• Pulmonary congestion Electrolyte abnormalities Malnutrition

• Albumin and amino acid loss

• Muscle wasting

• Increased adipose tissue

• Fibrin formation in dialysate

The preferred route of administration is intraperitoneal (IP) rather than IV to achieve maximum concentrations at the site of infection. Antibiotics can be administered IP intermittently as a single large dose in one exchange per day or continuously as multiple smaller doses with each exchange. Intermittent administration requires at least 6 hours of dwell time in the peritoneal cavity to allow for adequate systemic absorption and provides adequate levels to cover the 24-hour period. However, continuous administration is better suited for PD modalities that require more frequent exchanges (less than 6-hour dwell time). The reader should refer to the ISPD guidelines for dosing recommendations for IP antibiotics in CAPD and automated PD patients.70 The dose of the antibiotics should be increased by 25% for patients with residual kidney function who are able to produce more than 100 mL urine output per day.

Once the organism has been identified and sensitivities are known, drug selection should be adjusted to reflect the susceptibilities of the organism. Streptococcal, staphylococ-cal, and enterococcal species sensitive to P-lactam antibiotics should be

treated with continuous IP dosing to increase efficacy and minimize resistance. Peritonitis caused by S. aureus or P. aeruginosa are often associated with catheter-related infections, which are difficult to treat and often require removal of the catheter. Rifampin 600 mg orally daily (in a single or divided dose) may be added to IP vancomycin for the treatment of methicillin-resistant S. aureus (MRSA), but should be limited to duration of 1 week to minimize the development of resistance. Two antibi-

otics are required for treatment of P. aeruginosa peritonitis. If multiple organisms are cultured, treatment should cover all of the organisms, including anaerobic organisms, and the patient should be evaluated for other intra-abdominal pathologies.7

Peritonitis caused by fungal organisms is associated with mortality in 25% of pa-

tients, which can be reduced by removing the catheter after fungal organisms are

identified. Empiric treatment should include IP amphotericin B and flucytosine. Although IP amphotericin administration is associated with chemical irritation and pain, penetration of amphotericin into the peritoneal cavity is poor with IV administration.

Fluconazole, voriconazole, or caspofungin may be suitable alternatives, depending on culture results.

Catheter-Related Infections

Catheter-related infections generally occur at the exit site or the portion of the catheter that is tunneled in the subcutaneous tissue. Previous infections increase the risk and incidence of catheter-related infections.

Pathophysiology. The major pathologic organisms responsible for causing catheter-related infections are S. aureus and P. aeruginosa. These organisms also cause the most serious catheter-related infections. S. epidermidis is found in less than 20% of catheter-related infections. Other organisms include diphtheroids, anaerobic bacteria, Legionella, and fungi.70

Exit-site infections present with purulent drainage at the site. Erythema may or may not be present with an exit-site infection. Tunnel infections are generally an extension of the exit-site infection and rarely occur alone. Symptoms of a tunnel infection may include tenderness, edema, and erythema over the tunnel pathway, but are often asymptomatic. Ultrasound can be used to detect tunnel infections in asymptomatic patients. Exit-site infections caused by S. aureus and P. aeruginosa often spread to tunnel infections and are the most common causes of catheter-infection-related peritonitis.

Treatment. Exit-site infections may be treated immediately with empiric coverage, or treatment may be delayed until cultures return. Empiric treatment of catheter-related infections should cover S. aureus. Coverage for P. aeruginosa should also be included

if the patient has a history of infections with this organism. Cultures and sensitivity testing are particularly important in tailoring antibiotic therapy for catheter-related infections to ensure eradication of the organism and prevent recurrence or related peritonitis.

Less severe infections may be treated with topical antibiotic cream, although this practice is controversial. Oral antibiotics are also effective for treatment of catheter-

related infections. Empiric or routine use of vancomycin for Gram-positive infections should be avoided unless the infection is caused by MRSA. Rifampin may be added to therapy for severe infections or slowly-resolving S. aureus infections, but mono-

therapy is not recommended. Oral fluoroquinolones are used as first-line agents to treat P. aeruginosa, which can be difficult to treat and require prolonged treatment. If the infection is slow to resolve or if it recurs, IP ceftazidime or a second agent should 70

be added. Treatment of catheter-related infections should be continued until the exit site appears normal with no erythema or drainage. Generally, at least 2 weeks of therapy or longer are required to ensure complete eradication of the organism and prevent future recurrence, which is common with S. aureus and P. aeruginosa. Infections that do not resolve may require replacement of the PD catheter. Catheter-related infections that present in conjunction with or progress to peritonitis with the same organism re-

quire removal of the PD catheter until the peritonitis is resolved. Prophylaxis of Peritonitis and Catheter-Related Infections

Prevention of peritonitis and catheter-related infections starts when the catheter is placed. The exit site should be properly cared for until it is well healed before it can be used for PD. Patients should receive proper instructions for care of the catheter during this time period, which can last up to 2 weeks. Patients should also be instructed on the proper techniques to use for dialysate exchanges to minimize the risk of infections during exchanges, which is the most common cause of peritonitis.

Intranasal S. aureus increases the risk of S. aureus exit-site infections, tunnel in-

fections, peritonitis, and subsequent catheter loss. Several measures have been used to decrease the risk of peritonitis caused by S. aureus, including mupirocin cream applied daily around the exit site, intranasal mupirocin cream twice daily for 5 days each month, or rifampin 300 mg orally twice daily for 5 days, repeated every 3 months.70 Mupirocin use is preferred over rifampin to prevent the development of resistance to rifampin, although mupirocin resistance has also been reported.70 Other measures that have been used to decrease both S. aureus and P. aeruginosa infections include gentamicin cream applied twice daily and ciprofloxacin otic solution applied daily to the exit site.70

Outcome Evaluation

Clinical improvement should be seen within 48 hours of initiating treatment for peritonitis or catheter-related infections. Perform daily inspections of peritoneal fluid or the exit site to determine clinical improvement. Peritoneal fluid should become clear with improvement of peritonitis and erythema, and discharge should remit with improvement of catheter-related infections. If no improvement is seen within 48 hours, obtain additional cultures and cell counts to determine the appropriate alterations in therapy.

Abbreviations Introduced in This Chapter

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