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M Meyran

Publications and source records attributed to M Meyran.

At least 73 records · Page 4Linked to original sources
PubMed1987

[Aminoside sensitivity of bacteria isolated in 1984 at the military hospital complex in the Paris region].

The minimal inhibiting concentrations (MIC) of 5 aminosids have been determined by the microdilution method in liquid medium of 4,582 bacterial strains isolated from various pathological samples: 1,039 Staphylococcus, 2,629 Enterobacteria, 759 Pseudomonas and 155 Acinetobacter. The phenotype of resistance has been defined for each strain by listing the antibiotics for which a resistance was observed. The frequencies of the bacterial resistances varied according to the aminosid (gentamicin, sisomicin, tobramycin, netilmicin and amikacin) and to the species studied. For the bacterial species studied, these frequencies of resistance to the aminosid family of antibiotic were weaker in the military hospitals in the district of Paris, than in different civil hospitals where similar studies were conducted.

Acinetobacter↗
PubMed1986

[In-vivo bacteriostatic and bactericidal activity of pefloxacine].

After oral ingestion of pefloxacin (400 mg every 12 hours for four days), the following characteristics were studied: bacteriostatic and bactericidal activity of urine for controls free of urinary tract infection on 6 "test" strains; kinetics of bacteriostatic and bactericidal activity of urine as compared to serum in patients with urinary tract infection. The urinary bacteriostatic level approximates bactericidal levels in healthy individuals. This level, that varies across bacterial species, remains steady between the third hour and the twenty-fourth hour following initiation of treatment: values found were 1/16 to 1/8192 for enterobacteria, 1/64 to 1/256 for Pseudomonas aeruginosa and 1/256 to 1/512 for Staphylococcus aureus. In patients, urinary killing curves show that bacteriuria decreases by 5 Log10 approximately, starting at the third hour. Urine was sterile by the sixth hour. In most cases, serum bacteriostatic activity was above 1/32 throughout treatment, with maximum levels being recorded on the fourth day (above 1/64). Bactericidal activity is similar to bacteriostatic activity.

Blood Bactericidal Activity↗
PubMed1986

[Present status of the sensitivity of Pseudomonas aeruginosa to aminoglycosides in France].

9,119 strains of P. aeruginosa were collected from 10 French hospitals from 1981 to 1984. The MIC of gentamicin (GM), sisomicin (SIS), tobramycin (TOB), dibekacin (DBK), netilmicin (NET), amikacin (AMK), and habekacin (HBK) was determined by the two fold microdilution method. 81% of the strains were susceptible to the 4 aminoglycosides. The MICs (geometric mean, mg/l) for these susceptible strains were: GM: 1.69, SIS: 1.58, TOB: 1.06, DBK: 1.12, NET: 2.73, AMK: 4.16, HBK: 2.70. 19% of the 9 119 strains were resistant to SIS, 18% to GM, 16% to TOB and DBK, 11% to NET, 3% to AMK and HBK. Among the 1 758 strains resistant to one or several aminoglycosides, the frequency of the resistance phenotypes was GM-SIS: 11%, GM-SIS-NET: 4.95%, GM-SIS-TOB-DBK: 32.7%, GM-SIS-TOB-DBK-NET: 34.45%, SIS-TOB-DBK-NET: 2.5%, SIS-TOB-DBK-NET-AMK-HBK: 2.39%, GM-SIS-TOB-DBK-NET-AMK-HBK: 11.61%. The mechanism of resistance of the phenotypes 1 to 6 is enzymatic. The mechanism of resistance of the phenotype 7 (resistance to the six aminoglycosides) is either enzymatic or due to decreased uptake or penetration of antibiotic. HBK and AMK are the aminoglycosides most frequently active against P. aeruginosa. The patterns of resistance to both antibiotics are the same. On a weight-for-weight basis, HBK is more active than AMK.

Aminoglycosides↗
PubMed1985

In-vitro comparison of macrolides, lincosamides and synergistins on Neisseria gonorrhoeae.

