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Biomedical subjects

C Quentin

Publications and source records attributed to C Quentin.

At least 19 recordsLinked to original sources
PubMed2004

Antibiotic resistance rates and phenotypes among isolates of Enterobacteriaceae in French extra-hospital practice.

Antibiotic resistance among members of the family Enterobacteriaceae was prospectively surveyed by eight French private laboratories over a 5-month period in 1999. A total of 2,599 consecutive and nonduplicate strains were collected, mainly (60.9%) from patients in the community. Most strains (82.9%) derived from urine. Escherichia coli was the predominant (73.9%) organism isolated. The overall rates of antibiotic resistance were as follows: amoxicillin, 53.4%; amoxicillin-clavulanic acid, 27.3%; ticarcillin, 44.2%; piperacillin-tazobactam, 3.2%; cephalothin, 29.2%; cefuroxime, 14.7%; cefoxitin, 11.5%; ceftazidime, 3.6%; cefotaxime, 2.8%; cefepime, 0.3%; imipenem, 0.1%; gentamicin (G), 3.8%; tobramycin (T), 5.0%; netilmicin (Nt), 3.7%; amikacin (A), 0.7%; nalidixic acid, 14.3%; ofloxacin, 10.4%; cotrimoxazole, 21.1%; nitrofurantoin, 12.7%; fosfomycin, 5.2%; tetracycline, 50.1%; and colistin, 12.5%. Beta-lactam resistance phenotypes essentially comprised penicillinase production (33.9%), overexpression of chromosomal cephalosporinase (4.6%), and synthesis of inhibitor-resistant TEM/OXA enzymes (1.5%) or extended-spectrum beta-lactamases (1.5%). Aminoglycoside resistance phenotypes consisted of GTNt (93 strains), TNtA (68 strains), GTNtA (14 strains), T (4 strains), GT (3 strains), G (1 strain), and reduced uptake/permeability (3 strains). Most of the nalidixic acid-resistant strains were resistant to ofloxacin (72.8%). Antibiotic resistance rates and phenotypes varied widely according to the bacterial group and the source of the strains. Significantly higher rates were observed in private healthcare centers than in the community, due to a higher proportion of both resistant species and resistant strains. However, multidrug-resistant isolates, including five extended-spectrum beta-lactamase-producing strains, were also recovered from the community.

Ambulatory Care↗
PubMed2001

Determination of moxifloxacin in growth media by high-performance liquid chromatography.

A direct injection high-performance liquid chromatographic method with column switching has been developed to determine moxifloxacin in Mueller-Hinton broth. A LiChrocart 4-4 pre-column filled with a LiChrospher 100 RP 18, 5 microm and a 150 x 4.6 mm I.D. column packed with a Supelcozil ABZ+ Plus were used and led to a retention time of 5.70 min. Fluorescence detection allowed one to reach a quantification limit of 0.05 microg/ml with a 100-microl sample size. The standard curves were linear from 0.05 to 3.2 microg/ml. Intra- and inter-day imprecisions within the linearity range were < or =4.76 and < or =5.75%, respectively. The mean relative errors for the same day and the day-to-day inaccuracies ranged from -2.93 to +4.50% and from -1.10 to +6.00%, respectively. The method was demonstrated to be useful for pharmacokinetic-pharmacodynamic studies of moxifloxacin in an in vitro model.

Anti-Infective Agents↗
PubMed2001

[Antibiotic resistance of Staphylococcus aureus in urban experience: 6 month study in Aquitaine].

