The Astros selected Trammell's contract from Triple-A Sugar Land on Friday.
With Jake Meyers (back) headed to the 10-day injured list, Trammell will provide outfield depth with the Astros. In 10 games with Sugar Land this season, Trammell has slashed .226/.455/.548 with five extra-base hits, including two home runs, five RBI, eight runs scored, four stolen bases and an 11:11 BB:K across 45 plate appearances.