Bacterial colonization of seromas after breast cancer surgery with and without local steroid prophylaxis

BACKGROUND: Seroma formation is a frequent postoperative sequela after mastectomy for primary breast cancer. We investigated the role of bacterial colonization of seroma fluid with three different culture methods and the effect of intracavitary steroids.

METHODS: The study group consisted of 212 patients scheduled for mastectomy from a previously performed double-blind randomized placebo-controlled intervention trial. The patients were allocated to a single dose of 80 mg of steroids (methylprednisolone) or saline, and the effect on seroma formation was investigated. From each aspiration, an equal volume of seroma fluid (10 mL) was distributed into one sterile transport tube (conventional method), one aerobic blood culture bottle and one anaerobic blood culture bottle.

RESULTS: There was significant variation in the number of bacterial species detected in seroma samples among the three culture methods, ranging from 18 species with the conventional culture tubes to 40 species with aerobic blood culture bottles. Patients receiving prophylactic steroids had significantly more frequent colonization than those in the saline group. Nevertheless, the clinical surgical site infection rate of 7.0% was equal between the two groups.

CONCLUSIONS: In general, data analysis of the entire set of case material did not succeed in demonstrating a relationship between a specific bacterial species or a combination of species and seroma formation. However, in the few patients with growth of a pathogenic species, both the duration of seroma formation and volume of seroma fluid were more pronounced.

TRIAL REGISTRATION: Ethics Committee of Copenhagen (H-4-2009-137), (EudraCT number 2009-016650-40), the Danish Data Protection Agency (code J. no. F.750.75-2), and the Danish Health and Medicines Authority (sponsor protocol code number 23837). Start date November 2010.