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Volume 13, Number 11—November 2007


Human Multidrug-Resistant Salmonella Newport Infections, Wisconsin, 2003–2005

Amy E. Karon*1Comments to Author , John R. Archer†, Mark J. Sotir*†1, Timothy A. Monson‡, and James J. Kazmierczak*†
Author affiliations: *University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA; †Wisconsin Division of Public Health, Madison, Wisconsin, USA; ‡Wisconsin State Laboratory of Hygiene, Madison, Wisconsin, USA;

Main Article

Table 1

Antimicrobial drug resistance patterns of human Salmonella Newport isolates among case-patients*

Resistant to Frequency (%)
Wisconsin (n = 268), 2003–2005 Rest of United States (n = 402), 2003–2004
None detected 95 (35) 317 (79)
>1 CLSI subclass† 173 (65) 85 (21)
>2 CLSI subclasses 150 (56) 81 (20)
>3 CLSI subclasses 150 (56) 77 (19)
>4 CLSI subclasses 150 (56) 74 (18)
>5 CLSI subclasses 146 (55) 71 (18)
At least ACSSuT‡ 139 (52) 69 (17)
At least ACSuTm§ 7 (3) 4 (1)
At least MDRAmpC¶ 137 (51) 68 (17)
Quinolone and cephalosporin (third generation)# 5 (2)** 2 (0.5)

*Based on data from the National Antimicrobial Resistance Monitoring System for Enteric Bacteria.
†CLSI, Clinical and Laboratory Standards Institute. Subclasses included aminoglycosides (kanamycin, gentamicin, streptomycin), aminopenicillins (ampicillin), β-lactamase inhibitor combinations (amoxicillin-clavulanic acid), first-generation cephalosporins (cephalothin), third-generation cephalosporins (ceftriaxone), cephamycins (cefoxitin), folate pathway inhibitors (trimethoprim-sulfamethoxazole), phenicols (chloramphenicol), quinolones (nalidixic acid, ciprofloxacin), sulfonamides (sulfisoxazole), and tetracyclines (tetracycline).
‡ACSSuT, ampicillin, chloramphenicol, streptomycin, sulfamethoxazole/sulfisoxazole, tetracycline.
§ACSuTm, ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole.
¶At least drugs to which MDRAmpC is resistant: chloramphenicol, streptomycin, trimethoprim-sulfamethoxazole, sulfisoxazole, tetracycline, amoxicillin-clavulanic acid, ampicillin, cefoxitin, cephalothin, and ceftriaxone. Note: the Wisconsin State Laboratory of Hygiene does not routinely test Salmonella isolates for resistance to ceftiofur, a third-generation cephalosporin that is related to ceftriaxone.
#Resistant to ciprofloxacin and/or nalidixic acid, and ceftriaxone.
**1 isolate in this category was also MDRAmpC.

Main Article

1Current affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia, USA