Volume 23, Number 1—January 2017
Estimated Incidence of Antimicrobial Drug–Resistant Nontyphoidal Salmonella Infections, United States, 2004–2012
|Resistance category||No. infections/100,000 person-years (95% credible interval)*
|Cipro†||0.35 (0.24–0.51)||0.05 (0.02–0.10)||0.15 (0.09–0.25)||0.005‡||0.002‡|
|Cef/Amp§||0.51 (0.35–0.70)||0.14 (0.08–0.23)||0.006‡||0.18 (0.08–0.29)||0.06 (0–0.13)|
|Amp-only¶||1.07 (0.86–1.32)||0.63 (0.43–0.87)||0.08 (0.03–0.16)||0.02 (0.01–0.05)||0.08 (0–0.18)|
|Any of the above #||1.93 (1.60–2.35)||0.82 (0.61–1.05)||0.24 (0.14–0.38)||0.20 (0.11–0.32)||0.14 (0.002–0.28)|
*Estimates and 95% credible intervals were derived by using Bayesian hierarchical models. Cipro, Cef/Amp, and Amp-only are mutually exclusive categories. Estimates for any clinically important resistance were derived by summing estimates for the mutually exclusive categories. Serotypes other than Typhimurium, Enteritidis, Newport, and Heidelberg were combined in an “other” category. For all NTS, estimates were derived by summing those derived for the 4 major serotypes and other category. Amp-only, resistant to ampicillin but susceptible to ceftriaxone and ciprofloxacin; Cef/Amp, resistant to ceftriaxone and ampicillin; Cipro, nonsusceptible to ciprofloxacin but susceptible to ceftriaxone; NTS, nontyphoidal Salmonella.
†Nonsusceptible to ciprofloxacin (MIC >0.12 μg/mL) but susceptible to ceftriaxone, with or without resistance to other agents.
‡Only 8, 7, and 2 isolates of Enteritidis, Newport, and Heidelberg, respectively, showed this resistance pattern; thus, state-year data were too sparse to use in the Bayesian hierarchical models. Crude estimates are shown, calculated as mean incidence for the serotype multiplied by mean resistance proportion over the 9 y.
§Resistant to ceftriaxone (MIC >4 μg /mL) and ampicillin (MIC >32 μg /mL), with or without nonsusceptibility to ciprofloxacin or resistance to other agents.
¶Resistant to ampicillin but susceptible to ceftriaxone and ciprofloxacin, with or without resistance to other agents.
#Nonsusceptible to ciprofloxacin, resistant to ceftriaxone, or resistant to ampicillin.