Antibiotic resistance of Staphylococcus aureus has been surveyed by eight city laboratories of the Aquitaine area, during a six month-period (january to june 1998). Antibiotic susceptibility testing has been performed by the disk diffusion method, and the results have been collected and analysed using the SIRscan system. After elimination of the redundant strains, a total of 747 isolates has been retained. They were mainly isolated from pus (64%) collected from patients of the community (40%) or hospitalized in 30 private clinics or nursing homes. The percentages of resistant strains (community/institutions) were: benzylpenicillin: 90% (87/92%), oxacillin: 39% (23/50%), kanamycin: 37% (22/47%); gentamicin: 13% (8/16%), tobramycin: 37% (21/47%), amikacin: 21% (13/27%); netilmicin: 6% (5/7%), erythromycin: 33% (30/35%), spiramycin: 72% (77/69%), lincomycin: 24% (17/29%), pristinamycin: 2% (1/2%), tetracycline: 17% (14/19%); pefloxacin: 40% (25/50%), fosfomycin: 9% (6/12%), rifampicin: 10% (7/13%), fusidic acid: 14% (11/15%), cotrimoxazole and vancomycin: 0%. Meticillin-susceptible strains of S. aureus were mostly sensitive to other antibiotics (< or = 6% resistant strains, except for erythromycin: 22%). Among meticillin-resistant S. aureus, heterogeneous strains with a KT phenotype, and various resistance patterns to the remaining antibiotics were predominant (61%), compared to the homogeneous strains with a KTG phenotype and multiresistant to the other antibiotics (32%). The frequencies of resistant strains were highly variable depending on the specimen, the laboratory and the health care institution, except for cotrimoxazole and vancomycin which were always active.

Anti-Bacterial Agents↗
PubMed2001

New approach for accurate simulation of human pharmacokinetics in an in vitro pharmacodynamic model: application to ciprofloxacin.

An in vitro pharmacodynamic model using a disposable dialyser unit and computer-controlled devices was developed. Feedback control of peristaltic pump flow rates is used to maintain constant flow rates, thus avoiding the problem of the modification of the physical properties of the tubing that generally occurs. Fast equilibrium is obtained with capillaries, which allows simulation of the same kinetic profile in the central and the peripheral compartments. Thus, more accurate simulation of plasma, extracapillary fluid or whole tissue kinetics can be performed. Our model was validated by simulation of a 30 min infusion of a 200 mg dose, and of an oral administration of a 500 mg dose of ciprofloxacin.

Administration, Oral↗
PubMed2001

SHV-16, a beta-lactamase with a pentapeptide duplication in the omega loop.

A clinical isolate of Klebsiella pneumoniae was found to be resistant to ampicillin (MIC of 128 microg/ml), ticarcillin (MIC of 512 microg/ml), and ceftazidime (MIC of 128 microg/ml) and susceptible to all other beta-lactams; a synergistic effect between clavulanate and ceftazidime suggested the presence of an extended-spectrum beta-lactamase (ESBL). Transconjugants in Escherichia coli were obtained at low levels (10(-7) per donor cell) and exhibited a similar beta-lactam resistance pattern (resistant to ampicillin, ticarcillin, and ceftazidime at 64 microg/ml). The ESBL, pI 7.6, was encoded by a large plasmid (>100 kb) which did not carry any other resistance determinant. The ESBL-encoding gene was amplified by PCR using bla(SHV)-specific primers and was sequenced. The deduced amino acid sequence of the SHV-16 ESBL showed that it differed from SHV-1 by only a pentapeptide insertion (163DRWET167) corresponding to a tandem duplication in the omega loop. The implication of the 163a-DRWET163b-DRWET sequence in ceftazidime resistance was confirmed by cloning either bla(SHV-1) or bla(SHV-16) in the same vector, subsequently introduced in the same E. coli strain. Under these isogenic conditions, SHV-16 conferred a 32-fold increase in ceftazidime MIC compared to that with SHV-1. Furthermore, site-directed mutagenesis experiments modifying either E166aA or E166bA revealed that the functional glutamic residue was that located in the first copy of the duplicated sequence. But surprisingly, the second E166b also conferred a low-level resistance to ceftazidime. This work is the first description of a class A enzyme exhibiting an extended substrate specificity due to an insertion instead of a nucleotide substitution(s) in a clinical isolate.

Amino Acid Sequence↗
PubMed2001

Nosocomial outbreak due to a multiresistant strain of Pseudomonas aeruginosa P12: efficacy of cefepime-amikacin therapy and analysis of beta-lactam resistance.

