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R Cluzel

Publications and source records attributed to R Cluzel.

At least 37 records · Page 2Linked to original sources
PubMed1987

Transferable resistance to third-generation cephalosporins in clinical isolates of Klebsiella pneumoniae: identification of CTX-1, a novel beta-lactamase.

Approximately 10% (89 isolates) of Klebsiella pneumoniae isolated in 1985 from patients in intensive care units in Clermont-Ferrand exhibited a complex resistance phenotype towards antibiotics. They were resistant to amino-, carboxy- and ureidopenicillins, aminoglycosides (except gentamicin), chloramphenicol, sulphonamides, tetracyclines and, most importantly, to cephalosporins (except cefoxitin and latamoxef) and to aztreonam. The metabolic profile of fifty isolates was identical and seven were selected for further study. All the resistance characters in these isolates were transferable to Escherichia coli by conjugation and were lost en bloc after treatment with ethidium bromide. Agarose gel electrophoresis of crude lysates of the wild types and their transconjugants indicated that the multiple resistances were mediated by a 95kb plasmid, pCF04. The seven isolates selected for study and their corresponding transconjugants, constitutively produced a plasmid-mediated beta-lactamase with a pI of 6.3 that was much more active against third-generation cephalosporins than against cephalothin. The substrate profile and the isoelectric-focusing behaviour of this enzyme differed from those of other known plasmid-mediated beta-lactamases, and the enzyme was designated CTX-1. A chromosomally-encoded SHV-1 (PIT-2) penicillinase (pI 7.7) was also present in the seven K. pneumoniae isolates but did not transfer. Resistance to aminoglycosides in the K. pneumoniae isolates was due to synthesis of a 6'-aminoglycoside acetyltransferase type IV. Our data indicate an epidemic of antibiotic multiply-resistant strains of K. pneumoniae producing a new beta-lactamase.

Cephalosporins↗
PubMed1986

[In vitro effect of piperacillin on aerobic bacteria. Variations according to the phenotypes of resistance to beta-lactam antibiotics].

In a first study the MICs of piperacillin (PIP), mezlocillin (MEZ), azlocillin (AZL), carbenicillin (CARB) and ticarcillin (TIC) against 563 strains of aerobic bacteria were compared. The MIC50 of PIP against E. coli and P. mirabilis was 0.5 to 1 mg/l, that is equal to those of MEZ and TIC but 2 or 3 times lower than those of AZL and CAR. The MIC50 of PIP and MEZ against Klebsiella, a species that is naturally resistant to TIC and CAR, was 4 mg/l. Enterobacter, Serratia and Citrobacter showed two populations of strains: the first was sensitive to the five penicillins tested (MIC50 of PIP: 1 to 2 mg/l); the second was resistant to all of them. PIP and AZL were more active (MIC50 8 mg/l) against Ps. aeruginosa than MEZ, TIC and CAR. All five penicillins had limited activity against Acinetobacter (MIC50 less than 16 mg/l). PIP, MEZ and AZL were more active than TIC and CAR against enterococci. In a second study, the activity of PIP was evaluated by standard sensitivity tests on 4993 strains of enterobacteria, Ps. aeruginosa and Acinetobacter classified according to their phenotype of resistance to beta-lactam antibiotics. PIP was regularly active against enterobacteria and Ps. aeruginosa strains devoid of acquired resistance. The activity of PIP was significantly reduced against enterobacteria strains with a phenotype suggesting induced penicillinase production. However, the inhibition zone diameters, although reduced, remained within what is now considered the sensitivity range (notably with E. coli and Proteus spp), which raises the problem of in vitro tests interpretation. PIP was active against E. coli strains with a "cephalosporinase" phenotype, but inactive against cefotaxime resistant strains of: Enterobacter, Citrobacter and Serratia. The activity of PIP on CAR-resistant Ps. aeruginosa strains was significantly reduced, but the inhibition zone diameter in one quarter of them was still within limits of sensitivity.

