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Tetracycline in combination with sodium dioctylsulfosuccinate show increased antimicrobial activity in resistant
G Simonetti1, N Simonetti, A Villa
1Institute of Microbiology, Faculty of Pharmacy, University of Rome La Sapienza, Rome, Italy.
Abstract:
We present evidence that sodium dioctylsulfosuccinate, at non inhibitory concentrations (1000 mg/L), is able to increase the antimicrobial activity of tetracycline in non susceptible bacterial and fungal strains. In culture inhibition tests, pretreatment with sodium dioctylsulfosuccinate caused a 52-fold decrease in the geometric mean MIC to tetracycline in 10 Candida albicans strains (p<0.01), a 165-fold decrease in the geometric mean MIC to tetracycline in 10 E. coli strains (p<0.001) and a significant decrease in the mean MIC of 3 strains of Candida krusei and Candida glabrata. In microbicidal tests, tetracycline in association with sodium dioctylsulfosuccinate killed 10(4) cfu tetracycline-resistant Candida albicans in 15 min and 10(4) CFU resistant E. coli in 3 min (p<0.001). Furthermore, in the N-acetyl-D-glucosamine test to calculate the number of hyphal cells, a combination of tetracycline (50 mg/L) (non inhibitory concentrations) plus sodium dioctylsulfosuccinate (25 mg/L) caused a 50-fold increase in the inhibition of hyphal cells in C. albicans (p<0.001); C. albicans cells treated with tetracycline plus sodium dioctylsolfosuccinate annulled the cell surface hydrophobicity (p<0.001). This increase in antimicrobial activity may be attributed to impairment and alteration of the membrane barrier within the microorganisms and a depletion of the thiol groups (p<0.001) critical to their efficiency.
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