An original case of<i>Francisella</i>tularensis subsp.<i>holarctica</i>bacteremia after a near-drowning accident

Ughetto, E.; Héry-Arnaud, Geneviève; Cariou, Marie-Estelle; Pelloux, Isabelle; Maurin, Max; Caillon, Jocelyne; Moreau, P.; Ygout, J.-F.; Corvec, Stéphane

doi:10.3109/23744235.2015.1028099

Cited by 14 publications

(12 citation statements)

References 12 publications

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“…in water sources is likely given the existence of waterborne cases of tularemia [5][6][7][9][10][11] and the observed acquisition of F. tularensis subsp. holarctica (Type B) during the aquatic life cycle of the mosquito vector [15,16].…”

Section: Discussionmentioning

confidence: 99%

Enhanced survival but not amplification of Francisella spp. in the presence of free-living amoebae

Buse

Schaefer

Rice

2016

Acta Microbiologica et Immunologica Hungarica

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Transmission of Francisella tularensis, the etiologic agent of tularemia, has been associated with various water sources. Survival of many waterborne pathogens within free-living amoeba (FLA) is well documented; however, the role of amoebae in the environmental persistence of F. tularensis is unclear. In this study, axenic FLA cultures of Acanthamoeba castellanii, Acanthamoeba polyphaga, and Vermamoeba vermiformis were each inoculated with virulent strains of F. tularensis (Types A and B), the attenuated live vaccine strain, and Francisella novicida. Experimental parameters included low and high multiplicity of infection and incubation temperatures of 25 and 30°C for 0-10 days. Francisella spp. survival was enhanced by the presence of FLA; however, bacterial growth and protozoa infectivity were not observed. In contrast, coinfections of A. polyphaga and Legionella pneumophila, used as an amoeba pathogen control, resulted in bacterial proliferation, cytopathic effects, and amoebal lysis. Collectively, even though short-term incubation with FLA was beneficial, the long-term effects on Francisella survival are unknown, especially given the expenditure of available amoebal derived nutrients and the fastidious nature of Francisella spp. These factors have clear implications for the role of FLA in Francisella environmental persistence.

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Section: Discussionmentioning

confidence: 99%

Enhanced survival but not amplification of Francisella spp. in the presence of free-living amoebae

Buse

Schaefer

Rice

2016

Acta Microbiologica et Immunologica Hungarica

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“…holarctica strain, a Type B biovar I, referred to as CHUGA-Ft6. This strain was isolated from a blood sample from a French patient suffering from a typhoidal form of tularaemia 19 . Interestingly, comparing FtFur to Fur from Escherichia coli (EcFur), Pseudomonas aeruginosa (PaFur), Legionella pneumophila (the agent of legionellosis, LpFur) and Yersinia pestis (the agent of plague, YpFur), we have evidenced that these proteins can be discriminated by their quaternary structure in solution 20 .…”

Section: Introductionmentioning

confidence: 99%

Structural and functional studies of the metalloregulator Fur identify a promoter-binding mechanism and its role in Francisella tularensis virulence

et al. 2018

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Francisella tularensis is a Gram-negative bacterium causing tularaemia. Classified as possible bioterrorism agent, it may be transmitted to humans via animal infection or inhalation leading to severe pneumonia. Its virulence is related to iron homeostasis involving siderophore biosynthesis directly controlled at the transcription level by the ferric uptake regulator Fur, as presented here together with the first crystal structure of the tetrameric F. tularensis Fur in the presence of its physiological cofactor, Fe2+. Through structural, biophysical, biochemical and modelling studies, we show that promoter sequences of F. tularensis containing Fur boxes enable this tetrameric protein to bind them by splitting it into two dimers. Furthermore, the critical role of F. tularensis Fur in virulence and pathogenesis is demonstrated with a fur-deleted mutant showing an attenuated virulence in macrophage-like cells and mice. Together, our study suggests that Fur is an attractive target of new antibiotics that attenuate the virulence of F. tularensis.

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“…In the past, the isolation of F. tularensis from the blood of infected patients has rarely been documented, possibly due to the poor sensitivity of blood culturing systems or the occurrence of bacteremia in the acute stages of infection ( Pittman et al, 1977 ). However, the number of reported tularemia bacteremia cases has increased with the use of improved blood culture isolation systems ( Reary and Klotz, 1988 ), and in recent years, more cases of tularemia bacteremia have been reported in the literature ( Haristoy et al, 2003 ; Sarria et al, 2003 ; Khoury et al, 2005 ; Fritzsch and Splettstoesser, 2010 ; Mohamed et al, 2012 ; Karagoz et al, 2013 ; Larssen et al, 2014 ; Nirkhiwale et al, 2015 ; Ughetto et al, 2015 ; Briere et al, 2016 ). Furthermore, studies have reported bacteremia in mice infected intranasally with F. tularensis LVS 48 h post-infection ( Chiavolini et al, 2008 ).…”

Section: Introductionmentioning

confidence: 99%

Isolation of Francisella tularensis and Yersinia pestis from Blood Cultures by Plasma Purification and Immunomagnetic Separation Accelerates Antibiotic Susceptibility Determination

et al. 2017

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The early symptoms of tularemia and plague, which are caused by Francisella tularensis and Yersinia pestis infection, respectively, are common to other illnesses, resulting in a low index of suspicion among clinicians. Moreover, because these diseases can be treated only with antibiotics, rapid isolation of the bacteria and antibiotic susceptibility testing (AST) are preferable. Blood cultures of patients may serve as a source for bacteria isolation. However, due to the slow growth rates of F. tularensis and Y. pestis on solid media, isolation by plating blood culture samples on proper agar plates may require several days. Thus, improving the isolation procedure prior to antibiotic susceptibility determination is a major clinically relevant need. In this study, we developed a rapid, selective procedure for the isolation of F. tularensis and Y. pestis from blood cultures. We examined drop-plating and plasma purification followed by immunomagnetic separation (IMS) as alternative isolation methods. We determined that replacing the classical isolation method with drop-plating is advantageous with respect to time at the expense of specificity. Hence, we also examined isolation by IMS. Sub-localization of F. tularensis within blood cultures of infected mice has revealed that the majority of the bacteria are located within the extracellular fraction, in the plasma. Y. pestis also resides within the plasma. Therefore, the plasma fraction was isolated from blood cultures and subjected to an IMS procedure using polyclonal anti-F. tularensis live vaccine strain (LVS) or anti-Y. pestis antibodies conjugated to 50-nm nano-beads. The time required to reach an inoculum of sufficient bacteria for AST was shortest when using the plasma and IMSs for both bacteria, saving up to 2 days of incubation for F. tularensis and 1 day for Y. pestis. Our isolation procedure provides a proof of concept for the clinical relevance of rapid isolation for AST from F. tularensis- and Y. pestis-infected patients.

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An original case ofFrancisellatularensis subsp.holarcticabacteremia after a near-drowning accident

Cited by 14 publications

References 12 publications

Enhanced survival but not amplification of Francisella spp. in the presence of free-living amoebae

Enhanced survival but not amplification of Francisella spp. in the presence of free-living amoebae

Structural and functional studies of the metalloregulator Fur identify a promoter-binding mechanism and its role in Francisella tularensis virulence

Isolation of Francisella tularensis and Yersinia pestis from Blood Cultures by Plasma Purification and Immunomagnetic Separation Accelerates Antibiotic Susceptibility Determination

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