The MIC of erythromycin, oleandomycin, spiramycin, josamycin, lincomycin and pristinamycin was determined for 100 strains of Neisseria gonorrhoeae isolated from cases of acute urethritis in men. The method of dilution in agar was used: blood agar with the addition of 'Polyvitex' and an innoculum of 10(3)-10(4) bacteria per spot. With respect to the break points defined by the C.F.A. all the strains of N. gonorrhoeae studied are sensitive to erythromycin, spiramycin, josamycin and pristinamycin, 12% strains are resistant to oleandomycin and 75% to lincomycin. The active antibiotics are classified as follows according to the active weight expressed by the MIC50: erythromycin, pristinamycin, 0.125 mg/l; josamycin, 0.5 mg/l; spiramycin, oleandomycin, 2 mg/l.

Anti-Bacterial Agents↗
PubMed1985

[In vitro activity of ceftriaxone on hospital bacteria. Results of a multicenter study].

Minimal inhibitory concentrations (MICs) of ceftriaxone were determined by agar dilution for 2 099 strains isolated in six teaching hospitals. MICs were less than 1 microgram/ml for the great majority of Enterobacteriaceae, with mode MICs varying across groups from less than 0.008 micrograms/ml for Proteus (mirabilis and indole-positive) to 0.25 for Enterobacter. Only a few resistant strains were found, mainly among Enterobacter and Citrobacter. Ceftriaxone proved noticeably less active against P. aeruginosa and Acinetobacter (mode MICs: 16 micrograms/ml). Haemophilus sp. and Gonococci, regardless of beta-lactamase production status, as well as Neisseria meningitidis, were highly susceptible (MIC less than 0.008-0.032). Ceftriaxone was moderately active against methicillin-susceptible staphylococci (MIC: 2 to 8 micrograms/ml) and failed to inhibit methicillin resistant strains. Enterococci were slightly susceptible or resistant, whereas the other Streptococci and Pneumococci had low MICs (0.03-0.25). A fairly wide range of MICs was found for anaerobes (Clostridium: 0.06-2, Bacteroides: 0.5-32). Our data show that its particularly strong activity against Proteus, Haemophilus and Neisseria sets ceftriaxone apart from the other third-generation cephalosporins.

Acinetobacter↗
PubMed1985

[Multicenter study of the in vitro effect of imipenem (N-formimidoyl-thienamycin) on hospital bacteria].

Minimal inhibitory concentrations (MICs) of imipenem were evaluated by agar dilution for 2 895 bacterial strains isolated in 9 hospitals. Imipenem proved highly active against Enterobacteriaceae, with an MIC less than or equal to 0.25 for 63% of the 1 556 tested strains, less than or equal to 1 for 89.6% and less than or equal to 4 for 99%. The different groups of Enterobacteriaceae exhibited similar mode MICs (0.12 to 0.25), with the exception of Serratia (0.25-0.5), P. mirabilis (0.5), indole-positive Proteus (2), and Providencia (1). MICs of most cefotaxime-resistant strains were within the susceptibility range. Imipenem also exhibited satisfactory activity against P. aeruginosa (mode MIC 1-2) and Acinetobacter sp. (mode MIC: 0.25-0.5). MICs ranged from 0.03 to 4 (mode MIC: 0.5) for Haemophilus sp. and 0.25 to 1 for Gonococci, regardless of beta-lactamase-production status. MICs for Meningococci were less than or equal to 0,06. Methicillin-susceptible Staphylococci had low MICs, ranging from 0.008 to 0.5 (mode MIC : 0.016); MICs for methicillin-resistant strains varied widely, from 0.016 to 64, and were higher after incubation at 30 degrees C. Streptococci, except for Enterococci, and Pneumococci were highly susceptible (usually 0.008-0.03); MICs for Enterococci varied from 0,12 to 32 (mode MIC: 1-2). Except for four C. difficile strains, all tested anaerobic strains were inhibited by concentrations less than or equal to 1 (mode MICs: 0.06 for C. perfringens and 0.03 for B. fragilis).

