<prompt> A preterm baby developed bullous lesion on the skin soon after bih. The X- ray shows periostitis. What should be the next investigation?VDRL for mother babyELISA for HIVPCR for TBHepatitis surface antigen for mother  <response>: The baby described in the question stem is most likely suffering from the early manifestations of congenital syphilis. As per the choices given VDRL is the test done to diagnose syphilis. Ref: Harrisons Principles of Internal Medicine, 16th Edition, Page 981; Skin Diseases Sexually Transmitted Infections, Uday Khopkar - 6th Edition, Page 257; Nelson 17th ,COGDT 10th Edition, Page 667;CPDT 18th Edition, Page 56. 