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Biomedical subjects

Anne Tristan

Publications and source records attributed to Anne Tristan.

11 recordsLinked to original sources

Whipple's disease with muscle impairment.

A 67-year-old man presented with myalgia, muscle atrophy, and a history of seronegative polyarthritis. Blood tests showed inflammation but no hematologic or immunologic abnormalities. Muscle biopsy revealed no vasculitis or myositis but Tropheryma whipplei was detected by polymerase chain reaction in muscle, blood, and duodenum specimens; this was confirmed by immunohistochemistry. Ceftriaxone led to clinical improvement. Although rare, Whipple's disease should be considered in the differential diagnosis of diffuse myopathy.

Actinomycetales↗

Pneumonia and new methicillin-resistant Staphylococcus aureus clone.

Necrotizing pneumonia caused by Staphylococcus aureus strains carrying the Panton-Valentin leukocidin gene is a newly described disease entity. We report a new fatal case of necrotizing pneumonia. An S. aureus strain with an agr1 allele and of a new sequence type 377 was recovered, representing a new, emerging, community-acquired methicillin-resistant clone.

Bacterial Toxins↗

Active infectious endocarditis: postoperative outcome.

OBJECTIVE: Many changes have occurred in the natural history and the management of active infectious endocarditis (AIE) in recent years. Therefore, the records of patients admitted in a tertiary care specialized hospital presenting with the Duke criteria were reviewed. METHODS: Adults operated on to treat AIE were included during a 3-year period. Patients presenting with AIE associated with a pacemaker were not included. Bacteriologic investigations included blood cultures, intraoperative samplings (including polymerase chain reaction), and serologies. Clinical and bacteriologic factors associated with hospital mortality were studied by univariate regression analysis (p < 0.05). RESULTS: Ninety-eight of 164 patients (60%) admitted with the diagnosis of AIE underwent valvular surgery. The duration between the beginning of AIE and surgery was 23 +/- 16 (mean +/- standard deviation) days. Only 45 patients had a previous history of valvular disease. Seventy-two patients presented with aortic and 41 with mitral valve AIE. Fifty suffered from embolic events. Streptococcus species were responsible in 64 cases (23 were Streptococcus bovis) and Staphylococcus species in 24 cases. Death occurred postoperatively in 19 patients. The factors associated with fatal outcome were preoperative hemodynamic instability, age, Parsonnet and Simplified Acute Physiology Score II scores, diabetes mellitus, preexisting valvulopathy, antiarrhythmic treatment, hypoalbuminemia, renal dysfunction, duration of extracorporeal circulation, and red cell allogeneic transfusions. The type of bacteria did not influence mortality. The mean intensive care unit and hospital stays were 10 and 39 days, respectively. Eleven patients suffered from neurologic sequelae; 2 years later, 2 of them presented with severe deficit and 1 had died. CONCLUSIONS: AIE necessitating cardiac surgery should be considered as a severe and resource-consuming disease.

Adult↗

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↗

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↗

[New Staphylococcus aureus strains].

Staphylococcus aureus strains are present in the nose of 30% of healthy humans and are responsible for skin and soft tissue infections. Deep seated infections secondarily occurred such as osteomyelitis or infective endocarditis. New toxin-associated clinical entities have been recognized such as the toxin shock syndrome, the staphylococcal scarlet fever, the staphylococcal scalded skin syndrome or the necrotising pneumonia. This later syndrome is associated with Panton Valentine leukocidin producing strains. It occurs mainly in children and has a lethality of 75%. New antibiotic resistances are also emerging, for vancomycin in hospital-acquired infections and for methicillin in community-acquired infections.

Dermatitis, Exfoliative↗

Characterization of the fibrinogen-binding surface protein Fbl of Staphylococcus lugdunensis.

The fbl gene of Staphylococcus lugdunensis encodes a protein Fbl that is 58 % identical to the clumping factor A (ClfA) of Staphylococcus aureus. The fbl gene was present in eight clinical isolates of S. lugdunensis. When Fbl was expressed on the surface of Lactococcus lactis it promoted adherence to immobilized fibrinogen and cell clumping in a fibrinogen solution. Purified recombinant Fbl region A bound to immobilized fibrinogen in a dose-dependent manner and inhibited the adherence of both Fbl-expressing and ClfA-expressing strains of L. lactis to fibrinogen. Adherence of S. lugdunensis and L. lactis Fbl(+) to immobilized fibrinogen was also inhibited by rabbit anti-Fbl region A antibodies and rabbit anti-ClfA region A antibodies, as well as by human immunoglobulin with a high level of anti-ClfA antibodies. Alignment of the A domains of CflA and Fbl revealed that all of the ClfA residues implicated in binding to the gamma-chain of fibrinogen are conserved in Fbl. Nevertheless Fbl had a tenfold lower affinity for fibrinogen, suggesting that sequence differences that occur elsewhere in the protein, possibly in beta-strand E of domain N2, affect ligand binding.

Amino Acid Sequence↗

Bacterial competition for human nasal cavity colonization: role of Staphylococcal agr alleles.

We examined the bacterial aerobic nasal flora of 216 healthy volunteers to identify potential competitive interactions among different species, with special emphasis on the influence of staphylococcal agr alleles. The Staphylococcus aureus colonization rate correlated negatively with the rate of colonization by Corynebacterium spp. and non-aureus staphylococci, especially S. epidermidis, suggesting that both Corynebacterium spp. and S. epidermidis antagonize S. aureus colonization. Most of the S. aureus and S. epidermidis isolates were agr typed by a PCR method. Only one S. aureus agr (agr(Sa)) allele was detected in each carrier. Multiple logistic regression of the two most prevalent agr(Sa) alleles (agr-1(Sa) and agr-2(Sa)) and the three S. epidermidis agr (agr(Se)) alleles showed a specific influence of the agr system. The results of this model did not support conclusions drawn from previous in vitro agr-specific cross-inhibition experiments. Our findings suggest that the agr alleles, which are strongly linked to the bacterial genetic background, may simply be associated with common biological properties--including mediators of bacterial interference--in the strains that bear them.

Adolescent↗

Use of multiplex PCR to identify Staphylococcus aureus adhesins involved in human hematogenous infections.

We have developed a multiplex PCR procedure to determine the distribution of nine adhesin genes in Staphylococcus aureus isolates. Only genes encoding bone sialoprotein binding protein and fibronectin binding protein B were significantly associated with hematogenous osteomyelitis/arthritis and native-valve endocarditis, respectively, suggesting their involvement in hematogenous tissue infections.

Adhesins, Bacterial↗