Effect of culture media and nutrients on biofilm growth kinetics of laboratory and clinical strains of Enterococcus faecalis

ObjectiveEnterococcus faecalis is a bacterial pathogen that is often associated with endodontic infections. Biofilm formation is a key virulence attribute in the pathogenicity of E. faecalis. In the present study, we comprehensively examined the effect of various culture media and nutrients on the development of E. faecalis biofilms.DesignA reference strain and a clinical isolate of E. faecalis were used in all experiments for comparison. Commonly used liquid culture media with different nutrient compositions were used to support the development of E. faecalis biofilms in a time-dependent assay. E. faecalis biofilms were quantified by colony forming unit (CFU) and crystal violet (CV) assays. Biofilm architecture and cellular viability were evaluated by scanning electron microscopy and confocal laser scanning microscopy.ResultsGrowth kinetics evaluated by CFU and CV assays and by microscopy showed that E. faecalis biofilms reached maturity at 72 h. “Pg broth” (Tryptic Soy Broth with yeast extract, hemen and vitamin K) promoted E. faecalis biofilm formation more than Brain Heart Infusion broth or Tryptic Soy Broth. Addition of 2% glucose enhanced biofilm formation. Thus, it seems that nutrients such as hemen, vitamin K and glucose are important for E. faecalis for the formation of biofilms.ConclusionThe present study demonstrated that nutrient-rich media containing glucose enhances the formation of E. faecalis biofilms, which exhibit maturation at 72 h.     

Outcome and Prognostic Factors After Adrenalectomy for Patients with Distant Adrenal Metastasis

Background

The purpose of this study was to describe a single-institution experience with adrenal metastasectomy and to elucidate factors that may bear prognostic significance.

Methods

This is a single-center, retrospective review of patients with adrenal metastasis who underwent adrenalectomy performed with curative intent between 2000 and 2012. The Kaplan–Meier method was used to evaluate overall survival from time of adrenalectomy to death or last follow-up. Primary endpoint was death from any cause. Clinical variables were examined for association with survival.

Results

The study included 62 patients with mean age of 60 (±12) years; 55 % (34 of 62) were male, 85 % (53 of 62) presented with isolated adrenal metastasis, and 82 % (51 of 62) had metachronous disease with median disease-free interval (DFI) of 22 months (range, 6–217 months). Non-small cell lung cancer (NSCLC) was the most common primary comprising 50 % of cases. Median survival for the study population was 30 months (range, 1–145 months) and 5-year survival was 31 %. Patients with NSCLC had significantly shortened survival compared with non-NSCLC with median and 5-year survival of 17 versus 47 months and 27 % versus 38 %, respectively (p = .033). Synchronous metastasis (p = .028) and DFI < 12 months (p = .038) were also associated with worse survival outcome, though male gender (p = .69) and oligometastatic disease (p = .62) were not.

Conclusions

Adrenal metastasectomy resulted in median survival of 30 months and 5-year survival of 31 %. Shorter survival was associated with lung primary, short disease-free interval, and synchronous metastasis, but not with the presence of oligometastatic disease provided that the primary cancer and additional metastatic lesions were adequately controlled and amenable to resection.