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F Martineau

Publications and source records attributed to F Martineau.

9 recordsLinked to original sources
PubMed2001

Development of a PCR assay for identification of staphylococci at genus and species levels.

We have developed a PCR-based assay which allows the detection of staphylococci at the genus level by targeting the tuf gene, which encodes the elongation factor Tu. Degenerate PCR primers derived from consensus regions of several tuf genes were used to amplify a target region of 884 bp from 11 representative staphylococcal species. Subsequently, the entire nucleotide sequence of these amplicons was determined. The analysis of a multiple alignment of these sequences revealed regions conserved among staphylococci but distinct from those of other gram-positive bacteria genetically related to staphylococci. PCR primers complementary to these regions could amplify specifically and efficiently a DNA fragment of 370 bp for all of 27 different staphylococcal species tested. There was no amplification with genomic DNA prepared from 53 nonstaphylococcal species tested to verify the specificity of the assay (20 gram positive and 33 gram negative). Furthermore, this assay amplified efficiently all 27 American Type Culture Collection (ATCC) staphylococcal reference strains as well as 307 clinical isolates of staphylococci from the Québec City region. Analysis of the multiple sequence alignment for the 884-bp fragment for the 11 staphylococcal species as well as comparison of the sequences for the 370-bp amplicon from five unrelated ATCC and clinical strains for each of the species S. aureus, S. epidermidis, S. haemolyticus, S. hominis, and S. saprophyticus demonstrated sufficient interspecies polymorphism to generate genus- and species-specific capture probes. This sequence information allowed the development of Staphylococcus-specific and species-specific (targeting S. aureus, S. epidermidis, S. haemolyticus, S. hominis, or S. saprophyticus) capture probes hybridizing to the 370-bp amplicon. In conclusion, this PCR assay is suitable for detection of staphylococci at both genus and species levels.

DNA Primers↗
PubMed2000

Lorazepam-induced modifications of saccadic and smooth-pursuit eye movements in humans: attentional and motor factors.

In a placebo-controlled, double-blind study, we measured the effects of low dose lorazepam on attentional and motor factors involved in saccadic and smooth pursuit eye movements. We manipulated the temporal interval between the extinction of the central fixation target and the appearance of a second eccentric target (gap/overlap step paradigm). The second target was either stationary (saccade trial) or moving in a direction opposite to the step (pursuit trial). Gap/overlap effects on the latency of saccadic and smooth pursuit eye movements were measured before and after oral intake of either lorazepam or placebo. Pharmacological effects on the dynamics and the accuracy of both types of eye movements were also investigated. In 14 healthy volunteers, we found that the temporal interval between fixation target offset and eccentric target onset modulates the latency of saccadic and smooth pursuit eye movements in a similar way. As compared to placebo, lorazepam significantly increased the latency of both types of eye movements, but did not modify the gap/overlap effect. Moreover, lorazepam significantly decreased the peak velocity of the first saccade towards the eccentric stationary target, as well as the gain of tracking towards the eccentric moving target. However, the overall accuracy of both behaviors was not significantly affected, indicating that systematic errors in foveating or tracking were detected and corrected by appropriate corrective or catch-up saccades, respectively. Results are discussed in terms of shared/different mechanisms for saccadic and pursuit systems in primates.

Adult↗
PubMed2000

Multiplex PCR assays for the detection of clinically relevant antibiotic resistance genes in staphylococci isolated from patients infected after cardiac surgery. The ESPRIT Trial.

Multiresistant staphylococci (82 Staphylococcus aureus and 114 coagulase-negative staphylococci) were characterized by testing with rapid multiplex polymerase chain reaction (PCR) assays for species identification and detection of associated antibiotic resistance genes. These 196 staphylococci were isolated from 149 adult patients who developed wound infection after elective coronary artery bypass grafts and/or valve surgery. The multiplex PCR assays allowed identification of the most common staphylococcal species with S. aureus- and Staphylococcus epidermidis-specific primers as well as the detection of the erythromycin resistance genes ermA, ermB, ermC and msrA, the aminoglycoside resistance gene aac(6')-aph(2"), the oxacillin resistance gene mecA and the penicillin resistance gene blaZ. There was a very good correlation between the genotypic analysis by PCR and the phenotype determined by standard methods of susceptibility testing and identification of staphylococcal species: 100% for erythromycin resistance, 98.0% for gentamicin resistance, 99.0% for oxacillin resistance, 100% for penicillin resistance and 100% for S. aureus and S. epidermidis species identification. This study suggests that the incidence and distribution of the tested clinically relevant antibiotic resistance genes in staphylococci associated with infections after cardiac surgery do not differ from those in strains from other infections. These multiplex PCR assays may be used as diagnostic tools to replace or complement standard methods of susceptibility testing and identification of staphylococci.

