Should antibiotics be started in this patient?

Antibiotic Therapy for Suspected Infections

Antibiotics should be started immediately in patients with ascitic fluid polymorphonuclear (PMN) count >250/mm³, signs of systemic infection, or septic shock, but are not indicated in patients without evidence of infection. 1

Decision Algorithm for Starting Antibiotics

Start Antibiotics Immediately When:

1. Confirmed infection is present:

   • Ascitic fluid PMN count >250/mm³ 1
   • Pleural fluid PMN count >250/mm³ (spontaneous bacterial empyema) 1
   • Signs of sepsis or septic shock 1, 2
   • Strangulated rectal prolapse due to risk of bacterial translocation 1

2. High-risk clinical scenarios:

   • Nosocomial or healthcare-associated infections 1
   • Peritonitis with signs of systemic infection 1
   • Complicated intra-abdominal infections with inadequate source control 1

Do Not Start Antibiotics When:

1. No evidence of infection:

   • Ascitic fluid PMN <250/mm³ without signs of infection 1
   • Bacterascites (positive culture but PMN <250/mm³) without symptoms 1
   • After proper conservative management of incarcerated rectal prolapse without signs of systemic infection 1

2. Source control is adequate:

   • Uncomplicated infections where source control is definitive 1
   • Drainage procedures that completely remove the infectious focus 1

Diagnostic Approach Before Starting Antibiotics

• Perform diagnostic paracentesis in all patients with ascites admitted to hospital, even without symptoms of infection 1
• Obtain ascitic fluid for cell count and bacterial culture before administering antibiotics 1
• Inoculate at least 10 mL of ascitic fluid into blood culture bottles at bedside to increase culture sensitivity to >90% 1
• Consider blood cultures to increase the possibility of isolating causative organisms 1

Antibiotic Selection When Indicated

• Community-acquired infections: First-line is IV third-generation cephalosporin 1
• Healthcare-associated or nosocomial infections: Broader spectrum antibiotics based on local resistance patterns 1
• Intra-abdominal infections: Empiric therapy should cover enteric gram-negative bacteria, with duration of 3-5 days if adequate source control is achieved 1

Monitoring Response to Therapy

• Repeat diagnostic paracentesis 48 hours after initiating antibiotics to assess response 1
• A decrease in PMN count <25% from baseline indicates lack of response and should prompt broadening of antibiotic coverage 1
• Consider secondary bacterial peritonitis if response is inadequate 1

Duration of Therapy

• 5-7 days is the recommended duration for spontaneous bacterial peritonitis 1
• 3-5 days for complicated intra-abdominal infections with adequate source control 1
• Antibiotics can be discontinued once PMN count decreases to <250/mm³ 1

Important Caveats and Pitfalls

1. Avoid unnecessary antibiotic use:

   • Empiric antibiotics are initiated four times more often than infections are confirmed 3
   • Prolonged empiric therapy in the absence of confirmed infection may be harmful 3
   • Bacterascites without symptoms usually self-resolves or represents contamination 1

2. Consider timing strategically:

   • For septic shock and bacterial meningitis, immediate antibiotics are critical 4
   • For less severe infections, waiting 4-8 hours for diagnostic results may be acceptable and promotes more targeted therapy 4

3. Antibiotic stewardship principles:

   • Obtain cultures before starting antibiotics whenever possible 5
   • De-escalate therapy based on culture results 5
   • Stop unnecessary antibiotics once absence of infection is likely 5
   • Drain infected foci and remove infected devices promptly 5

By following this evidence-based approach, you can ensure appropriate antibiotic use that maximizes patient benefit while minimizing unnecessary exposure and resistance development.