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Jerome Etienne

Publications and source records attributed to Jerome Etienne.

At least 37 records · Page 2Linked to original sources
PubMed2005

Analysis of the genetic diversity of Legionella by sequencing the 23S-5S ribosomal intergenic spacer region: from phylogeny to direct identification of isolates at the species level from clinical specimens.

This study focuses on the interest of the hypervariable 23S-5S ribosomal intergenic spacer region (ISR) of the genus Legionella to analyze the phylogenic diversity of Legionella at the species and subspecies levels and to identify isolates directly from clinical specimens. The method, using a real-time PCR assay with a single primer pair followed by sequencing, was able to identify correctly 49 reference strains of Legionella belonging to 37 different species, including those implicated in human infections, and to clearly differentiate the three subspecies of L. pneumophila. Based on sequence similarities, the 23S-5S ISR sequences were much more variable than the rpoB and mip sequences (P<0.0001 by the Wilcoxon signed rank test). The 23S-5S ISR method was able to cluster Legionella species in accordance with phenotypic traits, such as autofluorescence or fatty acid membrane composition. Using maximum parsimony methods, the rpoB and 23S-5S ISR data sets were shown to be incongruent (P<0.001). In contrast, the 23S-5S ISR and the mip data sets were found to be congruent (P=0.313), suggesting the interest of combining these two regions to demonstrate phylogenetic links between Legionella species. This molecular assay was shown able to both detect Legionella DNA directly in respiratory specimens from patients exhibiting a Legionella infection and provide accurate identification of the bacterium at the species level in the tested specimens. These properties open a wide range of applications to the 23S-5S ISR sequencing method, from taxonomic analyses to clinical and epidemiological investigations.

DNA, Bacterial↗
PubMed2005

Comparative prevalence of superantigen genes in Staphylococcus aureus isolates causing sepsis with and without septic shock.

BACKGROUND: Staphylococcus aureus superantigens are associated with the pathogenesis of toxic shock syndrome, but their involvement in septic shock is unknown. METHODS: We compared the distribution of 11 superantigen genes in S. aureus blood culture isolates obtained from patients with sepsis who did and did not have septic shock (19 and 61 patients, respectively), as well as from patients with suppurative infections (101 patients) and patients with colonization (25 patients). RESULTS: The prevalence of the enterotoxin A gene (sea) increased significantly with the severity of infection (P<.001), whereas the prevalence of the enterotoxin gene cluster (egc) decreased significantly (P=.009). CONCLUSION: Enterotoxin A (SEA) might play a key role in sea-positive S. aureus sepsis by triggering over-expression of inflammatory mediators associated with shock. Novel treatments targeting superantigens, especially the sea gene, might be beneficial in the treatment of S. aureus sepsis.

Adult↗
PubMed2005

Staphylococcus aureus RNAIII and the endoribonuclease III coordinately regulate spa gene expression.

Staphylococcus aureus RNAIII is one of the largest regulatory RNAs, which controls several virulence genes encoding exoproteins and cell-wall-associated proteins. One of the RNAIII effects is the repression of spa gene (coding for the surface protein A) expression. Here, we show that spa repression occurs not only at the transcriptional level but also by RNAIII-mediated inhibition of translation and degradation of the stable spa mRNA by the double-strand-specific endoribonuclease III (RNase III). The 3' end domain of RNAIII, partially complementary to the 5' part of spa mRNA, efficiently anneals to spa mRNA through an initial loop-loop interaction. Although this annealing is sufficient to inhibit in vitro the formation of the translation initiation complex, the coordinated action of RNase III is essential in vivo to degrade the mRNA and irreversibly arrest translation. Our results further suggest that RNase III is recruited for targeting the paired RNAs. These findings add further complexity to the expression of the S. aureus virulon.

Antigens, Bacterial↗
PubMed2005

Virulence determinants in Staphylococcus aureus and their involvement in clinical syndromes.

Staphylococcus aureus is a major human pathogen responsible for a variety of toxin-mediated and suppurative diseases. About 50 staphylococcal virulence factors have been described to date. In this review, we examine the clinical implications of key staphylococcal virulence factors in toxin-mediated diseases, septic shock, and severe focal infections such as arthritis, infective endocarditis, pneumonia acquired during mechanical ventilation, and necrotizing pneumonia. Staphylococcal pathogenicity is sometimes due principally to a single virulence factor, as in toxic shock syndrome and necrotizing pneumonia. In contrast, several virulence factors are involved in other staphylococcal disease, such as septic shock. A better knowledge of the mechanism of action of each virulence factor involved in the different staphylococcal diseases could open the way to the use of specific inhibitors in the clinical setting.

