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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.

Author information

1
Pathology and LaboratoryMedicine, David Geffen School of Medicine, University of California, Los Angeles.
2
Mi Next Generation Science Core Laboratory, Children's Hospital Los Angeles, California.
3
Icahn School of Medicine at Mount Sinai, New York, New York.
4
National Center for Emerging and Zoonotic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
5
Department of Infectious Disease Epidemiology, Imperial College London, United Kingdom; and.
6
Division of Infectious Diseases, David Geffen School of Medicine, University of California, Los Angeles.

Abstract

Background:

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

Methods:

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.

Results:

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.

Conclusions:

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.

KEYWORDS:

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

PMID:
28362935
DOI:
10.1093/cid/ciw876
[Indexed for MEDLINE]

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