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

AIMS: 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. METHODS AND RESULTS: 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). CONCLUSIONS: 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. SIGNIFICANCE AND IMPACT OF STUDY: This study presents a novel CLS with a broad spectrum of antimicrobial activity against catheter-associated infections, particularly in long-term catheters.

Adherence to clinical practice guidelines for the treatment of candidemia at a Veterans Affairs Medical Center.

OBJECTIVES: The primary objective of this study was to examine the appropriateness of candidemia management at a Veterans Affairs Medical Center as recommended by the 2009 Infectious Diseases Society of America (IDSA) guidelines for treatment of Candida infections. METHODS: A retrospective analysis of 94 adult patients with blood cultures positive for Candida spp. was performed. Patients were stratified by severity of disease into two groups: non-neutropenic, mild-moderate disease (Group 1, n = 54, 56%) and non-neutropenic, moderate-severe disease (Group 2, n = 40, 42%). RESULTS: Adherence to the IDSA recommendations for recommended antifungal drug, dose, and duration of therapy was low in both groups (16.7% in Group 1 and 17.5% in Group 2). Although adherence was not associated with higher clinical resolution of infection (P = 0.111), it was associated with a significantly lower mortality rate (P = 0.001) when compared to variance from the guidelines at 6 weeks. CONCLUSION: Although adherence to published guidelines for treating patients with candidemia was suboptimal at our institution, patients that were managed based on the guidelines had a statistically lower mortality rate.

Characteristics of biofilm on tunneled cuffed hemodialysis catheters in the presence and absence of clinical infection.

BACKGROUND: Biofilm occurring on the surface of tunneled hemodialysis (HD) catheters is difficult to eradicate and often is associated with recurrent bacteremia. We studied biofilm formation on catheters from patients with and without bacteremia to identify the location of bacterial growth and measure biofilm thickness. STUDY DESIGN: Prospective observational study. SETTING & PARTICIPANTS: 76 adult HD patients; 26 had HD catheters removed for bacteremia and 50 had catheters removed for reasons other than infection. PREDICTORS: Segment of catheter, reason for catheter removal. OUTCOMES & MEASUREMENTS: Microbiological growth and biofilm thickness on the outer and luminal surfaces of extravascular and intravascular catheter segments. RESULTS: Catheter cultures were positive in 16 (62%) patients with bacteremia and 15 (30%) when the catheter was removed for non-infection-related reasons. In catheters with positive cultures, the outer surface of the extravascular segment was the most common site of bacterial growth (15/16 [94%] and 11/15 [73%] for bacteremic and nonbacteremic patients, respectively). Bacteremic patients had significantly thicker biofilm on all catheter surfaces, and in bacteremic patients, the biofilm was significantly thicker on the outer compared with the luminal surface for both extravascular (14.53 ± 6.17 vs 11.97 ± 5.01 µm; P < 0.001) and intravascular (12.21 ± 5.3 vs 9.46 ± 3.71 µm; P < 0.001) segments. Extravascular segments had significantly thicker biofilm compared with intravascular segments on both the outer (P < 0.001) and luminal (P < 0.001) surfaces. Similarly, in patients for whom the catheter was removed for non-infection-related reasons, the catheter had thicker biofilm on the outer compared with the inner surface in both extravascular (2.19 ± 2.84 vs 1.62 ± 2.33 µm; P < 0.001) and intravascular (1.92 ± 2.62 vs 1.29 ± 2.33 µm; P < 0.001) segments. Similar to catheters from bacteremic patients, the outer and luminal surfaces of the extravascular segments of the catheters had significantly thicker biofilm compared with their corresponding surfaces on the intravascular segments. LIMITATIONS: Observational study. CONCLUSIONS: The outer surface of the extravascular segment of tunneled dialysis catheters in both bacteremic and nonbacteremic HD patients has the thickest biofilm and highest microbiological yield, and biofilm is thicker in patients with bacteremia. This knowledge is important for designing preventive strategies and also in the management of patients with catheter infection.