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Molecular epidemiology of sequential nursery epidemics caused by multiresistant Klebsiella pneumoniae
Abstract:
Multiresistant Klebsiella pneumoniae has been endemic among adult patients at Vanderbilt University Medical Center since 1973. Multiresistant K. pneumoniae was absent from pediatric wards until 1979, when it produced an epidemic in the intensive care nursery followed a year later by a second epidemic involving K. pneumoniae of the same serotype. The 105 megadalton (Md) conjugative resistance (R) plasmid (pCER7999) transferring multiple antibiotic resistance in the adult, endemic strain was found also in isolates from the first epidemic in the intensive care nursery. The mother of a child in the nursery harbored E. coli containing the same 105 Md R plasmid. The second epidemic also involved a 105 Md conjugative R plasmid, which, however, by molecular analysis was different from the first epidemic plasmid and also pCER7999. Thus, the second epidemic resulted from the introduction of a new, unrelated multiresistant K. pneumoniae strain. Contemporary hospital epidemiology often requires the application of molecular techniques for an understanding of nosocomial infections.
Insights
Multiresistant Klebsiella pneumoniae spread to a pediatric intensive care unit via a shared 105 megadalton (Md) plasmid. A second epidemic involved a new strain, highlighting the need for molecular tracking in hospital infections.
Area of Science:
- Microbiology
- Epidemiology
- Molecular Biology
Background:
- Multiresistant Klebsiella pneumoniae has been endemic in adult patients since 1973.
- The pathogen was absent from pediatric wards until 1979.
- An epidemic occurred in the intensive care nursery in 1979, followed by a second epidemic in 1980.
Purpose of the Study:
- To investigate the molecular epidemiology of multiresistant Klebsiella pneumoniae outbreaks in a pediatric intensive care nursery.
- To determine the role of plasmids in the transmission of antibiotic resistance.
Main Methods:
- Plasmid analysis (105 megadalton R plasmid pCER7999).
- Molecular typing of Klebsiella pneumoniae strains.
- Epidemiological investigation of nosocomial infections.
Main Results:
- The 105 megadalton (Md) conjugative resistance (R) plasmid (pCER7999) was identified in the adult endemic strain and the first nursery epidemic isolates.
- The mother of an infant in the nursery harbored E. coli with the same 105 Md R plasmid, suggesting a transmission route.
- The second epidemic involved a different 105 Md conjugative R plasmid, indicating the introduction of a new Klebsiella pneumoniae strain.
Conclusions:
- The first pediatric intensive care nursery epidemic was linked to the endemic adult strain via a shared R plasmid.
- The second epidemic resulted from the introduction of a distinct, unrelated multiresistant Klebsiella pneumoniae strain.
- Molecular techniques are crucial for understanding and controlling nosocomial infections caused by multiresistant bacteria.