Coagulation disorders in patients with severe leptospirosis are associated with severe bleeding and mortality

ErpY-like Protein Interaction with Host Thrombin and Fibrinogen Intervenes the Plasma Coagulation through Extrinsic and Intrinsic Pathways

The survival and proliferation of pathogenic Leptospira within a host are complex phenomena that require careful consideration. The ErpY-like lipoprotein, found on the outer membrane surface of Leptospira, plays a crucial role in enhancing the bacterium's pathogenicity. The rErpY-like protein, in its recombinant form, contributes significantly to spirochete virulence by interacting with various host factors, including host complement regulators. This interaction facilitates the bacterium's evasion of the host complement system, thereby augmenting its overall pathogenicity. The rErpY-like protein exhibits a robust binding affinity to soluble fibrinogen, a vital component of the host coagulation system. In this study, we demonstrate that the rErpY-like protein intervenes in the clotting process of the platelet-poor citrated plasma of bovines and humans in a concentration-dependent manner. It significantly reduces clot density, alters the viscoelastic properties of the clot, and diminishes the average clotting rate in plasma. Furthermore, the ErpY-like protein inhibits thrombin-catalyzed fibrin formation in a dose-dependent manner and exhibits saturable binding to thrombin, suggesting its significant role in leptospiral infection. These findings provide compelling evidence for the anticoagulant effect of the ErpY-like lipoprotein and its significant role in leptospiral infection.

In silico analysis and functional characterization of a leucine-rich repeat protein of Leptospira interrogans

Pathogenic spirochetes of the genus Leptospira are the causative agent of leptospirosis, a widely disseminated zoonosis that affects humans and animals. The ability of leptospires to quickly cross host barriers causing infection is not yet fully understood. Thus, understanding the mechanisms of pathogenicity is important to combat leptospiral infection. Outer membrane proteins are interesting targets to study as they are able to interact with host molecules. Proteins containing leucine-rich repeat (LRR) domains are characterized by the presence of multiple regions containing leucine residues and they have putative functions related to host-pathogen interactions. Hence, the present study aimed to clone and express the recombinant protein encoded by the LIC11098 gene, an LRR protein of L. interrogans serovar Copenhageni. In silico analyses predicted that the target protein is conserved among pathogenic strains of Leptospira, having a signal peptide and multiple LRR domains. The DNA sequence encoding the LRR protein was cloned in frame into the pAE vector, expressed without mutations in Escherichia coli and purified by His-tag chromatography. Circular dichroism (CD) spectrum showed that the recombinant protein was predominantly composed of β-sheets. A dose-dependent interaction was observed with cellular and plasma fibronectins, laminin and the complement system component C9, suggesting a possible role of the protein encoded by LIC11098 gene at the initial stages of infection.

An Insight Into Various Manifestations of Leptospirosis: A Unique Case Series From a State in Eastern India

BACKGROUND

Leptospirosis presents with highly variable clinical manifestations affecting different organ systems in different individuals. The presentation ranges from an asymptomatic or mild disease to a severe disease associated with multiorgan failure and higher mortality. Leptospirosis is highly underreported due to a lack of diagnostic modalities and less suspicion among clinicians.

METHODOLOGY

We present this single-center retrospective case series of 12 cases, which include various common and uncommon scenarios by which the disease can present and can be missed due to lack of suspicion. The study contains individual patient characteristics including demographic, laboratory, clinical, and treatment data. The association between these variables and mortality was analyzed using p-values and results were described. A p-value of<0.05 was considered statistically significant.

RESULTS

A total of 12 cases were included in the study. The male-to-female ratio was 3:1. The mean age was higher (37.75±9.81 years) in cases who died than those who recovered (34.25±14.09). Factors like history of alcoholism, presence of chronic liver disease (CLD), jaundice, acute renal failure, requirement of dialysis, and requirement of intensive care were significantly associated with increased risk of death (odds ratio >1, p-value <0.05). The most common symptom of presentation was fever in 11 (91.66%) cases. Jaundice and renal failure were significantly associated with death (odds ratio 1.2, p-value 0.04). The requirement of intensive care treatment (odds ratio 2.1, p-value 0.05) and dialysis (odds ratio 39.66, p-value 0.03) were also significantly associated with death. The percentage of death was lower in the group of patients who received combination antibiotic therapy.

CONCLUSION

Leptospirosis has varied presentations in different individuals and the diagnosis can be missed due to lack of specific signs and symptoms. Severe diseases involving multiple organs and preexisting comorbidities are associated with higher mortality rates. Timely diagnosis and treatment are necessary to reduce mortality and increase survival.

Severe Jarisch-Herxheimer Reaction (JHR) in a leptospirosis patient: A case report

Leptospirosis is a zoonosis that is related to potential respiratory, renal, neurological, and cardiovascular failure. At present, antibiotics are the recommended treatment, but due to the underlying cause of the disease, they may induce the Jarisch-Herxheimer reaction (JHR) within 24 hours. At the same time, we speculate that JHR may aggravate the natural course of leptospirosis. Considering that there are few available reports on this event, we will share a case of pulmonary hemorrhagic leptospirosis, where antibiotic treatment is suspected to have triggered the JHR. This report is expected to improve clinical attention to the relationship between leptospirosis and JHR.

