In vitro activities of N-acetyl cysteine and levofloxacin as a catheter lock therapy against catheter-associated infections.

Abstract

Since management of catheter-associated infections, which are generally biofilm-based, is attempted in certain patients such as older and frail patients by using a catheter lock solution (CLS), we examined the combination of N-acetyl cysteine (NAC), an antibiofilm agent, and levofloxacin, a broad-spectrum antimicrobial agent, for this purpose. Intravascular catheters were colonized with methicillin-resistant Staphylococcus epidermidis, levofloxacin-sensitive/methicillin-resistant Staph. aureus, levofloxacin-resistant/methicillin-resistant Staph. aureus, vancomycin-resistant Enterococcus, Escherichia coli, Klebsiella pneumoniae or Pseudomonas aeruginosa and treated with a CLS containing normal saline, NAC, levofloxacin or NAC plus levofloxacin (NACLEV) and then cultured to assess their antimicrobial activities. We also examined antibiofilm and antimicrobial activities of each CLS by scanning electron microscopy (SEM) and the mechanical integrity of catheters exposed to CLS. Treatment of colonized catheters with NACLEV-CLS significantly reduced colonization (p<0.005) against all pathogens. SEM images also indicate reduction in colonization with NACLEV-CLS with considerable reduction in both visible bacteria and the associated biofilm. Mean tensile strength of catheters exposed to CLS was not significantly different compared to controls (p>0.05). These in vitro results suggest that NACLEV-CLS can significantly reduce all bacterial colonization and potentially help salvage infected catheters without affecting the catheter's mechanical integrity. This study presents a novel CLS with a broad spectrum of antimicrobial activity against catheter-associated infections, particularly in long-term catheters.