Effect of ethanol/trisodium citrate lock on microorganisms causing hemodialysis catheter-related infections

This in vitro study tested the effectiveness of a novel 30% ethanol/4% trisodium citrate (TSC) lock solution against the most common pathogens causing hemodialysis catheter-related infections.

Clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) (n = 4), methicillin-sensitive S. aureus (MSSA) (n = 8), methicillin-resistant Staphylococcus epidermidis (MRSE) (n = 8), Pseudomonas aeruginosa (n = 4) and Escherichia coli (n = 4) were tested in duplicate. Bacterial suspensions of each isolate were made in a control solution of normal saline and Mueller-Hinton broth (MHB), and in a lock solution of ethanol 30%, TSC 4% and MHB. Suspensions were incubated at 37 degrees C for 48 h. Colony counts were determined from samples collected at t = 0 h (before exposure to the ethanol/TSC lock), t = 1 h (one hour after exposure to the ethanol/TSC lock), t = 24 h and t = 48 h. To confirm the absence of viable organisms in the lock solution, the remaining volume at 48 h was filtered through a 0.45 microm filter. The filter was rinsed with 15 mL sterile water and plated on tryptic soy agar (TSA).

All controls demonstrated significant growth over 48 h. In the lock solutions, initial inocula were reduced to 0 viable colonies by t = 1 h (6-log kill), and there was no growth at t = 24 and 48 h. Filtering of lock solutions also showed no growth. These results were consistent among duplicates of all isolates.

The 30% ethanol/4% TSC lock solution consistently eradicated MRSA, MSSA, MRSE, P. aeruginosa and E. coli within 1 h of exposure. Experiments are currently underway to test this novel lock solution on preventing biofilm production by these pathogens.