Effect of Preventing Staphylococcus Aureus Carriage on Rates of Peritoneal Catheter-Related Staphylococcal Infections. Literature Synthesis

Objective

To determine whether specific preventive measures reduce the rate of peritoneal catheter-related infections and peritoneal catheter loss due to Staphylococcus aureus.

Design

Structured literature synthesis.

Methods

Relevant studies were identified by medline search, from personal files, and from the reference lists of retrieved articles. We analyzed English-language studies on treatment targeted at S. aureus, with at least 10 subjects and at least 3 months of follow-up, and data on staphylococcal peritoneal dialysis catheter infections. We excluded noncontrolled studies. Two investigators abstracted data using a structured form.

Results

W e evaluated six studies with concurrent controls and eight studies with historical controls. In one randomized, placebo-controlled, blinded study, periodic nasal mupirocin ointment reduced the rate of staphylococcal exit-site infection from 0.42 to 0.12 episodes/patient-year ( p = 0.006), but had no effect on the rates of staphylococcal tunnel infection, peritonitis, or catheter loss. In one randomized study without placebo control, periodic oral rifampin reduced the rate of staphylococcal exit-site infection from 0.65 to 0.22 epi/pt-yr ( p = 0.011), but had no effect on the rate of staphylococcal peritonitis. In another nonblinded, randomized, controlled study, the use of either rifampin or mupirocin was associated with low rates of staphylococcal catheter infections and catheter loss. In one study with historical controls, the rate of staphylococcal exit-site infection and peritonitis was lower after oral rifampin prophylaxis. In seven other studies comparing nasal or exit-site mupirocin to historical controls, the rate of staphylococcal exit-site infection decreased from 0.17 to 0.05 epi/pt-yr, the rate of staphylococcal peritonitis decreased from 0.18 to 0.06 epi/pt-yr, and the rate of catheter loss decreased from 0.09 to 0.05 epi/pt-yr during the mupirocin period.

Conclusion

The literature provides strong evidence that staphylococcal carriage prophylaxis using either oral rifampin or mupirocin ointment in the nares or exit site reduces significantly the rate of exit-site infection due to Staphylococcus aureus. Weaker evidence based on studies with historical controls suggests that rifampin or mupirocin prophylaxis also reduces the rate of staphylococcal peritonitis and peritoneal catheter loss. Studies with a stronger level of evidence are needed to verify this last point.

Emergence of Mupirocin-ResistantStaphylococcus Aureusin Chronic Peritoneal Dialysis Patients using Mupirocin Prophylaxis to Prevent Exit-Site Infection

Objective

To determine the prevalence of the carriage of Staphylococcus aureus (SA), methicillin-resistant Staphylococcus aureus (MRSA), and mupirocin-resistant Staphylococcus aureus (MuRSA) in chronic peritoneal dialysis (CPD) patients after 4 years of prophylactic mupirocin application to the exit site, in a peritoneal dialysis unit.

Methods

Three swabs were collected from the nares, axillae/groin, and exit site, respectively, from 149 patients on CPD between May and July 2001. All swabs were cultured on solid selective agar (mannitol salt agar) and in mannitol salt broth. Staphylococcus aureus isolates were tested for methicillin resistance using oxacillin screening plates, and mupirocin resistance using E-test strips. Low-level MuRSA was defined as minimum inhibitory concentration (MIC) of 4 mg/mL or more, and high-level MuRSA as MIC of 256 mg/mL or more.

Results

Staphylococcus aureus was isolated from 26 (17%) patients (25 from nares/axilla/groin, and 1 from the exit site). High-level MuRSA was isolated from 4 patients (3% of the total study population; 15% of total SA isolates). No MRSA was detected. One patient with high-level MuRSA had peritonitis due to SA, resulting in treatment failure and catheter loss, soon after the swabs were collected for the study.

Conclusion

We report the emergence of high-level MuRSA in CPD patients after a 4-year practice of continuous use of mupirocin in a small number of patients in our unit. Our results may have significant implications for the future practice of prophylactic use of mupirocin by CPD patients to prevent exit-site infection.

