NDT Advance Access originally published online on August 5, 2006
Nephrology Dialysis Transplantation 2006 21(11):3185-3188; doi:10.1093/ndt/gfl425
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Catheter-related bacteraemia in haemodialysis patients with HIV infection
Division of Nephrology, University of Alabama at Birmingham, Birmingham, AL, USA
Correspondence and offprint requests to: Michael Allon, MD, Division of Nephrology, PB, Room 226, 728 Richard Arrington Blvd, Birmingham, AL 35233, USA. Email: mdallon{at}uab.edu
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Abstract |
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Background. Tunnelled catheters are used for dialysis in over 25% of haemodialysis (HD) patients and are a major risk factor for bacteraemia. HIV-positive patients may be at particularly increased risk of catheter-related bacteraemia (CRB) due to their immunocompromised state. The present case-controlled study compared catheter-related bacteraemia with HIV-positive and HIV-negative haemodialysis patients.
Methods. Using a prospective computerized vascular access database, we identified 33 HIV-positive haemodialysis patients who had a tunneled dialysis catheter placed during a 6.5-year period. Their catheter outcomes were compared with those observed in 55 age-, sex- and access date-matched control haemodialysis patients.
Results. The two groups were similar in terms of age, sex, diabetes, hypertension and peripheral vascular disease, but the HIV patients were more likely to be black (94 vs 76%, P = 0.03). CRB occurred in 52% of the HIV patients and 49% of the controls (P = 0.83). The median infection-free catheter survival was similar in HIV-positive and negative patients (165 vs 119 days, P = 0.12). Among patients with CRB, the likelihood of a Gram-negative infection was similar in both groups (18 vs 30%, P = 0.37). However, polymicrobial CRB was more likely in HIV patients (41 vs 15%, P = 0.049). HIV-positive patients were more likely to be hospitalized for treatment of CRB than HIV-negative patients (29 vs 7%, P = 0.05).
Conclusion. CRB is equally likely in HIV-positive and control haemodialysis patients. However, CRB is likely to be more severe in HIV-positive patients, as judged from the greater likelihood of polymicrobial infection and of hospitalization.
Keywords: catheter; HIV; infection; vascular access
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Introduction |
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Tunnelled catheters are used for vascular access in 28% of US haemodialysis patients [1]. Bacteraemia is a common complication in catheter-dependent patients, and may result in hospitalization, metastatic infections or even death [2,3]. There is little published on the frequency or clinical features of catheter-related bacteraemia (CRB) in HIV-positive dialysis patients. Patients with HIV infection are immunocompromised, as manifested by impairments in lymphocyte and neutrophil function [4]. Moreover, one study reported that immunocompromised dialysis patients are at increased risk for CRB [5]. Thus, it is a plausible hypothesis that HIV-positive patients may be more susceptible to CRB.
One study reported a similar frequency of CRB in HIV-positive and control patients [6]. However, it observed an increased likelihood of Gram-negative bacteraemia in HIV-positive patients. The study design was limited by the inclusion of multiple catheters and multiple episodes of bacteraemia per patient, thereby giving disproportionate weight to a subset of patients experiencing frequent infections.
The goal of the present study was to compare the risk of CRB in HIV-positive dialysis patients, as compared with matched HIV-negative controls, to evaluate the pathogenic organisms and to assess the impact on cumulative catheter survival.
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Methods |
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Patient population
The University of Alabama at Birmingham (UAB) provides chronic haemodialysis to approximately 450 patients at five dialysis units in the metropolitan Birmingham area. The medical care of all the patients is provided by 10 clinical nephrologists, who are all full-time university faculty in the Division of Nephrology and serve as medical directors of the dialysis units. Faculty members in the Department of Radiology and Division of Transplant Surgery perform the vascular access procedures.
Dialysis catheter management
Two full-time vascular access coordinators in the Division of Nephrology were responsible for scheduling all the access procedures and maintaining a prospective computerized database of all the interventions [7]. Tunnelled dialysis catheters were placed for immediate vascular access in patients lacking a usable permanent access (fistula or graft). Both the patient and the nurse wore a mask during connection and disconnection of the catheter to the dialysis tubing. The catheter hubs were soaked with an iodine solution for 5 min prior to initiating the connection and new hubs were placed on the catheter at the termination of each dialysis session.
