Biomedical subjects

Patrice Francois

Publications and source records attributed to Patrice Francois.

26 records · Page 2Linked to original sources

PubMed2003

Lack of biofilm contribution to bacterial colonisation in an experimental model of foreign body infection by Staphylococcus aureus and Staphylococcus epidermidis.

The contribution of in vivo biofilm-forming potential of Staphylococcus aureus and Staphylococcus epidermidis was studied in an experimental model of foreign body infections. Increasing inocula (from 10(2) to 10(7) organisms) of ica-positive strains of S. aureus and S. epidermidis and their ica-negative isogenic mutants (the ica locus codes for a major polysaccharide component of biofilm) were injected into subcutaneously implanted tissue cages in guinea pigs. Surprisingly, bacterial counts and time-course of tissue cage infection by ica-positive strains of S. aureus or S. epidermidis were equivalent to those of their respective ica-negative mutants, in the locally infected fluids and on tissue-cage-inserted plastic coverslips.

Animals↗

PubMed2003

Comparison of fluorescence and resonance light scattering for highly sensitive microarray detection of bacterial pathogens.

Microarrays have emerged as potential tools for bacterial detection and identification. Given their high parallelism, they might represent a breakthrough in current diagnostic methods, provided they can be coupled to simplified labeling protocols and detected with adequate sensitivities. We describe here a technique to directly label total bacterial RNA, thus avoiding the multiple steps and possible biases associated with enzymatic amplification (e.g. PCR). We have then compared the performances of one white-light source and two laser-based fluorescence scanners for detection reliability and sensitivity. Our study reveals that nanoparticle-labeled bacterial RNA generates reproducible resonance light scattering signals that are at least 50 times more intense than state-of-the-art confocal-based fluorescence signals.

Light↗

PubMed2003

Patient compliance with medical advice given by telephone.

Data on compliance with medical advice given by telephone consultation services are currently lacking. The aim of this study was to assess patient compliance with medical advice given by a call center. A cross-sectional telephone survey was carried out on a random sample of 463 callers 72 hours after contacting the Grenoble Dial 15 center in France. Four hundred nine subjects (88.3%) participated in the study. Of these, 286 callers (69.9%) complied with the medical advice given. Compliance was 61.4% among patients who were advised to treat themselves, 83.9% among patients who were advised to consult a general practitioner during business hours, and 64.0% among patients who were advised to go to an accident and ED (P <.01). The survey pointed out adverse events resulting from the service. Assessing patient compliance can be an important source of information for improving aspects of patient management provided by telephone consultation services.

Adult↗

PubMed2003

Rapid detection of methicillin-resistant Staphylococcus aureus directly from sterile or nonsterile clinical samples by a new molecular assay.

A rapid procedure was developed for detection and identification of methicillin-resistant Staphylococcus aureus (MRSA) directly from sterile sites or mixed flora samples (e.g., nose or inguinal swabs). After a rapid conditioning of samples, the method consists of two main steps: (i) immunomagnetic enrichment in S. aureus and (ii) amplification-detection profile on DNA extracts using multiplex quantitative PCR (5'-exonuclease qPCR, TaqMan). The triplex qPCR assay measures simultaneously the following targets: (i) mecA gene, conferring methicillin resistance, common to both S. aureus and Staphylococcus epidermidis; (ii) femA gene from S. aureus; and (iii) femA gene from S. epidermidis. This quantitative approach allows discrimination of the origin of the measured mecA signal. qPCR data were calibrated using two reference strains (MRSA and methicillin-resistant S. epidermidis) processed in parallel to clinical samples. This 96-well format assay allowed analysis of 30 swab samples per run and detection of the presence of MRSA with exquisite sensitivity compared to optimal culture-based techniques. The complete protocol may provide results in less than 6 h (while standard procedure needs 2 to 3 days), thus allowing prompt and cost-effective implementation of contact precautions.

Bacterial Proteins↗

PubMed2003

Assessment of a structured in-hospital educational intervention addressing breastfeeding: a prospective randomised open trial.

OBJECTIVE: To determine whether a single one-to-one in-hospital education session could increase the rate of breastfeeding at 17 weeks. DESIGN: A prospective, randomised, parallel group, open trial. SETTING: A level two maternity hospital in France. SAMPLE: Breastfeeding mothers who were employed outside the home prenatally and were delivered of a healthy singleton. INTERVENTION: A structured one-to-one in-hospital education session. METHODS: One hundred and six mother-infant pairs were allocated to the intervention group and 104 to the control group (receiving usual verbal encouragement). A total of 93 mother-infant pairs in the intervention group and 97 in the control group provided complete data for final evaluation of efficacy. MAIN OUTCOME MEASURE: Rate of breastfeeding at infant age of 17 weeks. RESULTS: There was no significant difference between the two groups in the rate of any breastfeeding (34.4% in the intervention group vs 40.2% in the control group, relative risk = 0.86 [0.52-1.40]), and in the rate of exclusive breastfeeding (14.0% in the intervention group vs 14.4% in the control group, relative risk = 0.97 [0.42-2.22]). CONCLUSION: Our findings suggest that a single in-hospital educational intervention has no effect on the breastfeeding rate at four months. Guidance provided by maternity staff should be reinforced by a long term multifaceted support programme in countries with a low to intermediate rate of breastfeeding.

