Efficacy of ceftriaxone, cefepime, doxycycline, ciprofloxacin, and combination therapy for Vibrio vulnificus foodborne septicemia

Foodborne Vibrio vulnificus infections are associated with higher rates of sepsis and mortality than wound infections; however, antibiotic efficacy studies have not been performed in foodborne infection models. The efficacies of ceftriaxone, cefepime, doxycycline, ciprofloxacin, and combination therapy were assessed in V. vulnificus intestinal infection in mice in order to model foodborne infections. In accordance with prior studies of cefotaxime, cefepime was synergistic with doxycycline and ciprofloxacin in vitro; combination therapy significantly decreased bacterial growth, by ≥2 log₁₀ units, from that with antibiotic monotherapy (P 0.01). In vivo, survival rates in the ceftriaxone (50%), doxycycline (79%), and ciprofloxacin (80%) groups were significantly higher than those in the control group (0%) (P 0.0001). Survival was significantly higher with ceftriaxone-doxycycline (91%) or ceftriaxone-ciprofloxacin (100%) therapy than with ceftriaxone (50%) (P ≤ 0.05). Survival with cefepime-doxycycline (96%) or cefepime-ciprofloxacin (90%) therapy was significantly higher than that with cefepime alone (20%) (P 0.001). There was no difference in survival between the combination therapy groups. Thus, we conclude that combination therapy was the most effective treatment for foodborne V. vulnificus septicemia. In a septic patient with a recent ingestion of raw seafood, cefepime in combination with doxycycline or ciprofloxacin should be initiated for coverage of resistant Gram-negative organisms and V. vulnificus pending a microbiological diagnosis. Once a diagnosis of foodborne V. vulnificus septicemia is established, treatment can safely transition to ceftriaxone in combination with doxycycline or ciprofloxacin.