Hyung Joon Yim MD, PhD¹, Sang Jun Suh MD¹, Young Kul Jung MD, PhD¹, Sun Young Yim MD, PhD², Yeon Seok Seo MD, PhD², Yu Rim Lee MD³, Soo Young Park MD, PhD³, Jae Young Jang MD, PhD⁴, Young Seok Kim MD, PhD⁵, Hong Soo Kim MD, PhD⁶, Byung Ik Kim MD, PhD⁷ & Soon Ho Um MD, PhD<sup>2,*

1</sup>Internal Medicine, Korea University Ansan Hospital, Ansan, Republic of Korea
²Internal Medicine, Korea University Anam Hospital, Seoul, Republic of Korea
³Internal Medicine, Kyungpook National University Hospital, Daegu, Republic of Korea
⁴Internal Medicine, Soonchunhyang University Seoul Hospital, Seoul, Republic of Korea
⁵Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Republic of Korea
⁶Internal Medicine, Soonchunhyang University Cheonan Hospital, Cheonan, Republic of Korea
⁷Internal Medicine, Sungkyunkwan University Kangbuk Samsung Hospital, Seoul, Republic of Korea

These authors contributed equally: Hyung Joon Yim, Sang Jun Suh.

^*Correspondence to Soon Ho Um MD, PhD

Objectives
For the prevention of spontaneous bacterial peritonitis (SBP) in cirrhotic patients with ascites, norfloxacin 400?mg per day is recommended as a standard regimen. This study aims to investigate whether ciprofloxacin once weekly administration is not inferior to norfloxacin once daily administration for the prevention of SBP.

Methods
This is an investigator-initiated open-label randomized controlled trial conducted at seven tertiary hospitals in South Korea. Liver cirrhosis patients with ascites were screened, and enrolled in this randomized controlled trial if ascitic protein ≤1.5?g/dL or the presence of history of SBP. Ascitic polymorphonucleated cell count needed to be <250/mm3. Patients were randomly assigned into norfloxacin daily or ciprofloxacin weekly group, and followed-up for 12 months. Primary endpoint was the prevention of SBP.

Results
One hundred twenty-four patients met enrollment criteria and were assigned into each group by 1:1 ratio (62:62). Seven patients in the norfloxacin group and five patients in the ciprofloxacin group were lost to follow-up. SBP developed in four patients (4/55) and in three patients (3/57) in each group, respectively (7.3% vs. 5.3%, P=0.712). The transplant-free survival rates at 1 year were comparable between the groups (72.7% vs. 73.7%, P=0.970). Incidence of infectious complication, hepatorenal syndrome, hepatic encephalopathy, and variceal bleeding rates were not significantly different (all P=ns). The factors related to survival were models representing underlying liver function.

Conclusion
Once weekly ciprofloxacin was as effective as daily norfloxacin for the prevention of SBP in cirrhotic patients with ascites.