[The activity of eight fluoroquinolones versus biolayers of Escherichia coli and Pseudomonas aeruginosa in siliconized latex urinary catheters].

OBJECTIVE

To evaluate the in vitro activity of eight fluoroquinolones against Escherichia coli and Pseudomonas aeruginosa biofilms on siliconized latex urinary catheters.

MATERIAL AND

METHODS

The MICs and MBCs of norfloxacin, ciprofloxacin, ofloxacin, levofloxacin, clinafloxacin, sparfloxacin, trovafloxacin, and moxifloxacin for two strains of E. coli (CBR-3 and CBR-4) and two strains of P. aeruginosa (HUS-3 and PBR-2) were determined according to the NCCLS guidelines. The susceptibility of bacteria attached to siliconized latex catheters to fluoroquinolones was also evaluated. Catheter segments containing 6 or 24 hours old biofilms were used as inocula for the studies of antimicrobial activity against bacterial biofilms.

RESULTS

MICs of ciprofloxacin for planktonic and attached bacteria were equal. MICs values for the others fluoroquinolones increased two or more times when bacterial biofilms were used as inocula, except for ofloxacin and E. coli CBR-4, trovafloxacin and E. coli CBR-3, and levofloxacin and trovafloxacin and P. aeruginosa PBR-4; in these cases the MIC values for planktonic and attached bacteria were similar. When bacteria attached to siliconized latex were used as inocula, MBCs values increased 8-> 4,096-fold for all the fluoroquinolones evaluated.

CONCLUSIONS

E. coli and P. aeruginosa biofilms on siliconized latex were more resistant to the bactericidal activity of fluoroquinolones than planktonic bacteria.