[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.

[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.

[Branhamella catarrhalis: incidence in pulmonary infections and determination of sensitivity to 5 antibiotics]. / Branhamella catarrhalis: incidence dans les infections pulmonaires et détermination de leur sensibilité à cinq antibiotiques.

This study reports 45 cases of respiratory tract infection associated with Branhamella catarrhalis, diagnosed by bacteriological examination out of 980 sputum samples studied over a 6 months period. These infections were observed mainly in patients with chronic respiratory disease (68.9%). More than half of the isolates were found in pure culture, others were isolated from mixed infections most often with Haemophilus influenzae, Streptococcus pneumoniae or H. influenzae plus S. pneumoniae. 64.7% of Branhamella catarrhalis isolates produced beta-lactamase. In vitro antimicrobial susceptibility testing demonstrated that the B. catarrhalis isolates, including beta-lactamase producing strains, were very susceptible to clavulanic acid plus amoxycillin (MIC90:0.12 microgram/ml) as well as to doxycycline and erythromycin (MIC90:0.5 microgram/ml).

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).

[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.