The Role of Peritoneal Dialysis as the First-Line Renal Replacement Modality

Twenty years after its introduction, peritoneal dialysis (PD) is a well-established alternative to hemodialysis (HD) as a modality of renal replacement therapy. Much debate and research is apparent in the literature, comparing hemodialysis and PD as “opposite” modalities and trying to ascertain which modality should be more optimal.

In our opinion, HD and PD are two distinct modalities, each with its own advantages and disadvantages. In addition, it is clear that for both HD and PD, rates of technique failure are high, causing patients to transfer between modalities. The question is thus not which modality is best, but rather, which flow-chart of modalities makes best use of the advantages of each modality, while avoiding its disadvantages. In this respect, HD and PD appear to be complementary modalities.

The better preservation of residual renal function, lower risk of infection with hepatitis B and C, better outcome after transplantation, preservation of vascular access, and lower costs are arguments to promote PD as a good initial treatment. When PD-related problems arise (adequacy, ultrafiltration, peritonitis, patient burnout), a timely transfer to HD has to be planned.

This editorial tries to review arguments supporting the complementary nature of both modalities, and especially the role of PD as the first-line renal replacement therapy.

Prevention of Peritonitis in Children on Peritoneal Dialysis

We reviewed methods of preventing peritonitis in children. A considerable body of evidence indicates that peritonitis rates are lowest with the use of a double-cuffed catheter, with a downward directed tunnel, placed by an experienced surgeon. Evidence in adults, but lacking in children, suggests that exit-site mupirocin will lower Staphylococcus aureus exit-site infections and thus peritonitis rates. The risk of peritonitis due to contamination can be diminished by the avoidance of spiking and by the provision of a long training period. Catheter removal and replacement for catheter-related peritonitis may be done simultaneously in certain circumstances and is useful in decreasing the risk of recurrent peritonitis. Antibiotic prophylaxis at the time of catheter insertion, for contamination, during dialysate leaks, and for invasive procedures appears to be useful in diminishing peritonitis risk.

Increasing Mupirocin Resistance of Staphylococcus Aureus in CAPD — Should it Continue to be Used as Prophylaxis?

This editorial summarizes the mechanisms of mupirocin resistance and the conditions that promote its development. While there is increasing evidence that high-level mupirocin resistance is developing during systematic use of mupirocin as prophylaxis against Staphylococcus aureus, the appearance of resistance does not preclude the beneficial effect of regular prophylaxis. Vigilance has to be exercised to notice larger-scale resistance that may require limiting the use of mupirocin.

Staphylococcus Aureus Prophylaxis and Trends in Gram-Negative Infections in Peritoneal Dialysis Patients

Objective

To examine gram-negative exit-site infection and peritonitis rates before and after the implementation of Staphylococcus aureus prophylaxis in peritoneal dialysis (PD) patients.

Design

Prospective data collection with periodic implementation of protocols to decrease infection rates in two PD programs.

Patients

663 incident patients on PD.

Interventions

Implementation of S. aureus prophylaxis, beginning in 1990.

Main Outcome Measures

Rates of S. aureus, gram-negative, and Pseudomonas aeruginosa exit-site infections and peritonitis.

Results

Staphylococcus aureus exit-site infection and peritonitis rates fluctuated without significant trends during the first decade (without prophylaxis), then began to decline during the 1990s subsequent to implementation of prophylaxis, reaching levels of 0.02/year at risk and zero in the year 2000. Gram-negative infections fell toward the end of the 1980s, due probably to the implementation of better connectology. However, there have been no significant changes for the past 6 years. There was little change in P. aeruginosa infections over the entire time period. Pseudomonas aeruginosa is now the most common cause of catheter infection and catheter-related peritonitis.

Conclusions

Prophylaxis against S. aureus is highly effective in reducing the rate of S. aureus infections but has no effect on gram-negative infections. Pseudomonas aeruginosa is now the most serious cause of catheter-related peritonitis.

Estimation of clinical efficiency of topical combination therapy patients with pyoderma complicated eczema

The results of direct open-label study of efficacy and portability of combination therapy with topical betamethasone dipropionate and mupirocin are presented. Material and methods. Twenty two patients with pyoderma complicated eczema were treated with ointment for external use (betamethasone dipropionate and mupirocin) 2 times a day for 14 days. Clinical efficacy was assessed by the reliability decrease of index EASI and dermatological symptoms scale index (DSSI). Results. Clinical convalescense was achieved in all patients by the 14th day of therapy. There was a statistically significant decrease in the indices EASI, DSSI. Portability were well. Conclusion. Our study results showed clinical efficacy and portability of topical combination therapy of betamethasone dipropionate and mupirocin in patients with pyoderma complicated eczema.

