Predicting peritoneal contamination
 with enterobacteria producing extendedspectrum beta-lactamases and choosing
 empirical antibacterial therapy for
 postoperative peritonitis in cancer patients

Enterobacteriaceae family microorganisms, specifically E. coli and K. pneumoniae isolates, are the most common activators of postoperative peritonitis in oncology. Many of these microorganisms produce extended-spectrum beta-lactamases (ESBL). The deemed resistance of ESBL-producing enterobacteria to all β-lactam antibiotics, except for carbapenems, leads to ineffectiveness of empiric antibiotic therapy. Purpose of the study: To define the risk factors of peritoneal contamination with ESBL-producing enterobacteria for choosing optimal empirical antibacterial therapy on the example of a specific cancer patient with postoperative peritonitis. Results: Independent risk factors of peritoneal contamination with ESBL-producing enterobacteria included “the administration of antibiotics for more than three days” (OR 106, 95% CI 21.0-537, p<0.001), “two or more relaparotomies” (OR 2.66, 95% CI 1.32-5.34, p =0.006), and “postoperative preventive antibiotic treatment” (OR 0.17, 95% CI 0.04-0.75, p =0.02). The obtained prognostic model allowed predicting the infection with ESBL-producing enterobacteria before establishing the postoperative peritonitis microbial etiology. The model sensitivity was 94.7%, overall predictive accuracy was 73.1. Conclusion: Prolonged administration of antibiotics (3rd-generation cephalosporins and/or fluoroquinolones) after cancer surgery to prevent surgical infections is the main independent risk factor of peritoneal contamination with ESBL- producing enterobacteria.