In silico prediction of molecular mechanisms of toxicity mediated by the leptospiral PF07598 gene family-encoded virulence-modifying proteins

Mechanisms of leptospirosis pathogenesis remain unclear despite the identification of a number of potential leptospiral virulence factors. We recently demonstrated potential mechanisms by which the virulence-modifying (VM) proteins-defined as containing a Domain of Unknown function (DUF1561), encoded by the PF07598 gene family-found only in group 1 pathogenic Leptospira-might mediate the clinical pathogenesis of leptospirosis. VM proteins belongs to classical AB toxin paradigm though have a unique AB domain architecture, unlike other AB toxins such as diphtheria toxin, pertussis toxin, shiga toxin, or ricin toxin which are typically encoded by two or more genes and self-assembled into a multi-domain holotoxin. Leptospiral VM proteins are secreted R-type lectin domain-containing exotoxins with discrete N-terminal ricin B-like domains involved in host cell surface binding, and a C-terminal DNase/toxin domain. Here we use the artificial intelligence-based AlphaFold algorithm and other computational tools to predict and elaborate on details of the VM protein structure-function relationship. Comparative AlphaFold and CD-spectroscopy defined the consistent secondary structure (Helix and ß-sheet) content, and the stability of the functional domains were further supported by molecular dynamics simulation. VM proteins comprises distinctive lectic family (QxW)₃ motifs, the Mycoplasma CARDS toxin (D3 domain, aromatic patches), C-terminal similarity with mammalian DNase I. In-silico study proposed that Gln412, Gln523, His533, Thr59 are the high binding energy or ligand binding residues plausibly anticipates in the functional activities. Divalent cation (Mg⁺²-Gln412) and phosphate ion (PO₄]^-3-Arg615) interaction further supports the functional activities driven by C-terminal domain. Computation-driven structure-function studies of VM proteins will guide experimentation towards mechanistic understandings of leptospirosis pathogenesis, which underlie development of new therapeutic and preventive measures for this devastating disease.

Case report: Leptospirosis with multi-organ failure complicated by massive upper gastrointestinal bleeding in a non-epidemic setting with successful management

Leptospirosis is a common zoonotic disease with a wide range of clinical manifestations, specifically in tropical regions. Weil's disease is considered a severe form of leptospirosis seen in a minority of leptospirosis cases with considerable mortality. These patients typically developed the triad of acute renal injury, jaundice, and hemorrhages. Herein, we reported a case of a 28-year-old male transferred to our intensive care unit due to severe leptospirosis with diffuse alveolar hemorrhage, cholestatic jaundice, acute respiratory distress, and renal injury. The patient was successfully managed with appropriate antimicrobial treatment and other supportive management, including mechanical ventilation, vasopressor, and corticosteroid therapy. Ten days after admission, the patient unexpectedly developed uncontrollable massive upper gastrointestinal bleeding, requiring immediate surgical interventions. Splenectomy, partial gastrectomy, along with gastro-esophageal anastomosis were performed. Following a prolonged hospitalization, the patient fully recovered and was discharged home with excellent clinical outcomes. This fulminant leptospirosis case described here should assist in informing medical professionals of the clinical significance of this serious, occasionally fatal illness. Moreover, leptospirosis should be considered in any location wherever risk factors are present, not just in epidemic and tropical areas. In this case, we pointed out that serious complications of leptospirosis, such as hemorrhage, may happen despite their rarity. In such cases, adopting an integrated multidisciplinary team approach is essential to prevent complications and reduce mortality.

Weil's Disease-Immunopathogenesis, Multiple Organ Failure, and Potential Role of Gut Microbiota

Leptospirosis is an important zoonotic disease, causing about 60,000 deaths annually. In this review, we have described in detail the immunopathogenesis of leptospirosis, the influence of cytokines, genetic susceptibility on the course of the disease, and the evasion of the immune response. These data are combined with information about immunological and pathomorphological changes in the kidneys, liver, and lungs, which are most affected by Weil's disease. The review also suggests a possible role of the gut microbiota in the clinical course of leptospirosis, the main mechanisms of the influence of gut dysbiosis on damage in the liver, kidneys, and lungs through several axes, i.e., gut-liver, gut-kidney, and gut-lungs. Modulation of gut microbiota by probiotics and/or fecal microbiota transplantation in leptospirosis may become an important area of scientific research.

Determinants of prolonged hospitalization and mortality among leptospirosis patients attending tertiary care hospitals in northeastern state in peninsular Malaysia: A cross sectional retrospective analysis

Background

Leptospirosis is the most common anthropozoonosis worldwide and imposes a major public health problem in many tropical countries. It is a leading cause of disease burden in form of mortality, morbidity and hospital admission. Identifying patients at high risk for mortality or for prolonged hospitalization may save lives and preserve economy. The aim of the current study is to identify significant factors associated with disease mortality and prolonged hospitalization.

Design

Cress-sectional retrospective study.

Settings

Tertiary care teaching hospitals in Kelantan, Peninsular Malaysia.

Participants

Adult patients proven to have leptospirosis depending on IgM ELISA were classified into two classes depending on prolonged hospitalization (>7 days or ≤ 7 days) and mortality (fatal cases or non-fatal cases). Patients' clinico-laboratory data were compared according to these two outcomes using the appropriate statistical test.

