This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
How to differentiate staphylococci and micrococci 
Select and explain. 
A. Catalase test, B. Hugh and Leifson's oxidation-fermentation test, C. Gram staining, D. AFS
B: Hugh and Leifson's oxidation-fermentation test
Answer: B: Hugh and Leifson's oxidation-fermentation test 
Explanation: Micrococci are gram-positive cocci which can be mistaken for S.aureus in culture but are larger and mostly in pairs, tetrads or irregular clusters. Micrococci is catalase and modified oxidase positive and oxidative in Hugh and Leifson's oxidation-fermentation test. Ref: Textbook of Ananthanarayan and paniker's; 10th Edition; Pg:209