Optimization of the use of ciprofloxacin.

AIMS: To compare mutant prevention concentration (MPC) of ciprofloxacin and time-killing curve with regards to 11 genotyped Escherichia coli. METHOD: MICs were determined using the E-test method. Time-killing studies were performed in accordance with the NCCLS guidelines. The genes gyrA, gyrB, parC, parE and marR were amplified by PCR and sequenced. The MPC was defined as the lowest antibiotic concentration preventing the growth of resistant colonies when 10(10) CFU/mL were spread on a solid medium. RESULTS: Strains with no genes gyrA, gyrB, parC, parE and marR mutation presented MIC less or equal to 0.023 mg/L and MPC less or equal to 0.25 mg/L. Strains with two mutations (gyrA and parC) presented MIC equal to 1.5 mg/L and MPC equal to 4 mg/L. Strains with one mutation (gyrA) presented MIC less or equal to 0.75 mg/L, but MPC ranged from 0.5 to 6 mg/L depending of the MIC of ciprofloxacin. The time-killing curves for ciprofloxacin showed a bactericidal activity of 0.25 mg/L in 1h for strains without mutation, compared with a bactericidal activity of 2 and 4 mg/L in 4h for strains with one and two mutations, respectively. CONCLUSION: For strains of E. coli resistant to nalidixic acid, it was necessary to evaluate the MIC of ciprofloxacin in order to asses the optimal dosage of ciprofloxacin.

Propionibacterium acnes contamination in lumbar disc surgery.

Previous studies have shown that Propionibacterium acnes may be responsible for low-grade infection of the intervertebral discs of patients with severe sciatica. The aim of this study was to prospectively investigate the presence of bacteria in disc fragment samples obtained during surgery for lumbar disc herniation. P. acnes was cultured from disc fragments in two (3.7%) of 54 patients studied. In addition, control cultures taken from ligamentum flavum and muscle from these two patients were also positive for P. acnes. Similar control cultures were positive for P. acnes from a further ten (18.5%) patients. Four air samples taken during surgery all contained P. acnes; the organism was also found from three of 54 laminar flow control cultures. Sample contamination appears the most likely cause for the presence of P. acnes in the lumbar disc fragment cultures.

Impact of restricting fluoroquinolone prescription on bacterial resistance in an intensive care unit.

The purpose of this study was to assess the effect of reducing prescription of fluoroquinolones in an intensive care unit (ICU) upon bacterial resistance, particularly as regards Pseudomonas aeruginosa. For six months between January 2001 and June 2001, administration of fluoroquinolones was kept to a minimum. A bacteriological screening of patients was performed to assess the incidence of fluoroquinolone-resistant bacteria. There was a 75.8% restriction in prescriptions of fluoroquinolones. There was no significant change in bacterial ecology between the periods preceding (12 months) and following (12 months) restriction. There was a significant recovery of sensitivity of P. aeruginosa to ciprofloxacin (P

Detection of an outbreak of methicillin-resistant Staphylococcus aureus with reduced susceptibility to glycopeptides in a French hospital.

Staphylococcus aureus isolates were screened for reduced susceptibility to glycopeptides with an initial glycopeptide agar screening test, followed by confirmation of the strains thus identified by two Etest strip techniques and population analysis. This procedure detected 48 methicillin-resistant S. aureus (MRSA) isolates with reduced susceptibility to glycopeptides from 24 patients among 883 MRSA isolates tested. The dissemination of a single clone was confirmed by pulsed-field gel electrophoresis.

[Epidemic outbreaks control involving Staphylococcus aureus with reduced sensitivity to glycopeptides]. / Contrôle de phénomènes épidémiques dus à des souches de Staphylococcus aureus de sensibilité diminuée aux glycopeptides.

This study describes two epidemic outbreaks involving Staphylococcus aureus with reduced sensitivity to glycopeptides, one in 2000 involving eight patients and the other in 2001-2002 involving 16 patients. These strains were detected rapidly, thanks to routine screening for the offending organisms in the bacteriology laboratory of our hospital. The clonal character of these strains was confirmed by pulsed field electrophoresis. The management of these epidemic outbreaks confirmed (i) the need for systematic adoption of standard precautions, (ii) the importance of circulating information in combating multi-resistant bacteria, as well as the difficulties in transferring colonised patients to different hospital wards, and (iii) the intermittent nature of S. aureus carriage, resulting in a need for prolonged surveillance of colonised and/or infected patients. In addition, our study underlines the value of a multi-disciplinary approach to the management of diffusion of multi-resistant bacteria.

Evaluation of BacT/Alert 3D liquid culture system for recovery of mycobacteria from clinical specimens using sodium dodecyl (lauryl) sulfate-NaOH decontamination.

A total of 52 mycobacterial isolates were recovered from 1,197 clinical specimens decontaminated by a sodium dodecyl (lauryl) sulfate (SDS)-NaOH protocol. Of these, 94% were recovered with the BacT/Alert 3D system (Organon Teknika, Durham, N.C.) and 79% were recovered on Löwenstein-Jensen (LJ) medium. Mean times to detection of organisms of the Mycobacterium tuberculosis complex (n = 47) were 22.8 days with LJ medium and 16.2 days with the system. The BacT/Alert 3D system is a rapid and efficient detection system which can be used with an SDS-NaOH decontamination procedure.

Performance of the chromogenic medium CHROMagar Staph Aureus and the Staphychrom coagulase test in the detection and identification of Staphylococcus aureus in clinical specimens.

CHROMagar Staph aureus (CSAM) (CHROMagar Microbiology, Paris, France) is a new chromogenic medium designed to enable detection of colonies of Staphylococcus aureus by their pink color. A total of 775 specimens were cultured in parallel on CHROMagar Staph aureus and conventional media. Among the 267 S. aureus strains recovered on at least one medium, 263 were isolated on CSAM medium (sensitivity, 98.5%), and 245 (sensitivity, 91.8%) were isolated on conventional media. The specificity of presumptive identification of S. aureus on the basis of pink colony color on CSAM medium was 97% (493 of 508). This specificity increased to 100% when coagulase detection with the Staphychrom coagulase test was added and to 98.8% when S. aureus surface components were detected by agglutination in the Pastorex Staph Plus test. Susceptibility testing of 67 S. aureus strains, performed in parallel on pink CSAM colonies and on colonies grown on blood agar, gave similar results. Thus, rapid and accurate recognition and identification of S. aureus isolates were achieved with CSAM as the primary isolation medium, followed by the staphylocoagulase Staphychrom test. Antimicrobial susceptibility testing (disk-diffusion method or ATB STAPH System) can be performed directly on pink CSAM colonies.