Characterization of blaKPC-containing Klebsiella pneumoniae isolates detected in different institutions in the Eastern USA.
BACKGROUND
The emergence of bla(KPC)-containing Klebsiella pneumoniae (KPC-Kp) isolates is attracting significant attention. Outbreaks in the Eastern USA have created serious treatment and infection control problems. A comparative multi-institutional analysis of these strains has not yet been performed.


METHODS
We analysed 42 KPC-Kp recovered during 2006-07 from five institutions located in the Eastern USA. Antimicrobial susceptibility tests, analytical isoelectric focusing (aIEF), PCR and sequencing of bla genes, PFGE and rep-PCR were performed. Results By in vitro testing, KPC-Kp isolates were highly resistant to all non-carbapenem beta-lactams (MIC(90)s >or= 128 mg/L). Among carbapenems, MIC(50/90)s were 4/64 mg/L for imipenem and meropenem, 4/32 mg/L for doripenem and 8/128 for ertapenem. Combinations of clavulanate or tazobactam with a carbapenem or cefepime did not significantly lower the MIC values. Genetic analysis revealed that the isolates possessed the following bla genes: bla(KPC-2) (59.5%), bla(KPC-3) (40.5%), bla(TEM-1) (90.5%), bla(SHV-11) (95.2%) and bla(SHV-12) (50.0%). aIEF of crude beta-lactamase extracts from these strains supported our findings, showing beta-lactamases at pIs of 5.4, 7.6 and 8.2. The mean number of beta-lactamases was 3.5 (range 3-5). PFGE demonstrated that 32 (76.2%) isolates were clonally related (type A). Type A KPC-Kp isolates (20 bla(KPC-2) and 12 bla(KPC-3)) were detected in each of the five institutions. rep-PCR showed patterns consistent with PFGE.


CONCLUSIONS
We demonstrated the complex beta-lactamase background of KPC-Kp isolates that are emerging in multiple centres in the Eastern USA. The prevalence of a single dominant clone suggests that interstate transmission has occurred.
Endimiani
Andrea
A
Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Research Service, Cleveland, OH 44106, USA.
Hujer
Andrea M
AM
Perez
Federico
F
Bethel
Christopher R
CR
Hujer
Kristine M
KM
Kroeger
Jennifer
J
Oethinger
Margret
M
Paterson
David L
DL
Adams
Mark D
MD
Jacobs
Michael R
MR
Diekema
Daniel J
DJ
Hall
Gerri S
GS
Jenkins
Stephen G
SG
Rice
Louis B
LB
Tenover
Fred C
FC
Bonomo
Robert A
RA
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D006801:Humans; D007525:Isoelectric Focusing; D007526:Isoelectric Point; D007710:Klebsiella Infections / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology* / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D017422:Sequence Analysis, DNA; D014481:United States; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000737:chemistry
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D001618:beta-Lactamases