Journal Article↗
PubMed2005

Thermonuclease gene as a target for specific identification of Staphylococcus intermedius isolates: use of a PCR-DNA enzyme immunoassay.

A PCR-DNA enzyme immunoassay (PCR-DEIA) was developed for identification of the coagulase-positive species Staphylococcus intermedius. Two PCR primers and a hybridization probe were designed to target specific sequences of the S. intermedius thermonuclease (nuc) gene. In addition to S. intermedius reference strains, the PCR-DEIA was tested using 295 veterinary and human S. intermedius isolates. A specific 933-bp DNA fragment was successfully amplified in 281 (94.9%) S. intermedius isolates. Five canine isolates showed an unexpected 2.8-kbp band. Except for 10 amplicons derived from equine, camel, and pigeon isolates, all positive PCR results (n = 288, 96.6%) were confirmed by the colorimetric microtiter plate DEIA hybridization. Isolates that failed both in amplification and DEIA hybridization were only observed in equine isolates (10/23, 43.5%). Except for the limitations with isolates of hoofed animals, the S. intermediusnuc PCR assay has potential for rapid identification of S. intermedius and differentiation from other coagulase-positive staphylococci including S. aureus.

Animals↗
PubMed2005

Clinical and environmental isolates of Legionella pneumophila serogroup 1 cannot be distinguished by sequence analysis of two surface protein genes and three housekeeping genes.

We used gene sequencing to determine whether clinical (sporadic, epidemic, and endemic) and environmental isolates of Legionella pneumophila serogroup (sg) 1 belong to specific lineages. A total of 178 clinical and environmental L. pneumophila sg 1 isolates, defined by pulsed-field gel electrophoresis and epidemiological data as sporadic, epidemic, or endemic, were analyzed for polymorphisms in five gene fragments. The fragments belonged to three housekeeping genes (coding for aconitase [acn], aspartate-beta-semialdehyde dehydrogenase [asd], and RNA polymerase beta subunit [rpoB]) and two surface protein genes (coding for the macrophage infectivity potentiator [mip] and the major outer membrane protein [mompS]). The phylogenetic tree inferred from sequence polymorphisms of the five genes identified two large clusters, one consisting of 133 poorly differentiated strains and containing two smaller clusters (10 and 2 strains) unrelated to each other and the other consisting of 42 strains. Clinical and environmental isolates could not be distinguished on this basis, and no link between genetic background and epidemiological type was found, suggesting that other factors are responsible for differences in pathogenicity.

Bacterial Proteins↗
PubMed2005

Clinical manifestations of staphylococcal scalded-skin syndrome depend on serotypes of exfoliative toxins.

We sought a possible correlation between the clinical manifestations of staphylococcal scalded-skin syndrome (SSSS) and the serotype of exfoliative toxins (ET) by PCR screening of the eta and etb genes in Staphylococcus aureus strains isolated from 103 patients with generalized SSSS and 95 patients with bullous impetigo. The eta gene and the etb gene were detected in, respectively, 31 (30%) and 20 (19%) episodes of generalized SSSS and 57 (60%) and 5 (5%) episodes of bullous impetigo. Both genes were detected in 52 (50%) episodes of generalized SSS and 33 (35%) episodes of bullous impetigo. To explain this link between etb and generalized SSSS, we examined the distribution of ETA- and ETB-specific antibodies in the healthy population (n = 175) and found that the anti-ETB antibody titer was lower than the anti-ETA titer. Thus, ETA is associated with bullous impetigo and ETB is associated with generalized SSSS, possibly owing to a lower titer of anti-ETB neutralizing antibodies in the general population.

Adolescent↗
PubMed2005

Consensus sequence-based scheme for epidemiological typing of clinical and environmental isolates of Legionella pneumophila.

