TABLE 6.

Antimicrobial resistance among S. Newport isolates from different host types

Antimicrobial agentResistance breakpointaNo. of resistant isolates (no. intermediate resistant)
Human (n = 258)Bovine (n = 20)Swine (n = 17)Chicken (n = 13)Turkey (n = 9)Reptile (n = 27)Otherb (n = 21)Total (n = 365)
Ampicillin≥3256 (1)16 (0)7 (0)4 (0)1 (0)0 (0)4 (0)88 (1)
Amoxicillin-clavulanic acid≥32/1627 (2)16 (0)7 (0)3 (0)0 (0)0 (0)4 (0)57 (2)
Ceftriaxone≥827 (0)16 (0)6 (0)3 (0)0 (0)0 (0)4 (0)56 (0)
Cephalothin≥3237 (1)16 (0)7 (0)4 (0)0 (0)0 (0)4 (0)68 (1)
Chloramphenicol≥3239 (1)17 (0)6 (0)4 (0)0 (0)0 (0)4 (0)70 (1)
Trimethoprim-sulfamethoxazole≥4/7617 (0)3 (0)2 (0)0 (0)0 (0)0 (0)3 (0)25 (0)
Cefoxitin≥3227 (0)16 (0)7 (0)3 (0)0 (0)0 (0)4 (0)57 (0)
Gentamicin≥166 (0)4 (0)2(0)1 (0)2 (0)0 (0)0 (0)15 (0)
Kanamycin≥6413 (0)8 (0)3 (0)2 (0)1 (0)0 (0)0 (0)27 (0)
Nalidixic acid≥326 (0)0 (0)0 (0)0 (0)0 (0)0 (0)1 (0)7 (0)
Sulfamethoxazole≥51263 (0)18 (0)8 (0)4 (0)2 (0)1 (0)4 (0)100 (0)
Streptomycin≥6459 (0)18 (0)8 (0)4 (0)1 (0)2 (0)4 (0)96 (0)
Tetracycline≥1656 (1)19 (0)8 (0)5 (0)0 (0)0 (0)5 (0)93 (1)
Ceftiofur≥827 (0)16 (0)7 (0)3 (0)0 (0)0 (0)4 (0)57 (0)
  • a MICs in μg/ml. The MICs (μg/ml) for intermediate resistance were as follows: ampicillin, 16; amoxicillin-clavulanic acid, 16/8; ceftriaxone, 2; cephalothin, 16; chloramphenicol, 16; cefoxitin, 16; gentamicin, 8; kanamycin, 32; streptomycin, 16; tetracycline, 8; and ceftiofur, 4. All of the isolates were sensitive to amikacin and ciprofloxacin (resistance breakpoints, ≥32 and ≥4 μg/ml, respectively).

  • b Isolates from animal feed, food, fertilizer, frog legs, horse, lion, meat, and rat.