Figure 1. Number of nontyphoidal Salmonella isolates with clinically important resistance, by resistance category, United States, 2004–2012. Three mutually exclusive categories were defined. Isolates in each category may have resistance to other agents: 99% of the 599 Cef/Amp isolates, 43% of the 467 Cipro isolates, and 89% of the 1,254 Amp-only isolates were resistant to >1 antimicrobial class other than cephems, quinolones, or penicillins. Amp-only, resistant to ampicillin but susceptible to ceftriaxone and ciprofloxacin; Cef/Amp, resistant to ceftriaxone (MIC >4 μg/mL) and ampicillin (MIC >32 μg/mL); Cipro, nonsusceptible to ciprofloxacin (MIC >0.12 μg /mL) but susceptible to ceftriaxone; NTS, nontyphoidal Salmonella.