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.
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.
Authors: Natalya Doroshenko; Boo Shan Tseng; Robert P Howlin; Jill Deacon; Julian A Wharton; Philipp J Thurner; Brendan F Gilmore; Matthew R Parsek; Paul Stoodley Journal: Antimicrob Agents Chemother Date: 2014-09-29 Impact factor: 5.191
Authors: Kevin D Mlynek; Mary T Callahan; Anton V Shimkevitch; Jackson T Farmer; Jennifer L Endres; Mélodie Marchand; Kenneth W Bayles; Alexander R Horswill; Jeffrey B Kaplan Journal: Antimicrob Agents Chemother Date: 2016-04-22 Impact factor: 5.191
Authors: Mandy Ng; Samuel B Epstein; Mary T Callahan; Brian O Piotrowski; Gary L Simon; Afsoon D Roberts; John F Keiser; Jeffrey B Kaplan Journal: Dose Response Date: 2013-07-25 Impact factor: 2.658