MIAMI (AP) — Federal authorities charged 107 doctors, nurses and social workers in seven cities with Medicare fraud Wednesday in a nationwide crackdown on unrelated scams that allegedly billed the taxpayer-funded program of $452 million — the highest dollar amount in a single Medicare bust in U.S. history.

It was the latest in a string of major arrests in the past two years as authorities have targeted fraud that's believed to cost the government between $60 billion and $90 billion each year. Stopping Medicare's budget from hemorrhaging that money will be key to paying for President Barack Obama's health care overhaul.

Health and Human Services Secretary Kathleen Sebelius and Attorney General Eric Holder partnered in 2009 to increase enforcement by allocating more money and staff and creating strike forces in fraud hot spots.