Air-Bubble Method of Locking Central-Vein Catheters for Prevention of Hub Colonization: A Pilot Study

Background: The major source of catheter‐associated bacteremia is contamination of the catheter hub during connection–disconnection procedures. A new method of catheter locking has been developed wherein anticoagulant is injected first, followed by a 0.1‐mL air bubble and 0.9 mL of bactericidal solution. The anticoagulant is then located at the catheter tip and the bactericidal solution is located at the catheter hub. The air bubble prevents mixing of the two solutions. The bactericidal solution was acidified concentrated saline (ACS). The 27% saline solution has a pH of 2.0. ACS was chosen because it is theoretically harmless if injected in the amount used to lock the catheter lumens. The goals of this pilot study were to determine whether the new method of catheter locking is easy to perform with available syringes and whether eventual injection of the experimental solution is well tolerated. Methods: Ten patients were randomly assigned, either to heparin lock (5 patients, 62 treatments) or air‐bubble method (5 patients, 56 treatments). In the control group, the catheters were locked with heparin, 5000 U/mL. In the experimental group, the catheters were locked with heparin, air bubble, and ACS. Altogether, the lumens were overfilled by 0.2 mL. Results: Compared to the routine method, the experimental method required a 1‐ to 2‐min‐longer procedure time. There were no errors in proper sequence of injections into the lumina. There were no episodes of bacteremia related to hub contamination in either group. In the air‐bubble group, there was one case of bacteremia associated with purulent drainage from the exit and the same organism in both cultures. In three instances in each group, the locking solution could not be aspirated and was injected without any subjective symptoms or objective signs. Conclusion: We conclude that the air‐bubble method of locking central‐vein catheters is easy to perform. In three instances of air‐bubble and ACS injection, there were no adverse effects. A full‐scale prospective randomized study is feasible and warranted.     

Surveillance cultures of tunneled cuffed catheter exit sites in chronic hemodialysis patients are of no benefit

Catheter-related infections are a major cause of morbidity and mortality in hemodialysis (HD) patients. This study evaluated the utility of surveillance swab cultures (Ssc) of tunneled cuffed catheter (TCC) exit sites as a prediction and prevention strategy for infection. A 6-month prospective-controlled trial with 94 chronic HD patients with a TCC who received monthly Ssc and were stratified by dialysis day into topical therapy based on Ssc results (Group A) or no therapy (Group B). Outcomes were exit site infection (ESI) and catheter-associated bacteremia (CAB). The overall monthly prevalence of positive Ssc was 14.9%. There was no difference in the number of positive Ssc (17.7% vs. 11.6%, p > 0.05) or ESI (19.6% vs.16.3%, p > 0.05) between Groups A and B, respectively. Catheter-associated bacteremia was higher in Group A (17.7% vs. 4.7%, p = 0.05). There were significantly more ESI in the patients treated for a positive Ssc. In Group A, the incidence of ESI was significantly higher in those treated for a positive vs. negative Ssc (55% vs. 12%, p = 0.009) and CAB rates trended higher with positive Ssc (22.2% vs. 16.7%, p > 0.05). The strategy of treating positive surveillance cultures is not beneficial. Positive Ssc do not predict the occurrence of catheter-related infection, and treatment of these cultures may lead to increased infection rates.     

Efficacy of preventing hemodialysis catheter infections with citrate lock

Prevalent use of tunneled dialysis catheters can reach 30%. Infection remains the most serious catheter‐related problem. Catheter locks are increasingly used for prevention, but are not yet recommended either by the Food and Drug Association or European Medicines Agency, on the basis of increasing bacterial resistance or lock toxicity. The aim was to test safety and effectiveness of citrate. A prospective, interventional study was conducted to assess the safety and efficacy of a 30% citrate lock in preventing catheter‐related bacteremia (CRB). A total of 157 prevalent tunneled catheters were locked with citrate and prospectively followed during a 1‐year period. The primary endpoint was first CRB diagnosed according to two of the diagnostic criteria for Catheter Infection of Centers for Disease Control and Prevention (CDC), namely definite and probable infection. The CDC criterion of possible but not proved infection was not considered. This citrate lock cohort (n = 157) had 10 episodes of CRB. We observed 0.49 CRB episodes/1000 patient‐days and the mean infection‐free catheter day was 130.6 ± 100.9. No clinically relevant adverse events were observed. No proved tunnel or exit site infection was observed and no patients died because of CRB. Catheter obstruction episodes were reported on 69 occasions out of 14 catheters. These results were compared with an historical cohort from a previous study of catheter locking with low‐dose gentamicin and did not show significant difference in efficacy. Citrate lock is effective in preventing CRB. No toxicity was observed. The use of citrate lock may have advantages over antibiotic locks: No reported bacterial resistance, lower industrial cost, and less manipulation.     

