Evaluation of the BDProbeTec ET DTB assay(1) for direct detection of Mycobacterium tuberculosis complex from clinical samples.

The purpose of this study was to evaluate the ability of BDProbeTec ET DTB system to detect Mycobacterium tuberculosis complex directly from clinical specimens. A total of 628 specimens (553 respiratory and 75 non respiratory specimens) were collected from 478 patients. These samples were tested with the BDProbeTec ET DTB assay and results were compared with acid fast microscopy and culture. Sixty eight out of 77 culture positive M. tuberculosis complex samples were detected with overall sensitivity and specificity of 89.5% and 98.2% respectively. Overall sensitivity was 100% in smear positive samples and 79% in smear negative samples. After resolution of discrepant results, sensitivity and specificity for respiratory samples were 91.6% and 98.7% respectively. BDProbeTec ET DTB assay demonstrated to be a rapid, sensitive and specific method for detection of M. tuberculosis complex.

[In vitro activity of pristinamycin against Streptococcus pneumoniae]. / Activité in vitro de la pristinamycine sur Streptococcus pneumoniae.

The activity of the pristinamycin was investigated using disk diffusion agar or ATB PNEUMO system and MIC determination using reference liquid medium method (NCCLS) on 749 S. pneumoniae strains isolated in Aquitaine in 1999. We have realized the killing curves against 10 isolates selected from erythromycin-susceptible and resistant S. pneumoniae strains. All the strains tested by ATB PNEUMO system were susceptible to pristinamycin, using disk diffusion agar, 6.8% of strains were intermediate or resistant. However the MIC's of pristinamycin determined by liquid dilution method against these strains were < 1 mg/L. These data suggest that the zone of inhibition around the disk was not correlated with MIC for erythromycin pneumococci and MIC testing must be performed. The results of killing curves showed a very good and rapid bactericidal activity of pristinamycin within two hours for concentration equal to 4 x MIC and four hours for 2 x MIC.

Comparative antimycobacterial activities of ofloxacin, ciprofloxacin and grepafloxacin.

Infections caused by non-tuberculous mycobacteria and multidrug-resistant Mycobacterium tuberculosis are difficult to treat. New compounds potentially active against these bacteria are therefore constantly being sought. Among them is grepafloxacin, a new C5 fluoroquinolone. A panel of 130 isolates of mycobacteria including 33 M. tuberculosis isolates and 97 isolates of different species of atypical mycobacteria were analysed for susceptibility to grepafloxacin, ofloxacin and ciprofloxacin. The MICs of these fluoroquinolones were determined using the agar-dilution method. Different mycobacterial species showed different degrees of susceptibility to grepafloxacin, ofloxacin and ciprofloxacin but little difference was observed between the MICs of the three antibiotics against strains of the same mycobacterial species. In addition, to evaluate the intracellular activity of these drugs, six strains of mycobacteria were studied using a human-macrophage infection model. Preliminary results of macrophage experiments showed that grepafloxacin was more active than ofloxacin and ciprofloxacin, particularly against Mycobacterium kansasii and, to a lesser degree, against Mycobacterium avium complex and Mycobacterium marinum. However, the three fluoroquinolones had comparable activities against M. tuberculosis.

Cellular pharmacology of lipophilic anthracyclines in human tumor cells in culture selected for resistance to doxorubicin.

We have studied the cytotoxicity and intracellular accumulation of two lipophilic anthracyclines, pirarubicin and idarubicin, as compared to doxorubicin, in two human tumor cell lines, MCF7 and K562, and in their doxorubicin-resistant counterparts, presenting the multidrug-resistant (MDR) phenotype. The new lipophilic anthracyclines were found to present a higher cytotoxicity and accumulation than the reference anthracycline, doxorubicin, and there was a significant inverse correlation between drug accumulation and IC50 in both cell types. With the aim of identifying the reasons for the higher cytotoxicity and accumulation of lipophilic anthracyclines, we used and compared the efficiency of three MDR modulators, verapamil, quinine and S-9788. We showed that all three were able to sensitize the resistant cells to the three anthracyclines, but with different efficiencies, S-9788 being the most active reverter and quinine the least active at equimolar doses. We also observed that there was no correlation between the abilities of a modulator to reverse resistance and to restore drug accumulation. In view of the sustained activity of the modulators to increase pirarubicin and idarubicin cytotoxicity and accumulation, as they do for doxorubicin, we conclude that the better efficiency of lipophilic anthracyclines is likely to be due to their high uptake rate rather than to a decreased activity of P-glycoprotein on these drug substrates.

