Common Cause of GI Illness Noted to be Highly Resistant to Antimicrobials

Antibiotic resistance to Salmonella is a serious concern for public health and clinical providers.

After testing 20,866 Salmonella isolates, researchers at the Centers for Disease Control and Prevention determined that roughly 20% of nontyphoidal blood isolates were resistant to first-line antimicrobial treatments.1

Additionally, 27% of isolates were resistant to at least one antimicrobial agent.

“It is a concerning finding that approximately one of every five isolates had resistance to first-line treatments in this study,” Cindy Friedman, MD, acting associate director of Antimicrobial Resistance in the CDC’s Division of Foodborne, Waterborne and Environmental Diseases and one of the study’s researchers told Infectious Disease Advisor in an email interview. “Antibiotic resistance to Salmonella is a serious concern for public health and clinical providers. We must be thoughtful about the use of antibiotics in both humans and food-producing animals.”

From 2003 to 2013, researchers with the National Antimicrobial Resistance Monitoring System (NARMS) tested 1189 blood Salmonella isolates and 19,677 Salmonella isolates from stool. 

Among the blood isolates resistant to at least one agent, 73.8% were resistant to a first-line agent. Approximately 5% of all Salmonella isolates that came from blood were resistant to ceftriaxone, double what NARMS researchers found in a study conducted from 1996 to 2007.

“There is increasing resistance to ceftriaxone which is considered a first-line treatment for Salmonella,” Dr Friedman said. “Treatment is not generally recommended for uncomplicated Salmonella infections; however when treatment is needed, we want to be able to use first line effective antimicrobial agents to treat the patient.”

Bacteremia was most common among patients with serotypes Dublin, Sandiego, Schwarzengrund, Poona, Panama, Heidelberg, Oranienburg, Rubislaw, and Enteritidis. Participants aged 65 to 84 years (OR=2.04; 95% CI, 1.73 to 2.41) and those ≥85 years (OR=2.10; 95% CI, 1.47 to 3.00) were more like to have bacteremia than those aged 18 to 64.

Dr Friedman said vaccinations, infection control, proper hygiene, and proper food safety techniques all play a role in preventing drug resistance but added that antibiotic use is “is the single most important factor leading to antibiotic resistance around the world.”

“Repeated use of antibiotics can increase the number of resistant bacteria in humans and animals,” she said. “Responsible use of antibiotics in the community, healthcare settings, and in food animal production is key to controlling the spread of resistance.”

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1.    Angelo KM, Reynolds, Karp BE, et al. Antimicrobial resistance among nontyphoidal salmonella isolated from blood in the United States, 2003–2013. J Infect Dis. 2016; doi:10.1093/infdis/jiw415.