexican state with the highest mortality due to hepatic cirrhosis. Therefore, it is imperative to obtain epidemiological data on HCV infection in asymptomatic people of this region. The objective of present study was to analyze the prevalence of antibodies and genotypes of(More)
The molecular mechanisms controlling expression of the long polar fimbriae 2 (Lpf2) of enterohemorrhagic Escherichia coli (EHEC) O157:H7 were evaluated. Primer extension was used to locate the lpfA2 transcriptional start site in EHEC strain EDL933 at 171 bp upstream of the lpfA2 start codon. Semi-quantitative RT-PCR demonstrated that the highest lpfA2(More)
Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 colonizes the human intestine and is responsible for diarrheal outbreaks worldwide. Previously we showed that EHEC produces long polar fimbriae (LPF) and that maximum expression is observed during the exponential phase of growth at 37 degrees C and pH 6.5. In this study, we analyzed the roles of(More)
The genus Klebsiella belongs to the family Enterobacteriaceae, and is currently considered to be non-motile and non-flagellated. In the present work, 25 Klebsiella strains isolated from nosocomial infections were assessed for motility under different growth conditions. One Klebsiella isolate, KpBUAP021, demonstrated a swim-like motility phenotype. The K.(More)
The presence of extended spectrum β-lactamase (ESBL) and plasmid-mediated AmpC β-lactamase (pAmpC) producing Escherichia coli, along with the mechanisms of antimicrobial resistance and the molecular types of isolates, was investigated in faecal samples from 53 healthy dogs in Mexico. Samples were inoculated on Levine agar plates with 2 µg/mL cefotaxime for(More)