Volume 17, Number 6—June 2011
Dispatch
Ciprofloxacin-Resistant Salmonella enterica Serotype Typhi, United States, 1999–2008
, Maria Sjölund-Karlsson, Sanghyuk Shin, Emily Harvey, Kevin Joyce, Lisa Theobald, Benjamin L. Nygren, Gary Pecic, Kathryn Gay, Jana Austin, Andrew Stuart, Elizabeth Blanton, Eric D. Mintz, Jean M. Whichard, and Ezra J. BarzilayTable 1
MICs of antimicrobial agents tested for 9 ciprofloxacin-resistant Salmonella enterica serotype Typhi isolates detected in the National Antimicrobial Resistance Monitoring System, United States, 1999–2008
| Antimicrobial class and agent* | MIC, µg/mL,* by patient no. (isolate) |
||||||||
|---|---|---|---|---|---|---|---|---|---|
| Patient 1 (MA-03) | Patient 2† (CA-05) | Patient 3 (CA-06) | Patient 4 (TX-06) | Patient 5 (AZ-06) | Patient 6 (NY-07) | Patient 7 (CA-07) | Patient 8 (NJ-07) | Patient 9 (LAC-07) | |
| Quinolones | |||||||||
| Ciprofloxacin | >4 | >4 | >4 | >4 | >4 | >4 | >4 | >4 | >4 |
| Nalidixic acid |
>32 |
>32 |
>32 |
>32 |
>32 |
>32 |
>32 |
>32 |
>32 |
| Aminoglycosides | |||||||||
| Amikacin | <0.5 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Gentamicin | <0.25 | <0.25 | <0.25 | <0.25 | <0.25 | <0.25 | <0.25 | <0.25 | <0.25 |
| Kanamycin | <8 | <8 | <8 | <8 | <8 | <8 | <8 | <8 | <8 |
| Streptomycin |
<32 |
<32 |
<32 |
>64 |
<32 |
<32 |
<32 |
<32 |
<32 |
| β-lactam–β-lactamase inhibitor | |||||||||
| Amoxicillin-clavulanic acid |
<1/0.5 |
<1/0.5 |
<1/0.5 |
8/4 |
<1/0.5 |
<1/0.5 |
<1/0.5 |
<1/0.5 |
<1/0.5 |
| Cephems | |||||||||
| Cefoxitin | 4 | 4 | 4 | 4 | 2 | 4 | 4 | 4 | 4 |
| Ceftiofur | 0.5 | 0.5 | 0.5 | 0.5 | 0.25 | 0.5 | 0.5 | 0.5 | 0.5 |
| Ceftriaxone |
<0.25 |
<0.25 |
<0.25 |
<0.25 |
<0.25 |
<0.25 |
<0.25 |
<0.25 |
<0.25 |
| Folate pathway inhibitors | |||||||||
| Sulfonamide‡ | >512 | >256 | <16 | >256 | >256 | <16 | >256 | <16 | <16 |
| Trimethoprim-
sulfamethoxazole |
>4/76 |
>4/76 |
<0.12/ 2.38 |
>4/76 |
>4/76 |
<0.12/ 2.38 |
>4/76 |
<0.12/ 2.38 |
<0.12/ 2.38 |
| Penicillins | |||||||||
| Ampicillin |
2 |
<1 |
<1 |
>32 |
<1 |
<1 |
<1 |
<1 |
<1 |
| Phenicols | |||||||||
| Chloramphenicol |
4 |
4 |
4 |
>32 |
4 |
4 |
4 |
4 |
4 |
| Tetracyclines | |||||||||
| Tetracycline | >32 | >32 | <4 | <4 | >32 | <4 | >32 | <4 | <4 |
*Classes of antimicrobial agents defined by the Clinical and Laboratory Standards Institute (CLSI) were used to categorize agents (7,13). MICs were interpreted by using CLSI criteria when available (7,13): ciprofloxacin (resistance breakpoint, >4 µg/mL); nalidixic acid (>32); amikacin (>64); gentamicin (>16); kanamycin (>64); amoxicillin-clavulanic acid (>32/16); cefoxitin (>32); ceftiofur (>8); ceftriaxone (>4); sulfamethoxazole/sulfisoxazole (>512); trimethoprim-sulfamethoxazole (>4/76); ampicillin (>32); chloramphenicol (>32); and tetracycline (>16). For streptomycin, resistance was defined as MIC >64 µg/mL (7). If growth was not inhibited by the highest concentration of the agent in the panel, the MIC was reported as above the highest concentration.
†Isolate was cultured from a blood specimen. Another isolate was cultured from fecal samples, which had MIC <0.5 µg/mL for amikacin and same MICs for other agents tested.
‡Sulfamethoxazole was used during 1999–2003 and sulfisoxazole since 2004 to represent sulfonamides.
