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Genotypic study of Citrobacter koseri, an emergent platelet contaminant since 2012 in France
Audrey Emery1, Nadine Marpaux2, Christian Naegelen2
1Hygiène Hospitalière, Centre Hospitalier Universitaire, Besançon, France.
Background:
Transfusion-transmitted bacterial infection is a rare occurrence but the most feared complication in transfusion practices. Between 2012 and 2017, five cases of platelet concentrates (PCs) contaminated with the bacterial pathogen Citrobacter koseri (PC-Ck) have been reported in France, with two leading to the death of the recipients. We tested the possibilities of the emergence of a PC-specific clone of C. koseri (Ck) and of specific bacterial genes associated with PC contamination.
Study Design And Methods:
The phylogenetic network, based on a homemade Ck core genome scheme, inferred from the genomes of 20 worldwide Ck isolates unrelated to PC contamination taken as controls (U-Ck) and the genomes of the five PC-Ck, explored the clonal relationship between the genomes and evaluated the distribution of PC-Ck throughout the species. Along with this core genome multilocus sequence typing approach, a Ck pan genome has been used to seek genes specific to PC-Ck isolates.
Results:
Our genomic approach suggested that the population of C. koseri is nonclonal, although it also identified a cluster containing three PC-Ck and eight U-Ck. Indeed, the PC-Ck did not share any specific genes.
Conclusion:
The elevated incidence of PCs contaminated by C. koseri in France between 2012 and 2017 was not due to the dissemination of a clone. The determinants of the recent outbreaks of PC contamination with C. koseri are still unknown.
Insights
Transfusion-transmitted bacterial infections are a serious risk. A study found that recent Citrobacter koseri contamination of platelet concentrates in France was not caused by a specific bacterial clone.
Area of Science:
- Microbiology
- Genomics
- Infectious Diseases
Background:
- Transfusion-transmitted bacterial infection is a rare but severe complication.
- Five cases of platelet concentrates (PCs) contaminated with Citrobacter koseri (Ck) were reported in France between 2012-2017, with two fatalities.
- The study investigated the potential emergence of a PC-specific Ck clone and associated genes.
Purpose of the Study:
- To determine if recent Citrobacter koseri contamination of platelet concentrates in France was linked to a specific bacterial clone.
- To identify potential bacterial genes associated with platelet concentrate contamination.
Main Methods:
- Genomic analysis using a core genome phylogenetic network of 20 unrelated Ck isolates and 5 PC-Ck isolates.
- Pan-genome analysis to identify genes specific to PC-Ck isolates.
- Core genome multilocus sequence typing (cgMLST) was employed.
Main Results:
- Genomic analysis indicated that Citrobacter koseri population is nonclonal.
- A cluster of three PC-Ck and eight unrelated Ck isolates was identified.
- No specific genes exclusively found in PC-Ck isolates were identified.
Conclusions:
- The increased incidence of C. koseri contaminated PCs in France was not due to the spread of a specific clone.
- The underlying causes of recent C. koseri platelet concentrate contamination outbreaks remain unknown.
