A US government report on drug-resistant foodborne bacteria in 2012 brings both good news and bad news.
On the positive side, surveillance of foodborne infections showed that multidrug-resistant Salmonella decreased over the past 10 years and that resistance to two important classes of antibiotics—cephalosporins and fluoroquinolones—remained low, the Centers for Disease Control and Prevention (CDC) said in a press release.
On the other hand, resistance by Salmonella typhi, the cause of typhoid fever, to quinolone drugs increased to 68%, raising concern that one of the common treatments for the disease may not work, the CDC reported.
The findings come from the latest report by the National Antimicrobial Resistance Monitoring System, which is operated by three federal agencies. The CDC, with help from state health departments, tracks resistant bacteria in humans, while the Food and Drug Administration (FDA) monitors resistance in retail meat and the US Department of Agriculture tracks it in food animals.
The CDC report compares resistance levels in human infections in 2012 to the levels during the period 2003 to 2007. The agency monitors resistance in clinical isolates of six types of foodborne bacteria from all 50 states. More than 5,000 isolates were tested in 2012, the statement said.
"Our latest data show some progress in reducing resistance among some germs that make people sick but unfortunately we're also seeing greater resistance in some pathogens, like certain types of Salmonella," Robert Tauxe, MD, MPH, deputy director of the CDC's Division of Foodborne, Waterborne, and Environmental Diseases, said in the press release.
The CDC noted several other findings in the report:
- About 20% of infections with Salmonella Heidelberg—a serotype linked to recent poultry-related outbreaks—were resistant to ceftriaxone, a cephalosporin drug. Ceftriaxone resistance makes Salmonella infections harder to treat, especially in children.
- Campylobacter resistance to ciprofloxacin stayed at 25%, despite the FDA's 2005 ban on the use of enrofloxacin, another fluoroquinolone drug, in poultry.
- Resistance of Shigella is at 2% for ciprofloxacin and 4% for azithromycin and is growing, but no strains were resistant to both drugs.
- Overall fluoroquinolone resistance stayed low, but there were hints of increased resistance of Salmonella Enteritidis, the most common Salmonella serotype, to ciprofloxacin. The drug is a first-line treatment for adults with severe salmonellosis, according to previous reports.
New method and steps
The agency also noted that the report introduces a new method for interpreting Campylobacter data and includes links to interactive graphs that permit users to choose a pathogen and an antibiotic and see the year-to-year resistance trends.
President Obama's proposed 2015 budget requests additional funding to enable the CDC to improve early detection and tracking of multidrug-resistant Salmonella and "other urgent resistance threats," the agency noted in the release. The agency estimated that with $30 million a year for 5 years, it could cut multidrug-resistant Salmonella infections by 25%.
Jul 1 CDC press release
Interactive graphs accompanying NARMS report
Mar 7, 2013, CIDRAP News story on Salmonella resistance to ceftriaxone and ciprofloxacin