CDC microbiologist, Valerie Albrecht, holds up two plates of methicillin-resistant Staphylococcus aureus (MRSA) in this undated CDC handout photo. The drug-resistant bacterium known as Methicillin-resistant Staphylococcus aureus costs $8 billion a year to treat and kills 20,000 Americans each year, but Pfizer’s scientists could be close to a vaccine to tame the superbug. To match Feature PFIZER-VACCINE/ REUTERS/CDC/Handout (UNITED STATES – Tags: HEALTH SCIENCE TECHNOLOGY) ATTENTION EDITORS – FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS – RTXZXDT