ABSTRACT
The discovery in 1998 that triclosan has a site-specific action in the bacterial cell as an inhibitor of NADH- or NADPH-dependent enoyl-acyl carrier protein reductase led to a lively debate in the scientific press. The thesis of this debate was that such a mode of action may allow triclosan to induce resistance and cross-resistance in bacterial cells. The debate last saw review in 2004, and this paper aims at updating our knowledge in this area, given recent research on the topic.
Subject(s)
Disinfectants/pharmacology , Drug Resistance, Bacterial , Fatty Acid Synthesis Inhibitors/pharmacology , Triclosan/pharmacology , Disinfectants/chemistry , Enoyl-(Acyl-Carrier-Protein) Reductase (NADH)/antagonists & inhibitors , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Fatty Acid Synthesis Inhibitors/chemistry , Triclosan/chemistryABSTRACT
AIMS: The effect of subminimal inhibitory concentrations (sub-MICs) of cefalexin, ciprofloxacin and roxithromycin was investigated on some virulence factors [e.g. coagulase, Toxic Shock Syndrome Toxin 1 (TSST-1) and biofilm formation] expressed by Staphylococcus aureus biofilms. METHODS AND RESULTS: Biofilms were grown with and without the presence of 1/16 MIC of antibiotics on Sorbarod filters. Eluate supernatants were collected, and coagulase and TSST-1 production were evaluated. Coagulase production was reduced in eluates exposed to roxithromycin when compared to control, while TSST-1 production was reduced in biofilms exposed to cefalexin and to a lesser extent, ciprofloxacin. In addition, the ability of Staph. aureus to produce biofilm in microtitre plates in the presence of sub-MIC antibiotics indicated that cefalexin induced biofilm formation at a wide range of sub-MICs. TSST-1 produced from the challenged and control biofilms was purified, and its proliferative activity was studied on single cell suspension of mouse splenocytes using MTS/PMS assay. No significant difference in the activity between the treated toxin and the control has been observed. CONCLUSIONS: Antibiotics at sub-MIC levels interfere with bacterial biofilm virulence expression depending on the type and concentration of antibiotic used. SIGNIFICANCE AND IMPACT OF THE STUDY: The establishment of sub-MICs of antibiotics in clinical situations may result in altered virulence states in pathogenic bacteria.
