Ann Lab Med.  2012 Jan;32(1):82-86. 10.3343/alm.2012.32.1.82.

Characterization of a Vancomycin-resistant Enterococcus faecium Outbreak Caused by 2 Genetically Different Clones at a Neonatal Intensive Care Unit

• Lee WG
• Ahn SH
• Jung MK
• Jin HY
• Park IJ

• KMID: 1781443
• DOI: http://doi.org/10.3343/alm.2012.32.1.82

Abstract

In July 2010, we identified an outbreak of vancomycin-resistant enterococci (VRE) in our 26-bed neonatal intensive care unit. We performed an epidemiological investigation after clinical cultures of 2 neonates were positive for VRE. Identification, susceptibility testing, and molecular characterization were performed. Cultures of 3 surveillance stool samples of inpatients and 5 environmental samples were positive for VRE. All isolates were identified as Enterococcus faecium containing the vanA gene. Two distinct clones were identified by performing pulsed-field gel electrophoresis. The 2 clones exhibited different pulsotypes, but they represented identical Tn1546 types. Two sequence types, ST18 and ST192, were identified among all of the isolates with multilocus sequence typing. Our investigation determined that the outbreak in the neonatal intensive care unit was caused by 2 genetically different clones. The outbreak may have occurred through clonal spread and horizontal transfer of the van gene.

Keyword

Enterococcus; Disease outbreak; Neonatal intensive care unit

MeSH Terms

Anti-Bacterial Agents/pharmacology
Bacterial Proteins/genetics
Bacterial Typing Techniques
Carbon-Oxygen Ligases/genetics
DNA, Bacterial/analysis
*Disease Outbreaks
Electrophoresis, Gel, Pulsed-Field
Enterococcus faecium/drug effects/*genetics/isolation & purification
Feces/microbiology
Genotype
Gram-Positive Bacterial Infections/diagnosis/epidemiology/*microbiology
Humans
Infant, Newborn
Intensive Care Units, Neonatal
Male
Multilocus Sequence Typing
Vancomycin/pharmacology
*Vancomycin Resistance

Figure

• 

  Fig. 1 Map of the neonatal intensive care unit showing the location of the patients with vancomycin-resistant enterococci (VRE). Numbered rectangles, location of beds inside the room; Gray rectangles, environmental locations that showed presence of VRE.

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  Fig. 2 Pulsed-field gel electrophoresis of vancomycin-resistant isolates. M, molecular weight marker; lane 1, isolate from index case 1; lane 2, isolate from index case 2; lane 3, isolate from contact patient 1; lanes 4 to 6, isolates from environment; lane 7, isolate from index case 2; lane 8, isolate from contact patient 2; lanes 9 and 10, isolates from environment; lane 11, isolate from contact patient 3.

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