TY - JOUR
T1 - High-level tolerance to triclosan may play a role in Pseudomonas aeruginosa antibiotic resistance in immunocompromised hosts
T2 - Evidence from outbreak investigation
AU - D'Arezzo, Silvia
AU - Lanini, Simone
AU - Puro, Vincenzo
AU - Ippolito, Giuseppe
AU - Visca, Paolo
PY - 2012
Y1 - 2012
N2 - Background and methods. Pseudomonas aeruginosa is a major infectious threat to immunocompromised patients. We recently reported a fatal epidemic of multidrug-resistant P. aeruginosa in an onchoematology unit, linked to massive contamination of a triclosan-based disinfectant. The aim of this study is to evaluate the antimicrobial activity of triclosan and chlorhexidine digluconate against the epidemic strain of P. aeruginosa, to confirm the hypothesis that the soap dispenser acted as a continuous source of the infection during the outbreak, and to explore the potential role of triclosan in increasing the level of resistance to selected antibiotics. Susceptibility tests and time-kill assays for disinfectans were performed using two commercial formulations containing triclosan and chlorhexidine digluconate, respectively. Antibiotic susceptibility testing was performed by the broth microdilution method. Findings. The P. aeruginosa epidemic strain exhibited an extremely high level of triclosan resistance (apparent MIC = 2,125 mg/L), while it was markedly susceptible to chlorhexidine digluconate (apparent MIC = 12.5 mg/L). Upon gradual adaptation to triclosan, the epidemic strain survived for a long period (> 120 h) in the presence of 3,400 mg/L (equivalent to 1.6 × MIC) of triclosan, concomitantly increasing the resistance to six antibiotics that are typical substrates of drug efflux pumps of the resistance nodulation division family. This effect was reversed by efflux pump inhibitors. Conclusions: The epidemic P. aeruginosa strain was resistant to triclosan and its previous exposure to triclosan increases antibiotic resistance, likely through active efflux mechanisms. Since P. aeruginosa can become tolerant to elevated triclosan concentrations, the use of triclosan-based disinfectants should be avoided in those healthcare settings hosting patients at high risk for P. aeruginosa infection.
AB - Background and methods. Pseudomonas aeruginosa is a major infectious threat to immunocompromised patients. We recently reported a fatal epidemic of multidrug-resistant P. aeruginosa in an onchoematology unit, linked to massive contamination of a triclosan-based disinfectant. The aim of this study is to evaluate the antimicrobial activity of triclosan and chlorhexidine digluconate against the epidemic strain of P. aeruginosa, to confirm the hypothesis that the soap dispenser acted as a continuous source of the infection during the outbreak, and to explore the potential role of triclosan in increasing the level of resistance to selected antibiotics. Susceptibility tests and time-kill assays for disinfectans were performed using two commercial formulations containing triclosan and chlorhexidine digluconate, respectively. Antibiotic susceptibility testing was performed by the broth microdilution method. Findings. The P. aeruginosa epidemic strain exhibited an extremely high level of triclosan resistance (apparent MIC = 2,125 mg/L), while it was markedly susceptible to chlorhexidine digluconate (apparent MIC = 12.5 mg/L). Upon gradual adaptation to triclosan, the epidemic strain survived for a long period (> 120 h) in the presence of 3,400 mg/L (equivalent to 1.6 × MIC) of triclosan, concomitantly increasing the resistance to six antibiotics that are typical substrates of drug efflux pumps of the resistance nodulation division family. This effect was reversed by efflux pump inhibitors. Conclusions: The epidemic P. aeruginosa strain was resistant to triclosan and its previous exposure to triclosan increases antibiotic resistance, likely through active efflux mechanisms. Since P. aeruginosa can become tolerant to elevated triclosan concentrations, the use of triclosan-based disinfectants should be avoided in those healthcare settings hosting patients at high risk for P. aeruginosa infection.
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U2 - 10.1186/1756-0500-5-43
DO - 10.1186/1756-0500-5-43
M3 - Article
C2 - 22260715
AN - SCOPUS:84855901559
VL - 5
JO - BMC Research Notes
JF - BMC Research Notes
SN - 1756-0500
M1 - 43
ER -