What is the initial antibiotic therapy for peritoneal dialysis peritonitis with elevated polymorphonuclear (PMN) cells?

Initial Antibiotic Therapy for Peritoneal Dialysis Peritonitis with Elevated PMN Cells

For peritoneal dialysis-related peritonitis with elevated polymorphonuclear (PMN) cells (>250 cells/mm³), immediate empirical treatment with intravenous third-generation cephalosporins such as cefotaxime 2g every 8 hours for 5 days plus intravenous albumin (1.5 g/kg at diagnosis and 1 g/kg on day 3) is recommended. 1

Diagnosis Confirmation

• A peritoneal fluid PMN count >250 cells/mm³ confirms the diagnosis of peritoneal dialysis-associated peritonitis and warrants immediate empirical antibiotic therapy 2
• Ascitic fluid should be collected for culture before initiating antibiotics, with bedside inoculation into blood culture bottles to increase sensitivity to >90% 2
• Simultaneous blood cultures should be obtained to increase the possibility of isolating causative organisms 2

First-Line Empirical Antibiotic Therapy

• Third-generation cephalosporins are the first-line treatment in settings where multidrug-resistant organisms (MDROs) are not prevalent 2, 1
• Recommended regimen: Cefotaxime 2g IV every 8 hours for 5 days 1
• A 5-day treatment course has been shown to be as effective as a 10-day course 2, 1
• Intravenous albumin (1.5 g/kg at diagnosis, followed by 1 g/kg on day 3) should be administered alongside antibiotics to significantly reduce the risk of hepatorenal syndrome and mortality 2, 1

Alternative Regimens Based on Clinical Context

• For patients who cannot tolerate IV therapy and have no vomiting, shock, grade II (or higher) hepatic encephalopathy, or serum creatinine >3 mg/dL, oral ofloxacin can be considered as effective as parenteral cefotaxime 2
• For nosocomial infections or patients with recent hospitalization and critically ill patients, broader spectrum antibiotics such as carbapenems may be necessary due to higher prevalence of MDROs 2
• The combination of ceftazidime plus a glycopeptide (like vancomycin) has shown superior resolution rates (86%) compared to first-generation cephalosporin plus aminoglycosides (66%) or glycopeptides plus aminoglycosides (75%) 3

Monitoring Treatment Response

• A repeat paracentesis should be performed after 48 hours of treatment to assess response 1
• Treatment failure is defined as failure of ascitic neutrophil count to decrease by at least 25% of pre-treatment value or worsening of clinical signs and symptoms 1
• If treatment fails, consider resistant bacteria requiring antibiotic change based on culture results or secondary bacterial peritonitis requiring surgical evaluation 2, 1

Differentiating from Secondary Bacterial Peritonitis

• Secondary bacterial peritonitis (due to surgically treatable intra-abdominal source) should be suspected if:
  • PMN count increases to >1,000/mm³ 2
  • Multiple organisms are seen on Gram stain or culture 2
  • Ascitic total protein concentration ≥1 g/dL 2
  • Ascitic glucose concentration ≤50 mg/dL 2
  • Ascitic PMN count does not drop after 48 hours of antibiotic treatment 2
• If secondary peritonitis is suspected, imaging tests such as abdominal CT should be performed 2

Common Pathogens and Resistance Considerations

• Spontaneous infections are typically monobacterial, with gram-negative bacteria (especially E. coli and Klebsiella) accounting for ~60% of infections 2
• There has been a shift toward gram-positive and multidrug-resistant organisms, particularly in nosocomial and healthcare-associated infections 2
• Regular monitoring of local resistance patterns is essential for guiding empirical therapy 2

Pitfalls to Avoid

• Delaying treatment until culture results are available is not advisable as it can worsen outcomes 2
• "Clinical diagnosis" without performing paracentesis is inadequate and can lead to inappropriate treatment 2
• Failure to administer albumin alongside antibiotics may result in higher mortality rates 2, 1
• Not considering local resistance patterns when selecting empirical therapy can lead to treatment failure 2
• Not differentiating between spontaneous and secondary bacterial peritonitis can lead to inappropriate management 2

By following this evidence-based approach to peritoneal dialysis-related peritonitis with elevated PMN cells, you can optimize patient outcomes and reduce morbidity and mortality associated with this serious complication.