Meta-analysis of methicillin-resistant Staphylococcus aureus colonization and risk of infection in dialysis patients

Patients undergoing dialysis are particularly vulnerable to methicillin-resistant Staphylococcus aureus (MRSA) infections. We performed a meta-analysis of published studies to estimate the prevalence of MRSA colonization in dialysis patients, time trends, and long-term risk of subsequent MRSA infections. Our search of the PubMed and Embase databases returned 5743 nonduplicate citations, from which we identified 38 relevant studies that included data on 5596 dialysis patients. The estimated prevalence of MRSA colonization was 6.2% (95% confidence interval [95% CI], 4.2% to 8.5%). The prevalence increased over time but remained stable after 2000. Stratification of patients according to dialysis modality and setting revealed that 7.2% (95% CI, 4.9% to 9.9%) of patients on hemodialysis were colonized with MRSA compared with 1.3% (95% CI, 0.5% to 2.4%) of patients on peritoneal dialysis (P=0.01), and that a statistically significant difference existed in the percentage of colonized inpatients and outpatients (14.2% [95% CI, 8.0% to 21.8%] versus 5.4% [95% CI, 3.5% to 7.7%], respectively; P=0.04). Notably, the risk of developing MRSA infections increased among colonized hemodialysis patients compared with noncolonized patients (relative risk, 11.5 [95% CI, 4.7 to 28.0]). The long-term (6-20 months) probability of developing a MRSA infection was 19% among colonized hemodialysis patients compared with only 2% among noncolonized patients. In summary, 6.2% of dialysis patients are MRSA colonized, and the average prevalence of colonization has remained stable since 2000. Colonization in hemodialysis patients is associated with increased risk of MRSA infection.

Prevention of peritoneal dialysis catheter infections in Saudi peritoneal dialysis patients: the emergence of high-level mupirocin resistance

PURPOSE

Exit-site infection (ESI) and peritonitis remain the major causes of morbidity and mortality in peritoneal dialysis (PD) patients. This study compared the effectiveness of local mupirocin ointment and gentamicin cream in preventing both gram-positive and gram-negative bacterial infections in PD patients.

METHODS

Patients from two centers (n = 203) were assigned to daily mupirocin ointment or gentamicin cream application. Infections were tracked prospectively by organisms and expressed as episodes per patient-year for both ESI and peritonitis.

RESULTS

The rate of gram-positive ESI was 0.31/episode/patient-year and 0.22 episodes/patient-year (p<0.05), whereas the rate of gram-negative ESI was 0.28 episode/patient-year and 0.11 episode/patient-year (p<0.01) in the mupirocin group and gentamicin group, respectively. Gram-positive ESI occurred in 17.1% vs 10.2% of patients (p<0.05), whereas 20% of and 5.1% of patients (p<0.001) had gram-negative ESI in the 2 groups respectively. S.aureus was cultured at exit-site in the mupirocin group in 27.8% patients, 60% (16.7% of the total Gram-positive isolates) of them being with high-level mupirocin-resistance. Pseudomonas aeruginosa was cultured in 21.8% of ESI in the mupirocin group, and in only 6.7% in the gentamicin group (p<0.01). Peritonitis rates were lower using gentamicin cream, 0.17 episode/patient-year compared with mupirocin, 0.39 episode/patient-year (p<0.01). With multivariate analysis, only gentamicin exit-site use was a significant predictor for lower catheter infection rate.

CONCLUSION

Prolonged use of mupirocin for ESI-prophylaxis is associated with the emergence of mupirocin-resistant S. aureus. Gentamicin cream is superior to mupirocin ointment in the prevention of PD catheter infections.