Acinetobacter↗
PubMed1985

beta-Lactamases of Pseudomonas aeruginosa and susceptibility against beta-lactam antibiotics.

A total of 4093 non-replicate Pseudomonas aeruginosa isolates supplied by 10 French hospitals from September 1981 to August 1983 was examined for susceptibility to ticarcillin (TIC) and to 11 other beta-lactam antibiotics. Overall incidence of TIC-resistance was low (20.9%) but variable between hospital, unit and culture site and primarily mediated by a constitutive beta-lactamase as observed by iodometric detection (66.3%). As suggested by analytical isoelectrofocusing on gel, PSE-1 (CARB-2) and OXA types were predominant but new types appeared. The comparative in vitro activities of 12 antipseudomonal beta-lactams appreciated by microtiter MICs with an inoculum of 10(5) CFU were established according to phenotype: TIC-susceptible, TIC-R with a constitutive beta-lactamase (PSE-1, OXA-1, OXA-2, OXA-3, PSE-2 and a new type, TEM-1 and TEM-2 and derepressed cephalosporinase) or without detectable activity. Different patterns of resistance were demonstrated, but imipenem, ceftazidime and aztreonam were the most active antibacterial agents.

Anti-Bacterial Agents↗
PubMed1985

[Comparative in vitro activity of 2 monobactams (RO 172301 (AMA 1080)and aztreonam), ceftazidime and cefotaxime on Gram-negative bacilli].

In vitro activities of two monobactams (RO 172301 and aztreonam), ceftazidime and cefotaxime against 739 bacterial strains belonging to different species of Gram negative aero-anaerobic bacilli were studied comparatively. Strains were studied according to their resistance phenotype to beta-lactams. Minimal inhibitory concentrations (MIC) of the four antibiotics were determined using the agar dilution method. RO 172301 and aztreonam exhibited a similar activity against P. aeruginosa with a MIC around 2 mg/l for 50% of strains and around 4 mg/l for 90% of strains. As compared to the two monobactams, ceftazidime was more active and cefotaxime less active (one halving dilution either way). Activity of antibiotics was not dependent upon the mechanism of resistance to beta-lactams, except for strains producing a constitutive cephalosporinase. Against Enterobacteriaceae, RO 172301 proved slightly more active than aztreonam and cefotaxime; ceftazidime was the least active drug. Only 12 of the 739 strains tested (1.6%) had a MIC for RO 172301 above 32 mg/l. The percentage of resistant strains was 2.4% for aztreonam and ceftazidime and 8.8% for cefotaxime.

Acinetobacter↗
PubMed1985

[In vitro study of the effects of a ticarcillin-clavulanic acid combination on Pseudomonas aeruginosa as a function of resistant phenotypes].

Activity of ticarcillin combined with clavulanic acid against 203 P. aeruginosa strains was studied. 159 strains produced a constitutive beta-lactamase with resistance to ticarcillin (MIC less than 128 mg/l) as a result. Minimal inhibitory concentrations (MICs) were determined using the agar dilution method for ticarcillin alone and combined with 4 and 8 mg/l clavulanic acid. Addition of clavulanic acid failed to change the activity of ticarcillin on ticarcillin-susceptible stains and on strains producing a constitutive cephalosporinase. A synergic effect was demonstrated for PSE and TEM type beta-lactamase producers and for OXA type beta-lactamase producers (4 halving dilutions and 1 to 2 halving dilutions respectively). However, because of the levels of baseline MICs, the combination brought the MIC of ticarcillin below the cutoff level for a small percentage of PSE strains (6%), moderate percentage of OXA strains (17 to 50%) and significant percentage of TEM strains. These percentages were slightly higher with 8 mg than 4 mg clavulanic acid. Given current data on the prevalence of the various beta-lactamases among resistant strains now being isolated in France, the ticarcillin + clavulanic acid combination will enable to achieve an MIC less than 128 mg/l for 11% (with 4 mg) or 16% (with 8 mg) of resistant strains.

