Clinical Outcomes and Microbiological Profiles of Patients with Culture-Confirmed Peritonitis.

Objective: This study aimed to identify pathogenic microorganisms and resistance profiles, clinical outcomes, and mortality-related risk factors in patients with culture-confirmed peritonitis.

Materials and methods: This single-center, retrospective study included patients aged ≥18 years who were followed up with a culture-confirmed diagnosis of peritonitis.

Results: Of the 134 patients, 54.5% (n=73) were male, and the mean age was 57.9 ± 16.1 years. Forty-three patients (32.1%) had primary peritonitis and 91 (67.9%) had secondary peritonitis. A total of 157 pathogens were isolated from 134 cases. The most common microorganisms were Escherichia coli (19.1%, n=9/47), coagulase-negative staphylococci (CoNS) (12.7%, n=6/47), Pseudomonas spp.(12.7%, n=6/47), Enterococcus spp. (10.6%, n=5/47), and Staphylococcus aureus (10.6%, n=5/47) in primary peritonitis and E. coli (27.3%, n=30/110), Enterococcus spp. (15.4%, n=17/110), Klebsiella pneumoniae (13.6%, n=15/110), Pseudomonas spp.(10.9%, n=12/110), and Candida spp. (%10.0, n=11/110) in secondary peritonitis. Among E. coli species, extended-spectrum beta-lactamase (ESBL) rates were 33% (n=3/9) in primary peritonitis and 63% (n=19/30) in secondary peritonitis. The 30-day mortality rate was 36.5% (n=49/134). Male gender (69.4% vs. 45.9%, p=0.009) and secondary perforation (14.3% vs. 4.7%, p=0.049) were more common in deceased patients, while peritonitis associated with peritoneal dialysis (2.0% vs. 11.7%, p=0.048) and peritonitis due to CoNS (0.0% vs. 9.4%, p=0.027) were less common in deceased patients than survivors. In addition, advanced age (63.6 ± 16.6 vs. 54.7 ± 14.9, p=0.001) and high aspartate aminotransferase (AST) levels (147 ± 412 vs. 135 ± 501, p=0.010) were associated with mortality.

Conclusions: This study highlights the importance of demographic characteristics, clinical features, and laboratory parameters for clinical outcomes in patients with peritonitis. Patients with secondary perforation-related peritonitis require close monitoring for clinical changes. Gram-positive bacteria and sensitive enteric bacilli for primary peritonitis and ESBL-producing Gram-negative bacteria for secondary peritonitis should be included in empirical treatment selection. Additionally, we recommend considering antifungal agents for severely ill patients with secondary peritonitis.