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P Allouch

Publications and source records attributed to P Allouch.

At least 19 recordsLinked to original sources
PubMed2006

FT-IR microspectroscopy for early identification of some clinically relevant pathogens.

AIMS: To investigate the potentials and limitations of Fourier transform-infrared (FT-IR) microspectroscopy as a tool to identify, at the level of microcolonies, pathogenic bacteria frequently isolated in the clinical environment. METHODS AND RESULTS: A total of 1570 FT-IR spectra from 164 gram-positive and gram-negative bacteria isolated from patients were recorded from 6 to 10-h old microcolonies of 50-150 microm size. A classification of 100% was obtained for the most frequent gram-positive bacteria, such as Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, and Enterococcus faecium at the species level. An average accuracy of about 80% was reached with Gram negative bacteria from the Enterobacteriaceae and Pseudomonaceae families; Enterobacter aerogenes, Enterobacter cloacae, Klebsiella spp., and Citrobacter koseri; and Proteus mirabilis and Escherichia coli. Results were comparable with FT-IR measurements on dried suspensions from 18-h cultures. CONCLUSIONS: Early identification of young microcolonies is feasible with FT-IR microscopy with a very high accuracy for gram-positive bacteria. Some improvement in the transfer of microcolonies is necessary to increase the accuracy for gram-negative bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Combination of FT-IR microscopy and multivariate data analysis could be a complementary, rapid, and reliable tool for screening and discriminating, at species and subspecies level, micro-organisms of clinical, food-borne, or environmental origins.

Animals↗
PubMed2004

[Indications of drug eluting stents].

The publication in 2001 of the first in-man results showing zero restenosis after sirolimus eluting stent implantation produced enormous excitement in the cardiological community. Today, both sirolimus and paclitaxel eluting stents have been shown in randomized trials to reduce restenosis as compared with conventional metallic stents. However, since drug eluting stents become available in Europe very little has changed in the every life of almost all interventional laboratories in Europe. The limitation currently impeding more widespread use of the new technology is nontechnical, nonmedical but economic. The high price of drug eluting stents relative to bare stents has been an obstacle to more widespread utilization of drug eluting stents.

Coronary Restenosis↗
PubMed2003

Frequency of isolation and antimicrobial susceptibility of bacterial pathogens isolated from patients with bloodstream infections: a French prospective national survey.

All bloodstream strains, total 1463, isolated during a 1 month period in 105 hospitals representing all geographical areas in France were collected to study their antimicrobial susceptibility. The three major species were Escherichia coli, Staphylococcus aureus and coagulase-negative staphylococci. Among the 242 S. aureus, 87 were resistant to methicillin and among those 99% were resistant to ciprofloxacin, 11.5% to gentamicin, 1% to quinupristin/dalfopristin and 8% were heterogeneously resistant to vancomycin. Study of the methicillin-resistant S. aureus indicated that 12 clones had disseminated in French hospitals, six being heterogeneously resistant to vancomycin. Among the Streptococcus pneumoniae, 43% showed decreased susceptibility to the penicillins and 42% to erythromycin. One isolate was highly resistant to fluoroquinolones. Gentamicin, cefotaxime, ciprofloxacin and gatifloxacin resistance was rare in Enterobacteriaceae with 95% of strains susceptible. The incidence of extended-spectrum beta-lactamases was quite low. Moreover more than 25% of Pseudomonas aeruginosa strains were resistant to ciprofloxacin and gentamicin. The magnitude of antibiotic resistance in bloodstream isolates, in particular Gram-positive bacteria, emphasizes the importance of hospital control measures, rational prescribing policies and new vaccine strategies.

Anti-Infective Agents↗
PubMed2003

Intramural neovascularization and haemorrhages are major long-term effects of intravascular gamma-radiation after stenting.

