Urethral obstruction from Cobb's collar in association with VACTERL.

SUMMARY: Cobb's collar is a rare intraluminal congenital cause of bulbar urethral obstruction that is commonly mislabelled congenital obstructive posterior urethral membrane (COPUM) but may be distinguished from this endoscopically as it has no connecting folds to the verumontanum. In this report, Cobb's collar is described for the first time in association with the VACTERL syndrome. The abnormality was diagnosed and treated by diathermy and dilatation at the time of endoscopic evaluation, with improvement of vesicoureteric reflux on micturating cystourethrogram and renal ultrasound.

Competitive exclusion as a mode of action of a novel Bacillus cereus aquaculture biological agent.

AIMS: To determine the contribution of potential modes of action of a Bacillus cereus aquaculture biological control agent in inhibition of the fish pathogen, Aeromonas hydrophila. METHODS AND RESULTS: When B. cereus was tested in plate well inhibition studies, no production of antimicrobial compounds was detected. Bacillus cereus had a high growth rate (0.96 h(-1)), whereas Aer. hydrophila concentration decreased by c. 70% in co-culture experiments. In nutrient limitation studies, B. cereus had a significantly higher growth rate when cultured under glucose (P < 0.05) and iron (P < 0.01) limitation in comparison with Aer. hydrophila. Bacillus cereus glucose (0.30 g l(-1) h(-1)) and iron (0.60 mg l(-1) h(-1)) uptake rates were also significantly higher (P < 0.01) than the Aer. hydrophila glucose (0.14 g l(-1) h(-1)) and iron (0.43 mg l(-1) h(-1)) uptake rates. Iron uptake was facilitated by siderophore production shown in time profile studies where relative siderophore production was c. 60% through the late exponential and sporulation phases. CONCLUSIONS: Competitive exclusion by higher growth rate, competition for organic carbon and iron, facilitated by siderophore production, could be identified as mechanisms of pathogen growth inhibition by B. cereus. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first elucidation of the mechanism of action of our novel B. cereus biological agent in growth attenuation of pathogenic Aer. hydrophila. This study enhances the application knowledge and attractiveness for adoption of B. cereus NRRL 100132 for exploitation in aquaculture.