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Partial characterization of Serratia marcescens nosocomial strains
V R Coria-Jiménez1, L Villa-Tanaka, C Ortíz-Torres
1Laboratorio de Investigación en Microbiologia, Escuela Nacional de Ciencias Biológicas, Instituto Politénico Nacional, México, D.F.
Abstract:
A nosocomial infection outbreak occurred in the Intensive Care Unit (ICU) of the Instituto Nacional de Pediatría (INP) in México City, during the months of March, April and May in 1988 Serratia marcescens was isolated as the etiological agent for this epidemic. Up to date, the source of contamination, the spreading and the pathogenic mechanisms which were involved in this outbreak remain unknown. In order to study the dynamics of the bacterial population involved in this outbreak, all strains of nosocomial S. marcescens isolated during 1988 were collected and studied. Eighty nosocomial strains were analysed. For this purpose we used four different markers: antibiotic susceptibility, presence of plasmids, exoenzyme production and pigment synthesis from a precursor. Using these markers, we were able to establish that five subpopulations of bacteria were present during the ICU outbreak, and that one of these subpopulations, VIII-A, was the most frequently isolated. A short time after this outbreak, we obtained S. marcescens isolates with similar properties which proceeded from other hospital units, suggesting intrahospital dissemination of the strain in question. We believe that, eventually, this study will allow us to establish bacterial spreading models within our institution.
Insights
A Serratia marcescens outbreak in a pediatric Intensive Care Unit (ICU) revealed five bacterial subpopulations. One subpopulation, VIII-A, was most common, indicating potential intrahospital spread of this nosocomial pathogen.
Area of Science:
- Microbiology
- Infectious Diseases
- Hospital Epidemiology
Background:
- Nosocomial infections pose significant risks in healthcare settings.
- Serratia marcescens is a known opportunistic pathogen causing hospital-acquired infections.
- An outbreak of Serratia marcescens occurred in the Intensive Care Unit (ICU) of the Instituto Nacional de Pediatría (INP) in Mexico City in 1988.
Purpose of the Study:
- To investigate the dynamics of the Serratia marcescens bacterial population during the 1988 nosocomial outbreak.
- To characterize the etiological agent and understand its spreading patterns within the institution.
Main Methods:
- Analysis of 80 nosocomial Serratia marcescens strains isolated in 1988.
- Utilized four markers: antibiotic susceptibility, plasmid presence, exoenzyme production, and pigment synthesis.
- Epidemiological and microbiological strain typing techniques were employed.
Main Results:
- Five distinct bacterial subpopulations of Serratia marcescens were identified during the ICU outbreak.
- Subpopulation VIII-A was the most frequently isolated strain.
- Similar Serratia marcescens strains were later isolated from other hospital units, suggesting intrahospital dissemination.
Conclusions:
- The study identified diverse Serratia marcescens subpopulations involved in the nosocomial outbreak.
- Evidence suggests the potential for intrahospital spread of specific Serratia marcescens strains.
- Findings contribute to establishing bacterial spreading models within healthcare institutions.