Adult↗

PubMed2002

Synaptotagmin II could confer Ca(2+) sensitivity to phagocytosis in human neutrophils.

Phagolysosome fusion and granule exocytosis in neutrophils are calcium-dependent processes. The calcium requirements vary between granule types, suggesting the presence of different calcium sensors. The synaptotagmins, a family of calcium-binding proteins, previously shown to participate in vesicle fusion and vesicle recycling in excitable cells, are putative calcium-sensors of exocytosis in excitable cells. In this study, we show that synaptotagmin II is present in human neutrophils and may participate in phagocytic and in exocytotic processes. In protein extracts from human neutrophils, we identified synaptotagmin II by Western blot as an 80 kDa protein. Subcellular fractionation revealed that synaptotagmin II was associated with the specific granules. In fMLP-stimulated cells, synaptotagmin II translocated to the plasma membrane. This correlated with the upregulation of complement receptor 3 (CR 3), reflecting the translocation of specific granules to the cell surface. Synaptotagmin II also translocated to the phagosome after complement-mediated phagocytosis in the presence of calcium. LAMP-1 translocated in parallel but probably was located to another subcellular compartment than synaptotagmin II. Under calcium-reduced conditions, neither synaptotagmin II nor LAMP-1 translocated to the phagosome. We therefore suggest a role for synaptotagmin II as calcium-sensor during phagocytosis and secretion in neutrophils.

Animals↗

PubMed2002

Comparison of levofloxacin, alatrofloxacin, and vancomycin for prophylaxis and treatment of experimental foreign-body-associated infection by methicillin-resistant Staphylococcus aureus.

The prophylactic and therapeutic activities of two fluoroquinolones, levofloxacin and alatrofloxacin (the L-Ala-L-Ala prodrug of trovafloxacin), were compared to those of vancomycin in two different experimental models of foreign-body-associated infections caused by methicillin-resistant but quinolone-susceptible Staphylococcus aureus (MRSA) isolates. In a guinea pig model of prophylaxis, subcutaneously implanted tissue cages were infected with 10(3) CFU of MRSA, which was a 100% infectious dose in control animals. A single dose of 50 mg of levofloxacin per kg of body weight, administered intraperitoneally 3 h before bacterial challenge, was more efficient than vancomycin for the prevention of infections in tissue cages with MRSA inocula of 10(4) and 10(5) CFU. In a rat model used to evaluate therapy of chronic tissue cage infection caused by MRSA, the efficacies of 7-day high-dose regimens of levofloxacin (100 mg/kg once a day [q.d.] or 50 mg/kg twice a day [b.i.d.]) or alatrofloxacin (50 mg/kg q.d.) were compared to the efficacy of vancomycin (50 mg/kg b.i.d.). Active levels of levofloxacin, trovafloxacin, and vancomycin were continuously present in tissue cage fluid, with the levels exceeding the minimal bactericidal concentrations for MRSA during therapy. The q.d. and b.i.d. regimens of levofloxacin had equivalent activities and were significantly (P < 0.05) more active than alatrofloxacin or vancomycin in decreasing the viable counts of MRSA in tissue cage fluids. No quinolone-resistant mutants emerged during therapy with either fluoroquinolone. The mechanisms explaining the inferior activity of alatrofloxacin compared to the activity of levofloxacin against chronic foreign-body-associated infections by MRSA are unknown.

Animals↗

PubMed2002

Increased expression of clumping factor and fibronectin-binding proteins by hemB mutants of Staphylococcus aureus expressing small colony variant phenotypes.

Small colony variants (SCVs) of Staphylococcus aureus are slow-growing subpopulations that cause persistent and relapsing infections. The altered phenotype of SCV can arise from defects in menadione or hemin biosynthesis, which disrupt the electron transport chain and decrease ATP concentrations. With SCVs, virulence is altered by a decrease in exotoxin production and susceptibility to various antibiotics, allowing their intracellular survival. The expression of bacterial adhesins by SCVs is poorly documented. We tested fibrinogen- and fibronectin-mediated adhesion of a hemB mutant of S. aureus 8325-4 that is defective for hemin biosynthesis and exhibits a complete SCV phenotype. In this strain, adhesion to fibrinogen and fibronectin was significantly higher than that of its isogenic, normally growing parent and correlated with the increased surface display of these adhesins as assessed by flow cytometry. Real-time quantitative reverse transcription-PCR demonstrated increased expression of clfA and fnb genes by the hemB mutant compared to its isogenic parent. The influence of the hemB mutation on altered adhesin expression was confirmed by showing complete restoration of the wild-type adhesive phenotype in the hemB mutant, either by complementing with intact hemB or by supplementing the growth medium with hemin. Increased surface display of fibrinogen and fibronectin adhesins by the hemB mutation occurred independently from agr, a major regulatory locus of virulence factors in S. aureus. Both agr-positive and agr-lacking hemB mutants were also more efficiently internalized by human embryonic kidney cells than were their isogenic controls, presumably because of increased surface display of their fibronectin adhesins.

Adhesins, Bacterial↗