Prevention of peritoneal dialysis-related infections

Despite substantial advances in peritoneal dialysis (PD) as a renal replacement modality, PD-related infection remains an important cause of morbidity, technique failure, and mortality. This review describes the microbiology and outcomes of PD peritonitis and catheter infection, followed by a discussion of several strategies that may reduce the risk of PD-related infections. Strategies that are reviewed include use of antibiotics at the time of PD catheter insertion, selection of PD catheter design and insertion technique, patient training, PD connectology, exit site prophylaxis, periprocedural prophylaxis, fungal prophylaxis, and choice of PD solutions.

Safety of Targeted Perioperative Mupirocin Treatment for Preventing Infections After Cardiac Surgery

BACKGROUND

Indiscriminate antibiotic use may lead to development of antibiotic resistance. Preoperative mupirocin treatment decreases Staphylococcus aureus carriage and may reduce subsequent surgical site infection, but is unlikely to benefit noncarriers. This study was undertaken to evaluate whether avoiding mupirocin in noncarriers places them at increased risk for subsequent postoperative infection.

METHODS

We conducted a retrospective cohort study examining incidence of postoperative infection in patients undergoing cardiac surgery at the Cleveland Clinic after introduction of a protocol of polymerase chain reaction screening for nasal S aureus carriage, and avoiding mupirocin treatment of noncarriers.

RESULTS

Between August 1, 2002, and May 31, 2004, 6,334 patients were screened for nasal carriage of S aureus before undergoing cardiac surgery. There was no significant difference in infection rates between carriers and noncarriers when examining the incidence of all infections (5.6% and 5.0%; relative risk [RR] 1.11 [95% confidence interval (CI): 0.86 to 1.43]), infections caused specifically by S aureus (1.04% and 0.80%; RR 1.30 [95% CI: 0.71 to 2.39]), any surgical site infection (3.1% and 3.2%; RR 0.97 [95% CI: 0.69 to 1.36]), S aureus surgical site infection (0.82% and 0.58%; RR 1.41 [95% CI: 0.71 to 2.82]), any bloodstream infection (3.1% and 2.5%; RR 1.21 [95% CI: 0.86 to 1.71]), and S aureus bloodstream infection (0.37% and 0.48%; RR 0.77 [95% CI: 0.30 to 2.03]). Mupirocin use declined substantially after introduction of the protocol.

CONCLUSIONS

A strategy of targeting perioperative mupirocin treatment to carriers leads to significant reduction in mupirocin use without increasing early postoperative infectious complications in noncarriers.

The impact of topical mupirocin on peritoneal dialysis infection in Singapore General Hospital

BACKGROUND

Peritonitis and exit-site infections (ESI) are major causes of morbidity in peritoneal dialysis (PD) patients. The application of topical mupirocin to exit sites reduces such complications, and prolongs life in PD. Since the year 2000, this topical treatment has been used in our hospital on new PD patients. We analysed the results of this protocol, and studied the effects of comorbidities on the incidence of peritonitis.

METHODS

We studied 740 incident PD patients, who were divided into two groups based on year of entry into PD (Group 1 from January 1998 to December 1999 inclusive, topical mupirocin not used, and Group 2 from January 2000 to March 2004 inclusive, topical mupirocin used). The variables we studied included gender, age, diabetic status, ischaemic heart disease, peripheral vascular disease, cerebrovascular disease and serum albumin.

RESULTS

The application of topical mupirocin at the exit site led to a significant reduction in the rate of peritonitis (0.443 vs 0.339 episodes per patient-year; P<0.0005) and in ESI (0.168 vs 0.156 episodes per patient-year; P<0.005), results attributed primarily by the significant (P<0.005) reduction in Staphylococcus aureus infection. There was also an unexpected lowering of Pseudomonas aeruginosa peritonitis in the mupirocin group (P<0.005). Stepwise multiple logistic regression analysis revealed that only the application of mupirocin and serum albumin levels were significant predictors of peritonitis.

CONCLUSIONS

Our study, although retrospective, has demonstrated that the topical use of mupirocin was associated with a significant reduction in ESI and peritonitis and, unexpectedly, with findings of fewer incidences of Pseudomonas peritonitis. Serum albumin level before the initiation of PD was a strong predictor of subsequent peritonitis. Mupirocin, with its low toxicity, ease of application and demonstrable beneficial effect in reducing ESI and peritonitis is now used on all of our incident PD patients.