Adult↗
PubMed2000

Correlation between the resistance genotype determined by multiplex PCR assays and the antibiotic susceptibility patterns of Staphylococcus aureus and Staphylococcus epidermidis.

Clinical isolates of Staphylococcus aureus (a total of 206) and S. epidermidis (a total of 188) from various countries were tested with multiplex PCR assays to detect clinically relevant antibiotic resistance genes associated with staphylococci. The targeted genes are implicated in resistance to oxacillin (mecA), gentamicin ¿aac(6')-aph(2"), and erythromycin (ermA, ermB, ermC, and msrA). We found a nearly perfect correlation between genotypic and phenotypic analysis for most of these 394 strains, showing the following correlations: 98% for oxacillin resistance, 100% for gentamicin resistance, and 98.5% for erythromycin resistance. The discrepant results were (i) eight strains found to be positive by PCR for mecA or ermC but susceptible to the corresponding antibiotic based on disk diffusion and (ii) six strains of S. aureus found to be negative by PCR for mecA or for the four erythromycin resistance genes targeted but resistant to the corresponding antibiotic. In order to demonstrate in vitro that the eight susceptible strains harboring the resistance gene may become resistant, we subcultured the susceptible strains on media with increasing gradients of the antibiotic. We were able to select cells demonstrating a resistant phenotype for all of these eight strains carrying the resistance gene based on disk diffusion and MIC determinations. The four oxacillin-resistant strains negative for mecA were PCR positive for blaZ and had the phenotype of beta-lactamase hyperproducers, which could explain their borderline oxacillin resistance phenotype. The erythromycin resistance for the two strains found to be negative by PCR is probably associated with a novel mechanism. This study reiterates the usefulness of DNA-based assays for the detection of antibiotic resistance genes associated with staphylococcal infections.

Anti-Bacterial Agents↗
PubMed2000

Development of a rapid PCR assay specific for Staphylococcus saprophyticus and application to direct detection from urine samples.

Staphylococcus saprophyticus is one of the most frequently encountered microorganisms associated with acute urinary tract infections (UTIs) in young, sexually active female outpatients. Conventional identification methods based on biochemical characteristics can efficiently identify S. saprophyticus, but the rapidities of these methods need to be improved. Rapid and direct identification of this bacterium from urine samples would be useful to improve time required for the diagnosis of S. saprophyticus infections in the clinical microbiology laboratory. We have developed a PCR-based assay for the specific detection of S. saprophyticus. An arbitrarily primed PCR amplification product of 380 bp specific for S. saprophyticus was sequenced and used to design a set of S. saprophyticus-specific PCR amplification primers. The PCR assay was specific for S. saprophyticus when tested with DNA from 49 gram-positive and 31 gram-negative bacterial species. This assay was also able to amplify efficiently DNA from all 60 strains of S. saprophyticus from various origins tested. This assay was adapted for direct detection from urine samples. The sensitivity levels achieved with urine samples was 19 CFU with 30 cycles of amplification and 0.5 CFU with 40 cycles of amplification. This PCR assay for the specific detection of S. saprophyticus is simple and rapid (approximately 90 min, including the time for urine specimen preparation).

DNA, Bacterial↗
PubMed1999

Development of a PCR assay for rapid detection of enterococci.

