This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Phenylalanine and Tyrosine metabolism Detail, Subject name: Biochemistry
Guthrie's bacterial inhibition test detects: 
Select and explain. 
A. Phenyl pyruvate, B. Phenyl alanine, C. Phenyl lactate, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Guthrie's bacterial inhibition test:- Screening test for phenylketonuria (PKU) Used to detect the abnormal presence of phenylalanine metabolites in blood i.e. Phenyl pyruvate Phenyl alanine Phenyl lactate. Procedure: A small amount of blood sample is taken from heel of the infant and placed in a medium with a strain of Bacillus subtilis, a bacteria that cannot grow without phenylalanine. If phenylalanine metabolites are present, then these bacteria reproduce, and the test result is positive, indicating that patient has PKU.