Over a 3-year period, 67 patients of the Hospital of Pau (Pau, France), including 64 patients hospitalized in the adult intensive care unit (ICU), were colonized and/or infected by strains of Pseudomonas aeruginosa P12, resistant to all potentially active antibiotics except colistin. Most patients were mechanically ventilated and presented respiratory tract infections. Since cefepime and amikacin were the least inactive antibiotics by MIC determination, all ICU patients were treated with this combination, and most of them benefited. Cefepime-amikacin was found highly synergistic in vitro. Ribotyping and arbitrary primer-PCR analysis confirmed the presence of a single clonal isolate. Isoelectrofocusing revealed that the epidemic strain produced large amounts of the chromosomal cephalosporinase and an additional enzyme with a pI of 5.7, corresponding to PSE-1, as demonstrated by PCR and sequencing. Outer membrane protein profiles on sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed the absence of a ca. 46-kDa protein, likely to be OprD, and increased production of two ca. 49- and 50-kDa proteins, consistent with the outer membrane components of the efflux systems, MexAB-OprM and MexEF-OprN. Thus, we report here a nosocomial outbreak due to multiresistant P. aeruginosa P12 exhibiting at least four mechanisms of beta-lactam resistance, i.e., production of the penicillinase PSE-1, overproduction of the chromosomal cephalosporinase, loss of OprD, and overexpression of efflux systems, associated with a better activity of cefepime than ceftazidime.

Adult↗
PubMed2000

Prospective survey of colonization and infection caused by SHV-4 producing Klebsiella pneumoniae in a neurosurgical intensive care unit.

The occurrence of extended-spectrum beta-lactamase producing enterobacteria (ESBLE) has been prospectively surveyed in a neurosurgical intensive care unit (ICU). Of the 47 patients examined, 8 were identified as faecal carriers, and 2 of them developed a subsequent urinary tract infection. ESBLE were also detected in the immediate environment of five colonized and/or infected patients. All isolates were Klebsiella pneumoniae of a particular biotype which exhibited a similar antibiotype and produced an SHV-4 type beta-lactamase. However, plasmid profiling and ribotyping revealed that strains isolated from seven patients of hall A were a single epidemic clone, whereas strains isolated from the eighth patient of hall B were different. Comparison between the characteristics of patients who carried an ESBLE during the surveillance period, and control patients who did not, showed that a recent surgery, and the length of ICU stay were significantly associated with the acquisition of ESBLE.

Cross Infection↗
PubMed2000

Antimicrobial resistance of mesophilic Aeromonas spp. isolated from two European rivers.

The activity of 19 antibiotics and four antiseptics and/or disinfectants was studied against 138 non-redundant strains of Aeromonas spp. (104 Aeromonas caviae, 22 Aeromonas sobria and 12 Aeromonas hydrophila) isolated from two European rivers. Antibiotic resistance frequencies were: nalidixic acid, 59%; tetracycline, 14%; fosfomycin, 8%; tobramycin and cotrimoxazole, 7%; cefotaxime, 4%; chloramphenicol, 2%; gentamicin, 1%. Most of the nalidixic acid-resistant strains were susceptible to fluoroquinolones (54-98%). Antibiotic resistance rates varied according to the source of the strains. All Aeromonas spp. strains were killed by 50 ppm of chlorine, cetylpyridinium chloride and peracetic acid, and by 1600 ppm of glutaraldehyde.

Aeromonas↗
PubMed2000

Impact of an urban effluent on antibiotic resistance of riverine Enterobacteriaceae and Aeromonas spp.

In order to evaluate the impact of an urban effluent on antibiotic resistance of freshwater bacterial populations, water samples were collected from the Arga river (Spain), upstream and downstream from the wastewater discharge of the city of Pamplona. Strains of Enterobacteriaceae (representative of the human and animal commensal flora) (110 isolates) and Aeromonas (typically waterborne bacteria) (118 isolates) were selected for antibiotic susceptibility testing. Most of the Aeromonas strains (72%) and many of the Enterobacteriaceae (20%) were resistant to nalidixic acid. Singly nalidixic acid-resistant strains were frequent regardless of the sampling site for Aeromonas, whereas they were more common upstream from the discharge for enterobacteria. The most common resistances to antibiotics other than quinolones were to tetracycline (24.3%) and beta-lactams (20.5%) for Enterobacteriaceae and to tetracycline (27.5%) and co-trimoxazole (26.6%) for Aeromonas. The rates of these antibiotic resistances increased downstream from the discharge at similar degrees for the two bacterial groups; it remained at high levels for enterobacteria but decreased along the 30-km study zone for Aeromonas. Genetic analysis of representative strains demonstrated that these resistances were mostly (enterobacteria) or exclusively (Aeromonas) chromosomally mediated. Moreover, a reference strain of Aeromonas caviae (CIP 7616) could not be transformed with conjugative R plasmids of enterobacteria. Thus, the urban effluent resulted in an increase of the rates of resistance to antibiotics other than quinolones in the riverine bacterial populations, despite limited genetic exchanges between enterobacteria and Aeromonas. Quinolone resistance probably was selected by heavy antibiotic discharges of unknown origin upstream from the urban effluent.