A previously described sequence-based epidemiological typing method for clinical and environmental isolates of Legionella pneumophila serogroup 1 was extended by the investigation of three additional gene targets and modification of one of the previous targets. Excellent typeability, reproducibility, and epidemiological concordance were determined for isolates belonging to both serogroup 1 and the other serogroups investigated. Gene fragments were amplified from genomic DNA, and PCR amplicons were sequenced by using forward and reverse primers. Consensus sequences are entered into an online database, which allows the assignment of individual allele numbers. The resulting sequence-based type or allelic profile comprises a string of the individual allele numbers separated by commas, e.g., 1,4,3,1,1,1, in a predetermined order, i.e., flaA, pilE, asd, mip, mompS, and proA. The index of discrimination (D) obtained with these six loci was calculated following analysis of a panel of 79 unrelated clinical isolates. A D value of > 0.94 was obtained, and this value appears to be sufficient for use in the epidemiological investigation of outbreaks caused by L. pneumophila. The D value rose to 0.98 when the results of the analysis were combined with those of monoclonal antibody subgrouping. Sequence-based typing of L. pneumophila is epidemiologically concordant and discriminatory, and the data are easily transportable. This consensus method will assist in the epidemiological investigation of L. pneumophila infections, especially travel-associated cases, by which it will allow a rapid comparison of isolates obtained in more than one country.

Bacterial Typing Techniques↗
PubMed2005

Frequent carriage of Panton-Valentine leucocidin genes by Staphylococcus aureus isolates from surgically drained abscesses.

Between 1 February and 15 April 2002, 95 patients were admitted to Gaston Bourret Territorial Hospital (New Caledonia, France) for drainage of community-acquired soft tissue abscesses. Staphylococcus aureus was detected in 68 cases (72%). Two-thirds of the patients with S. aureus infection had furuncles, which were located on the limbs in 82% of cases. The median interval between symptom onset and hospital admission was 5.7 days. Three-quarters of the patients were Melanesians living in tribes. Fifty-four S. aureus isolates were screened for toxin genes. Panton-Valentine leucocidin (PVL) genes were detected in 48 isolates (89%), the exfoliative toxin A gene was detected in 1 isolate, and no toxin genes were detected in 4 isolates. S. aureus nasal carriage was detected in 39.7% of patients with S. aureus infections. Two infecting S. aureus strains and two nasal carriage strains were resistant to methicillin. Comparative pulsed-field gel electrophoresis, performed in 16 cases, showed that five of six patients with PVL-positive nasal carriage strains were infected by the same strains. In contrast, 8 of 10 patients with PVL-negative nasal carriage strains were infected by PVL-positive strains. PVL genes thus appear to be a major virulence factor in both primary and secondary S. aureus skin infections.

Abscess↗
PubMed2005

Staphylococcus aureus Panton-Valentine leukocidin directly targets mitochondria and induces Bax-independent apoptosis of human neutrophils.

Panton-Valentine leukocidin (PVL) is a pore-forming toxin secreted by Staphylococcus aureus that has recently been associated with necrotizing pneumonia. In the present study, we report that in vitro, PVL induces polymorphonuclear cell death by necrosis or by apoptosis, depending on the PVL concentration. PVL-induced apoptosis was associated with a rapid disruption of mitochondrial homeostasis and activation of caspase-9 and caspase-3, suggesting that PVL-induced apoptosis is preferentially mediated by the mitochondrial pathway. Polymorphonuclear cell exposure to PVL leads to mitochondrial localization of the toxin, whereas Bax, 1 of the 2 essential proapoptotic members of the Bcl-2 family, was still localized in the cytosol. Addition of PVL to isolated mitochondria induced the release of the apoptogenic proteins cytochrome c and Smac/DIABLO. Therefore, we suggest that PVL, which belongs to the pore-forming toxin family, could act at the mitochondrion level by creating pores in the mitochondrial outer membrane. Furthermore, LukS-PV, 1 of the 2 components of PVL, was detected in lung sections of patients with necrotizing pneumonia together with DNA fragmentation, suggesting that PVL induces apoptosis in vivo and thereby is directly involved in the pathophysiology of necrotizing pneumonia.

Apoptosis↗
PubMed2005

Methicillin-resistant Staphylococcus aureus in neonatal intensive care unit.