Results

Of the 525 patients enrolled, 136 (25.9%) had prolonged hospitalization. The mean length of stay was 6.77 ± 5.68 days. Logistic regression analysis identified acute kidney injury (AKI) (OR 2.3), Jaundice (OR 2.7), elevated alanine aminotransferase (ALT) (OR 2), and prolonged prothrombin time (PT) (OR 1.9) independently associated with prolonged hospitalization. Case fatality rate was 6.48% and around one third of fatal cases had prolonged hospitalization of more than seven days. Factors associated with leptospirosis mortality included age >40 years (p < 0.001), patients presented with tachypnea (p = 0.002), pulmonary infiltrate (p < 0.001), T-wave changes (p < 0.001), atrial fibrillation (p = 0.013), conducting abnormality (p < 0.001), chronic kidney diseases (p < 0.001), multiple organ dysfunctions (p < 0.0010), respiratory failure (p < 0.001), pneumonia (p < 0.001), sepsis (p = 0.004), low venous PH (p = 0.042), AKI (P < 0.001), elevated AST (p < 0.001) or ALT (p = 0.004), hypoalbuminemia (p < 0.001), rhabdomyolysis (p < 0.001), severe thrombocytopenia (p = 0.042), prolonged PT (p < 0.001) or prolonged aPTT (p < 0.017).

Conclusions

Significant proportion of leptospirosis patients (25.9%) had prolonged hospital stay and less proportion died (6.48%). Early identifying patients with factors associated with prolonged hospitalization and death will positively impact practitioners' decisions regarding the proper and fast course of management including ICU admission.

Role of Diagnostics in Epidemiology, Management, Surveillance, and Control of Leptospirosis

A One Health approach to the epidemiology, management, surveillance, and control of leptospirosis relies on accessible and accurate diagnostics that can be applied to humans and companion animals and livestock. Diagnosis should be multifaceted and take into account exposure risk, clinical presentation, and multiple direct and/or indirect diagnostic approaches. Methods of direct detection of Leptospira spp. include culture, histopathology and immunostaining of tissues or clinical specimens, and nucleic acid amplification tests (NAATs). Indirect serologic methods to detect leptospiral antibodies include the microscopic agglutination test (MAT), the enzyme-linked immunosorbent assay (ELISA), and lateral flow methods. Rapid diagnostics that can be applied at the point-of-care; NAAT and lateral flow serologic tests are essential for management of acute infection and control of outbreaks. Culture is essential to an understanding of regional knowledge of circulating strains, and we discuss recent improvements in methods for cultivation, genomic sequencing, and serotyping. We review the limitations of NAATs, MAT, and other diagnostic approaches in the context of our expanding understanding of the diversity of pathogenic Leptospira spp. Novel approaches are needed, such as loop mediated isothermal amplification (LAMP) and clustered regularly interspaced short palindromic repeats (CRISPR)-based approaches to leptospiral nucleic acid detection.

Pituitary apoplexy and panhypopituitarism following acute leptospirosis

Leptospirosis is a common tropical febrile illness which may manifest with the hepatorenal syndrome and systemic hemorrhagic manifestations. Pituitary apoplexy is a rare but life-threatening condition characterized by a hemorrhage within the pituitary gland or a pituitary adenoma. Apoplexy is very rarely associated with some inducing events such as infectious diseases such as dengue hemorrhagic fever, Hantaan virus, Puumala virus have also been reported to cause pituitary apoplexy. We present the first case of pituitary apoplexy in a patient who was being treated for leptospirosis and discuss the possible mechanisms of apoplexy in the scenario presented. We also review other reports of infectious causes that may result in pituitary apoplexy.

A Review on Host-Leptospira Interactions: What We Know and Future Expectations

Leptospirosis is a widespread zoonosis caused by pathogenic Leptospira spp. It is considered a neglected infectious disease of human and veterinary concern. Our group has been investigating proteins annotated as hypothetical, predicted to be located on the leptospiral surface. Because of their location, these proteins may have the ability to interact with various host components, which could allow establishment of the infection. These proteins act as adherence factors by binding to host receptor molecules, such as the extracellular matrix (ECM) components laminin and glycosaminoglycans to help bacterial colonization. Leptospira also interacts with the host fibrinolytic system, which has been demonstrated to be a powerful tool for invasion mechanisms. The interaction with fibrinogen and thrombin has been shown to reduce fibrin clot formation. Additionally, the degradation of coagulation cascade components by secreted proteases or by acquired surface plasmin could also play a role in reducing clot formation, hence facilitating dissemination during infection. Interaction with host complement system regulators also plays a role in helping bacteria to evade the immune system, facilitating invasion. Interaction of Leptospira to cell receptors, such as cadherins, can contribute to investigate molecules that participate in virulence. To achieve a better understanding of the host-pathogen interaction, leptospiral mutagenesis tools have been developed and explored. This work presents several proteins that mediate binding to components of the ECM, plasma, components of the complement system and cells, to gather research achievements that can be helpful in better understanding the mechanisms of leptospiral-host interactions and discuss genetic manipulation for Leptospira spp. aimed at protein function validation.

Unhappy Triad: Infection with Leptospira spp. Escherichia coli and Bacteroides uniformis Associated with an Unusual Manifestation of Portal Vein Thrombosis

Portal vein thrombosis (PVT) is a rare disease with an incidence of 0.7/100,000 inhabitants per year. Septic PVT (pylephlebitis) usually occurs secondary to infection in the anatomic region drained by the portal venous system. We report on a 76-year-old German male who was admitted with a history of recurrent fever and acute renal failure. Blood cultures taken on admission showed Escherichia coli, as well as Bacteroides uniformis after an extended incubation period of 90 h. In addition, infection with Leptospira spp. was diagnosed serologically. Computerized tomography of the abdomen revealed an extensive PVT along with signs of colonic diverticulitis. Symptoms resolved under prolonged antimicrobial therapy with beta-lactams and adequate heparinization. A myeloproliferative disorder could be excluded. There was no evidence of an underlying coagulation disorder. Imaging controls showed an almost complete resolution of the PVT after 6 months of anticoagulation therapy. To the best of our knowledge, this is the first report of such an “unhappy triad,” which includes atypical manifestations of leptospirosis and involvement of other intestinal bacteria.