Structural changes that might influence the structural integrity of the vessel in response to intravascular brachytherapy (IVB) and stenting were examined, focus being on the importance of neovascularization in rabbit stented arteries. Stents were implanted in the infrarenal aortas of rabbits, immediately followed by gamma IVB or a sham radiation procedure, and the arteries harvested at 6 months. Labelling for von Willebrand factor showed an increase in adventitial and medial neovascularization in irradiated versus control arteries group (5.04+/-0.89 versus 1.51+/-0.23 mm(-2), respectively; p=0.004). Moreover, intramedial haemorrhages (free hemosiderin deposition) and inflammation (macrophages) were only observed in irradiated arteries. No significant change in expression of matrix metalloproteinase 1, 2 or 3 was observed between the irradiated and control group while collagen content decreased in the irradiated versus the control group (10.05%+/-1.48% versus 31.92%+/-3.12%, respectively; p<0.001). The study supports the hypothesis that IVB associated with stenting induces late deleterious effects on the medial layer, characterized by formation of intramural neovessels, haemorrhages and a decrease in collagen content.

Animals↗
PubMed2002

[Susceptibility of Pseudomonas aeruginosa to antibiotics isolated from patients of intensive care units in France in 1998. Resistant phenotypes to beta-lactams].

Pseudomonas aeruginosa is responsible for nosocomial infections and demonstrates many types of resistance mechanisms to antibiotics. Thus, in vitro susceptibility survey are frequently required. In this study, susceptibility has been assessed on 105 non redundant consecutive strains isolated from ICU's in 18 general hospitals, from 01.02.98 to 30.06.98. Only clinically significant samples have been considered. MICs have been measured for nine beta-lactams, three aminoglycosides, one fluoroquinolone and colistine. For ticarcilline resistant strains, phenotype has been assessed on Mueller-Hinton medium supplemented with beta-lactamases inhibitor. Transferable beta-lactamases has been identified using pl and PCR. MIC 50 and MIC 90 (mg/L) for beta-lactams are the following (MIC 50-->90): ticarcilline (16-->512), ticarcilline + clavulanic acid (16-->512), piperacilline (4-->512), pipéracilline + tazobactam (4-->64), aztreonam (4-->16), cefsulodine (4-->32), ceftazidime (2-->16), cefepime (4-->16), imipeneme (1-->8). For aminoglycosides: gentamicine (2-->32), tobramycine (1-->32), amikacine (4-->16). For ciprofloxacine (0.25-->32) and colistine (0.5-->2). According to CA-SFM break points recommendations, 50% of isolated strains are resistant to gentamicine, one out of three for ticarcilline + clavulanic acid (29%), one out of four for tobramycine (25%) and ciprofloxacine (25%), one out of ten for amikacine (9%), tazocilline (8%) and imipeneme (9%). Resistance to ceftazidime and aztreonam is uncommon (respectively 2%-1%) and never observed for cefepim. For ticarcilline resistant strains, (38% of total isolates) the following phenotypes have been detected: 6.7% non enzymatic resistance, 15.2% transferable beta-lactamase (TEM 4.8%, CARB 4.8%, TEM + CARB 4.8% and OXA-10 and derivated 0.9%) and 16.2% high level cephalosporinase. Extended-spectrum beta-lactamase has never been detected. TEM beta-lactamase is associated with resistance to amikacine and ciprofloxacine.

Aminoglycosides↗
PubMed2002

Multivariate analysis of determinants of bacterial contamination of whole-blood donations.

BACKGROUND AND OBJECTIVES: Introduction of bacteria into blood components at the collection stage seems to be a frequent occurrence. We therefore assessed determinants of bacterial contamination of whole-blood donations to gain insight into contamination mechanisms and direct prevention. MATERIALS AND METHODS: A cross-sectional study was carried out on donors accepted for whole-blood donation in four French blood banks. Each blood bank used its own two-stage procedure for phlebotomy site preparation. Contamination was identified by culturing two 15-ml samples (collected aseptically at the outset of donation) in a BacT/Alert 240 system. Determinants were assessed by logistic regression analysis. RESULTS: Bacterial contamination, mainly by skin flora, occurred in 76 (2.2%) out of 3385 donations. Significant determinants were as follows: the blood bank (odds ratio [OR] range = 3.0-5.6, P < 0.001); lack of repetition of scrub (OR = 2.7, P = 0.032); and donor age > 35 years (OR = 1.8, P = 0.036). CONCLUSION: Systematic scrub repetition should be implemented to reduce bacterial contamination by skin flora at the collection stage. Further research is required to clarify the role of different antiseptic agents and of donor age.