Identification of a Bombyx collagenous protein with multiple short domains of Gly-Xaa-Yaa repeats: cDNA characterization and regulation of expression.

Using a differential screening strategy, a 2 kb cDNA was isolated from a differentiating Bombyx mori imaginal wing discs library. The available reading frame of 1710 bp specifies a conceptual protein with two distinct regions: a 395 amino acid region corresponding to 105 repetitions of the Gly-Xaa-Yaa triple-helical forming unit arranged in 9 domains of 12-54 residues interspaced by short interruptions of 3-17 residues and a C-terminal domain of 175 amino acids devoided of triplets. These characteristics suggest that the encoded protein is a new member of the collagen superfamily, the first one characterized in Bombyx. Northern blots reveal a unique 7.4 kb mRNA in imaginal wing discs, epidermis and brain. In wing discs, the 7.4 kb transcripts accumulate during the last larval moult and the spinning stage. In vitro studies reveal that this accumulation is dose dependent and detectable within 1 h in response to 20-hydroxyecdysone which acts without de novo protein synthesis. A model of regulation of transcript accumulation with regards to the hormonal level is proposed.

[In vitro activity of six beta-lactams against 295 strains of enterobacteriaceae and P. aeruginosa isolated from neutropenic patients]. / Activité in vitro de six beta-lactamines vis-à-vis de 295 souches d'entérobactéries et P. aeruginosa isolées chez des patients neutropéniques.

The in vitro activity of two new beta-lactam agents, cefpirome (CPO) and cefepime (FEP), was investigated against 295 Gram-negative bacilli (250 enterobacteriaceae and 45 P. aeruginosa) isolated from neutropenic patients. They were compared with ceftazidime (CAZ), piperacillin-tazobactam (TZP), imipenem (IPM) and cefotaxime (CTX). All enterobacteriacae were susceptible to IPM, 16 strains were intermediately susceptible or resistant to CAZ (1 strain of E. coli, 4 of Morganella morganii and 11 of Enterobacter. The 250 strains of enterobacteriacea were susceptible to FEP (MIC < 1 mg/l) and only one strain among them was intermediately susceptible to CPO. Among 45 strains of P. aeruginosa, 21 strains were susceptible to CPO, 30 to FEP, 31 to TZP, 32 to CAZ and 34 to IPM. All the strains were inhibited by less than 32 mg/l of FEP and IPM.

Genes expressed during the differentiation of the pupal wings are also transiently expressed during the larval moult in Bombyx mori.

By a differential screening of cDNA libraries made with RNAs present in differentiating imaginal wing discs of Bombyx mori, we have isolated clones whose expression is dramatically modified during the formation of the pupal wings. The RNAs corresponding to all but one of these clones are also transiently accumulated in the wing primordia during the last larvo-larval moult and in response to 20-hydroxyecdysone injections. If the injections are made to juvenilized larvae the expression of the same genes is stimulated but the range of the stimulation is reduced. It is suggested that in Bombyx, cells of the wings reach the pupal stage of differentiation by steps corresponding to the phases during which high levels of ecdysteroids are present.

Analysis of cellular fatty acids and proteins by capillary gas chromatography and sodium dodecyl sulphate polyacrylamide gel electrophoresis to differentiate Mycobacterium avium, Mycobacterium intracellulare and Mycobacterium scrofulaceum (MAIS) complex species.

Infections due to atypical mycobacteria have increased during the past 30 years. Species of Mycobacterium avium, Mycobacterium intracellulare and Mycobacterium scrofulaceum are among the most common non-tuberculous mycobacteria isolated from patients with AIDS or immunosuppressed. These three organisms are taxonomically closely related and identification, according to cultural characteristics and biochemical tests, is not always evident, so some of these related strains are grouped in a "MAIS" complex. Analysis of cellular constituents is an aid to identification. Gas chromatography was used to study mycolic acids and a secondary alcohol was found which is a discriminating constituent between M. scrofulaceum and the other two species. The lipidic analysis was not able to separate M. avium and M. intracellulare, so cell proteins were considered. Sodium dodecyl sulphate polyacrylamide gel electrophoresis of proteins reflects genetic relatedness between strains; the different patterns obtained from these three species are described and it is shown that this method is very useful in classification and epidemiology.

