Author:
Tarquinio Keiko,Confreda Kelsey,Shurko James,LaPlante Kerry
Abstract
ABSTRACTIndwelling medical devices have become a major source of nosocomial infections, especiallyPseudomonas aeruginosainfections, which remain the most common cause of ventilator-associated pneumonia (VAP) in neonates and children. Using medical grade polyvinyl chloride endotracheal tubes (ETTs), the activity of tobramycin and polymyxin E was quantified in a simulated prevention and treatment static time-kill model using biofilm-formingP. aeruginosa. The model simulated three clinical conditions: (i) planktonic bacteria grown in the presence of antibiotics (tobramycin and polymyxin E) without ETTs, (ii) planktonic bacteria grown in the presence ofP. aeruginosa, antibiotic, and ETTs (simulating prevention), and (iii) a 24-h-formedP. aeruginosabiofilm grown on ETTs prior to antibiotic exposure (simulating treatment). In the model simulating “prevention” (conditions 1 and 2 above), tobramycin alone or in combination with polymyxin E was more bactericidal than polymyxin E alone at 24 h using a concentration of greater than 2 times the MIC. However, after a 24-h-old biofilm was allowed to form on the ETTs, neither monotherapy nor combination therapy over 24 h exhibited bactericidal or bacteriostatic effects. Against the same pathogens, tobramycin and polymyxin E, alone or in combination, exhibited bactericidal activity prior to biofilm attachment to the ETTs; however, no activity was observed once biofilm formed on ETTs. These findings support surveillance culturing to identify pathogens for a rapid and targeted approach to therapy, especially whenP. aeruginosais a potential pathogen.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology
Cited by
16 articles.
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