Adult↗
PubMed2001

Efficacy of a new collection procedure for preventing bacterial contamination of whole-blood donations.

BACKGROUND: Transfusion-related bacterial contamination is a serious problem. The introduction of bacteria into donations at the collection stage seems frequent, despite well-conducted phlebotomy site preparation. Additional preventive measures are required. STUDY DESIGN AND METHODS: The aim of this study was to assess the potential efficacy of excluding the first 15 mL of blood to reduce the bacterial contamination of donations. A special device allowed the aseptic collection of two samples at the beginning of donation: S1 (first 15 mL) and S2 (next 15 mL). Bacteriologic cultures of S1 and S2 were performed by using an automated system. The procedure's efficacy was measured by the proportion of positive donations in S1 that were then negative in S2. RESULTS: S1 and/or S2 were positive in 76 (2.2%) of 3385 donations. In about three-fourths of the culture-positive donations, contamination was detected in the first 15-mL sample only. Gram-positive cocci accounted for 81 percent of species, gram-positive bacilli for 14 percent, and gram-negative bacilli for 5 percent. The new procedure would have prevented the introduction of bacteria in 55 donations, reducing to 0.6 percent the risk of contamination from the first 15 mL collected. CONCLUSION: Although the final effect on blood component bacterial contamination rates cannot be derived from the study, excluding the first 15 mL of blood may reduce the rate of bacterial contamination in donations.

Adult↗
PubMed2001

Investigating microbial (micro)colony heterogeneity by vibrational spectroscopy.

Fourier transform infrared and Raman microspectroscopy are currently being developed as new methods for the rapid identification of clinically relevant microorganisms. These methods involve measuring spectra from microcolonies which have been cultured for as little as 6 h, followed by the nonsubjective identification of microorganisms through the use of multivariate statistical analyses. To examine the biological heterogeneity of microorganism growth which is reflected in the spectra, measurements were acquired from various positions within (micro)colonies cultured for 6, 12, and 24 h. The studies reveal that there is little spectral variance in 6-h microcolonies. In contrast, the 12- and 24-h cultures exhibited a significant amount of heterogeneity. Hierarchical cluster analysis of the spectra from the various positions and depths reveals the presence of different layers in the colonies. Further analysis indicates that spectra acquired from the surface of the colonies exhibit higher levels of glycogen than do the deeper layers of the colony. Additionally, the spectra from the deeper layers present with higher RNA levels than the surface layers. Therefore, the 6-h colonies with their limited heterogeneity are more suitable for inclusion in a spectral database to be used for classification purposes. These results also demonstrate that vibrational spectroscopic techniques can be useful tools for studying the nature of colony development and biofilm formation.

Candida albicans↗
PubMed2001

Classification and identification of enterococci: a comparative phenotypic, genotypic, and vibrational spectroscopic study.

Rapid and accurate identification of enterococci at the species level is an essential task in clinical microbiology since these organisms have emerged as one of the leading causes of nosocomial infections worldwide. Vibrational spectroscopic techniques (infrared [IR] and Raman) could provide potential alternatives to conventional typing methods, because they are fast, easy to perform, and economical. We present a comparative study using phenotypic, genotypic, and vibrational spectroscopic techniques for typing a collection of 18 Enterococcus strains comprising six different species. Classification of the bacteria by Fourier transform (FT)-IR spectroscopy in combination with hierarchical cluster analysis revealed discrepancies for certain strains when compared with results obtained from automated phenotypic systems, such as API and MicroScan. Further diagnostic evaluation using genotypic methods-i.e., PCR of the species-specific ligase and glycopeptide resistance genes, which is limited to the identification of only four Enterococcus species and 16S RNA sequencing, the "gold standard" for identification of enterococci-confirmed the results obtained by the FT-IR classification. These results were later reproduced by three different laboratories, using confocal Raman microspectroscopy, FT-IR attenuated total reflectance spectroscopy, and FT-IR microspectroscopy, demonstrating the discriminative capacity and the reproducibility of the technique. It is concluded that vibrational spectroscopic techniques have great potential as routine methods in clinical microbiology.

Bacterial Typing Techniques↗
PubMed2001

[Secondary effects of brachytherapy in the treatment of coronary restenosis].

