Volume 27, Number 6—June 2021
Increased Incidence of Antimicrobial-Resistant Nontyphoidal Salmonella Infections, United States, 2004–2016
|Resistance category||Change in no. infections/year‡
||2015–2016 vs. 2004–2008||2015–2016 vs. 2010–2014|
|Any clinically important resistance§||222,000||159,000||166,000||63,000‡||56,000|
*Amp-only, resistant to ampicillin (MIC >32 µg/mL) but susceptible to ceftriaxone and ciprofloxacin; BHM, Bayesian hierarchical model; Cef/Amp, resistant to ceftriaxone (MIC >4 µg/mL) and ampicillin; Cipro, nonsusceptible to ciprofloxacin (MIC >0.12 µg/mL) but susceptible to ceftriaxone; CrI, credible interval. †Point estimates extrapolated to the entire US population were calculated by multiplying mean estimates for culture-confirmed infections (derived using BHM) by the multiplier of 29 and the average total U.S. population for 2015–2016 (322 million). The multiplier of 29 is the mean estimate of the total number of infections for every culture-confirmed nontyphoidal Salmonella infection. The 95% CrIs were not derived. Extrapolated point estimates were rounded to the nearest thousand. ‡Model-derived mean estimates of changes in resistance incidence (Table 2) used to calculate extrapolated estimates are reported as significant if the 95% CrIs do not include 0; the extrapolated estimates corresponding to these BHM-derived estimates are shown in bold font. Although the 95% CrIs of extrapolated estimates were not derived, they can be assumed to include 0 if the 95% CrIs of BHM-derived estimates include 0. §An overall category of clinically important resistance includes any of 3 resistance patterns (i.e., resistant to ceftriaxone, resistant to ampicillin, or nonsusceptible to ciprofloxacin). Amp-only, Cef/Amp, and Cipro are mutually exclusive categories of clinically important resistance. Isolates with any clinically important resistance might have resistance to other agents tested. Model estimates for overall clinically important resistance were derived separately and might differ from the sum of BHM estimates for the 3 mutually exclusive categories; thus, extrapolated estimates for the overall category might differ from the sum of mutually exclusive categories. ¶Resistant to >3 classes of antimicrobial agents.