In vitro activities of vancomycin and teicoplanin against coagulase-negative staphylococci isolated from neutropenic patients.

This study reports the in vitro activities of vancomycin and teicoplanin against 185 coagulase-negative staphylococcal strains isolated from 80 neutropenic patients who received different antibiotic treatments. All strains were susceptible to vancomycin: MICs for 50 and 90% of strains tested were 2 and 4 mg/liter, respectively. Teicoplanin was less active, and MICs displayed a wider range. For only teicoplanin was there a correlation between resistance and previous treatment. At the 4- and 32-mg/liter breakpoint levels, only 20% of the strains isolated from patients without glycopeptide treatment were intermediate or resistant, whereas 49.2% of the strains from patients who had received vancomycin or teicoplanin or both were intermediate or resistant.

[Effect of various technics in the determination of sensitivity of Pseudomonas aeruginosa to imipenem]. / Influence de différents facteurs techniques dans la détermination de la sensibilité de Pseudomonas aeruginosa à l'imipénème.

The in vitro activity of imipenem was determined against 115 isolates of Pseudomonas aeruginosa. The susceptibility was compared according to two technics: disk diffusion method and minimal inhibitory concentration determinations (MIC), this, with three different Mueller Hinton agar (Diagnostics Pasteur, bioMérieux, Amor Equipement Scientifique) and two inocula. There is not inoculum effect. On the contrary, except for extreme values, there is discrepancies in the activity according to the medium. The correlation between zone diameters and MIC values is less good when Mérieux and AES Mueller Hinton agar were used.

[In vitro effect of combinations of daunorubicin and antibiotics against various bacterial strains]. / Activité in vitro des associations daunorubicine et antibiotiques sur diverses espèces bactériennes.

The associations of daunorubicin with various antibiotics were studied by the broth dilution method ("checkboard" technic). The FIC Index were calculated to evaluate the effect of the various combinations. Antibiotics tested were chosen according to the bacterial species: vancomycin, cefotaxime, oxacillin, tobramycin, rifampicin against 15 isolates of Staphylococcus, ampicillin, piperacillin, vancomycin, rifampicin against 10 isolates of enterococci, piperacillin, ofloxacin, tobramycin against 5 E. coli strains. No antagonistic effect was observed whatever the antibiotic or bacterial strain. Against enterococci, all combinations showed a synergistic or additive effect, the most pronounced effect being demonstrated with rifampicin (FIC Index value around 0.3). Among the combinations tested against Staphylococcus, the combination daunorubicin + tobramycin demonstrated synergy against all but 1 strain tested, the combinations including oxacillin, cefotaxime or rifampicin showed a synergistic or additive effect, combinations including vancomycin showed addition or no drug interaction. Antibiotics tested against E. coli gave a synergistic combined drug effect in some cases, more often an additive effect, some time no interaction, depending on the strain.

[In vitro sensitivity of Mycobacterium avium and Mycobacterium xenopi to erythromycin, roxithromycin and doxycycline]. / Sensibilité in vitro de Mycobacterium avium et Mycobacterium xenopi a l'érythromycine, roxithromycine et doxycycline.

The comparative in vitro activity of erythromycin, roxithromycin and doxycycline against 20 isolates of M. avium and 20 M. xenopi was evaluated by two technics: a standard macrobroth dilution (7H9) and the 1% standard proportion method on lowenstein medium. M. avium was highly and uniformly resistant to doxycycline (MIC 50: 64 mg/l). For macrolides some strains were moderately susceptible to roxithromycin and at a lower level to erythromycin the MIC 50 and MIC 90 were respectively 8 and 16 mg/l for roxithromycin, 16 and 64 mg/l for erythromycin. Both macrolides were active against most of the strains of M. xenopi MIC 90 and MBC 90 were respectively 0.25 and 1 mg/l for roxithromycin, 0.5 and 2 mg/l for erythromycin. Doxycycline was less active inhibiting 90% of strains only at 16 mg/l.

[Randomized prospective study of ceftazidime versus a cefotaxime-tobramycin combination in acute leukemia in therapeutic aplasia]. / Etude prospective randomisée, de la ceftazidime versus l'association céfotaxime-tobramycine, dans les leucémies aiguës en aplasie thérapeutique.

