PT  - JOURNAL ARTICLE
AU  - MALTHE M. KRISTIANSEN
AU  - CLARA LEANDRO
AU  - DIANE ORDWAY
AU  - MARTA MARTINS
AU  - MIGUEL VIVEIROS
AU  - TERESA PACHECO
AU  - JOSEPH MOLNAR
AU  - JETTE E. KRISTIANSEN
AU  - LEONARD AMARAL
TI  - Thioridazine Reduces Resistance of Methicillin-resistant <em>Staphylococcus aureus</em> by Inhibiting a Reserpine-sensitive Efflux Pump
DP  - 2006 May 01
TA  - In Vivo
PG  - 361--366
VI  - 20
IP  - 3
4099  - http://iv.iiarjournals.org/content/20/3/361.short
4100  - http://iv.iiarjournals.org/content/20/3/361.full
SO  - In Vivo2006 May 01; 20
AB  - Previous studies suggested that the phenothiazine chlorpromazine (CPZ) could reverse or reduce the antibiotic resistance of bacteria. In some areas of the world, the majority of Staphylococcus aureus isolates are now resistant to methicillin, prompting this study to see whether such resistance can be altered by phenothiazine thioridazine (TZ), an agent with equal antibacterial activity, which is free of the severe side-effects associated with chronic administration of CPZ. The results indicated that, whereas methicillin-sensitive strains of Staphylococcus aureus (MSSA) were not rendered more susceptible to oxacillin, resistance to oxacillin by highly-resistant strains (MRSA) could be significantly reduced by sub-inhibitory concentrations of TZ. Reserpine, an inhibitor of efflux pumps, was also shown to reduce the resistance of MRSA strains to oxacillin in a concentration-dependent manner. The phenothiazines have been shown, by others, to inhibit the efflux pumps of bacteria and the mechanism by which MRSA are rendered more susceptible to oxacillin in the presence of TZ is believed to be due to a similar efflux pump. Copyright © 2006 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved