The microbiology of secondary and postoperative pancreatic infections: implications for antimicrobial management.

HYPOTHESIS: We reviewed our experience with secondary pancreatic infections with a focus on preemptive intervention and the potential alteration of the recovered microbial flora. The pathogens associated with postoperative pancreatic infections were analyzed with respect to nonenteric organisms, if any, that were recovered. We hypothesized that our findings might alter the antimicrobial management of these patients. DESIGN: Retrospective review. SETTING: Hospitals affiliated with the University of Tennessee Health Science Center, Memphis. PATIENTS: Patients developing secondary and postoperative pancreatic infections following severe acute pancreatitis. METHODS: Factors examined relative to secondary pancreatitis included preoperative antibiotic use and antecedent extrapancreatic infections potentially implicated in seeding the pancreatic bed. Patients who had elective resection received 24 to 48 hours of antibiotic prophylaxis. RESULTS: Twenty-two patients required surgery for secondary infections following severe acute pancreatitis, with 29 pathogenic isolates being recovered. Of these 22 patients, 14 received vancomycin hydrochloride prior to surgical intervention. Of those 14 patients, 6 had isolates recovered at the time of surgery that were positive for Enterococcus faecalis and 5 of these isolates were vancomycin resistant. Eight of the 22 patients received antifungal prophylaxis with no fungi recovered from intraoperative culture. However, 2 of the 14 patients who did not receive empiric therapy had isolates that were positive for fungi. Five patients who required an urgent operation for sepsis had pathogenic isolates that were similar to those recovered from central lines. Postoperative infections occurred in 40 of 225 patients (17.8%) who had an elective pancreatic resection, with 72 pathogenic isolates being recovered. Of these 40 patients, 22 (55.0%) had polymicrobial infections. Of the 72 pathogenic isolates recovered from patients, 34 (47.2%) were gram-positive organisms, 15 (20.8%) were fungal organisms, and 17 (23.6%) were drug-resistant bacteria. CONCLUSIONS: Prolonged vancomycin use in patients with severe acute pancreatitis is associated with the acquisition of vancomycin-resistant enterococci. Empiric antifungal therapy may reduce the incidence of secondary fungal pancreatic infections. Systemic bloodstream infections at extrapancreatic sites can lead to seeding of pancreatic pseudocysts. Postoperative infections frequently include gram-positive, fungal, and drug-resistant organisms, and empiric therapy directed at these pathogens should be utilized until definitive culture results are obtained.