In a prospective study, 157 patients with prolonged aplasia (PMN less than 500/mm3 during more than 21 days), hospitalized in a protected environment unit, were randomly assigned to receive ceftazidime alone or cefotaxime + tobramycin for initial febrile episodes. Age, sex, underlying diseases, duration of neutropenia, digestive decontamination regimen, clinical and microbiological characteristics of infections were similar in the two groups. Patients were evaluated for their initial response to antibiotics (defervescence in 48 hours, maintained 7 days) and long term response (prevention of another infection during aplasia). The overall initial response to ceftazidime was 48/71 (68 per cent) and to cefotaxime + tobramycin 55/86 (64 per cent). The long term response to ceftazidime was 33/71 (46.5 per cent) and to cefotaxime + tobramycin 31/86 (36 per cent). In conclusion, ceftazidime alone was as effective as cefotaxime + tobramycin in the first line treatment of febrile episodes in neutropenic patients.

[Evolution of bacterial resistance to five aminoglycosides. A study of 3,354 strains isolated in a hospital milieu]. / Evolution de la résistance bactérienne à cinq aminosides. Etude portant sur 3,354 souches isolées en milieu hospitalier.

The authors studied the susceptibility to 5 aminoglycosides (amikacin, dibekacin, gentamicin, netilmicin and tobramycin) of 3,354 strains isolated at the Centre Hospitalier Sud in Bordeaux during 1987. The results are compared to those obtained in 1984 on 2,818 strains. Amikacin remains the most active aminoside against the Enterobacteriaceae and Acinetobacter; against Pseudomonas, tobramycin has become the best one at that time, as well as netilmicin against Staphylococcus aureus. Evolution: no significative increase of Enterobacteriaceae resistance to aminoglycosides was observed during the last 3 years except for Providencia and Serratia. For Acinetobacter and Pseudomonas, percentage of resistant strains is respectively two-fold and three-fold higher. Although resistance increased in that species, netilmicin and amikacin showed a still good activity against Staphylococcus aureus.

In vitro activity of four fluoroquinolones against eighty-six isolates of mycobacteria.

The in vitro activity of pefloxacin, norfloxacin, ofloxacin and ciprofloxacin against 86 strains of mycobacteria was evaluated by broth dilution. While Mycobacterium avium, Mycobacterium scrofulaceum and Mycobacterium chelonae were resistant to all four antibacterials, the susceptibility of the other species, Mycobacterium tuberculosis, Mycobacterium kansasii, Mycobacterium xenopi and Mycobacterium fortuitum, depended on the antibiotic. Ofloxacin and ciprofloxacin (MIC90: 0.5 - 2 mg/l) were more active than pefloxacin and norfloxacin (MIC90: 2 - 16 mg/l).

[Intestinal decontamination in the neutropenic patient. Apropos of a prospective randomized study]. / La décontamination intestinale chez le patient neutropénique. A propos d'une étude prospective randomisée.

Sixty-five patients undergoing remission-induction chemotherapy for acute leukemia in a protected environment unit were randomly assigned to selective antimicrobial modulation of the intestinal flora (SAM) with trimethoprim-sulfamethoxazole, or total antibiotic decontamination (TAD) with gentamicin, vancomycin and colimycin. Digestive tract colonization with Streptococcus D was more prevalent in the SAM group (p less than 0.01); colonization with yeasts was more prevalent in the TAD group (p less than 0.001). However, there was no difference between the two groups as regards to clinically and microbiologically documented infections, septicemias and survival. Selective antimicrobial modulation with trimethoprim-sulfamethoxazole is as effective and cheaper than total antibiotic decontamination with gentamicin, vancomycin and colimycin.

[Bacteriostatic activity of azlocillin, gentamycin, amikacin singly or in combination on 200 strains of Pseudomonas aeruginosa]. / Activité bactériostatique de l'azlocilline, gentamicine, amikacine seuls et en association sur 200 souches de Pseudomonas aeruginosa.

In vitro activity of azlocillin, gentamicin, and amikacin, alone or in combination was evaluated against 200 clinical isolates of Pseudomonas aeruginosa. The minimum inhibitory concentrations (MICs) were determined by a standard technique. For the evaluation of synergistic activities, one antibiotic was added in a concentration equivalent to one-fourth its MIC to increasing concentrations of the other antibiotic. The MIC for 50% of the strains was 3.25 micrograms/ml for gentamicin, 3 micrograms/ml for amikacin and 7 micrograms/ml for azlocillin. No significant difference could be seen between the two combinations, the percentage of synergy was 37% for azlocillin-gentamicin and 36% for azlocillin-amikacin. No antagonism was observed.