Molecular Epidemiologic Analysis of a Cluster of Klebsiella Pneuminiae Infection in Neonatal Intensive Care Unit

Jin, Sung Soo; Kim, Jong Hyun; Hur, Jae Kyun; Kang, Jin Han

Abstract

PURPOSE: Klebsiella pneumoniae is a major nosocomial pathogen in neonatal intensive care unit (NICU). Sequential outbreaks of K. pneumoniae infection in NICU could occur due to antibiotic resistant strains or persistent environmental sources in NICU. When these outbreaks are happen, epidemiological analysis must be performed to discover the nosocomial sources and clarify the nature of the outbreaks strains. We conducted a molecular epidemiological study to recognize sources and natures of the repeated K. pneumoniae infections in our NICU from July to November 1997.
METHODS
Fourteen clinical specimens isolated from K. pneumoniae infected newborn infants and 2 environmental K. pneumoniae strains isolated from surveillance cultures were studied. To establish the epidemiological analysis, we used field inversion gel electrophoresis (FIGE) for genomic DNA typing, and plasmid DNA typing. Also, an antibiogram was obtained from susceptibility tests of isolated K. pneumoniae.
RESULTS
The results of genomic DNA typing using FIGE and antibiogram showed 4 different patterns, and plasmid DNA typing analysis showed 9 different patterns. Twelve strains out of 14 clinical isolates were almost identical with the two environmental strains, when comparing the genotypic patterns. And these 12 identical strains of FIGE profile showed similar plasmid DNA patterns. The strains could be classified into 5 different types.
CONCLUSION
Plasmid DNA typing method and FIGE have the power to discriminate in epidemiological analysis of K. pneumoniae outbreaks. Our study results suggest that repeated K. pneumoniae infections in NICU can be caused by clusters of K. pneumoniae from environmental sources.