A Novel Leptospira interrogans Protein LIC13086 Inhibits Fibrin Clot Formation and Interacts With Host Components

Leptospirosis is a neglected zoonosis, caused by pathogenic spirochetes bacteria of the genus Leptospira. The molecular mechanisms of leptospirosis infection are complex, and it is becoming clear that leptospires express several functionally redundant proteins to invade, disseminate, and escape the host’s immune response. Here, we describe a novel leptospiral protein encoded by the gene LIC13086 as an outer membrane protein. The recombinant protein LIC13086 can interact with the extracellular matrix component laminin and bind plasminogen, thus possibly participating during the adhesion process and dissemination. Also, by interacting with fibrinogen and plasma fibronectin, the protein LIC13086 probably has an inhibitory effect in the fibrin clot formation during the infection process. The newly characterized protein can also bind molecules of the complement system and the regulator C4BP and, thus, might have a role in the evasion mechanism of Leptospira. Taken together, our results suggest that the protein LIC13086 may have a multifunctional role in leptospiral pathogenesis, participating in host invasion, dissemination, and immune evasion processes.

Jaundice and Thrombocytopenia in an acute abdomen with concurrent Appendicitis and spontaneous Rectal perforation: An unusual presentation of human leptospirosis

Leptospirosis, a bacterial infection attributed to the group leptospira, remains a globally emerging public-health issue in many endemic tropical, subtropical and temperate zones of the world. The burden is expected to inflate with population shifts related to violent storms and urban floods leading to poor housing and inadequate sanitation. Leptospirosis may mimic other illnesses such as influenza, dengue fever, typhoid and malaria due to its myriad presentation ranging from a mild, self-limiting febrile illness to hepatorenal dysfunction, myocarditis, pulmonary haemorrhage, meningitis, optic neuritis and rhabdomyolysis. The classical gastrointestinal manifestation of leptospirosis without hepatorenal dysfunction (Weil's disease) is a rare entity. We report a rare presentation of concurrent appendicitis and rectal perforation in a patient, whose jaundice and thrombocytopenia led to a suspicion of leptospirosis, confirmed by serology and fulfilment of parameters under the modified Faine's criteria. The patient was managed successfully and discharged in a stable condition.

Leptospiral Immunoglobulin-Like Domain Proteins: Roles in Virulence and Immunity

The virulence mechanisms required for infection and evasion of immunity by pathogenic Leptospira species remain poorly understood. A number of L. interrogans surface proteins have been discovered, lying at the interface between the pathogen and host. Among these proteins, the functional properties of the Lig (leptospiral immunoglobulin-like domain) proteins have been examined most thoroughly. LigA, LigB, and LigC contain a series of, 13, 12, and 12 closely related domains, respectively, each containing a bacterial immunoglobulin (Big) -like fold. The multidomain region forms a mostly elongated structure that exposes a large surface area. Leptospires wield the Lig proteins to promote interactions with a range of specific host proteins, including those that aid evasion of innate immune mechanisms. These diverse binding events mediate adhesion of L. interrogans to the extracellular matrix, inhibit hemostasis, and inactivate key complement proteins. These interactions may help L. interrogans overcome the physical, hematological, and immunological barriers that would otherwise prevent the spirochete from establishing a systemic infection. Despite significant differences in the affinities of the LigA and LigB proteins for host targets, their functions overlap during lethal infection of hamsters; virulence is lost only when both ligA and ligB transcription is knocked down simultaneously. Lig proteins have been shown to be promising vaccine antigens through evaluation of a variety of different adjuvant strategies. This review serves to summarize current knowledge of Lig protein roles in virulence and immunity and to identify directions needed to better understand the precise functions of the Lig proteins during infection.

Phagocyte Escape of Leptospira: The Role of TLRs and NLRs

The spirochetal bacteria Leptospira spp. are causative agents of leptospirosis, a globally neglected and reemerging zoonotic disease. Infection with these pathogens may lead to an acute and potentially fatal disease but also to chronic asymptomatic renal colonization. Both forms of disease demonstrate the ability of leptospires to evade the immune response of their hosts. In this review, we aim first to recapitulate the knowledge and explore the controversial data about the opsonization, recognition, intracellular survival, and killing of leptospires by scavenger cells, including platelets, neutrophils, macrophages, and dendritic cells. Second, we will summarize the known specificities of the recognition or escape of leptospire components (the so-called microbial-associated molecular patterns; MAMPs) by the pattern recognition receptors (PRRs) of the Toll-like and NOD-like families. These PRRs are expressed by phagocytes, and their stimulation by MAMPs triggers pro-inflammatory cytokine and chemokine production and bactericidal responses, such as antimicrobial peptide secretion and reactive oxygen species production. Finally, we will highlight recent studies suggesting that boosting or restoring phagocytic functions by treatments using agonists of the Toll-like or NOD receptors represents a novel prophylactic strategy and describe other potential therapeutic or vaccine strategies to combat leptospirosis.

Hemostatic derangement in leptospirosis: A prospective cross-sectional study

Context:

Coagulation abnormalities have been observed among leptospirosis patients. However, coagulopathy in severe leptospirosis has not been further characterized.