Enterococci are becoming major nosocomial pathogens, and increasing resistance to vancomycin has been well documented. Conventional identification methods, which are based on culturing, require 2 to 3 days to provide results. PCR has provided a means for the culture-independent detection of enterococci in a variety of clinical specimens and is capable of yielding results in just a few hours. However, all PCR-based assays developed so far are species specific only for clinically important enterococci. We have developed a PCR-based assay which allows the detection of enterococci at the genus level by targeting the tuf gene, which encodes elongation factor EF-Tu. Initially, we compared the nucleotide sequences of the tuf gene from several bacterial species (available in public databases) and designed degenerate PCR primers derived from conserved regions. These primers were used to amplify a target region of 803 bp from four enterococcal species (Enterococcus avium, E. faecalis, E. faecium, and E. gallinarum). Subsequently, the complete nucleotide sequences of these amplicons were determined. The analysis of a multiple alignment of these sequences revealed regions conserved among enterococci but distinct from those of other bacteria. PCR primers complementary to these regions allowed amplification of genomic DNAs from 14 of 15 species of enterococci tested (E. solitarius DNA could not be amplified). There was no amplification with a majority of 79 nonenterococcal bacterial species, except for 2 Abiotrophia species and several Listeria species. Furthermore, this assay efficiently amplified all 159 clinical isolates of enterococci tested (61 E. faecium, 77 E. faecalis, 9 E. gallinarum, and 12 E. casseliflavus isolates). Interestingly, the preliminary sequence comparison of the amplicons for four enterococcal species demonstrated that there were some sequence variations which may be used to generate species-specific internal probes. In conclusion, this rapid PCR-based assay is capable of detecting all clinically important enterococci and has potential for use in clinical microbiology laboratories.

Bacterial Typing Techniques↗
PubMed1998

Species-specific and ubiquitous-DNA-based assays for rapid identification of Staphylococcus aureus.

Staphylococcus aureus is the cause of serious infections in humans, including endocarditis, deep-seated abscesses, and bacteremia, which lead to toxic and septic shock syndromes. Rapid and direct identification of this bacterium specifically and ubiquitously directly from clinical specimens would be useful in improving the diagnosis of S. aureus infections in the clinical microbiology laboratory. A wide variety of kits based on biochemical characteristics efficiently identify S. aureus, but the rapidity and the accuracy of each of these methods combined with testing of clinically relevant antibiotic resistance genes need to be improved. On the basis of hybridization assays with randomly selected clones from an S. aureus genomic library, we have identified a chromosomal DNA fragment which is specific for S. aureus and which detected all 82 S. aureus isolates tested. This 442-bp fragment was sequenced and was used to design a set of PCR amplification primers. The PCR assay was also specific and ubiquitous for the identification from bacterial cultures of 195 clinical strains of S. aureus isolated from a variety of anatomical sites and obtained from hospitals throughout the world. The PCR assay that we have developed is simple and can be performed in about 1 h. This DNA-based test provides a novel diagnostic tool for the diagnosis of S. aureus infections.

Cloning, Molecular↗
PubMed1996

Species-specific and ubiquitous DNA-based assays for rapid identification of Staphylococcus epidermidis.

Staphylococcus epidermidis is an aerobic gram-positive coccus that is now recognized among the coagulase-negative staphylococci as an etiological agent with an important range of pathogenicity in humans. Several diagnostic kits based on biochemical or immunological reactions can efficiently identify Staphylococcus aureus. However, these tests are often unreliable for the identification of coagulase-negative staphylococcal species including S. epidermidis. Since DNA-based assays for the species-specific identification of S. epidermidis remain unavailable, we have developed such tests in order to improve the accuracy and the rapidity of tests for the diagnosis of S. epidermidis infections. On the basis of the results of hybridization assays with clones randomly selected from an S. epidermidis genomic library, we identified a chromosomal DNA fragment which is specific and 100% ubiquitous for the identification of S. epidermidis. This 705-bp fragment was sequenced and used to design PCR amplification primers. PCR assays with the selected primers were also highly specific and ubiquitous for the identification from bacterial cultures of clinical isolates of S. epidermidis from a variety of anatomic sites. While three strains of S. capitis were misidentified as S. epidermidis with the API Staph-Ident system and 2.5% of the S. epidermidis identifications were inconclusive with the MicroScan Autoscan-4 system, the PCR assay was highly specific and allowed for the correct identification of all 79 S. epidermidis strains tested. The PCR assays developed are simple and can be performed in about 1 h. The DNA-based tests provide novel diagnostic tools for improving the diagnosis of S. epidermidis infections.

Bacteriological Techniques↗