Document Detail

Resistance of artificial biofilms of Pseudomonas aeruginosa to imipenem and tobramycin.
MedLine Citation:
PMID:  10052899     Owner:  NLM     Status:  MEDLINE    
Viable cells of Pseudomonas aeruginosa were entrapped in alginate gel layers and incubated in a minimal glucose (15 g/L)-yeast extract (2 g/L)-salt medium to form artificial biofilm-like structures. After cultivation for 2 days, the biomass distribution inside the polymer was highly heterogeneous. The cell number reached approximately 1011 cells/g gel in the outer regions of the gel structures whereas the inner areas were less colonized (c. 10(8) cells g/gel). Killing of immobilized organisms by imipenem and tobramycin were compared with free-cell experiments (inoculum c. 10(9) cells/mL). Sessile-like bacteria displayed a higher resistance to the two antibiotics used alone or in combination than did suspended cells. Exposure for 10 h to 20 x MIC imipenem and 15 x MIC tobramycin reduced the number of viable immobilized bacteria to 0.3% and 3%, respectively, of the initial cell population, whereas these antibiotic concentrations were much more efficient (bactericidal) against free-cell cultures (5 log kill in 6 h). A synergic effect of tobramycin and imipenem was detected on bacterial suspensions but not on biofilm-like structures. Effective diffusivity measurements showed that the diffusion of imipenem in the alginate layer was not hindered. A slight but significant enhancement of beta-lactamase induction in immobilized cells as compared with their suspended counterparts was insufficient to explain the high resistance of sessile-like bacteria.
L Coquet; G A Junter; T Jouenne
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of antimicrobial chemotherapy     Volume:  42     ISSN:  0305-7453     ISO Abbreviation:  J. Antimicrob. Chemother.     Publication Date:  1998 Dec 
Date Detail:
Created Date:  1999-08-09     Completed Date:  1999-08-09     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  7513617     Medline TA:  J Antimicrob Chemother     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  755-60     Citation Subset:  IM; S    
Laboratoire des Polymères, Biopolymères, Membranes, UMR 6522 du CNRS, Bois Guillaume, France.
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MeSH Terms
Anti-Bacterial Agents / pharmacology*
Biofilms / drug effects*
Cells, Immobilized
Drug Resistance, Microbial
Imipenem / pharmacology*
Microbial Sensitivity Tests
Pseudomonas aeruginosa / drug effects*,  growth & development
Thienamycins / pharmacology*
Tobramycin / pharmacology*
beta-Lactamases / metabolism
Reg. No./Substance:
0/Anti-Bacterial Agents; 0/Thienamycins; 32986-56-4/Tobramycin; 74431-23-5/Imipenem; EC

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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