The Maryland Senate and House of Delegates passed the Keep Antibiotics Effective Act in separate actions.
If approved by the governor, the law would make Maryland the second state in the U.S. to prohibit routine antibiotic use in livestock. California passed similar legislation restricting use on farm animals in 2015.
"This is a big win for everyone who is concerned about the increasing threat of antibiotic resistance," said Mae Wu, senior attorney at the Natural Resources Defense Council. "Maryland has shown that it takes this threat seriously and wants to protect its residents."
The legislation has broad support among public health officials concerned about the threat of antibiotic resistance.
In the U.S., up to 70 percent of human use antibiotics are sold for use on animals. Advocates say the bill will protect human health by ending inappropriate and unnecessary use of antibiotics in animal agriculture.
The bill bans the routine use of medically important antibiotics in food-producing animals that are not sick, but allows the use of antibiotics to treat sick animals and control disease outbreaks.
"The overwhelming bi-partisan support for the Keep Antibiotics Effective Act demonstrates that safeguarding antibiotics is not just a trend." said Maryland Emily Scarr, director of Maryland PIRG. "We hope more states, retailers, and producers will now become inspired to protect public health by taking action to restrict use of antibiotics on farms."