Aims:

The aim of this study was to evaluate conventional coagulation and rotational thromboelastometry (ROTEM^®) parameters in leptospirosis patients.

Settings and Design:

This prospective cross-sectional comparative study included patients presenting to a tertiary hospital in Sri Lanka with clinically and serologically confirmed leptospirosis (14 severe and 6 mild), dengue (6), sepsis (5), and 6 healthy individuals.

Subjects and Methods:

Blood samples were collected between the 3^rd and 10^th days of illness for prothrombin time (PT), activated partial thromboplastin time (aPTT), thrombin time (TT), fibrinogen, lupus anticoagulant, factors VII and VIII, D-dimer, platelet count, and ROTEM.

Statistical Analysis Used:

ANOVA post hoc comparison using Bonferroni was applied to compare groups.

Results:

PT and aPTT were prolonged in leptospirosis patients and were corrected with normal plasma. TT was not significantly prolonged in leptospirosis. Fibrinogen was significantly elevated in severe leptospirosis (P = 0.001) and sepsis (P = 0.001) compared with healthy controls and dengue. Thirty percent of leptospirosis patients had thrombocytopenia (17% in mild and 36% in severe). No significant differences were seen in inTEM clotting time (CT) and exTEM CT in leptospirosis when compared to the other three groups. inTEM clot formation time (CFT) and exTEM CFT in dengue were significantly higher compared to severe (P = 0.001) and mild (P = 0.005) leptospirosis. inTEM maximum clot firmness (MCF) (P = 0.001) and exTEM MCF (P = 0.001) were significantly lower in dengue than in leptospirosis. Only one patient with leptospirosis had bleeding manifestations.

Conclusions:

Abnormalities in conventional coagulation parameters occur in leptospirosis. However, ROTEM parameters in leptospirosis are not significantly altered.

The interplay between host haemostatic systems and Leptospira spp. infections

Hemostasis is a defence mechanism that protects the integrity of the vascular system and is comprised of the coagulation cascade, fibrinolysis, platelet aggregation, and vascular endothelium. Besides the primary function in preserving the vascular integrity, the haemostatic system cooperates with immune and inflammatory processes to eliminate invading pathogens during microbial infections. Under pathological manifestations, hemostasis must therefore interact in a coordinated manner with inflammatory responses and immune reactions. Several pathogens can modulate these host-derived countermeasures by specifically targeting certain haemostatic components for their own benefit. Thus, the ability to modulate host defence systems has to be considered as an essential bacterial virulence mechanism. Complications that bacterial pathogens can induce are therefore often the consequence of evoked host responses. A comprehensive understanding of the molecular mechanisms triggered in infectious processes may help to develop prophylactic methods and novel therapies for the patients suffering from a particular infectious disease. This review aims to provide a critical updated compiling of recent studies on how the pathogenic Leptospira can interact with and manipulate the host haemostatic systems and the consequences for leptospirosis pathogenesis.

Leptospira interrogans Bat proteins impair host hemostasis by fibrinogen cleavage and platelet aggregation inhibition

Leptospirosis is a worldwide spread zoonosis, caused by pathogenic Leptospira. Evidences suggest that compromised hemostasis might be involved in the leptospirosis pathophysiology. In the genome of L. interrogans serovar Copenhageni, we found two genes coding for proteins which comprise von Willebrand factor (VWF) A domains (BatA and BatB). As VWF A domains exhibit multiple binding sites which contributes to human VWF hemostatic functions, we hypothesized that the L. interrogans BatA and BatB proteins could be involved in the hemostatic impairment during leptospirosis. We have cloned, expressed in Escherichia coli, and purified recombinant BatA and BatB. The influence of recombinant BatA and BatB on different in vitro hemostatic assays evaluating the enzymatic activity, platelet aggregation and fibrinogen integrity was investigated. We describe BatB as a new serine protease which is able to cleave thrombin chromogenic substrate, fibrin, fibrinogen, gelatin and casein; while BatA is active only towards fibrinogen. BatA and BatB interfere with the platelet aggregation induced by VWF/ristocetin and thrombin. Our results suggest an important role of the L. interrogans serovar Copenhageni Bat proteins in the hemostasis dysfunction observed during leptospirosis and contribute to the understanding of the leptospirosis pathophysiological mechanisms.

Mortality of leptospirosis associated acute kidney injury (LAKI) & predictors for its development in adults: A systematic review

Leptospirosis is the most widely spread zoonosis and Leptospirosis Associated Acute Kidney Injury (LAKI) is common and fatal if not properly and swiftly treated. The aim of this review is to evaluate the mortality of LAKI and to identify the risk factors for its development. An electronic search was performed to identify the studies included LAKI patients series. Only studies which investigated mortality or risk factors for LAKI development in adults were included. Twenty-three studies with 24 patients series were included in the final analysis and included 1698 patients. The median series mortality was 10.05% (range 0-33.3%) with a total of 223 death. Only four studies identified the independent risk factors for LAKI development which were oliguria, jaundice, arrhythmia, crackles, elevated direct bilirubin level, elevated activated prothrombin time, hyperbilirubinemia and leukocytosis. Although the mortality of LAKI is high, its predictors are not studied enough in literature.

