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A typical case of cross-acquisition? The importance of genotypic characterization of bacterial strains
M J Bonten1, C A Gaillard, F H van Tiel
1Department of Internal Medicine, University Hospital Maastricht, The Netherlands.
Abstract:
A 33-year-old trauma patient died of Serratia marcescens pneumonia and septic shock. Isolates from this patient were phenotypically identical to strains isolated from the only other intensive care unit patient colonized with S marcescens. Although cross-acquisition was suspected strongly, serotyping and plasmid analysis demonstrated that the isolates were genotypically different, underscoring the importance of genotypic characterization.
Insights
A trauma patient died from Serratia marcescens pneumonia. Although isolates appeared identical, genetic analysis revealed they were different strains, highlighting the need for genotypic identification in infection control.
Area of Science:
- Infectious Diseases
- Microbiology
- Critical Care Medicine
Background:
- Serratia marcescens is an opportunistic pathogen frequently associated with hospital-acquired infections.
- Intensive care units (ICUs) are high-risk environments for the transmission of multidrug-resistant organisms.
- Pneumonia and septic shock are severe complications that can arise from S. marcescens infections.
Observation:
- A fatal case of Serratia marcescens pneumonia and septic shock occurred in a 33-year-old trauma patient.
- Phenotypically similar S. marcescens isolates were recovered from another ICU patient colonized with the same species.
- Initial suspicion pointed towards cross-acquisition between the two patients within the ICU setting.
Findings:
- Serotyping and plasmid analysis revealed genotypic differences between the S. marcescens isolates from the two patients.
- Despite phenotypic similarities, the isolates were not identical, suggesting independent acquisition or distinct strains.
- This genetic distinction challenges the initial assumption of direct cross-transmission based solely on phenotypic characteristics.
Implications:
- Genotypic characterization is crucial for accurately tracing the source and transmission pathways of bacterial infections.
- Relying solely on phenotypic methods may lead to misinterpretations in infection control and outbreak investigations.
- Enhanced molecular typing techniques are essential for robust epidemiological surveillance and effective prevention of healthcare-associated infections.