Azlocillin↗
PubMed1986

[In vitro comparative study of piperacillin-aminoglycosides combinations against Enterococci and Enterobacteriaceae].

The hundred and ninety-two combinations were tested against 17 strains chosen from the results of MIC determination (disc method): 5 enterococci exhibiting low level resistance (r) or high level resistance (R) to streptomycin (S) and gentamicin (G): 2 strains Sr Gr, 2 strains SR Gr and 1 strain Sr GR; 12 enterobacteria chosen for their resistance phenotypes to beta-lactams and aminoglycosides and because they are the most frequent clinical isolates: 2 strains Amos Tics Ctns (group 1), 4 strains AmoR Tics CtnR (gr. II), 4 strains AmoR TicR Ctns (gr. III) and 2 strains AmoR TicR CtnR (gr. IV). MIC and MBC were assessed for the 17 strains (Mueller Hinton broth). Combinations were carried out by a checkerboard micromethod. FBC index was calculated for each combination. Against enterococci the 50 combinations were: piperacillin versus ampicillin + aminoglycosides (streptomycin, tobramycin, amikacin, gentamicin, netilmicin). Against enterobacteria piperacillin was combined with different aminoglycosides depending on their resistance phenotypes. These combinations were compared with ticarcillin or mezlocillin or cefotaxime + aminoglycosides (total number 142). The species studied produced different results: with the enterococci Gr synergistic effects (FBC = 0.62-0.75) were rare; additive and indifferent effects were predominant. With the GR strain some antagonistic effects were observed. With the enterobacteria, in groups I and II synergistic effects were frequent and almost equivalent regardless of the beta-lactam chosen. In groups III and IV (TicR) piperacillin MICs were greater than or equal to 128 mg/l and mezlocillin MICs greater than 512 mg/l; the synergistic effects were significant (FBC from 0.25 to 0.62). beta-lactam + amikacin or netilmicin, and especially piperacillin + amikacin, were found to have the most frequent synergistic effects upon the strains tested. Mezlocillin combinations cannot be used clinically; the use of piperacillin combinations requires further discussion. On the other hand, cefotaxime + aminoglycosides combinations are active against those TicR strains.

Aminoglycosides↗
PubMed1986

A comparison of agar dilution, identification of beta-lactamases and disc diffusion methods for assessing the sensitivity to ticarcillin-clavulanic acid.

The in-vitro antibacterial activity of Timentin has been evaluated with a view to proposing valid criteria for sensitivity and resistance. Minimal inhibitory concentrations (MIC) were determined for 284 strains including Enterobacteriaceae, Pseudomonas aeruginosa, Acinetobacter spp., staphylococci and enterococci. The same strains were also used for the determination of inhibition zones around discs containing 75 micrograms ticarcillin and 10 micrograms clavulanic acid, and a straight regression line was drawn correlating MIC with inhibition zones. The bacterial population was subsequently grouped according to the diameters of inhibition zones of the antibiogram for 2427 strains of Enterobacteriaceae classified by phenotypes. The comparison of MICs of Timentin and ticarcillin for these strains shows that for penicillinase-producing strains, the Timentin MIC is lower than for ticarcillin whereas cephalosporinase-producing strains have equal MICs for the two. Finally strains that produce many different beta-lactamases are not affected by the presence of clavulanic acid. These results should make it possible to propose provisional zone diameters for determining sensitivity and resistance to Timentin.

Agar↗
PubMed1986

Identification of a nonfimbrial adhesive factor of an enterotoxigenic Escherichia coli strain.

An enterotoxigenic Escherichia coli strain (strain 2230), isolated from a patient with acute infantile diarrhea, was found to adhere only to the brush border of human intestinal epithelial cells. This strain does not hemagglutinate human, bovine, chicken, or guinea pig erythrocytes. The adhesion of E. coli 2230 appears to be mediated by a nonfimbrial bacterial surface protein of 16,000 daltons which can be extracted by heating the bacteria at 60 degrees C for 20 min. This surface protein is implicated as an adhesive factor because pretreatment of enterocytes with this protein extract completely inhibits the adhesion of E. coli 2230. This adhesive factor is serologically distinct from other adhesive factors found in enterotoxigenic E. coli strains. A plasmid DNA of 66 megadaltons is involved in the synthesis of this nonfimbrial adhesive factor.