Weil's disease with haemoptysis and acute respiratory distress syndrome

A 35-year-old male patient reached the emergency department after an episode of massive haemoptysis a few hours ago. Fever and dyspnea were mentioned to be present the last 5 days. His medical history included only malaria, successfully treated 2 years ago. Clinical examination revealed high fever, jaundice, cyanosis, tachypnea and bilateral rales on pulmonary auscultation. Laboratory investigation showed high erythrocyte sedimentation rate and C reactive protein, leucocytosis, anaemia, mild thrombocytopaenia, renal impairment, hyperbilirubinaemia and abnormal liver function tests; arterial blood gas analysis showed respiratory alkalosis with severe hypoxia. Thoracic X-ray revealed bilateral pulmonary infiltrates, whereas abdominal and heart ultrasound detected hepatomegaly and small pericardial infusion, respectively. The diagnosis of leptospirosis along with acute respiratory distress syndrome was confirmed by positive IgM Leptospira antibodies. Empirical treatment with triple antibiotic therapy and corticosteroids was applied. The patient was discharged after 1 week, without any symptoms and with almost normal laboratory tests.

Building prognostic models for adverse outcomes in a prospective cohort of hospitalised patients with acute leptospirosis infection in the Philippines

Leptospirosis is endemic to the Philippines. Ten per cent of cases will develop severe or fatal disease. Predicting progression to severity is difficult. Risk factors have been suggested, but few attempts have been made to create predictive models to guide clinical decisions. We present two models to predict the risk of mortality and progression to severe disease. Data was used from a prospective cohort study conducted between 2011 and 2013 in San Lazaro Hospital, Manila. Predictive factors were identified from a literature review. A strategy utilizing backwards stepwise-elimination and multivariate fractional polynomials identified key predictive factors. A total of 203 patients met the inclusion criteria. The overall mortality rate was 6.84%. Multivariable logistic regression revealed that neutrophil counts [OR 1.38, 95% CI 1.15-1.67] and platelet counts [OR 0.99, 95% CI 0.97-0.99] were predictive for risk of mortality. Multivariable logistic regression revealed that male sex (OR 3.29, 95% CI 1.22-12.57) and number of days between symptom onset and antibiotic use (OR 1.28, 95% CI 1.08-1.53) were predictive for risk of progression to severe disease. The multivariable prognostic models for the risks of mortality and progression to severe disease developed could be useful in guiding clinical management by the early identification of patients at risk of adverse outcomes.

[Update on leptospirosis]

Leptospirosis is a worldwide spirochetal zoonosis whose global incidence is increasing and is probably underestimated. Leptospirosis has long been associated with occupational contact with animals (rats and cattle) and has become in developed countries a pathology more related to recreational activities with exposure to fresh water (canoeing, swimming, canyoning) and to an environment contaminated by urine from leptospires excretory rodents. Leptospirosis should be one of the differential diagnoses to be considered when returning from travel to tropical areas, particularly Southeast Asia, and particularly during the rainy season. The clinical symptoms, particularly in the initial phase, are not specific and can limit to a flu-like syndrome or "dengue-like" making diagnosis often difficult. It is then necessary to look carefully for clinical (muscle pain, cough, conjunctival involvement, jaundice) and biological arguments (thrombocytopenia, cholestasis, rhabdomyolysis, frank elevation of CRP) that will help to diagnose leptospirosis and lead to quick antibiotic therapy before the progression to a severe icterohaemorrhagic (Weil's disease) or respiratory form associated with significant mortality. Treatment is based on injectable beta-lactams in severe forms (mainly cephalosporins) and amoxicillin, doxycycline or azithromycin in non-severe forms. Some atypical or delayed forms of leptospirosis occurring in the late immune phase of the disease are to know. Rapid diagnostic tools are currently being studied to improve diagnosis in remote areas and facilitate access to early treatment.

Leptospirosis Pathophysiology: Into the Storm of Cytokines

Leptospirosis is a neglected tropical zoonosis caused by pathogenic spirochetes of the genus Leptospira. Infected reservoir animals, typically mice and rats, are asymptomatic, carry the pathogen in their renal tubules, and shed pathogenic spirochetes in their urine, contaminating the environment. Humans are accidental hosts of pathogenic Leptospira. Most human infections are mild or asymptomatic. However, 10% of human leptospirosis cases develop into severe forms, including high leptospiremia, multi-organ injuries, and a dramatically increased mortality rate, which can relate to a sepsis-like phenotype. During infection, the triggering of the inflammatory response, especially through the production of cytokines, is essential for the early elimination of pathogens. However, uncontrolled cytokine production can result in a cytokine storm process, followed by a state of immunoparalysis, which can lead to sepsis and associated organ failures. In this review, the involvement of cytokine storm and subsequent immunoparalysis in the development of severe leptospirosis in susceptible hosts will be discussed. The potential contribution of major pro-inflammatory cytokines in the development of tissue lesions and systemic inflammatory response, as well as the role of anti-inflammatory cytokines in contributing to the onset of a deleterious immunosuppressive cascade will also be examined. Data from studies comparing susceptible and resistant mouse models will be included. Lastly, a concise discussion on the use of cytokines for therapeutic purposes or as biomarkers of leptospirosis severity will be provided.

Plasminogen Activator Inhibitor 1 for Predicting Sepsis Severity and Mortality Outcomes: A Systematic Review and Meta-Analysis

Objectives

Plasminogen activator inhibitor-1 (PAI-1), a crucial regulator of fibrinolysis, is increased in sepsis, but its values in predicting disease severity or mortality outcomes have been controversial. Therefore, we conducted a systematic review and meta-analysis of its predictive values in sepsis.

Methods

PubMed and Embase were searched until August 18, 2017 for studies that evaluated the relationships between PAI-1 levels and disease severity or mortality in sepsis.

