Table 2. Estimated incidence and changes in the incidence of antimicrobial-resistant culture-confirmed nontyphoidal Salmonella infections, by resistance category, United States, 2015–2016 versus 2004–2008 and 2010–2014*.
| Resistance category | Mean (95% CrI) |
|||||
|---|---|---|---|---|---|---|
| Change in resistance incidence, per 100,000 persons per year‡ |
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| Resistance incidence, per 100,000 persons per year† |
2015–2016 vs. 2004–2008 | 2015–2016 vs. 2010–2014 | ||||
| 2015–2016 | 2004–2008 | 2010–2014 | ||||
| Any clinically important resistance§ | 2.38 (1.93–2.86) | 1.70 (1.44–1.98) | 1.78 (1.46–2.15) | 0.68 (0.13 to 1.24)‡ | 0.60 (−0.002 to 1.20) | |
| Multidrug resistance¶ | 1.83 (1.45–2.25) | 1.51 (1.27–1.79) | 1.42 (1.16–1.70) | 0.32 (−0.17 to 0.82) | 0.41 (−0.07 to 0.92) | |
| Amp-only§ | 1.19 (0.85–1.56) | 1.00 (0.78–1.25) | 0.96 (0.73–1.21) | 0.19 (−0.25 to 0.63) | 0.23 (−0.21 to 0.67) | |
| Cef/Amp§ | 0.49 (0.37–0.65) | 0.43 (0.31–0.58) | 0.42 (0.30–0.56) | 0.06 (−0.13 to 0.26) | 0.08 (−0.11 to 0.26) | |
| Cipro§ | 0.70 (0.55–0.88) | 0.29 (0.19–0.41) | 0.41 (0.26–0.64) | 0.41 (0.22 to 0.61)‡ | 0.29 (0.02–0.52)‡ | |
*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. †Mean estimates of resistance incidence and 95% CrIs were derived using BHMs. Serotypes other than Enteritidis, Typhimurium, Newport, I 4,[5],12:i:-, and Heidelberg were combined into the “other” category. For all nontyphoidal Salmonella, estimates were derived by summing those for the 6 serotype categories. State-year data were too sparse to use in the BHMs to estimate mean resistance incidence for Cef/Amp among Enteritidis and Cipro among Newport and Heidelberg (4, 5, and 6 Enteritidis isolates, 7, 2, and 8 Newport isolates, and 0, 1, and 3 Heidelberg isolates in 2015–2016, 2004–2008, and 2010–2014, respectively). ‡Resistance incidence in 2015–2016 was compared with that from 2 reference periods, 2004–2008 and 2010–2015 (e.g., increase if 2015–2016 > reference). Mean changes are reported as significant (bold font) if the 95% CrIs (rounded to 2 decimals) do not 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 estimates for the 3 mutually exclusive categories. ¶Resistant to >3 classes of antimicrobial agents.