Brachytherapy is proposed for the treatment or prevention of coronary restenosis with encouraging results, especially in intra-stent restenosis. The results of the first clinical studies show benefit, for example those of the American SCRIPPS trial with a 3 year follow-up. However, recent reports in the literature have described secondary effects associated with this technique: 1) stenoses occurring at the limits of the irradiated segments which are attributed to a proliferative effect of low doses on damaged tissue; 2) late occlusions at the irradiated site: their incidence is estimated at 9% at 6 months. The mechanisms of these thromboses are not understood but delayed re-endothelialisation probably plays a rôle; 3) finally, irradiation is associated with uncovered dissection probably related to delayed healing. Other long-term trials are necessary to provide a more complete assessment of the secondary effects of brachytherapy, especially with regards to their mechanisms, prevention and treatment.

Angioplasty↗
PubMed2000

In vitro activity of teicoplanin against gram-positive cocci.

The glycopeptide susceptibility of 443 clinical isolates of gram-positive cocci collected from nine general hospitals in 1996 was determined according to the recommendations of the CA-SFM (the Antibiogram Committee of the French Society for Microbiology). In total, 234 isolates of Staphylococcus aureus, 84 isolates of coagulase-negative staphylococci (CNS), 98 enterococci and 27 streptococci were collected. The mecA gene confirming resistance to methicillin was found in 42.7% of S. aureus isolates and 51.2% of CNS isolates. No resistance to teicoplanin and vancomycin was found in S. aureus but four isolates of CNS had an MIC of teicoplanin > or = 8 mg/L. All isolates of Enterococcus faecalis tested were susceptible to both glycopeptides. This study confirms that teicoplanin has a very good in vitro activity against gram-positive cocci, isolated in France from nosocomial infections.

Anti-Bacterial Agents↗
PubMed1999

Epidemiological study of Staphylococcus aureus resistant to methicillin responsible for nosocomial infections in nine French hospitals.

A number of European studies found that nosocomial infections were caused by a limited number of methicillin-resistant Staphylococcus aureus (MRSA) strains. A study was undertaken to determine the number of MRSA clones responsible for nosocomial infections in France. Strains responsible for nosocomial infections meeting CDC criteria were collected one week every month from June to October 1997 in nine French hospitals. Strains that were positive by the oxacillin-resistance screening test were studied for the IS 431, femA, and mecA genes. Strain type was identified using pulsed-field gel electrophoresis of fragments produced by Smal digestion. Susceptibility to antimicrobials was evaluated based on inhibition zone diameters and minimal inhibitory concentrations determined using the agar dilution method. The 83 strains studied were distributed across four pulsotypes. Eleven resistance phenotypes were identified by ascending hierarchical classification based on inhibition zone diameters. MRSAs responsible for nosocomial infections belong to a limited number of clones that express variable levels of resistance to antimicrobials.

Anti-Bacterial Agents↗
PubMed1998

FT-IR spectroscopy as an emerging method for rapid characterization of microorganisms.

Statistical methods such as principal component analysis and cluster analysis were used to analyze ATR-FT-IR spectra obtained from bacterial whole cells. Both methods gave satisfactory results and are conclusive in showing that they can discriminate and classify bacterial strains of clinical origin exhibiting different resistance mechanisms. This approach places FT-IR spectroscopy at the forefront of those new potential techniques that could be used in the rapid screening of microorganisms.

Escherichia coli↗
PubMed1997

ATR-FTIR spectroscopic investigation of E. coli transconjugants beta-lactams-resistance phenotype.

Hyphenation of attenuated total reflection Fourier transform infrared spectroscopy and cluster analysis has been used to characterise a susceptible Escherichia coli K12 strain and the transconjugants TEM-1, TEM-2, TEM-3, SHV-2, SHV-3, SHV-4. A good discrimination of the susceptible strain from the transconjugants was obtained. Although a limited success was achieved in the differentiation of SHV and TEM phenotypes in general, results obtained with TEM-2 and SHV-3 were convincing. Spectral differences observed are ascribed to the global effects of the conjugation process, particularly their repercussions in the nucleic acids and carbohydrate absorbing regions, rather than to beta-lactamase point-mutations.

Conjugation, Genetic↗