Results

A total of 112 and 251 entries were retrieved from the databases, of which 18 studies were included in the final meta-analysis. A total of 4,467 patients (36% male, mean age: 62 years, mean follow-up duration: 36 days) were analyzed. PAI-1 levels were significantly higher in non-survivors than survivors [odds ratios (OR): 3.93, 95% confidence interval (CI): 2.31-6.67, P < 0.0001] and in patients with severe sepsis than in those less severe sepsis (OR: 3.26, 95% CI: 1.37-7.75, P = 0.008).

Conclusion

PAI-1 is a significant predictor of disease severity and all-cause mortality in sepsis. Although the predictive values of PAI-1 reached statistical significance, the clinical utility of PAI-1 in predicting outcomes will require carefully designed prospective trials.

Pathology and pathogenesis of human leptospirosis: a commented review

Leptospirosis is an acute bacterial septicemic febrile disease caused by pathogenic leptospires, which affect humans and animals in all parts of the world. Transmission can occur by direct contact with infected animals or, more commonly, through indirect contact with water or soil contaminated with urine from infected animals. Leptospires enter the body by penetrating mucous membranes or skin abrasions and disseminate through the hematogenic route. In humans, leptospirosis may cause a wide spectrum of symptoms. Most cases have a biphasic clinical presentation, which begins with the septicemic phase followed by immune manifestations. The severe forms of the disease may be life threatening with multisystem damage including renal failure, hepatic dysfunction, vascular damage, pulmonary hemorrhage and muscle lesions. In this review, we present and discuss the pathogenesis of the human disease and the mechanisms of cell membrane injuries, which occur mainly due to the presence of leptospires and/or their antigen/s in the host tissues.

Leptospira Infection Interferes with the Prothrombinase Complex Assembly during Experimental Leptospirosis

Leptospirosis is a worldwide zoonotic and neglected infectious disease of human and veterinary concern, caused by pathogenic Leptospira species. Although bleeding is a common symptom of severe leptospirosis, the cause of hemorrhage is not completely understood. In severe infections, modulation of hemostasis by pathogens is an important virulence mechanism, and hemostatic impairments such as coagulation/fibrinolysis dysfunction are frequently observed. Here, we analyze the coagulation status of experimentally infected hamsters in an attempt to determine coagulation interferences and the origin of leptospirosis hemorrhagic symptomatology. Hamsters were experimentally infected with L. interrogans. The lungs, kidneys, and livers were collected for culture, histopathology, and coagulation assays. L. interrogans infection disturbs normal coagulation in the organs of animals. Our results suggest the presence of a thrombin-like factor or FX activator, which is able to activate FII in the leptospirosis organ extracts. The activity of those factors is accelerated in the prothrombinase complex. Additionally, we show for the first time that live leptospires act as a surface for the prothrombinase complex assembly. Our results contribute to the understanding of leptospirosis pathophysiological mechanisms and may open new routes for the discovery of novel treatments in the severe manifestations of the disease.

Hemorrhagic, Hemostatic, and Thromboelastometric Disorders in 35 Dogs with a Clinical Diagnosis of Leptospirosis: A Prospective Study

Background

Leptospirosis in dogs is occasionally associated with a hemorrhagic syndrome, the pathophysiology of which is not fully understood.

Hypothesis/Objectives

To characterize hematologic, hemostatic, and thromboelastometric abnormalities in dogs with leptospirosis and to study their association with hemorrhagic diatheses and outcomes.

Animals

Thirty‐five client‐owned dogs.

Methods

A prospective observational single cohort study was conducted. Results from the CBC, coagulation tests (prothrombin, activated partial thromboplastin and thrombin times, fibrinogen, fibrin(ogen) degradation products, and D‐dimer concentrations), rotational thromboelastometry (TEM), signalment, hemorrhagic diatheses, occurrence of disseminated intravascular coagulation (DIC) at admission, and survival to discharge were recorded.

Results

The most common hematologic and hemostatic abnormalities were anemia (30/35), thrombocytopenia (21/35), and hyperfibrinogenemia (15/35). Eight dogs were diagnosed with DIC. A normal TEM profile was found in 14 dogs, a hypercoagulable profile in 14 dogs, and a hypocoagulable profile in 7 dogs. The 8 dogs with hemorrhagic diatheses at admission had significantly decreased platelet counts (P = .037) and increased D‐dimer concentrations (P = .015) compared with other dogs. Dogs with a hypocoagulable profile exhibited more hemorrhagic diatheses compared with the dogs that had normal and hypercoagulable profiles (P = .049). The mortality rate was lower in dogs with a hypercoagulable profile than in those with a hypocoagulable profile (21% vs 57%; P = .043). Disseminated intravascular coagulation was not a significant prognostic factor.

Conclusions and Clinical Importance

Thromboelastometric parameters were altered in dogs with both hypercoagulable and hypocoagulable profiles. A hypocoagulable profile was significantly correlated with hemorrhagic diathesis and higher mortality rate.

Determinants of mortality and impact of therapy in patients with leptospirosis admitted for intensive care in a Sri Lankan hospital--a three year retrospective study

INTRODUCTION

Leptospirosis is a disease of epidemic proportions in Sri Lanka. There is paucity of data on the determinants of mortality and impact of therapy in patients with leptospirosis admitted to critical care settings in endemic territories.

METHODOLOGY

This retrospective cross-sectional study was performed in patients with serologically confirmed leptospirosis admitted to the intensive care unit of the General Hospital, Kalutara from January 2011 to April 2014. Associations between socio-epidemiological, clinical and laboratory parameters and patient mortality were examined.

