The assay on a defined medium of the effects of β-2-thienylalanine on the growth of anaerobic bacterial isolates from phenylketonuric patients

Abstract

Faecal samples were taken from three diet-managed phenylketonuric children to determine effects ofβ-2-thienylalanine (β-2-t) on indigenous bacteria. From sample swabs, 127 anaerobes were identified and tested forβ-2-t inhibition on a phenylalanine (Phe)-free medium, Anaerobe Inhibition Test (AIT) agar. Of the isolates, 77.9% grew sufficiently to assay reactions on at least 25% of AIT plates. Using Phe-containing Columbia agar, 86.5% of the strains could be assayed. None of 28Bacteroides cultures was inhibited byβ-2-t on AIT. Of the genera,Bifidobacterium, Eubacterium, Lactobacillus, Peptostreptococcus, andPropionibacterium, no isolates which would grow on AIT were inhibited. At least one isolate of each of the generaPeptococcus, Fusobacterium, andClostridium was inhibited. Of 127 total isolates, only nine were inhibited byβ-2-t on AIT, and inhibition was abolished on Columbia agar. Thirty-nine ‘aerobes’ were isolated from the same patients. Strains of the genera tested reacted similarly to previously tested strains from non-PKU sources. Also, anaerobically isolatedEscherichia coli were inhibited, whileStreptococcus faecalis cultures were not, confirming results on aerobically-isolated non-PKU cultures of the same species. These studies, the first dealing withβ-2-t and anaerobic bacteria, suggest that little change in intestinal bacterial populations might be expected during in vivoβ-2-t treatment.