A neonatal intensive care unit outbreak was caused by a strain of methicillin-resistant Staphylococcus aureus previously found in the community (ST45-MRSA-IV). Fifteen infected neonates were identified, 2 of whom died. This outbreak illustrates how a rare community pathogen can rapidly spread through nosocomial transmission.

Anti-Bacterial Agents↗
PubMed2004

Rapid detection of Panton-Valentine leukocidin from clinical isolates of Staphylococcus aureus strains by real-time PCR.

To allow rapid identification of Panton-Valentine leukocidin (PVL)-producing Staphylococcus aureus strains, a real-time PCR assay for detection of PVL was developed. This assay is convenient, since it can be applied directly on bacterial suspensions and does not require previous DNA purification. Furthermore, the assay was found to be highly reproducible, robust and specific, since positive results were generated exclusively with PVL-positive S. aureus strains, and neither with PVL-negative strains nor staphylococci other than S. aureus.

Bacterial Toxins↗
PubMed2004

Two cases of fatal shock after transfusion of platelets contaminated by Staphylococcus aureus: role of superantigenic toxins.

We detected Staphylococcus aureus superantigenic toxins in the platelet infusion bags that had been used for 2 patients who subsequently developed transfusion-associated Staphylococcus aureus infection. Both patients, who were immunodeficient, developed manifestations of toxic shock syndrome and septic shock, and they died soon after the onset of infection.

Aged↗
PubMed2004

Staphylococcus aureus isolates associated with necrotizing pneumonia bind to basement membrane type I and IV collagens and laminin.

To investigate how Panton-Valentine leukocidin (PVL)-positive Staphylococcus aureus (PPSA) strains associate with specific bronchial lesions during community-acquired necrotizing pneumonia, we examined PPSA strains and PVL-negative S. aureus (PNSA) strains for their binding behavior to extracellular matrix (ECM) proteins, primary human airway epithelial cell (HAEC) cultures, and human airway mucosa damaged ex vivo. Compared with PNSA strains, PPSA strains exhibited increased affinity for damaged airway epithelium and especially for exposed basement membrane. PPSA strains, compared with PNSA strains, showed stronger affinity for type I and IV collagens and laminin, a property associated with the presence of the cna gene. PPSA and PNSA culture supernatants similarly damaged HAEC layers, whereas recombinant PVL had no effect, suggesting that an S. aureus exoprotein other than PVL might contribute to the observed airway epithelial damage. These results suggest that epithelial damage, possibly due to viral infection (which usually precedes necrotizing pneumonia) and/or to a non-PVL S. aureus exoproduct action, may permit binding of PPSA to exposed type I and IV collagens and laminin--the PVL cytotoxin being involved later during necrotizing pneumonia.

Adhesins, Bacterial↗
PubMed2004

Neutralization of Staphylococcus aureus Panton Valentine leukocidin by intravenous immunoglobulin in vitro.

Panton Valentine leukocidin (PVL) may be responsible for pulmonary necrosis in necrotizing Staphylococcus aureus pneumonia, a highly lethal infection. Commercial intravenous immunoglobulin (IVIg) preparations containing antibodies against PVL might have therapeutic value in this setting, as an adjunct to antimicrobial chemotherapy. To test this possibility, we determined anti-PVL antibody titers in commercial IVIg and the capacity of IVIg to prevent the cytopathic effects of PVL in vitro. Specific enzyme-linked immunosorbent assays based on purified recombinant PVL (rPVL) showed that IVIg contained specific anti-PVL antibodies. The cytotoxicity of rPVL and of crude culture supernatants of PVL-producing S. aureus strains were investigated by measuring ethidium-bromide incorporation by polymorphonuclear neutrophils (PMNs) in flow cytometric assays, as well as PMN ultrastructural changes by transmission electron microscopy. IVIg was found to neutralize pore formation and the cytopathic effect of both rPVL and S. aureus culture supernatants.

Bacterial Toxins↗
PubMed2004

Staphylococcus aureus isolates with reduced susceptibility to glycopeptides belong to accessory gene regulator group I or II.

We used multiplex PCR to determine the agr group membership of 18 European glycopeptide heterointermediate and intermediate-resistant Staphylococcus aureus strains. Of the 15 agr group I strains, 13 were resistant and 2 were susceptible to methicillin. The remaining three strains, like the United States and Japanese control strains, belonged to agr group II.

Anti-Bacterial Agents↗