In vitro activity of antimicrobial combinations against multidrug-resistant Pseudomonas aeruginosa

Introduction Pseudomonas aeruginosa isolates related to nosocomial infections are often resistant to multiple antibacterial agents. In this study, antimicrobial combinations were evaluated to detect in vitro synergy against clinical isolates of P. aeruginosa. Methods Four clinical P. aeruginosa isol...

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Bibliographic Details
Published in:Revista da Sociedade Brasileira de Medicina Tropical
Main Authors: Denissani Aparecida Ferrari dos Santos Lima, Margarida Maria Passeri do Nascimento, Lucia Helena Vitali, Roberto Martinez
Format: Article in Journal/Newspaper
Language:English
Published: Sociedade Brasileira de Medicina Tropical (SBMT) 2013
Subjects:
Pseudomonas aeruginosa
Antimicrobial synergy
Beta-lactam agents
Fosfomycin
Tobramycin
Rifampin
Arctic medicine. Tropical medicine
RC955-962
Arctic
Online Access:https://doi.org/10.1590/0037-8682-0012-2013
https://doaj.org/article/1c84110a367e4c0f8b192456d0e48825
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Summary:Introduction Pseudomonas aeruginosa isolates related to nosocomial infections are often resistant to multiple antibacterial agents. In this study, antimicrobial combinations were evaluated to detect in vitro synergy against clinical isolates of P. aeruginosa. Methods Four clinical P. aeruginosa isolates were selected at random among other isolates from inpatients treated at the public University hospital in Ribeirão Preto, SP, Brazil. Two isolates were susceptible to imipenem (IPM-S) and several other antimicrobials, while the other two isolates were imipenem and multidrug resistant (IPM-R). The checkerboard method was used to assess the interactions between antimicrobials. Results Combinations of imipenem or other anti-Pseudomonas drugs with complementary antibiotics, such as aminoglycosides, fosfomycin and rifampin, reached synergy rates of 20.8%, 50%, 62.5% and 50% for the two IPM-S and two IPM-R Pseudomonas isolates, respectively. Imipenem, piperacillin-tazobactam and ceftazidime yielded a greater synergy rate than cefepime or ciprofloxacin. Synergist combinations were more commonly observed when the complementary drug was tobramycin (65%) or fosfomycin (57%). Conclusions Some antibacterial combinations led to significant reductions of the minimum inhibitory concentrations of both drugs, suggesting that they could be clinically applied to control infections caused by multidrug-resistant P. aeruginosa.

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