More than 2 million people in the U.S. are sickened by antibiotic-resistant germs each year, and at least 23,000 die, according to the first report from the Centers for Disease Control and Prevention to rank the threats.
Three bacteria, including drug-resistant gonorrhea, are classified as urgent threats with the potential to become widespread. Another 11 bacteria and a fungus are referred to as serious perils by the CDC report.
Bacterial resistance was identified shortly after antibiotics were first used in the 1940s, said Steve Solomon, acting director for the epidemiology and analysis program office at the Atlanta-based CDC. In the past, there were always more antibiotics in development. Now, the antibiotic pipeline has largely dried up, leaving doctors without new weapons against the illnesses -- a “nightmare,” Solomon said.
“The cushion of new antibiotics is gone,” Solomon, a report author, said by telephone. “We’re right at the edge of this cliff where we’re approaching the post-antibiotic era.”
The three most serious threats are C. difficile, which causes life-threatening diarrhea, carbapenem-resistant Enterobacteriaceae, which includes E.coli and affects mostly people in health-care settings, and gonorrhea, a sexually transmitted infection, according to the report
These three bacteria have the biggest clinical and economic impact, and the greatest current and projected incidence, according to the report. They are also among the easiest to transmit and have few treatment options. C. difficile alone causes 250,000 infections and 14,000 deaths at a cost of $1 billion each year, according to the report.
“The use of antibiotics is the single most important factor leading to antibiotic resistance around the world,” the researchers wrote in the report. That includes use by humans, for whom about 50 percent of prescribed drugs aren’t needed or aren’t effective, as well as use by animals.
In the past, “there was a sense that resistance wasn’t a huge problem because there would always be another antibiotic coming down the pipe, and for 50 to 60 years, that was kind of true,” the CDC’s Solomon said. No more.
Some of the best ways to protect against antibiotic-resistant bugs are preventive, said Daniel McQuillen, a member of the Infectious Disease Society of America and a senior staff physician in infectious diseases at Lahey Hospital & Medical Center in Burlington, Massachusetts.
That includes encouraging hand-washing and in-hospital programs to evaluate whether the antibiotics being prescribed are appropriate, he said.
These kinds of interventions were probably what caused a decline in the incidence of methicillin-resistant Staphylococcus aureus, or MRSA infections, according to separate study, published in JAMA Internal Medicine.
Cases of invasive MRSA from health-care settings dropped by a third in 2011, compared with 2005. Hospital infections dropped by 50 percent, the report found.
The decrease in community-acquired infections was only 5 percent, according to the authors, led by Raymund Dantes, a researcher at the CDC. MRSA is one of the organisms deemed to be a “serious” risk, according to the larger CDC report.
Many farmers routinely use antibiotics for healthy livestock, in order to promote growth and prevent illness. That practice means germs are given widespread exposure to antibiotics, making it more likely that the microbes will mutate in the animals, spreading into meat.
When the meat is eaten, the resistant bacteria may sicken humans, or swap DNA with the flora in the human gut, a recipe for transferring resistance. It’s difficult to compare human and animal use, though “ there is evidence that more antibiotics are used in food production,” the report said.
The CDC report says that the use of antibiotics in animals for promoting growth isn’t necessary and the practice should be “phased out.”
There have been previous reports of antibiotic resistance in specific species, though this is the first that unites them all, Solomon said.
“We’re reporting the results of infections and deaths as a group because we’re trying to make a case that there’s a big-picture problem,” he said.
Large pharmaceutical companies don’t make enough return on investment by making antibiotics to support developing more, McQuillen said. A proposal called Generating Antibiotic Incentives Now that created incentives for drug companies and researchers to develop antibiotics was included in the FDA reauthorization legislation passed last year by Congress.
“That’s probably not enough,” McQuillen said in a telephone interview. The Infectious Disease Society of America, an advocacy group of infectious disease specialists based in Arlington, Virginia, is also supporting other measures to expand the antibiotic pipeline, McQuillen said.
The group is pushing for a research and development tax credit for companies working on antibiotics, as well as the Strategies to Address Antimicrobial Resistance Act. That would boost resources to development of antibiotics, intensify efforts to track resistant germs, and encourage more-appropriate use of antibiotics.