KANSAS CITY, Mo. -- Two children seriously injured in the Joplin, Mo., tornado in May 2011 showed up at Children’s Mercy Hospital in Kansas City suffering from antibiotic-resistant infections from dirt and debris in their wounds.

Physicians tried different drugs, but at first nothing seemed to work.

Blame the overuse of antibiotics in livestock, according to the doctors familiar with their cases.

“These kids had some really highly resistant bacteria that they clearly had not picked up in a hospital,” said Jason Newland, director of the Children Mercy’s antibiotic stewardship program.

Newland and other doctors believe those infections are part of the price we are paying for a half-century of overusing antibiotics in cattle and other meat animals in the United States.

“If you look at tonnage, 80 percent of the total of all the antibiotics we use in the States is used in meat animals,” Newland said.

As in humans, bacteria growing inside animals that are given antibiotics can develop a resistance to the medicines, Newland explained. That resistant bacteria can then be transferred to the soil through animal waste.

During severe storms, such as the EF5 tornado which killed 161 people in Joplin, that contaminated soil can end up in open wounds, and even modern medicine is challenged in combating the serious infections that can occur.

“We are increasingly treating kids with antibiotic-resistant infections who were at the last antibiotic we could possibly use on them,” Newland said. “In the next 20 years, will we see antibiotics resistant to everything?”

A yearlong investigation by The Kansas City Star found a multimillion-dollar-a-year pharmaceutical arms race in the beef industry is not just about curing sick cows.

It’s also about fattening cattle cheaply and quickly, driven in part by efforts to maximize profits, according to food safety advocates. In fact, the same number of cattle today are producing twice as much meat as they did in the 1950s because of genetics, drugs and more efficient processing.

Despite decades of warnings, the federal government has failed to pass meaningful regulation of animal drug use, failed to adequately monitor the harmful residues they leave behind, and failed to stop the consumption of meat contaminated with such substances.

Consider:

•  Last year, an Arizona lab discovered a strain of antibiotic resistant MRSA in meat that can infect humans. MRSA is the potentially fatal staph infection that sometimes races through hospitals.

•  Mexico rejected contaminated meat that U.S. rules allow Americans to eat. A shipment of U.S. beef in 2008 contained high levels of copper, a byproduct of industry and antibiotics, which can damage kidneys. The U.S. Department of Agriculture, which hasn’t set allowable amounts of copper in meat, couldn’t stop it from distribution in the United States.

•  Until it tightened monitoring this year, the government couldn’t even stop the sale of meat containing arsenic, one of the residues found in cattle treated with antibiotics. High levels of the poison can cause vascular disease and hypertension in humans. Many U.S. veterinarians who specialize in treating cattle said in a recent survey that they were concerned about the overuse and improper use of antibiotics and other drugs. Some blamed salesmen intent on making more money. Based on sales data alone, the amount of drugs used in livestock is increasing, and beef samples are showing greater numbers of antibiotic-resistant pathogens.