The impact of topical mupirocin on peritoneal dialysis infection rates in Singapore General Hospital

BACKGROUND

Peritonitis and exit-site infections (ESI) are major causes of technique failure and morbidity in peritoneal dialysis (PD) patients. Topical mupirocin on the exit-site has been shown to reduce such complications and prolong life in PD. Since the year 2000, such an approach has been adopted for our new incident PD population. We now report the results of this new protocol. We also studied the effect of co-morbidity on peritonitis occurrence.

METHODS

A total of 740 incident PD patients were studied. Patients were divided into two groups based on year of entry into PD (Group 1 from January 1998-December 1999 without topical mupirocin and Group 2 from January 2000-March 2004 with topical mupirocin). Variables studied included gender, age, diabetic status, ischaemic heart disease, peripheral vascular disease, cerebrovascular disease and serum albumin.

RESULTS

Topical mupirocin at the exit-site has led to a significant reduction in peritonitis rate (0.443 vs 0.339 episodes/patient-year; P<0.0005) and ESI (0.168 vs 0.156 episodes/patient-year; P<0.005) attributed primarily to the significant reduction in Staphylococcus aureus infections. There was an unexpected finding of lower Pseudomonas aeruginosa peritonitis in the mupirocin group (P<0.005). Stepwise multiple logistic regression analysis revealed that only mupirocin application and serum albumin were significant predictors of peritonitis.

CONCLUSIONS

Our study, although limited by its retrospective nature, demonstrated that topical mupirocin was associated with a significant reduction in ESI and peritonitis with unexpected findings of lower Pseudomonas peritonitis. Serum albumin prior to the initiation of PD was a strong predictor of subsequent peritonitis. Mupirocin, with its low toxicity, ease of application and demonstrable beneficial effect in reducing ESI and peritonitis is now used on all incident PD patients.

Routine use of mupirocin at the peritoneal catheter exit site and mupirocin resistance: still low after 7 years

OBJECTIVE

The purpose of this study (the third in a series of similar studies) is to evaluate the prevalence of Staphylococcus aureus (SA), methicillin-resistant SA (MRSA) and mupirocin-resistant SA (MuRSA) carriers in a peritoneal dialysis centre where patients have been instructed to use prophylactic mupirocin ointment at the catheter exit site over the last 7 years.

METHODS

Swabs were taken from catheter exit site, nares, axillae and groin in 147 chronic peritoneal dialysis out-patients between November 2003 and January 2004. Axillae/groin and nasal samples were pooled and cultured in the same medium, whereas exit site swabs were cultured separately. All SA isolated were tested for methicillin and mupirocin resistance using oxacillin screening plates and E-test strips.

RESULTS

Sixteen of 147 patients (10.9%) were found to be SA carriers: of these 13 (8.8%) had a positive nasal/axillae/groin culture; two (1.4%) had both nasal/axillae/groin- and exit site-positive culture; and one (0.7%) had only exit site-positive culture. In these 16 SA carriers, we found mupirocin-resistant strains (MuRSA) in four patients (25%) and MRSA in two patients (12.5%). Among the four MuRSA carriers, one had both nasal/axillae/groin- and exit site-positive culture and three had only nasal/axillae/groin-positive culture. Three high-level resistance and one low-level resistance MuRSA carriers were isolated. One MuRSA strain was also methicillin resistant. All MRSA strains were sensitive to vancomycin and rifampicin.

CONCLUSION

After 7 years' routine use of prophylactic mupirocin ointment at the catheter exit site in non-selected chronic peritoneal dialysis patients, MuRSA was found in 25% of SA strains isolated or in 2.7% of the patients. Compared with our previous study, 3 years earlier, there is no significant increase in the MuRSA prevalence in peritoneal dialysis patients who routinely apply mupirocin ointment at the catheter exit site.