Adhesiveness↗
PubMed1986

Resistance to beta-lactams in Enterobacteriaceae: distribution of phenotypes related to beta-lactamase production.

Phenotypes of susceptibility to amoxycillin (Amo), ticarcillin (Tic), cephalothin (Ctn) were determined in 1366 isolates of Enterobacteriaceae by disk method and beta-lactamases were identified in 243 strains belonging to different phenotypes of amoxycillin-resistant strains. AmoR TicR CtnS strains (25%) were penicillinase producers and all of them were susceptible to the combination amoxycillin/clavulanic acid (Amo/CA) and ticarcillin/clavulanic acid (Tic/CA). Amo1/R TicS CtnR strains (12%) were cephalosporinase producers and resistance to Amo/CA was observed, except for Proteus vulgaris. AmoR TicR CtnR strains (18%) often produced two beta-lactamases (penicillinase and cephalosporinase) and they were resistant to Amo/CA; in this group, susceptibility to Tic/CA depends on the nature and the amount of the beta-lactamase produced, except for Serratia marcescens for which antibiotic resistance is probably due to other mechanisms. Tic/CA resistance was mainly found in Serratia marcescens (41%) and Enterobacter cloacae (36%).

Amoxicillin↗
PubMed1986

[In-vitro activity of cefonicid on hospital bacteria. Regression line and proposal for critical values].

Antimicrobial activity of cefonicid, a new second generation cephalosporin, against 315 hospital isolates (4th trimester 1984) was investigated. E. coli and Proteus mirabilis were the most susceptible species. All E. coli strains except one were inhibited at 8 mg/l (modal MIC: 0.5); MICs of all indole + Proteus were 8 mg/l (modal MIC: 0.06). Another group was moderately susceptible: MICs of Klebsiella and Citrobacter ranged from 0.12 to 128 mg/l, but MICs of 50% of these strains were less than or equal to 4 mg/l; MIC was less than or equal to 8 mg/l for 75% of indole + Proteus and Providencia strains; tested Proteus vulgaris were especially resistant (MICs greater than 128 mg/l). Most Enterobacter and Serratia strains showed little susceptibility (modal MIC for both species greater than or equal to 128 mg/l). MICs of all tested Pseudomonas aeruginosa strains were greater than 128 mg/l. 20 of the 24 tested Acinetobacter strains had a MIC of greater than or equal to 128 mg/l. For Staphylococcus aureus, 88% of methicillin-sensitive strains were inhibited by concentrations of 2 to 4 mg/l whereas methicillin-resistant strains were resistant to cefonicid (75%: MIC greater than 64 mg/l). Enterococci were resistant to cefonicid. A correlation curve was established (Enterobacteria and Staphylococci). On the basis of cefonicid's pharmacokinetic characteristics, critical concentrations are proposed.

Bacteria↗
PubMed1985

[Carbenicillin resistance of gram-negative bacteria: incidence, biochemical and genetic determinism].

