Volume 12, Number 8—August 2006
Research
Carbapenem Resistance in Klebsiella pneumoniae Not Detected by Automated Susceptibility Testing
Fred C. Tenover*
, Rajinder K. Kalsi†, Portia P. Williams‡, Roberta B. Carey*, Sheila Stocker*, David Lonsway*, J. Kamile Rasheed*, James W. Biddle*, John E. McGowan‡, and Bruce Hanna†
, Rajinder K. Kalsi†, Portia P. Williams‡, Roberta B. Carey*, Sheila Stocker*, David Lonsway*, J. Kamile Rasheed*, James W. Biddle*, John E. McGowan‡, and Bruce Hanna†Table 1
Carbapenem susceptibility and strain typing results for isolates tested in the study*
| Organism | Imipenem broth microdilution MIC† (μg/mL) and CLSI interpretation | Meropenem broth microdilution MIC (μg/mL) and CLSI interpretation | PFGE profile | Hospital identification no. |
|---|---|---|---|---|
| 1 Klebsiella pneumoniae | 8 I | 16 R | A | 1 |
| 2 K. pneumoniae | 16 R | >16 R | A | 1 |
| 3 K. pneumoniae | 16 R | 16 R | A | 2 |
| 4 K. pneumoniae | 8 I | 8 I | A | 2 |
| 5 K. pneumoniae | 16 R | >16 R | A | 2 |
| 6 K. pneumoniae | 16 R | 16 R | A | 2 |
| 7 K. pneumoniae | 16 R | 16 R | A | 3 |
| 8 K. pneumoniae | 32 R | 16 R | A | 4 |
| 9 K. pneumoniae | 16 R | >16 R | B | 1 |
| 10 K. pneumoniae | 16 R | >16 R | B | 1 |
| 11 K. pneumoniae | 16 R | 16 R | C | 4 |
| 12 K. pneumoniae | 16 R | 16 R | D | 1 |
| 13 K. pneumoniae | 16 R | 16 R | E | 4 |
| 14 K. pneumoniae | 16 R | >16 R | F | 1 |
| 15 K. pneumoniae | 16 R | >16 R | F1 | 4 |
| K. pneumoniae 1534 (control) | 16 R | >16 R | NA | NA |
| Serratia marcescens 525 (control) | >16 R | >16 R | NA | NA |
*CLSI, Clinical and Laboratory Standards Institute; PFGE, pulsed-field gel electrophoresis; NA, not applicable.†Interpretations of MIC results used CLSI criteria (18); I, intermediate; R, resistant.