CRB was diagnosed in patients having fever or chills, positive blood cultures and no clinical evidence for an alternate source of bacteraemia [2]. The blood cultures were obtained from both the catheter and from a peripheral vein (if possible). Patients with suspected CRB (fever or chills) were initiated on systemic broad-spectrum antibiotic therapy according to a nurse-driven protocol. The antibiotic regimen was modified subsequently on the basis of organisms grown from the cultures and their sensitivities. In conjunction with the systemic antibiotics, the patients also had an antibiotic-heparin lock instilled into both catheter lumens at the end of each dialysis session in an attempt to sterilize the biofilm while salvaging the catheter [8–10]. Surveillance cultures were obtained routinely after completing a 3-week course of systemic antibiotics. If the patient had persistent fever or chills 48–72 h after initiation of antibiotics or if the surveillance blood cultures were positive, the catheter was replaced. CRB was treated on an out-patient basis unless the patient's symptoms were sufficiently severe to warrant hospitalization. The dialysis nurses implemented this protocol without calling the nephrologists for instructions unless the patient was haemodynamically unstable (hypotension or severe rigors).
Catheter dysfunction (inability to aspirate blood or to sustain a dialysis blood flow >250 ml/min) was treated by instillation of tissue plasminogen activator (tPA), 2 mg per port for 30–60 min. If the catheter dysfunction was not resolved by tPA instillation, the patient was referred for catheter exchange.
Data collection and analysis
Institutional Review Board approval was obtained to review the patients’ medical records for research purposes. Using a database that contained the medical diagnoses of all dialysis patients at our institution, we identified all patients with HIV infection receiving haemodialysis at our institution during the 6.5-year period between 1 January 1999 and 30 June 2005. The computerized access database was then used to obtain a comprehensive list of all tunnelled dialysis catheters placed. For each patient, we included only the first tunnelled dialysis catheter placed. Femoral catheters were excluded as their outcomes are far inferior to those placed in the internal jugular vein [11]. By this process we identified 33 HIV-positive patients who received a tunnelled dialysis catheter.
To obtain a group of age-, sex- and date-matched control patients, the following procedure was used. For each index HIV patient receiving a tunnelled dialysis catheter, the computerized database was used to generate a list of all patients receiving a tunnelled dialysis catheter in the 4-month time period starting 2 months before the index procedure and ending 2 months following the index case. We excluded from this master list any patients with HIV infection. We then selected patients of the same gender as the index case. Finally, we selected up to two HIV-negative patients whose ages were closest to that of the index case and not differing by more than 10 years. Because the HIV-positive dialysis patients were substantially younger than the HIV-negative controls, our predetermined selection process resulted in only one possible HIV-negative matched control for 11 of the HIV-positive patients receiving a tunnelled dialysis catheter. By this process, we compiled a group of 55 matched HIV-negative control patients.
In addition, demographic and clinical information was collected on the study patients, including age, sex, race, presence of diabetes, hypertension and peripheral vascular disease. For patients experiencing CRB, we recorded the organism(s) grown from the blood culture, and whether the patient required hospitalization for medical management of the bacteraemia.
Statistical analyses
The clinical characteristics were compared between HIV-positive and control patients using Student t-tests or chi-square analysis, with a P-value <0.05 considered to be statistically significant. Infection-free catheter survival was calculated from the date of catheter placement to the first episode of CRB. Cumulative catheter survival was calculated from the placement date to the removal date (due to infection or dysfunction). Catheter survival was censored at the time of patient death, kidney transplant, transfer to an outside dialysis unit, elective catheter removal due to a mature access or data analysis (30 September 2005). Kaplan–Meier survival analysis techniques were used to model catheter survival time and the log rank test used to compare the survival of patient subgroups.
