Is Ceftriaxone and Metronidazole Combination Effective in the Empirical Therapy of Intra-Abdominal Infections?

Objective: Ceftriaxone and metronidazole (CEF/MET) combination therapy is commonly used in the empirical therapy of intra-abdominal infections (IAIs). We aimed to evaluate the treatment response in patients started on empirical CEF/MET therapy and contribute current treatment data on IAIs. Methods: A retrospective analysis was conducted on patients receiving parenteral antibiotic therapy in the general surgery department between 2016 and 2018. Patients aged 18 and older who received CEF/MET therapy for more than 24 hours with a diagnosis of IAI were included. Patient characteristics, antibiotic use and/or surgical history in the last three months, infection source, need for surgical intervention, and clinical and laboratory data were evaluated. Treatment response was analyzed in groups of patients with or without treatment changes. Results: 10,649 patients were evaluated; 591 (5.5%) received CEF/MET therapy, and 297 (50.2%) met the study criteria. Among them, 243 (81.8%) received only CEF/MET treatment (Group 1), while 54(18.2%) received additional antibiotics (median day 5) (Group 2). There was a statistically significant correlation between malignancy, antibiotic use in the last three months and history of surgical intervention and treatment change (p=0.001). The gallbladder (63%) or the biliopancreatic tract (12.1%) were the infection foci in 75.1% of all patients. Treatment was modified in 9.6% of the patients with an infection focused on the gallbladder and 55.6% of the patients with an infection focused on the biliopancreatic tract (p=0.001). Patients with treatment modification had more extended hospital stays and higher mortality rates (p=0.001). Conclusion: Empirical CEF/MET initiation is appropriate for IAIs with a gallbladder focus, yielding a favourable response in four out of five patients. However, CEF/MET therapy may be insufficient in patients with a biliopancreatic tract focus, a history of antibiotic use, malignancy, or surgical intervention, despite source control. Therefore, learning the source of infection and patient characteristics will contribute to the determination of the antibiotic to be selected in empirical treatment, increase treatment success, shorten the hospitalization period, and reduce mortality.