In Vitro and In Vivo Activities of Levofloxacin against Biofilm-Producing Pseudomonas aeruginosa

Abstract

Interactions between biofilm cells of Pseudomonas aeruginosa and levofloxacin were studied. P. aeruginosa incubated for 6 days with Teflon sheets formed a biofilm on its surface. Against the biofilm bacteria, levofloxacin at an MIC determined by the standard method for the strain was highly bactericidal whereas gentamicin, ceftazidime, and ciprofloxacin showed no significant killing activity. Levofloxacin, ciprofloxacin, and gentamicin, but not ceftazidime, exhibited killing activity against nongrowing cells of the strain incubated in phosphate buffer. In addition, levofloxacin, ciprofloxacin, and ceftazidime, but not gentamicin, showed the ability to penetrate an agar containing alginate. These findings may explain the efficacy of levofloxacin and the ineffectiveness of gentamicin and ceftazidime against biofilm bacteria; however, the cause of the ineffectiveness of ciprofloxacin still remains to be determined. In experimental pneumonia in guinea pigs, in which the biofilm mode of growth of the strain was observed in the lung, only levofloxacin exhibited substantial therapeutic efficacy. These findings suggest the significant role of levofloxacin in therapy of biofilm bacterium-associated infectious diseases.

Synergistic effect of lipopeptide biosurfactant with antibiotics against Escherichia coli CFT073 biofilm

“…It is now well established that adherent cells have a higher resistance compared with planktonic forms [26][27][28][29][30]. Thus, novel approaches of combining different antimicrobial compounds to increase their efficacy are beginning to be explored.…”

Pathogenesis and clinical manifestations of chronic colonization by Pseudomonas aeruginosa and its biofilms in the airway tract

“…10,168,169 When experimentally formed P. aeruginosa biofi lm was placed in cultures of mouse bronchoalveolar lavage fl uid (BALF), erythrocytes, but not phagocytic cells, adhered to the surface of the mass. 110 The inherent resistance of biofi lm-associated bacteria has been attributed to their reduced susceptibility to microcidal agents which cannot penetrate into the biofi lm, 159,161,170 as well as retardation of the diffusion of the microcidal agents, 171,172 and inactivation of the agent in the outer layers of the biofi lm. 23 The bacteria located in the lower stratum of the biofi lm are limited to a slow-growing or stationary state 133 and are more resistant to antimicrobial agents than actively growing cultures.…”

Activity of levofloxacin and ciprofloxacin on biofilms and planktonic cells of Stenotrophomonas maltophilia isolates from patients with device-associated infections

“…Since fluoroquinolones kill non-growing bacteria and can penetrate biofilms, they are interesting agents against sessile bacteria [11].…”