Clavulanic Acid↗
PubMed1984

[Comparative effect of beta-lactam activity on Pseudomonas aeruginosa as a function of resistance phenotypes].

In a multicentre study of the distribution in France of constitutive beta-lactamases produced by Ps. aeruginosa, the activities of 12 antibiotics were investigated comparatively according to resistance phenotypes. Antibiotics with the best activity, on a weight-for-weight basis, against "wild" non carboxypenicillin-resistant strains were ureidopenicillins among penicillins, ceftazidime and cefsulodin among cephalosporins and a new beta-lactam compound: N-formimidoyl-thienamycin. Thirty per cent of carboxypenicillin-resistant strains do not possess constitutive beta-lactamases. With most antibiotics, except N-f-thienamycin, minimum inhibitory concentrations (MICs) against these strains were increased 2 or 3-fold. However, the MICs of ureidopenicillins remained well below critical concentrations. The activities of the penicillins tested and of cefoperazone and cefsulodin against strains with constitutive beta-lactamases were considerably reduced. Those of other cephalosporins, such as cefotaxime, ceftriaxone, moxalactam, ceftazidime and azthreonam were little modified. However, in view of the plasma concentrations obtained, with the exception of ceftazidime and azthreonam the MICs of these cephalosporins were too high for satisfactory therapeutic results to be expected. Ps. aeruginosa strains producing beta-lactamases of the chromosomal cephalosporinase type are still rare (0.9%), but their number seems to be increasing. These strains, probably selected by treatments, are resistant to all beta-lactam antibiotics, and their degree of resistance to cephalosporins, ceftazidime included, is particularly high.

Anti-Bacterial Agents↗
PubMed1984

[Distribution of constituent beta-lactamases in Pseudomonas aeruginosa].

Acquired resistance of Pseudomonas aeruginosa to beta-lactam antibiotics, e.g. ticarcillin, has the following characters: The incidence of ticarcillin-resistant strains is about 21% but it varies with hospitals from 10.9 to 35.1%. Resistance is predominantly due to beta-lactamases, which are produced by two-thirds of the strains (64.4% in 1982, 67.9% in 1983). The presence of beta-lactamase positive strains is dependent upon the type of patient, the hospital unit (e.g. urology or burns) and the nature of the specimen collected. Most beta-lactamase positive strains spontaneously produce one single penicillinase of the CARB (53.8%), OXA (30.5%) or TEM (8.7%) type. New types of beta-lactamases may develop and hydrolyse beta-lactam antibiotics such as ticarcillin, azlocillin, cefoperazone or cefsulodin. With beta-lactam antibiotics (cefotaxime, moxalactam, ceftazidime) that resist hydrolysis, bacterial resistance is due to production of a constitutive beta-lactamase of the cephalosporinase type. This enzyme has recently appeared and its incidence is low (6.8%). Associated beta-lactamases (e.g. penicillinase plus cephalosporinase) are exceptional.

Anti-Bacterial Agents↗
PubMed1984

[In vitro activity of ceftizoxime on hospital bacteria. Results of a multicenter study].

The susceptibility to ceftizoxime of all bacterial strains isolated from seven university-affiliated hospitals over one month was tested with disk-diffusion technique. Additionally, the MIC of 1937 strains selected at random was evaluated by the agar dilution method. The majority of Enterobacteriaceae are inhibited at a concentration of less than 1 microgram/ml with a mode MIC varying from 0.008 to 0.12 among the various groups. A few Enterobacter and Citrobacter strains are resistant. Little activity was demonstrated by ceftizoxime on Pseudomonas aeruginosa and Acinetobacter sp. (mode MIC 32 and 8 micrograms/ml respectively). Haemophilus sp. (MIC 0.01-0.03) and Neisseria (MIC less than 0,008-0,016) are very susceptible to the drug. The MIC of methicillin-sensitive strains of Staphylococcus aureus varies from 1 to 4 micrograms/ml ; Enterococci are less susceptible, whereas other Streptococci and Pneumococci have low MICs (less than 0.008-0.025). The susceptibility of anaerobic pathogens varies widely between species, and within species ; MIC ranges from 0.008 to 32 micrograms/ml for Clostridium sp. and 0.25 to 128 micrograms/ml for Bacteroides sp.

