Intermittent bacteremia detected in an asymptomatic apheresis platelet donor with repeat positive culture forEscherichia coli: a case report

The Significance of Clinical Suspicion: From Pitting Edema to Streptococcus infantarius Endocarditis

As advancements in medicine progress, greater emphasis has been placed on laboratory values and imaging rather than the clinical picture. This, as a result, has led to a decline in the use of clinical history and physical examinations. In many instances, some details of the history are glossed over, and performing a physical examination has become more lackadaisical. Here, we would like to present a unique case of a patient who presented to the emergency department with only pitting edema that was worsening for the past few weeks. Vitals were noted to be unremarkable, and the rest of the physical examination only revealed mild ascites and a new heart murmur, which was not present in his previous documented clinic visits. Due to this concerning physical examination finding, a cardiology and hepatology workup was done. It was then revealed that the patient had severe aortic and mitral valve vegetation suggesting infective endocarditis with severe aortic insufficiency due to Streptococcus infantarius. Due to the bacterium being a member of the Streptococcus bovis species, a colonoscopy was done, which revealed multiple tubular adenomas. A discussion regarding S. infantarius will be held, as well as the unique details of tubular adenomas causing S. infantarius bacteremia. The importance of physical examination and clinical suspicion will also be discussed.

Two cases of Streptococcus dysgalactiae subspecies equisimilis infection transmitted through transfusion of platelet concentrate derived from separate blood donations by the same donor

BACKGROUND

Transfusion-transmitted bacterial infections (TTBIs) in Japan have been largely prevented due to a short shelf life of 3.5 days after blood collection for platelet concentrate (PC) and washed PCs (WPCs; PC in which 95% plasma is replaced by platelet additive solution).

CASE PRESENTATION

Case 1: In January 2018, a woman in her 50s with aplastic anaemia who received WPC transfusion and developed a fever the next day and Streptococcus dysgalactiae subspecies equisimilis (SDSE) was detected in the residual WPC. Case 2: In May 2018, a man in his 60s with a haematologic malignancy who received PC transfusion and developed chills during the transfusion. SDSE was detected in the patient's blood and residual PC. The contaminated platelet products were both manufactured from blood donated by the same donor. The multi-locus sequencing typing revealed that SDSE detected in case 1 was identical to that from case 2; however, whole blood subsequently obtained from the donor was culture negative.

CONCLUSION

WPC and PC produced from two blood donated 106 days apart by the same donor were contaminated with SDSE of the same strain and both caused TTBIs. Safety measures should be considered regarding blood collection from a donor with a history of bacterial contamination.

Genotypic and phenotypic characteristics of Escherichia coli involved in transfusion-transmitted bacterial infections: implications for preventive strategies

BACKGROUND

Transfusion-transmitted bacterial infections (TTBIs) are the main residual infectious complications of transfusions. Escherichia coli and platelet (PLT) concentrates may be epidemiologically associated, leading to severe, if not lethal, TTBIs. We investigated the genotypic and phenotypic reasons for this clinically deleterious combination.

STUDY DESIGN AND METHODS

We investigated a French national E. coli strain collection related to six independent episodes of TTBIs. Their phenotypic characterizations included antibiotic susceptibility testing, growth testing under different culture conditions, serum survival assays, and virulence in a sepsis mouse model. Their genotypic characterizations included polymerase chain reaction phylotyping, whole genome sequencing, and a subsequent in silico analysis.

RESULTS

We highlighted a selection process of highly extraintestinal virulent strains, mainly belonging to the B2 phylogroup, adapted to the hostile environment (high citrate concentration and a bactericidal serum effect) of apheresis-collected platelet concentrates (PCs). Compared to controls, the E. coli TTBI strains grew faster in the PCs due to a superior ability to capture iron. The in vitro growth performances were highly compatible with blood-derived product real-life conditions, including storage conditions and delays. The consistent serum resistance of TTBI strains promotes their survival in both the donor's and the receiver's blood and in the PCs.

CONCLUSION

This study pointed out that E. coli strains responsible for TTBI exhibit very specific traits. They belong to the extraintestinal pathogenic phylogroups and have a high intrinsic virulence. They can be resistant to complement, capture iron, and grow in the apheresis-collected PCs. These findings therefore support the reinforcement of the postdonation information.

Metagenomics in pooled plasma, with identification of potential emerging infectious pathogens

BACKGROUND

Many emerging infectious pathogens are well known for existing in healthy blood donors and could be transmitted via blood transfusion or plasma derivatives usage. Therefore, there is an urgent need to discover the pathogens in qualified blood donation to avoid potential threats to blood safety.

STUDY DESIGN AND METHODS

The objective of this study was to investigate the microbiome that existed in pooled plasma from different manufacturers in Chengdu and Guiyang. Random polymerase chain reaction, large-scale clone sequencing, and bioinformatics were used to investigate the metagenomics and microbiome structure of pooled plasma. Among detected microbiomes, potential pathogens were subsequently identified.

RESULT

After host DNA cleaning, 551 clones were classified as bacteria; 88 clones were classified as viruses, and four clones were considered to be parasites, respectively. Thirteen kinds of bacteria and two kinds of parasites that might potentially threaten blood safety were identified along with six kinds of nonpathogenic viruses. The infection status of one identified pathogen Coxiella burnetii was evaluated in 1638 plasma samples. The reactive rate of immunoglobulin (Ig)G1 was 1.10% (18/1638), the reactive rate of IgG2 was 0.85% (14/1638), and the reactive rate of IgM was 0.98% (16/1638).

CONCLUSION

Some pathogens that were already considered as threats to blood safety were discovered in those pooled plasma such as C. burnetii, Orientia tsutsugamushi, and Plasmodium sp. As a result, we should initiate some specific tests in the endemic area on plasma donors to enhance the blood safety in China.