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Evaluation of biofilm production by P seudomonas aeruginosa from canine ears and the impact of biofilm on antimicrobial susceptibility in vitro
Author(s) -
Pye Charlotte C.,
Yu Anthony A.,
Weese J. Scott
Publication year - 2013
Publication title -
veterinary dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.744
H-Index - 60
eISSN - 1365-3164
pISSN - 0959-4493
DOI - 10.1111/vde.12040
Subject(s) - biofilm , microbiology and biotechnology , gentamicin , pseudomonas aeruginosa , otitis , antimicrobial , enrofloxacin , antibiotics , neomycin , bacteria , polymyxin b , polymyxin , biology , medicine , ciprofloxacin , genetics
Background Pseudomonas aeruginosa is a common cause of canine otitis; P . aeruginosa biofilm formation has been documented in human medicine, but the role of biofilms in canine disease is not well documented. Bacteria within biofilms can be more resistant to antibiotics compared with their planktonic form; therefore, understanding the biofilm‐forming capacity of isolates and their susceptibility to antimicrobials is important when developing treatment regimens. Hypothesis/Objectives To evaluate the biofilm‐forming capacity of canine otic isolates of P . aeruginosa and to compare the minimal inhibitory concentration ( MIC ) of the planktonic versus biofilm‐embedded bacteria. Methods Biofilm‐forming ability was assessed using a microtitre plate assay. Broth microdilution was used to assess the MIC s of neomycin, polymyxin B , enrofloxacin and gentamicin for the planktonic and biofilm‐embedded bacteria. Results Eighty‐three isolates from dogs with otitis were tested; 33 (40%) were classified as biofilm producers. Biofilm MIC s for polymyxin B , neomycin, gentamicin and enrofloxacin were significantly higher than for the planktonic form ( P < 0.05). Conclusions and clinical importance Biofilm production by otitis isolates of P . aeruginosa is common and may play a role in the pathogenesis of disease. The MIC s for biofilm‐embedded bacteria differ from their planktonic counterparts, potentially leading to a lack of response to treatment. If polymyxin B , gentamicin, neomycin or enrofloxacin is to be used for topical treatment of a P seudomonas otitis, the concentration of the medication should be increased, in particular if addressing chronic otitis, because biofilms may have developed.