Bernadina, 24, was 3-for-18 (.167) with Syracuse when he received the promotion.
"I was kind of surprised when I got the call up. They told me [Tuesday]," Bernadina said. "It was only [Tuesday] when I was supposed to play center field in Syracuse."
This will be Bernadina's third Major League stint. After two callups last year, Bernadina hit .211 with two RBIs. He also hit a combined .335 (153-for-457) with nine home runs, 54 RBIs and 41 stolen bases in 120 games between Harrisburg and Triple-A Columbus.
With Milledge out of the picture, Elijah Dukes will be the everyday center fielder, while Austin Kearns and Josh Willingham will rotate in right field. Acta didn't rule out Adam Dunn starting in right field and putting Willingham in left when the latter gets the start.
"We are trying to help the team, put the best guys out there," Acta said. "It does help that we have options and the depth. We are not doing very well. I guess we did what we had to do."
As for Davis, he was the Nationals' Minor League Player of the Year in 2008, hitting .310 with 25 home runs and 76 RBIs. The Nationals could replace him on the 40-man roster with right-hander Jordan Zimmermann, who will make his Major League debut Monday against the Braves.
In other news, shortstop Cristian Guzman is not going on the disabled list after all. His left hamstring strain is improving and hopes to be in the lineup by this weekend against the Marlins. Guzman worked on the treadmill and took batting practice Wednesday without any problems.
"I feel the pain just a little bit. It's not so bad," Guzman said.
Guzman suffered a left hamstring strain in the bottom of the ninth inning on Monday. Facing Phillies closer Brad Lidge to lead off the inning, Guzman singled down the right-field line. As he started running the bases, Guzman felt pain in his leg, but he kept running hard. As he reached first base, it looked like Guzman would try for second, but he stopped after the pain in his leg worsened.
Second baseman Ronnie Belliard, who had been dealing with lower back problems, will be available to play against the Phillies on Thursday.