Patterns and infection outcomes of bacterial colonization in patients with indwelling abdominal drains for malignant ascites

Po Chung Chan, Ka Wai Alice Cheung, Chun Hung Chan, Lie Meng Hwang, Sing Hung Lo


Background: Indwelling abdominal drains for intermittent drainage is an effective treatment for refractory malignant ascites, bacterial colonization and subsequent drain-related infection is however a common concern. This study aimed to investigate the patterns of bacterial colonization and the subsequent infection outcomes in patients with indwelling abdominal drains.
Methods: All consecutive advanced cancer patients with newly inserted indwelling abdominal drains and who were under the service of the ascites clinic of our institution for intermittent drainage between January 2011 and March 2018 were screened for study eligibility. Patients with positive surveillance ascitic fluid culture without immediate drain-related infection were included in the final analysis. Clinical information during the drainage period was prospectively collected using standardized clinical assessment forms. These assessment forms and other medical records were retrospectively reviewed.
Results: Sixty nine patients developed bacterial colonization without immediate infection during the study period. The most common cancer diagnosis was hepatocellular carcinoma (HCC), which comprise 30.4% of the population. Central venous catheters (CVCs) were inserted in 76.8% of patients and pigtail drains in 23.2% as the indwelling abdominal drain. The median duration from drain insertion to the development of bacterial colonization was 18.0 days. Staphylococci, Diphtheroid bacilliand Enterococci were the most common types of bacteria isolated during colonization. Thirty patients (43.5%) developed drain-related infection subsequently and the median time from bacterial colonization to development of infection was 14.5 days. The incidence rate of drain-related infection after bacterial colonization was 1.78 per 100-catheter days and the 1-month infection-free survival was 54.4%. Five patients (7.2%) developed peritonitis and 4 of them died from the infection episode. Decrease in body mass index (BMI) (P=0.03), having 3 or more episodes of drainage in the ascites clinic before bacterial colonization (P=0.03), presence of Escherichia coli (P=0.04) and Bacillus species (P=0.04) in surveillance ascitic fluid culture were significantly correlating with infection outcomes in univariate analyses. HCC as cancer diagnosis (OR 8.85, 95% CI: 1.86–42.07, P=0.006) and decrease in body weight (OR 1.20, 95% CI: 1.02–1.42, P=0.03) were significant factors that correlated with infection outcomes in multivariate analysis.
Conclusions: Bacterial colonization and subsequent progression into drain-related infection are common in patients on indwelling abdominal drains for malignant ascites. Staphylococci is the most common type of bacteria causing both colonization and subsequent drain-related infection. HCC and decrease in body weight are significant factors that correlate with infection outcomes after bacterial colonization.