Cardinals outfielder Alan Ahmady was suspended for the second time in three years on Thursday after testing positive for a drug of abuse, becoming the fourth Minor Leaguer banned by Major League Baseball in the last two days.

Ahmady and Giants Minor League catcher Leonardo Rojas received 50-game suspensions without pay, a day after Toronto's Jose Brito and the Mets' Hengelbert Rojas were banned 50 games apiece in the Dominican Summer League. All four suspensions become effective at the start of next season.

Ahmady, who ended this season with Class A Advanced Palm Beach, previously was suspended 50 games at the start of the 2010 campaign. The ban announced Thursday follows a second violation for an undisclosed drug of abuse.

The 24-year-old -- St. Louis' 11th-round pick in 2009 out of Fresno State -- batted .292 with five homers, 46 RBIs and a .389 on-base percentage across three levels this season and reached Double-A Springfield for the second year in a row.

Leonardo Rojas, who tested positive for metabolites of Nandrolone, was the Giants' 15th-round pick in June out of Miami Dade South Community College in Miami, Fla. He hit .250 in 21 games for the Rookie-level Arizona League Giants.

Brito, a 17-year-old right-hander who tested positive for metabolites of Stanozolol, appeared in four games for the DSL Blue Jays this season, his first in the Minors.

Hengelbert Rojas, an 18-year-old outfielder from Venezuela, tested positive for metabolites of Stanozolol and Nandrolone. He hit .270 in 60 games for the Mets' DSL affiliates this summer.

Nandrolone is an anabolic steroid that, in the past, has been used in the treatment of osteoporosis in postmenopausal women. It's commonly known as Deca-Durabolin and allegedly was used by Barry Bonds, Roger Clemens and Olympian Marion Jones.

Stanozolol is a synthetic anabolic steroid derived from testosterone that is sometimes prescribed by veterinarians to encourage muscle growth, red blood cell production, bone density and to stimulate the appetite of weakened animals. It's also been linked to bodybuilders and several former and current baseball players.

Major League Baseball has suspended 91 players in 2012, including seven this week, for violations of the Minor League Drug Prevention and Treatment Program.