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Results |
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The HIV-positive patients were similar to their matched HIV-negative controls in terms of age, sex, diabetes, hypertension, peripheral vascular disease and frequency of hepatitis B and C infection (Table 1). However, the HIV-positive patients were more likely to be black. CRB was diagnosed in 52% (17 of 33) of the HIV-positive patients and in 49% (27 of 55) of the controls (P = 0.83). The median infection-free catheter survival was similar in both groups (165 vs 119 days, P = 0.12) (Figure 1). Infection-free survival at 1 year was 16% in the HIV-positive patients and 9% in the controls. The hazard ratio for CRB in the HIV-positive patients was 0.63 (95% confidence interval, 0.34–1.14). The frequency of CRB was 4.0 per 1000 days in the HIV-positive patients and 5.6 per 1000 days in the control group.
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Both HIV-positive and control patients grew a broad spectrum of Gram-positive and Gram-negative bacteria. The specific organisms grown in study patients with CRB are summarized in Table 2. The likelihood of a Gram-negative bacteraemia was similar in both groups (18 vs 30%, P = 0.37). However, polymicrobial bacteraemia was more common among HIV-positive patients (7 of 17 or 41%) than in HIV-negative patients (4 of 27 or 15%, P = 0.049). Finally, hospitalization for the management of CRB occurred more frequently in HIV-positive patients (5 of 17 or 29%) than in HIV-negative patients (2 of 27 or 7%, P = 0.05).
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Permanent catheter failure requiring replacement occurred in 45% (15 of 33) of the HIV-positive patients and 36% (20 of 55) of the controls (P = 0.40). Refractory infection accounted for 53% (8 of 15) of the failures in the HIV-positive patients and 65% (13 of 20) of the failures in the control group (P = 0.49). Finally, cumulative catheter survival was similar in both study groups (median survival, 472 vs 184 days, P = 0.90) (Figure 2). Cumulative catheter survival at 1 year was 51% in the HIV-positive patients and 49% in the controls. The hazard ratio for catheter failure in the HIV-positive patients was 1.04 (95% CI, 0.53–2.07).
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Discussion |
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In the present study, infection-free catheter survival was similar in HIV-positive patients as compared with HIV-negative controls (median survival of about 5.5 vs 4 months). However, CRB in HIV-positive patients was more likely to be polymicrobial and more likely to result in hospitalization. Thus, although the frequency of bacteraemia was similar, episodes of bacteraemia were more severe in HIV-positive patients. Due to the retrospective nature of this study, it was not possible to exclude the possibility that the nephrologists were more likely to hospitalize for the management of CRB when the patient was HIV-positive. However, this explanation seems unlikely, given that the management of CRB at our centre was protocol-driven, and the dialysis nurses called the nephrologists only about those patients who were medically unstable (hypotension or severe rigors).
The procedure for determining the matched control patients was quite successful in the present study (Table 1). In addition, selecting control patients receiving a tunnelled dialysis catheter during the same time period should have controlled for unmeasured changes in the practice pattern over the study period. Unlike the study by Mokrzycki et al. [6], the current study considered only the first tunnelled catheter and the first episode of CRB for each patient. By using this approach, we attempted to minimize potential bias due to the occurrence of multiple infections in a subset of patients. Although the sample size may have been too small to detect small differences in risk of bacteraemia between the groups, it is evident from Figure 1 that bacteraemia was not more likely in the HIV-positive patients. Also, in contrast to the study by Mokrzycki et al. [6], we did not observe a higher frequency of Gram-negative bacteraemia in HIV-positive dialysis patients.
In summary, our preliminary results suggest that HIV-positive patients with tunnelled dialysis catheter are no more likely to experience CRB than are HIV-negative controls. However, their infections appear to be more severe as judged from the likelihood of polymicrobial bacteraemia and the requirement for hospitalization. However, the current study is limited by its relatively small sample size and inadequate statistical power to demonstrate modest differences in CRB between HIV-positive and HIV-negative dialysis patients. A large, prospective multicentre study will be required to confirm the observations suggested by the current pilot study.
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Acknowledgements |
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This research was supported in part by grant number 1 K24 DK59818-01 from the NIDDK to M.A. Other than this grant source, none of the authors have a conflict interest for this manuscript.
Conflict of interest statement. None declared.
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References |
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- Centers for Medicare, & Medicaid Services. (2004) 2003 Annual Report: End Stage Renal Disease Clinical Performance Measures Project. Am J Kidney Dis 44:Suppl 2, S1–S92.
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Accepted in revised form: 20. 6.06
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