All issues > Volume 49(2); 2006

Original Article

Korean J Pediatr. 2006;49(2):150-156. Published online February 15, 2006.

Molecular-epidemiologic study on outbreak of colonization by extended spectrum β-lactamase producing Klebsiella pneumoniae in neonatal intensive care unit

Nu-Lee NL Jun¹, Mi-Na MN Kim², Jae-Sim JS Jeong³, Yang-Soo YS Kim³, Ellen Ai-Rhan ER Kim¹, Ki-Soo KS Kim¹, Soo-Young SY Pi¹

¹Division of Neonatology, Department of Pediatrics, Asan Medical Center, University of Ulsan College
²Department of Laboratory Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seo
³Department of Hospital Infection Control, Asan Medical Center, University of Ulsan College of Medici

Correspondence Ellen Ai-Rhan ER Kim ,Email: arkim@amc.seoul.kr

Abstract

Purpose
: The aims of this study included assessment of molecular-epidemiologic features during an outbreak of colonization of extended spectrum β-lactamase producing Klebsiella pneumoniae(ESBL- KPN) and re-evaluation of their colonized status one year later.
Methods
: Rectal swab cultures for ESBL-KPN from all hospitalized infants and newly admitted infants were obtained during the outbreak of colonization from July to December, 2000. The pattern of XbaI-digested chromosomal DNA of isolates were analyzed by pulsed-field gel electrophoresis. Weekly rectal swab cultures were obtained during the outbreak until patients were either discharged or decolonized. Patients discharged after being colonized had follow up stool cultures a year later.
Results
: A total of 80 patients(28.5 percent) were colonized. Of those, 53 whose pulsed-field gel electrophoresis(PFGE) was possible only once, were ESBL-KPN grouped into six cluster clones and 10 single clones : 28 patients(52.8 percent) were colonized with type A, the most common clone, followed by type B in 11 patients(20.8 percent). Of those 12 patients in whom serial PFGE was done more than twice, type A was predominant. Narrowed-down in strains occurred from types A, B, C, D and three single clones at initiation of the study into types A and type B after three months of strict infection control. Among 75 patients(93.7 percent) who were sent home after being colonized, 30 patients were re-called for stool cultures a year later : All of them were decolonized.
Conclusion
: This study demonstrates the importance of infection control as the diversity of ESBL- KPN strains could be narrowed into fewer strains. Colonization of ESBL-KPN could be reversed upon return to the community.

Keywords :Extended spectrum β-lactamase producing K. pneumoniae, Pulsed-field-gel-electrophoresis, Colonizatio