Volume 14, Number 7—July 2008
Letter
Klebsiella pneumoniae Carbapenemase–2, Buenos Aires, Argentina
Table
Antibiotic susceptibility, isolectric focusing of β-lactamases and PCR of antimicrobial resistance determinants in Klebsiella pneumoniae, Citrobacter freundii clinical isolates, Salmonella transconjugants, and recipient and control strains*
| Type of testing | Clinical isolates |
Transconjugants and recipient strains |
Control strains |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| K.p. M9171 | C.f. M9169 | Salmonella M9204† | Salmonella M9190‡ | Salmonella M1744 | K.p. D5/07§ | K.p. C2¶ | E. coli ATCC 25922 | ||||
| MICs (µg/mL) | |||||||||||
| Antimicrobial agent | |||||||||||
| Imipenem | 32 | 1.0 | 1.0 | 1.0 | 0.12 | 2.0 | 0.12 | 0.25 | |||
| Impenem/clavulanate | 32 | 0.25 | 0.25 | 0.25 | 0.12 | 0.5 | 0.12 | 0.25 | |||
| Impenem/APB | 2.0 | 0.12 | 0.25 | 0.12 | 0.12 | 0.12 | 0.12 | 0.25 | |||
| Imipenem/EDTA# | 32 | 0.25 | 1.0 | 1.0 | 0.12 | 2.0 | 0.12 | 0.12 | |||
| Meropenem | 32 | 1.0 | 0.5 | 1.0 | 0.015 | 2.0 | 0.03 | 0.03 | |||
| Meropenem/clavulanate | 32 | 0.12 | 0.03 | 0.06 | 0.015 | 1.0 | 0.03 | 0.03 | |||
| Meropenem/APB | 1.0 | 0.06 | 0.03 | 0.03 | 0.015 | 0.12 | 0.03 | 0.03 | |||
| Meropenem/EDTA# | 32 | 1.0 | 0.5 | 1.0 | 0.015 | 2.0 | 0.03 | 0.03 | |||
| Ertapenem | 128 | 2.0 | 1.0 | 1.0 | 0.008 | 16 | 0.06 | 0.015 | |||
| Ertapenem/clavulanate | 128 | 0.25 | 0.03 | 0.06 | 0.008 | 16 | 0.06 | 0.008 | |||
| Ertapenem/APB | 8.0 | 0.008 | 0.015 | 0.03 | 0.008 | 0.5 | 0.03 | 0.008 | |||
| Cefoxitin | 64 | 64 | 4.0 | 8.0 | 2.0 | ND | ND | 4 | |||
| Ceftazidime | 256 | 16 | 16 | 32 | 0.06 | ND | ND | 0.25 | |||
| Ceftazidime/clavulante | 16 | 32 | 0.5 | 0.5 | 0.06 | ND | ND | ND | |||
| Cefepime | 32 | 4.0 | 16 | 16 | 0.03 | ND | ND | 0.03 | |||
| Cefepime/clavulanate | 16 | 0.25 | 0.5 | 0.25 | 0.03 | ND | ND | ND | |||
| Tigecycline** |
1.0 |
0.25 |
ND |
ND |
ND |
ND |
ND |
0.25 |
|||
| Isolectric focusing results | |||||||||||
| pI band†† |
5.4 + 6.7 + 7.6 |
5.4 + 6.7 + >9.0 |
6.7 |
6.7 |
None |
ND |
ND |
None |
|||
| PCR results | |||||||||||
| Β-lactamase | |||||||||||
| blaKPC | + | + | + | + | – | + | – | ND | |||
| blaampC | – | + CIT/ CMY | – | – | – | – | + CIT/ CMY | ND | |||
| blaPER-2 | + | – | – | – | – | ND | ND | ND | |||
| blaSHV | + | – | – | – | – | ND | ND | ND | |||
| blaTEM-1 | + | + | – | – | – | ND | ND | ND | |||
*K.p., Klebsiella pneumoniae; C.f., Citrobacter freundii; E. coli, Escherichia coli; APB, 3-aminophenylboronic acid; IEF, isoelectric focusing; pI, isoelectric point; ND, not determined; +, positive; –, negative.
†M9204 transconjugant derived from K. pneumoniae M9171.
‡M9190 transconjugant derived from C. freundii M9169.
§Control strain producing KPC-2.
¶Control strain producing CMY-2.
#EDTA 0.4 mmol/L.
**Microdilution (JustOne, Trek Diagnostic Systems, Cleveland, OH, USA). Breakpoints according to US Food and Drug Administration (susceptible <2 μg/mL).
††Underlined pI bands indicated activity against third-generation cephalosporins