Prophylactic antibiotics alter the bacteriology of infected necrosis in severe acute pancreatitis

BACKGROUND: Use of appropriate prophylactic antibiotics has been shown to decrease infectious complications and mortality rate in patients with severe acute pancreatitis, but its influence on the bacteriology of secondary pancreatic infection is poorly defined. STUDY DESIGN: Operative cultures from 61 consecutive patients with pancreatic necrosis treated during routine prophylactic antibiotic use (1993-2001) were compared with 34 consecutive patients with necrosis treated before routine antibiotic use (1977-1992). RESULTS: The two groups of patients were similar in demographics, etiology of pancreatitis, and severity of illness. All patients in the antibiotic group received prophylactic antibiotics compared with only 38% (13 of 34) in the control group. Routine broad-spectrum prophylactic antibiotics altered the bacteriology of secondary pancreatic infection in severe acute pancreatitis from predominantly gram-negative coliforms (56% versus 26%, p = 0.005) to predominately gram-positive organisms (23% versus 52%, p = 0.009) without a significant increase in either the rate of beta-lactam resistance or fungal infections. The overall hospital stay in patients treated with prophylactic antibiotics was significantly reduced (61 +/- 24 days versus 41 +/- 28 days, p = 0.002), and there was a trend toward a decline in mortality rate in the antibiotic treatment group. CONCLUSION: Routine broad-spectrum prophylactic antibiotic use has altered the bacteriology of secondary pancreatic infection in severe acute pancreatitis from predominantly gram-negative coliforms to predominantly gram-positive organisms without altering the rate of beta-lactam resistance or fungal superinfection.