Infective spondylodiscitis in patients on high‐flux hemodialysis and on‐line hemodiafiltration

Infective spondylodiscitis (ISD) is a rare but potentially devastating condition in hemodialysis (HD) patients. Reports are limited especially in patients receiving high‐flux HD and hemodiafiltration (HDF). In a retrospective analysis, 13 patients on our maintenance high‐flux HD/HDF program were identified as having has infective spondylodiscitis over a 10‐year period (1997–2006), an incidence of approximately 1 episode every 215 patient‐years. The incidence was around 3 times higher in patients dialyzing with tunnelled central venous catheters (TCVC) than in those with arteriovenous fistulae. Affected patients were elderly (mean age 70 years) and had multiple comorbidities. Access problems, particularly TCVC infection, were common in the months preceding it's onset. Tunnelled central venous catheter removal during these episodes did not necessarily prevent it. Diagnosis was based on a history of back pain, raised C‐reactive protein, positive blood cultures, and characteristic magnetic resonance findings. Many patients were apyrexial and had normal white cell counts. In our patients on high‐flux HD/hemodiafiltration, its incidence appears comparable to that in conventional HD settings. No patients had infection with waterborne organisms. Blood cultures were positive in 77%. Gram‐positive organisms predominated, particularly Staphylococcus aureus. The major route of infection was hematogenous, with the most likely source the venous access. All received antibiotics for 6 to 12 weeks or until death. Only 2 patients underwent surgical drainage. Mortality was high (46%) and predicted by the development of complications, and by pre‐existing cardiovascular comorbidity. Prevention, using strategies to reduce the prevalence of bacteremia, including limiting the use of TCVC, should be an overriding aim.     

Catheter-related bacteremia caused by Comamonas testosteroni in a hemodialysis patient

Comamonas testosteroni has rarely been implicated as a human pathogen. In general, the outcome of C. testosteroni infections is favorable. We report a case of fatal bacteremia caused by C. testosteroni in a 64-year-old woman on hemodialysis.     

Hemodialysis catheter infection with unusual presentation and grave outcome

Bacteremia from central venous catheter (CVC) infection causes morbidity and mortality in patients on hemodialysis (HD). Diagnosis of the infection can be difficult and may require special imaging. A 70-year-old man with diabetic nephropathy was on HD for 11 months through a permanent CVC. Because of symptomatic osteoporosis, he had kyphoplasty in three lumbar vertebrae (L2, L3, L4) 6 months after starting HD. Severe back pain persisted after kyphoplasty. Throughout the HD period, the exit site of the CVC had a clean appearance, there was no fever, and blood leukocyte counts were normal. During the 11th month of HD, he complained of subjective fever at home. Blood count revealed normal leukocyte count with neutrophilic predominance and blood cultures grew methicillin-resistant Staphylococcus aureus (MRSA). Echocardiogram revealed no heart valve vegetations, but irregular thickening of the CVC wall. Fluorodeoxyglucose positron-emission tomography-computed tomography (FDG-PET-CT) revealed severe inflammation of the CVC wall and a picture consistent with osteomyelitis and severe destruction of the body of the 11th thoracic vertebra. He was treated with intravenous vancomycin and removal of the CVC, the wall of which was grossly inflamed and grew in culture MRSA. Three weeks later, he discontinued HD because of persistent severe back pain. CVC infection with bacteremia and remote infectious foci having grave sequelae can develop in HD patients with paucity of clinical manifestations. FDG-PET-CT is a useful imaging tool in establishing the presence and extent of both the CVC infection and remote metastatic infectious foci.     

Carriage of Staphylococcus aureus in the nose of patients on regular dialysis treatment using hemodialysis catheters

In the hemodialysis population, the incidence of Staphylococcus aureus colonization has been documented to be as high as 80%; effective prophylaxis of vascular access infection and bacteremia is a worthwhile goal in the management of hemodialysis population. Surveillance of 50 hemodialysis patients for S. aureus‐positive nasal cultures was performed by monthly nasal swabs over a 12‐month period. All patients were performing dialysis using hemodialysis catheters thrice weekly. All positive cultures were treated with a prophylactic antibiotic regimen. Thirty‐one patients (62%) had one or more positive cultures. The surveillance period was longer in the S. aureus nasal carriers (p < 0.01). The frequency of positive cultures correlated with the duration of surveillance (p < 0.05). The incidence of S. aureus bacteremia was greater in patients with three or more positive cultures (p < 0.05). This study suggests that continuous surveillance for S. aureus nasal colonization is essential to properly identify all hemodialysis patients using catheters at risk of developing S. aureus bacteremias.     

Inserting tunnelled hemodialysis catheters using elective guidewire exchange from nontunnelled catheters: Is there a greater risk of infection when compared with new‐site replacement?

The objective is to evaluate bacteremia outcomes and survival rates when using guidewire exchange to place tunnelled hemodialysis catheter (THDC) compared with a new-site replacement. Retrospectively, all patients were identified who received a THDC between January 1, 2000 and January 1, 2007. Any THDC having received antibiotic line locks or tunnel-to-tunnel exchange were excluded. This left 408 THDC placed in 329 patients: 46 guidewire exchange, 362 new-site replacement. Bacteremia rate from the new-site insertion group was 3.0 per 1000 catheter days, the guidewire exchange group demonstrated a rate of 2.8 per 1000 catheter days. Local infection rates did not differ between the groups at 1.2 per 1000 catheters days. The actuarial catheter survival rates using Kaplan-Meier survival analysis demonstrated no difference between the 2 groups. The placing of tunnelled cuffed hemodialysis catheters to replace temporary catheters using a guidewire exchange did not contribute to further episodes of sepsis and has the advantage of preserving venous access and minimizing invasive procedures for the patient.