Of nine hundred ampicillin resistant (Amp-R) enterobacteria strains, isolated in hospital between July and December 1981, 73,7% are also carbenicillin-resistant (Carb-R). This particular double resistance varies depending upon the species considered: indole positive Proteus (23%), Enterobacter cloacae (64%), Citrobacter freundii (67%), Acinetobacter calcoaceticus (73%), Proteus mirabilis (75%), Serratia marcescens (90%), Escherichia coli (91%), Providencia stuartii (96%) and Klebsiella pneumoniae (100%). The biochemical and genetic basis of resistance to beta-lactamines was studied in 27 strains belonging to these 9 species. A constitutive beta-lactamase was found in all the strains. These enzymes were identified by determination of the isoelectric point on crude sonic extracts, the enzymic activity profile, the inhibition by clavulanic acid and cloxacillin of enzyme activity. Two types of enzymes were predominant: TEM-1 (20 strains) and TEM-2 (7 strains); two strains of Klebsiella pneumoniae produced both SHV-1 and TEM-1. The transfer by conjugation to E. coli K12 of ampicillin and carbenicillin resistance was obtained with 14 strains: (E. coli: 9, C. freundii: 1, K. pneumoniae: 1, E. cloacae: 2, P. stuartii: 1). In all strains but one E. coli we noted the co-transfer of other antibiotic resistance markers.

Ampicillin↗
PubMed1985

[In vitro effect of ceftriaxone on hospital bacteria. Line of regression and critical values].

Antimicrobial activity of ceftriaxone, a new third generation cephalosporin, against hospital isolates was investigated. 312 strains belonging to the most commonly recovered species were studied using the following methods: agar diffusion (disk antibiotic testing), agar dilution (determination of MIC) and dilution in a liquid medium with subculture to agar plates (determination of MBC). Except for a few Citrobacter strains and rare Serratia strains, all Enterobacteriaceae tested proved highly susceptible, with MICs less than or equal to 1 mg/l and mode MICs ranging from 0.003 mg/l (Proteus) to 0.25 mg/l (Enterobacter). MICs ranged from 16 to 32 mg/l for Acinetobacter (mode MICs: 16 mg/l) and 16 to greater than or equal to 128 for Pseudomonas (mode MIC greater than or equal to 128 mg/l). Methicillin-susceptible staphylococci were moderately susceptible to ceftriaxone (MIC: 2 to 8 mg/l) whereas methicillin-resistant staphylococci and enterococci were resistant (MIC greater than or equal to 64 mg/l). Bactericidal activity was excellent: MBC/MIC less than or equal to 2 (except for a few Serratia strains). A correlation curve was established. Given the high serum concentrations of ceftriaxone (achieved with the usual maximal dosage) and its unusually extended half-life (7 to 8 h), the following cutoff concentrations can be proposed: C less than or equal to 4 mg/l, corresponding to greater than or equal to 20 mm: susceptible bacteria C greater than 32 mg/l, corresponding to less than 15 mm: resistant bacteria.

Acinetobacter↗
PubMed1984

[Technic for assaying cefotaxime and desacetylcefotaxime in serum by high performance liquid chromatography].

Different high performance liquid chromatography (HPLC) methods for determination of cefotaxime (Ctx) and desacetyl cefotaxime (D-Ctx) are used. The method described presents the following advantages: a fast extraction and efficient deproteinization of serum samples are achieved with Sep-Pak cartridges; the mobile phase is a mixture of methanol - bidistilled water - acetic acid which permits the simultaneous dosage of Ctx and D-Ctx under the same chromatographic process. The retention times are respectively 7 mn 05 s and 10 mn 40 s for D-Ctx and Ctx. The results of 92 assays were compared with microbiological procedures.

Cefotaxime↗
PubMed1984

[Comparative multicenter study of 2 methods of determining sensitivity to antibiotics. Gel diffusion method and semiautomatic method in fluid ABAC medium].

Susceptibility of 60 bacterial isolates to 15 antibiotics was determined by two methods in three laboratories: 48 Gram negative bacilli and 12 Staphylococci were selected because of "intermediate" susceptibility to at least one antibiotic. Results show a good correlation between the two methods: more than 90% for carbenicillin, cefazolin, cefoxitin, cefamandole, kanamycin, tobramycin, amikacin, erythromycin, pristinamycin and fusidic acid, between 80 and 90% for penicillin G, ampicillin, oxacillin, gentamicin, doxycycline, chloramphenicol, spiramycin and clindamycin, less than 80% for neomycin, tetracycline, minocycline and oleandomycin. Interpretation criteria are different in the two methods for rifampicin, colistin and cotrimoxazole. Between the three laboratories, correlation was 90,3% and 88,6% for disc diffusion method and ABAC system respectively.