Peritoneal catheter exit-site infections: predisposing factors, prevention and treatment

Catheter-related infections, exit-site-tunnel infections and peritonitis remain the Achilles heel of peritoneal dialysis. Although the overall incidence of peritoneal-dialysis-related infectious complications has been reduced since the introduction of the Y-set and double bag system, approximately one-fifth of peritonitis episodes are associated with catheter exit-site and tunnel infections. Since its development in 1968, the Tenckhoff catheter has become one of the most widely used peritoneal catheters, and many have proposed that a number of modifications have made it a better choice. Controversies concerning the effect on exit-site infections of catheter(s) with one or two cuffs, with straight, coiled, Swan-Neck, or other modifications led to the randomized controlled studies that are reviewed in this paper. Several studies have confirmed that mupirocin, applied at the exit-site as part of regular exit-site care, reduces the risk of S. aureus exit-site and tunnel infections. Recently, the emergence on a world-wide basis of mupirocin-resistant S. aureus (MuRSA) in peritoneal dialysis patients has brought this prophylactic strategy into question. However the low frequency of resistant organisms after four years of mupirocin prophylaxis suggests that we can continue its use with annual surveillance. Once established, exit-site infections may respond to appropriate treatment, but if not the only option may be catheter removal and replacement. Although peritonitis risk has decreased over the past decade, mainly due to improvements in connection technology, exit-site and tunnel infections have not. An exit-site infection that does not respond to treatment may lead to tunnel infection and to persistent peritonitis, which may require catheter removal and occasionally discontinuation of the peritoneal dialysis. Therefore it is important to be familiar with these factors that predispose to exit-site infection and to know how to prevent and to treat such infections. This review will discuss factors that predispose to catheter-related exit-site infections, techniques of exit-site care, and ways to prevent exit-site infection, with emphasis on S. aureus infections and their treatment.

Infection with antimicrobial-resistant microorganisms in dialysis patients

The prevalence of antimicrobial-resistant microorganisms in various health care settings, including outpatient dialysis facilities, has increased dramatically in the last decade. Antimicrobial use and patient-to-patient transmission of resistant strains are the two main factors that have contributed to this rapid increase. Methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci are commonly isolated as a cause of hemodialysis (HD) catheter-related bacteremia and peritoneal dialysis (PD)-related catheter infection and peritonitis. The widespread use of vancomycin in dialysis patients is of concern because of an increase in the prevalence of vancomycin-resistant enterococci (VRE) in dialysis patients. Staphylococci with reduced sensitivity to vancomycin have also appeared in dialysis patients. A more recent problem is the appearance of S. aureus isolates with a high degree of resistance to the topical antimicrobial agent mupirocin. This has been seen in PD patients who have received prophylactic application of mupirocin at the peritoneal catheter exit site. Appropriate antimicrobial use will help protect the efficacy of currently used antibiotics, such as vancomycin. Published guidelines for use of vancomycin should be followed. New antimicrobials such as linezolid and quinupristin/dalfopristin have activity against VRE and MRSA, but resistance to these agents has already occurred. Preventing transmission of antimicrobial-resistant microorganisms in health care settings, including outpatient dialysis facilities, is important in limiting the spread of these resistant organisms.

Peritonitis in peritoneal dialysis

Peritonitis, an infectious complication of peritoneal dialysis, continues to account for much of the morbidity associated with this techniques. The clinical presentation and laboratory data used in diagnosis the peritonitis, as well as its differential diagnosis will be reviewed in this article. The distribution of pathogens is an important outcome determinant, Gram-negative infections being associated with greater rates of catheter loss and higher death rates. Among the five routes of peritoneal contamination, intraluminal and periluminal contamination account for most of the infections. Due to the two prevention methods implemented in the care of the PD population, the incidence of peritonitis has decreased over the last two decades. The recommendations for empiric treatment of peritonitis have changed over the years, as more was learnt about antibiotic resistance and drug toxicity. Future research to address enteric peritonitis, as well as biocompatible dialysis solution or biocompatible catheter materials is needed to further reduce the incidence of PD peritonitis.

Mupirocin resistance after long-term use for Staphylococcus aureus colonization in patients undergoing chronic peritoneal dialysis

