In 78 games this season, Suzuki has hit .223 with a .284 on-base percentage while slugging .311. He has three homers and 25 RBIs.
Suzuki's addition will be welcomed in Oakland. John Jaso is on the disabled list and Derek Norris broke his left big toe on Tuesday, leaving rookie Stephen Vogt as the only healthy catcher on the A's 40-man roster.
With Suzuki out of Washington, Wilson Ramos is the only catcher on the Nationals' active roster, though Jhonatan Solano has played in 16 games and is currently at Triple-A Syracuse.
Bacus was drafted by Oakland in the ninth round of the 2012 First-Year Player Draft. He was 9-5 with a 3.56 ERA for Class A Beloit this year. Bacus will report to Class A Hagerstown.
AJ Cassavell is a reporter for MLB.com. Follow him on Twitter @ajcassavell. Jane Lee contributed to this report. This story was not subject to the approval of Major League Baseball or its clubs.