title: Tetracycline in combination with sodium dioctylsulfosuccinate show increased antimicrobial activity in resistant microorganisms.
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.
authors.affiliation: Institute of Microbiology, Faculty of Pharmacy, University of Rome La Sapienza, Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Simonetti
authors.forename: N
authors.initials: N
authors.lastname: Simonetti
authors.forename: A
authors.initials: A
authors.lastname: Villa
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects* / Q000472:pathogenicity; D004143:Dioctyl Sulfosuccinic Acid / Q000494:pharmacology*; D004347:Drug Interactions; D004352:Drug Resistance, Microbial; D004359:Drug Therapy, Combination; D008826:Microbial Sensitivity Tests; D013501:Surface-Active Agents / Q000494:pharmacology*; D013752:Tetracycline / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D013501:Surface-Active Agents; D004143:Dioctyl Sulfosuccinic Acid; D013752:Tetracycline