Latos (6-11) logged his first victory since June 27, holding the struggling Pirates to two runs on four hits and a walk while striking out seven.
The right-hander broke a six-start winless streak with the victory, in which Logan Forsythe collected three RBI and Will Venable added three hits, two RBI and a run scored.
The decision was San Diego's fourth straight win and completed a three-game sweep of the Pirates at PNC Park.
Kevin Correia (12-10) was tagged with the loss, yielding four runs on five hits and four walks over 5 2/3 innings.
Brandon Wood smacked a three-run homer for the Pirates.