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Clin Infect Dis. 2017 Apr 1;64(7):894-901. doi: 10.1093/cid/ciw876.

Evolution and Transmission of Carbapenem-Resistant Klebsiella pneumoniae Expressing the blaOXA-232 Gene During an Institutional Outbreak Associated With Endoscopic Retrograde Cholangiopancreatography.

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Pathology and LaboratoryMedicine, David Geffen School of Medicine, University of California, Los Angeles.
Mi Next Generation Science Core Laboratory, Children's Hospital Los Angeles, California.
Icahn School of Medicine at Mount Sinai, New York, New York.
National Center for Emerging and Zoonotic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
Department of Infectious Disease Epidemiology, Imperial College London, United Kingdom; and.
Division of Infectious Diseases, David Geffen School of Medicine, University of California, Los Angeles.



Whole-genome sequencing (WGS) is an emerging and powerful technique by which to perform epidemiological studies in outbreak situations.


WGS was used to identify and evaluate an outbreak of OXA-232-expressing carbapenem-resistant Klebsiella pneumoniae (CRKP) transmitted to 16 patients over the course of 40 weeks via endoscopic retrograde cholangiopancreatography procedures at a single institution. WGS was performed on 32 OXA-232 CRKP isolates (1-7 per patient) and single-nucleotide variants (SNVs) were analyzed, with reference to the index patient's isolate.


Interhost genetic diversity of isolates was between 0 and 15 SNVs during the outbreak; molecular clock calculations estimated 12.31 substitutions per genome per year (95% credibility interval, 7.81-17.05). Both intra- and interpatient diversification at the plasmid and transposon level was observed, significantly impacting the antibiogram of outbreak isolates. The majority of isolates evaluated (n = 27) harbored a blaCTX-M-15 gene, but some (n = 5) lacked the transposon carrying this gene, which resulted in susceptibility to aztreonam and third- and fourth-generation cephalosporins. Similarly, an isolate from a colonized patient lacked the transposon carrying rmtF and aac(6')lb genes, resulting in susceptibility to aminoglycosides.


This study broadens the understanding of how bacteria diversify at the genomic level over the course of a defined outbreak and provides reference for future outbreak investigations.


CRE outbreak; ERCP; OXA-232; carbapenem-resistant Klebsiella pneumoniae.; whole-genome sequencing

[Indexed for MEDLINE]

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