Mupirocin (Mup) has been used extensively to prevent Staphylococcus aureus (SAu) infections in patients undergoing peritoneal dialysis (PD). Resistance to Mup has been reported, but its relevance after long-term use of this drug in PD is unknown. Colonization by SAu was treated with topic Mup in our unit between September 1990 and December 2000. Sensitivity to Mup was tested in 437 strains of SAu isolated from 155 PD patients and 62 dialysis partners. Resistance to Mup was classified as low (minimal inhibitory concentration [MIC] > or = 8 microg/mL) or high (MIC > or = 512 microg/mL) degree. MIC90 was 0.125 microg/mL in 1990 to 1996 (5% low, 0% high-degree resistance), 64 microg/mL in 1997 to 1998 (6.6% low, 8.3% high-degree resistance), and 1,024 microg/mL in 1999 to 2000 (2.3% low, 12.4% high-degree resistance). Mup-resistant SAu were isolated from 25 patients and 13 partners a median of 15 months after starting PD. Resistance was associated frequently with repeated treatments of SAu recolonization, but was detected in 3 cases at the start of PD therapy. The accumulated incidence of SAu exit-site infection in the period 1997 to 2000 was 32.3% in patients colonized by Mup-resistant SAu as compared with 14.5% in those colonized by Mup-sensitive SAu (P = 0.03). Mup-resistant SAu have emerged in a significant proportion of our PD patients and dialysis partners. This emergence has resulted in a moderate, but significant, increase in the risk of SAu exit-site infection and raises concerns about the future of Mup as the therapy of choice for SAu colonization in patients undergoing chronic PD.

Staphylococcus aureus infections in dialysis patients: focus on prevention

Staphylococcus aureus infections are a major cause of morbidity and hospitalization in dialysis patients. The risk of infection relates to the type of access. Patients with acute hemodialysis (HD) catheters are at the greatest risk of S. aureus bacteremia, followed by tunneled HD catheters, and grafts. Patients with a fistula have a rate similar to that of peritoneal (PD) patients. In PD patients, however, S. aureus is the second most common cause of peritonitis, is often associated with a catheter infection, and frequently requires catheter removal for resolution. S. aureus infections in dialysis patients are much more common in nasal carriers. S. aureus moves from the nasal reservoir to the hands and skin, and from there to infect the access. Therefore, prevention of infection can be aimed at treating the carriage or in applying antibiotics at the catheter exit site, thus preventing colonization and subsequent infection of the catheter. For HD patients with a permanent access (either fistula or graft), intranasal mupirocin, twice a day for 5 days followed by a once weekly application, is effective in reducing the risk of S. aureus bacteremia. Cost analysis indicates that treating all patients would result in more cost savings than treating just carriers. For patients with acute HD catheters, exit site mupirocin applied as part of routine care during each HD treatment, reduces the risk of S. aureus exit site infection and bacteremia. For PD patients, S. aureus infections can be diminished by using mupirocin at the exit site as part of daily exit site care. Prophylaxis against S. aureus is under utilized in dialysis patients and, if implemented, could lower the rate of these serious infections.

Peritoneal dialysis. Prevention and control of infection

In spite of the reduction in peritonitis and catheter-related infection rates in patients undergoing peritoneal dialysis, these infections remain major sources of morbidity and transfer to haemodialysis. Touch contamination at the time of doing the exchanges is still a major cause of peritonitis and leads to Gram-positive organisms (coagulation-negative staphylococcus) being the most common pathogens. Newer exchange techniques have reduced this incidence but the more serious pathogens (Staphylococcal aureus, pseudomonas and fungi) remain a major problem. Treatment has to be immediate, and hence empirical, giving adequate cover for both Gram-positive and Gram-negative organisms. The use of vancomycin as an initial antibacterial has been discontinued because of the problem of vancomycin-resistant enterococcus. Recent guidelines advocate the use of a first generation cephalosporin combined with ceftazidime (if the urine output is >100 ml/day) or an aminoglycoside in anuric patients. Subsequent therapy changes are made upon bacterial isolation and sensitivities. Vancomycin is reserved for methicillin-resistant staphylococcus. Peritoneal catheter-related infections (exit site and tunnel) are predominantly caused by S. aureus and pseudomonal organisms and can be difficult to eradicate. Tunnel infections invariably involve the catheter dacron cuffs and therefore are more likely to lead to peritonitis; in this situation catheter removal is the treatment of choice. Treatment of exit-site infections is with oral antibacterials (penicillinase-resistant penicillins, cefalexin). Vancomycin is avoided if possible. The identification that nasal carriage of S. aureus predisposes to exit-site and tunnel infections has led to prophylactic regimens to combat this problem. Mupirocin applied at the exit site leads to a reduction in catheter-related infections and peritonitis.