Anti-Bacterial Agents↗
PubMed1984

[Antibiotic sensitivity test. Comparative multicenter study of the gel diffusion and ATB methods].

The ATB method is a new method for antibiotic susceptibility testing. In a collaborative study, it was compared to a standard disc diffusion method. 23 strains were tested to determine reproducibility and 969 strains were used in the comparative study. Reproducibility of both methods is equivalent; differences due to strains were observed. Agreement between both methods is 87,9%, minor discrepancies are 8,7% and major discrepancies are 3,3%. Significant differences were found for carbenicillin and cefalotin and confirmed by MIC determination using the agar dilution method. Overall results show that the ATB method is reliable and comparable to disc diffusion for routine susceptibility testing.

Automation↗
PubMed1984

[Qualitative and quantitative analysis of the residual hand flora after hygienic-type washing with a soap and a foaming antiseptic solution].

Activity of a liquid soap and of a 4% povidone iodine detergent solution on hand skin flora after application for one minute ("hygienic type" handwashing) was studied. Samples were taken using a "bag" washing method. Total aerobic flora was determined quantitatively. Transient flora (Gram negative bacilli and mannitol positive Staphylococci) was determined both quantitatively and qualitatively. 54 determinations were performed (29 with liquid soap and 25 with povidone iodine) on 17 volunteers of the staff of the hospital bacteriology laboratory. After application of liquid soap, total flora, i.e. 10(6) bacteria per hand, was not reduced and the number of mannitol positive Staphylococci was increased. With povidone iodine, the reduction in total flora was 0.2-0.3 log 10 and the number of mannitol positive Staphylococci was decreased. With both products, Gram negative bacilli were eliminated in 60% of cases and greatly reduced in the remainder.

Hand↗
PubMed1983

[In vitro action of moxalactam on hospital bacteria. Results of a multicenter survey].

The high potency of Moxalactam on three major groups of bacteria, i.e. Enterobacteriae, Haemophilus and Bacteroïdes, predicted by previous studies, has been confirmed by the study of hospital strains in this multicenter investigation. Among these groups, the proportion of resistant strains is very low. However, Moxalactam is not superior to older agents on staphylococci, Streptococci and Listeria, and is less active than certain new agents on Pseudomonas. Moxalactam is one of the best "third generation" cephalosporins. It is remarkable by its potency against Bacteroides fragilis and its weak activity on Streptococci and Pneumococci. The unanswered question concerns the future of resistant strains: will they remain exceptional or will they multiply?

Bacteria↗
PubMed1983

[In vitro activity of combinations of cefotaxime and moxalactam with aminoglycosides on beta-lactamase-producing Enterobacteriaceae].

The in vitro synergistic activities of cefotaxime (Ctx) or moxalactam (Mox) in combination with gentamicin, amikacin, dibekacin or netilmicin were compared against 15 beta-lactamases non-producing or producing isolates of Enterobacteriaceae. The strains were classified according to their resistance to ampicillin (Am), carbenicillin (Cb) and cephalotin (Ce), but all were sensitive to the antibiotics tested in combination. In vitro checkerboard studies were performed using a microtiter technique for the selected strains. The FIC index was less than or equal to 0.62 for AmR CbR CeR strains (E. coli, E. cloacae, Serratia), for AmR CbS CeR strains (E. cloacae, Serratia, P. vulgaris) and for AmS CbS CeR strains (Serratia, P. morganii). These combinations were frequently additive (FIC = 0.75 - 1.0) against the AmS CbS CeS or AmR CbR CeS strains. Thus, the synergistic activities of Ctx and Mox in combination with an aminoglycoside seem to be correlated with beta-lactamase type produced by the Enterobacteriaceae.

Aminoglycosides↗