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Patrick Trieu-Cuot

Publications and source records attributed to Patrick Trieu-Cuot.

25 records · Page 2Linked to original sources
PubMed2002

Formation of D-alanyl-lipoteichoic acid is required for adhesion and virulence of Listeria monocytogenes.

The dlt operon of Gram-positive bacteria comprises four genes (dltA, dltB, dltC and dltD) that catalyse the incorporation of D-alanine residues into the cell wall-associated lipoteichoic acids (LTAs). In this work, we characterized the dlt operon of Listeria monocytogenes and constructed a D-Ala-deficient LTA mutant by inactivating the first gene (dltA) of this operon. The DltA- mutant did not show any morphological alterations and its growth rate was similar to that of the wild-type strain. However, it exhibited an increased susceptibility to the cationic peptides colistin, nisin and polymyxin B. The virulence of the DltA- mutant was severely impaired in a mouse infection model (4 log increase in the LD50) and, in vitro, the adherence of the mutant to various cell lines (murine bone marrow-derived macrophages and hepatocytes and a human epithelial cell line) was strongly restricted, although the amounts of surface proteins implicated in virulence (ActA, InlA and InlB) remains unaffected. We suggest that the decreased adherence of the DltA- mutant to non-phagocytic and phagocytic cells might be as a result of the increased electronegativity of its charge surface and/or the presence at the bacterial surface of adhesins possessing altered binding activities. These results show that the D-alanylation of the LTAs contributes to the virulence of the intracellular pathogen L. monocytogenes.

Alanine↗
PubMed2002

Genome sequence of Streptococcus agalactiae, a pathogen causing invasive neonatal disease.

Streptococcus agalactiae is a commensal bacterium colonizing the intestinal tract of a significant proportion of the human population. However, it is also a pathogen which is the leading cause of invasive infections in neonates and causes septicaemia, meningitis and pneumonia. We sequenced the genome of the serogroup III strain NEM316, responsible for a fatal case of septicaemia. The genome is 2 211 485 base pairs long and contains 2118 protein coding genes. Fifty-five per cent of the predicted genes have an ortholog in the Streptococcus pyogenes genome, representing a conserved backbone between these two streptococci. Among the genes in S. agalactiae that lack an ortholog in S. pyogenes, 50% are clustered within 14 islands. These islands contain known and putative virulence genes, mostly encoding surface proteins as well as a number of genes related to mobile elements. Some of these islands could therefore be considered as pathogenicity islands. Compared with other pathogenic streptococci, S. agalactiae shows the unique feature that pathogenicity islands may have an important role in virulence acquisition and in genetic diversity.

Amino Acid Sequence↗
PubMed2002

Taxonomic dissection of the Streptococcus bovis group by analysis of manganese-dependent superoxide dismutase gene (sodA) sequences: reclassification of 'Streptococcus infantarius subsp. coli' as Streptococcus lutetiensis sp. nov. and of Streptococcus bovis biotype 11.2 as Streptococcus pasteurianus sp. nov.

The taxonomic dissection of the Streptococcus bovis-Streptococcus equinus group was carried out upon obtaining sequences for the manganese-dependent superoxide dismutase gene (sodA) of the type strains of S. bovis, Streptococcus caprinus, S. equinus, Streptococcus gallolyticus, Streptococcus infantarius, Streptococcus macedonicus and Streptococcus waius. The sodA sequences of 29 streptococcal strains of animal and human origin that were related to S. bovis were also sequenced. A phylogenetic analysis of the sodA sequences revealed that the S. bovis-S. equinus group comprises five different clusters that correspond to five distinct species. The type strains of S. bovis and S. equinus were associated in the same cluster, corresponding to the species S. equinus. The type strains of S. caprinus, S. gallolyticus, S. macedonicus and S. waius were associated in the same cluster, which defined a single species containing S. gallolyticus and its junior synonym S. caprinus, and S. macedonicus and its junior synonym S. waius. The two subspecies thought to constitute the species S. infantarius, namely S. infantarius subsp. infantarius and 'S. infantarius subsp. coli', were located in two distinct clusters. One of these clusters defined the species S. infantarius and included the type strain of S. infantarius subsp. infantarius. The other cluster defined 'S. infantarius subsp. coli', leading to the proposal of its reclassification as the novel species Streptococcus lutetiensis (NEM 782T = CIP 106849T). The remaining cluster comprised all of the strains previously identified as belonging to S. bovis biotype 11.2, leading to the proposal to reassign these strains to the novel species Streptococcus pasteurianus (NEM 1202T = CIP 107122T). The results of the phylogenetic analysis were confirmed by DNA-DNA hybridization experiments, thus demonstrating that sequence databases of defined DNA targets, such as sodA, may constitute a valuable alternative approach for modern bacterial systematics.

Animals↗
PubMed2002

Native valve endocarditis due to Enterococcus hirae.

Enterococcus hirae is a rare isolate in clinical specimens. We describe a case of native aortic-valve endocarditis that was caused by Enterococcus hirae in a 72-year-old man. This is the first reported case of endocarditis due to this organism.

Aged↗
PubMed1997

Use of an excision reporter plasmid to study the intracellular mobility of the conjugative transposon Tn916 in gram-positive bacteria.

An excision reporter plasmid was constructed to characterize the intracellular mobility of Tn916 in various Gram-positive bacteria. The reporter component of this plasmid is a chloramphenicol-resistance gene which has been insertionally inactivated with the integrative vector pAT112 containing the attachment site of Tn916. Tn916-mediated excision of pAT112, to produce clones resistant to chloramphenicol, was detected in Enterococcus faecalis BM4110, Listeria monocytogenes L028-Str and Streptococcus gordonii BM120, but not in Lactococcus lactis MG1363-RF or in Streptococcus pneumoniae BM124, and always depended upon the ability of the bacterial host to generate circular forms of the transposon. The results suggest that (i) the excision event, although required, is not sufficient for conjugal transfer to occur and (ii) there is no linear relationship between the donor potential of E. faecalis strains and either the excision frequency of pAT112 or the copy number of Tn916 circular intermediates per cell in these hosts. Excision of pAT112 occurred mainly during the late exponential phase of growth of E. faecalis and L. monocytogenes and this recombination event was not stimulated by heat shock, salt and alcohol stresses or by the presence of tetracycline in the medium.

Chloramphenicol Resistance↗
PubMed1996

The inlA gene required for cell invasion is conserved and specific to Listeria monocytogenes.

The Gram-positive bacterium Listeria monocytogenes can actively induce its own uptake by epithelial cells and fibroblasts through a surface-exposed 80 kDa protein, internalin (InIA), encoded by inIA. We studied the distribution and the DNA polymorphism of inIA sequences in a wide variety of wild strains of L. monocytogenes as compared to other Listeria species. This was done by PCR-amplifying inIA sequences encoding the fifteen repeats A and the three repeats B of InIA. inIA-repeated sequences were only found in L. monocytogenes. The amplified fragment of inIA encoding the repeats A displayed an AIuI DNA polymorphism which arises from point mutations. These results indicate that inIA required for cell invasion is specific to L. monocytogenes and that the intragenic repeats only exhibit a genetic heterogeneity due to point mutations and not to recombinations.

Bacterial Proteins↗