Characterization of blaKPC-containing Klebsiella pneumoniae isolates detected in different institutions in the Eastern USA

• Published in: Journal of antimicrobial chemotherapy 2009-03, Vol.63 (3), p.427-437
• Main Authors: Endimiani, Andrea, Hujer, Andrea M., Perez, Federico, Bethel, Christopher R., Hujer, Kristine M., Kroeger, Jennifer, Oethinger, Margret, Paterson, David L., Adams, Mark D., Jacobs, Michael R., Diekema, Daniel J., Hall, Gerri S., Jenkins, Stephen G., Rice, Louis B., Tenover, Fred C., Bonomo, Robert A.
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - pharmacology; Antibiotics. Antiinfectious agents. Antiparasitic agents; Bacterial Typing Techniques; beta-Lactam Resistance; beta-Lactamases - biosynthesis; beta-Lactamases - chemistry; Biological and medical sciences; carbapenemases; Cluster Analysis; DNA Fingerprinting; DNA, Bacterial - genetics; Electrophoresis, Gel, Pulsed-Field; Enterobacteriaceae; ESBLs; Genotype; Humans; Isoelectric Focusing; Isoelectric Point; Klebsiella Infections - microbiology; Klebsiella pneumoniae; Klebsiella pneumoniae - drug effects; Klebsiella pneumoniae - enzymology; Klebsiella pneumoniae - isolation & purification; Medical sciences; Microbial Sensitivity Tests; Molecular Epidemiology; Original Research; PFGE; Pharmacology. Drug treatments; rep-PCR; Sequence Analysis, DNA; United States
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkn547

Background The emergence of blaKPC-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 β-lactams (MIC90s ≥ 128 mg/L). Among carbapenems, MIC50/90s 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: blaKPC-2 (59.5%), blaKPC-3 (40.5%), blaTEM-1 (90.5%), blaSHV-11 (95.2%) and blaSHV-12 (50.0%). aIEF of crude β-lactamase extracts from these strains supported our findings, showing β-lactamases at pIs of 5.4, 7.6 and 8.2. The mean number of β-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 blaKPC-2 and 12 blaKPC-3) were detected in each of the five institutions. rep-PCR showed patterns consistent with PFGE. Conclusions We demonstrated the complex β-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.