Aeromonas↗
PubMed1999

Presence of mefA and mefE genes in Streptococcus agalactiae.

Eighteen unrelated clinical isolates of Streptococcus agalactiae with the M phenotype harbored an mef gene. DNA sequencing showed that one of nine strains contained mefA (producing one amino acid substitution), whereas the remaining eight carried mefE (identity, 100%). Restriction analysis of PCR products indicated that the nine other strains also contained mefE.

Bacterial Proteins↗
PubMed1999

Molecular characterization of TEM-59 (IRT-17), a novel inhibitor-resistant TEM-derived beta-lactamase in a clinical isolate of Klebsiella oxytoca.

A clinical isolate of Klebsiella oxytoca (Kox 443) was found to have a low-level resistance to broad-spectrum penicillins (MICs of amoxicillin and ticarcillin, 256 and 32 microg/ml, respectively), without substantial potentiation by 2 microg of clavulanic acid per ml (amoxicillin- and ticarcillin-clavulanate, 128 and 8 microg/ml, respectively), while being fully susceptible to cephalosporins and other beta-lactam antibiotics. These resistances were carried by a ca. 50-kb conjugative plasmid that encodes a single beta-lactamase with a pI of 5.6. Compared to TEM-2, this enzyme exhibited a 3- to 30-fold higher Km and a decreased maximal hydrolysis rate for beta-lactams; higher concentrations of suicide inactivators (5- to 500-fold higher concentrations giving a 50% reduction in hydrolysis) were required for inhibition. Nucleotide sequence analysis revealed identity between the blaTEM gene of Kox 443 and the blaTEM-2 gene, except for a single A-to-G change at position 590, leading to the amino acid change from Ser-130 Gly. This mutation has not been reported previously in the TEM type beta-lactamases produced by clinical strains, and the novel enzyme was called TEM-59 (alternative name IRT-17). This is the first description of an inhibitor-resistant TEM-derived enzyme in the species K. oxytoca.

Aged↗
PubMed1999

Impact of an urban effluent on the bacterial community structure in the Arga River (Spain), with special reference to culturable gram-negative rods.

The Arga River is an interesting system in which to study the impact of urban effluent pollution because it receives a single effluent in the form of wastewater discharge from the city of Pamplona. To analyze the extent of this discharge, total bacteria, culturable heterotrophic bacteria, and Gram-negative heterotrophic bacteria were enumerated and 409 isolates of the latter were identified. One sampling station was located upstream from the inflow, while five were located up to 30 km downstream. Bacterial counts increased drastically downstream from the wastewater inflow. Total bacterial numbers decreased along the 30 km downstream, the last station attaining similar values to those recorded upstream from the discharge. However, culturable heterotrophic and Gram-negative heterotrophic bacteria levels generally remained significantly higher within the 30 km zone investigated. Among the 409 isolates identified, Aeromonas spp. were the most frequent both upstream and downstream from the discharge. In contrast, although strains belonging to different genera of Enterobacteriaceae were found in all stations, their occurrence was significantly higher just downstream from the polluted discharge. Acinetobacter spp., which were never found upstream, were detected in all stations below the discharge. Our results clearly show that the bacterial community structure changes definitively downstream from the discharge and that Aeromonas were common throughout the sampling zone. Thus they cannot be considered good indicators of pollution in this setting compared to some genera of Enterobacteriaceae or some species of Acinetobacter, the distribution of which correlated better with the distance from the wastewater discharge.

Acinetobacter↗
PubMed1998

Molecular characterization of a TEM-21 beta-lactamase in a clinical isolate of Morganella morganii.

A clinical isolate of Morganella morganii, with reduced susceptibility to expanded-spectrum cephalosporins and aztreonam, was found to produce an extended-spectrum beta-lactamase with a pI of 6.4. The nucleotide sequence of the encoding gene was that of the gene encoding TEM-21. This is the first molecular characterization of an extended-spectrum beta-lactamase in M. morganii.

Base Sequence↗