Antimicrobial susceptibility of microorganisms isolated from patients with intraabdominal infection in Korea: A multicenter study

Background: This study evaluated the antimicrobial susceptibility of pathogens isolated from Korean patients with intraabdominal infections (IAIs). Methods: This multicenter study was conducted at 6 university-affiliated hospitals in Korea between 2016 and 2018. All patients with microbiologically proven IAIs were retrospectively included, while patients with spontaneous bacterial peritonitis or continuous ambulatory peritoneal dialysis peritonitis were excluded. Identification and antimicrobial susceptibility testing were performed using automated microbiology systems. Results: A total of 2,114 non-duplicated clinical isolates were collected from 1,571 patients. Among these pathogens, 510 (24.1%) were isolated from nosocomial infections, and 848 isolates (40.1%) were associated with complicated IAIs. The distribution of the microorganisms included aerobic gram-negative (62.6% of isolates), aerobic gram-positive (33.7%), anaerobic (0.9%), and fungal (2.8%) pathogens. The most common pathogens were Escherichia coli (23.8%), followed by Enterococcus spp. (23.1%) and Klebsiella spp. (19.8%). The susceptibility rates of E. coli and Klebsiella spp. to major antibiotics were as follows: amoxicillin/clavulanate (62.5%, 83.0%), cefotaxime (61.4%, 80.7%), ceftazidime (63.7%, 83.1%), cefepime (65.3%, 84.3%), ciprofloxacin (56.4%, 86.3%), piperacillin/tazobactam (99.0%, 84.8%), amikacin (97.4%, 98.3%), and imipenem (99.8%, 98.8%). The susceptibility rates of Enterococcus spp. to ampicillin were 61.0%, amoxicillin/clavulanate, 63.6%; ciprofloxacin, 49.7%; imipenem, 65.2%; and vancomycin, 78.2%. The susceptibility rates of Pseudomonas aeruginosa and Acinetobacter spp. to imipenem were 77.4% and 36.7%, respectively. Conclusion: Enterococcus spp. with susceptibility to limited antibiotics was one of the main pathogens in Korean IAIs, along with E. coli and Klebsiella spp., which were highly susceptible to imipenem, amikacin, and piperacillin/tazobactam. Meanwhile, the low susceptibilities of E. coli or Klebsiella spp. to amoxicillin/clavulanate, advanced-generation cephalosporins, and ciprofloxacin should be considered when determining empirical antibiotic therapy in clinical practice.