Bacteria↗
PubMed1984

[Multicenter study of the antibacterial activity of a new cephalosporin: CM 40874].

Minimal inhibitory concentrations (MIC) of CM were evaluated on 2 548 bacterial strains isolated in 8 hospitals. CM demonstrated high activity on Enterobacteriaceae, the MIC being less than or equal to 0.125 micrograms/ml for 71% of the 1 362 strains tested, less than or equal to 1 for 99.6%, and less than or equal to 4 for 99.9%. Mode MIC varies little among the different groups of Enterobacteriaceae (from 0.06 to 0.12 micrograms/ml), with the exception of Serratia sp. (mode MIC : 0.25) and Klebsiella oxytoca (mode MIC : 0.03). Most of Enterobacter, Serratia, and Citrobacter sp. strains not inhibited by cefotaxime are readily inhibited by CM at the same concentrations than susceptible strains. CM has less activity on P. aeruginosa (MIC 2-32 micrograms/ml) and Acinetobacter sp. (MIC 8-128). Staphylococci (MIC 32) and Enterococci are not susceptible. Variable activity is found against other Streptococci. CM inhibits Haemophilus sp. at MICs of 0.12 to 0.5 micrograms/ml and Gonococci at MICs of 0.03 to 0.5 (whether the strains produce beta-lactamase or not). Meningococci have a mode MIC of 0.03 micrograms/ml (range 0.008 to 0.25). Thus, CM 40874 is a new third generation cephalosporin with high activity on Enterobacteriaceae, including those strains not susceptible to cefotaxime and good activity on Haemophilus sp. and Neisseria sp. This additional activity is probably supported by enhanced resistance to enzymatic inactivation by beta-lactamases.

Bacteria↗
PubMed1984

[Determination of the minimum bactericidal concentration. Influence of various technical factors].

Measurement of minimal bactericidal concentrations of antibiotics is requisite to select the most appropriate drugs in severe infections. However, MBC assays are reliable only if the various technical modalities are well-standardized. We determined MBCs of ampicillin (E. coli), gentamicin (E. coli, P. aeruginosa, S. aureus), cefazolin (E. coli), ticarcillin (P. aeruginosa), and oxacillin (S. aureus), for different values of a number of parameters : inoculum from a 4 h and 18 h culture, measurement of MBC for 99.9% and 99.99% of bacteria, plate microdilution and macrodilution in plastic or glass test tubes, inoculation under a 1 ml or 0.1 ml volume, determination of MIC and subculture at the 24th hour, with or without Vortex agitation at the 20th hour. Most MBCs were identical for 99.9% and 99.99% of bacteria. Conversely, results were significantly modified by changes in other factors. Very high MBCs were consistently found in plastic tubes. MBCs were higher after inoculation under a 1 ml volume than under a 0.1 ml volume. MBC was usually similar to MIC with the microdilution technique, or with glass tubes, inoculation under a 0.1 ml volume and subculture at the 24th hour following Vortex agitation at the 20th hour.

Anti-Bacterial Agents↗
PubMed1983

[In vitro activity of azthreonam on hospital Gram-negative bacilli. Results of a multicenter study].

This work reports a multicenter study of antibacterial activity of azthreonam, a new antibacterial agent of the monobactam group, on Gram negative rods. Enterobacteriaceae are very sensitive to azthreonam (modal MIC: 0,06 micrograms/ml); some strains have higher MIC greater than or equal to 8 micrograms/ml, particularly among Enterobacter, Serratia and Citrobacter. Azthreonam has a good activity on Pseudomonas aeruginosa: 90% of the strains are inhibited by 8 micrograms/ml or less. Acinetobacter are less sensitive with a modal MIC of 32 micrograms/ml. Haemophilus are inhibited by low concentrations, 0,06 to 0,12 micrograms/ml usually.

Anti-Bacterial Agents↗