According to the National Antimicrobial Resistance Monitoring System (NARMS) data collected in 2019, the majority (78%) of Salmonella isolates collected from humans were not resistant to any of the antimicrobials tested under NARMS. In humans, the overall level of resistance remains relatively unchanged from 2018, and is in line with other data from 2006 to 2017, where 76–85% of Salmonella tested were susceptible to all antimicrobials.
The NARMS Integrated Summary 2019, published by FDA in cooperation with the Centers for Disease Control and Prevention (CDC) and the USDA’s Food Safety and Inspection Service (USDA-FSIS), is a national public health system that monitors certain pathogens in human and animal samples for resistance to antimicrobial drugs used in human and veterinary medicine. The report features antimicrobial resistance data in bacteria isolated from humans (by CDC), raw retail meats (by FDA), and animals at slaughter (by USDA) to examine trends in resistance to the most important antimicrobial agents.
Trends in 2019 Data
Where Resistance Is Holding Steady
According to the NARMS data collected in 2019, the majority (78%) of Salmonella isolates collected from humans were not resistant to any of the antimicrobials tested under NARMS. In humans, the overall level of resistance remains relatively unchanged from 2018, and is in line with other data from 2006 to 2017, where 76–85% of Salmonella tested were susceptible to all antimicrobials.
Where Resistance May Have Changed
The overall level of Salmonella resistance has held steady in NARMS samples, however resistance patterns have changed within specific serotypes, FDA notes. Salmonella Infantis, a multidrug-resistant serotype that emerged in 2014, accounted for a large part of overall Salmonella resistance. Salmonella Infantis is resistant to critically important antimicrobial drugs, including ceftriaxone, and shows decreased susceptibility to ciprofloxacin.
The multidrug-resistant Salmonella serotype I 4,[5],12:i:- continued its increasing trend since 2010, FDA says. This serotype is monitored closely because it is sometimes resistant to ceftriaxone and ciprofloxacin, which are antibiotics routinely used to treat several Salmonella infections.
Fluoroquinolone resistance in Campylobacter continues to increase, but FDA says it is not clear what’s driving this trend.
Where Resistance Is Uncommon
FDA says only 1% of Salmonella isolated from humans showed decreased susceptibility to azithromycin, with serotype Newport comprising the majority (53%) of the isolates.
In 2019, none of the Salmonella or E. coli isolates from animals, animal products or retail meats harbored any of the known colistin resistance genes.
Read the full report here.