RESULTS

Forty-five patients were included. The mean age was 49.11(SD = 16.95) and majority (92%) were male. Percentage mortality was 44.4%. Patient mortality was associated with age > 40 (p = 0.012), symptoms of uremia (p = 0.017), evidence of CNS involvement (p = 0.039), presence of oliguria (p = 0.002) and anuria (p = 0.014), presence of multi-organ dysfunction syndrome (MODS) (p < 0.001), CRP > 96 (p = 0.036), platelet count < 20,000 (p = 0.045), Potassium > 5.0 (p = 0.05), metabolic acidosis with pH < 7.2 (p = 0.03), INR > 2 (p = 0.037) and requirement of mechanical ventilation (p < 0.001). Cox regression analysis revealed MODS and potassium > 5 to be independently associated with mortality.

CONCLUSIONS

A high mortality rate is noted. The presence of MODS and serum potassium concentration > 5.0 was independently associated with mortality in this retrospective study of patients with confirmed leptospirosis in a critical care setting.

Modulation of Hemostatic and Inflammatory Responses by Leptospira Spp

Leptospirosis is a worldwide spread zoonotic and neglected infectious disease of human and veterinary concern that is caused by pathogenic Leptospira species. In severe infections, hemostatic impairments such as coagulation/fibrinolysis dysfunction are frequently observed. These complications often occur when the host response is controlled and/or modulated by the bacterial pathogen. In the present investigation, we aimed to analyze the modulation of the hemostatic and inflammatory host responses by the bacterial pathogen Leptospira. The effects of leptospires and their secreted products on stimulation of human intrinsic and extrinsic pathways of coagulation were investigated by means of altered clotting times, assembly and activation of contact system and induction of tissue factor. We show that both extrinsic and intrinsic coagulation cascades are modulated in response to Leptospira or leptospiral secreted proteins. We further find that the pro-inflammatory mediator bradykinin is released following contact activation at the bacterial surface and that pro-coagulant microvesicles are shed from monocytes in response to infection. Also, we show that human leptospirosis patients present higher levels of circulating pro-coagulant microvesicles than healthy individuals. Here we show that both pathways of the coagulation system are modulated by leptospires, possibly leading to altered hemostatic and inflammatory responses during the disease. Our results contribute to the understanding of the leptospirosis pathophysiological mechanisms and may open new routes for the discovery of novel treatments for the severe manifestations of the disease.

Leptospirosis is one of the most relevant and spread zoonotic and neglected infectious diseases affecting humans and other mammals, and is caused by pathogenic bacteria of the genus Leptospira. During infectious diseases, when bacterial pathogens control and/or modulate the host response, impaired hemostasis and inflammation are frequently observed. Here we studied the effects of leptospires and their secreted products on stimulation of human intrinsic and extrinsic pathways of coagulation, showing that both coagulation cascades are modulated in response to Leptospira or leptospiral secreted proteins. We further find that activation of the coagulation cascades culminates in the release of the pro-inflammatory mediator bradykinin and noted an induction of pro-coagulant microvesicles. These findings contribute to a better understanding of the local and systemic hemostastic complications during leptospirosis. Collectively, our results show how leptospires can affect host responses, possibly leading to altered host responses during the disease and giving rise to the leptospirosis symptomatology.

Successful treatment of severe hypokalemia in a dog with acute kidney injury caused by leptospirosis

OBJECTIVE

To report the case management of a patient with severe hypokalemia resulting in cardiopulmonary arrest caused by infection with leptospirosis.

CASE SUMMARY

A 3-year-old intact female Dachshund presented for polyuria, polydipsia, and refractory hypokalemia, which progressed to flaccid paralysis and cardiorespiratory arrest. Following successful resuscitation, the dog was apneic and managed with mechanical ventilation while volume status and electrolytes were corrected. The dog showed rapid improvement allowing for weaning from the ventilator within the first day. The dog was identified as having leptospirosis causing severe kaliuresis (fractional excretion of potassium 31%). Following discharge from hospital, the dog was managed with doxycycline, oral potassium supplementation, and spironolactone and made a full clinical recovery.

NEW OR UNIQUE INFORMATION PROVIDED

This report identifies an unusually severe presentation of leptospirosis in a dog from a region where the disease is not considered common, which was successfully treated despite cardiopulmonary arrest on initial presentation.

Interaction of spirochetes with the host fibrinolytic system and potential roles in pathogenesis

The pathogenic spirochetes Borrelia burgdorferi, B. hermsii, B. recurrentis, Treponema denticola and Leptospira spp. are the etiologic agents of Lyme disease, relapsing fever, periodontitis and leptospirosis, respectively. Lyme borreliosis is a multi-systemic disorder and the most prevalent tick-borne disease in the northern hemisphere. Tick-borne relapsing fever is persistent in endemic areas worldwide, representing a significant burden in some African regions. Periodontal disease, a chronic inflammatory disorder that often leads to tooth loss, is caused by several potential pathogens found in the oral cavity including T. denticola. Leptospirosis is considered the most widespread zoonosis, and the predominant human disease in tropical, undeveloped regions. What these diseases have in common is that they are a significant burden to healthcare costs in the absence of prophylactic measures. This review addresses the interaction of these spirochetes with the fibrinolytic system, plasminogen (Plg) binding to the surface of bacteria and the generation of plasmin (Pla) on their surface. The consequences on host-pathogen interactions when the spirochetes are endowed with this proteolytic activity are discussed on the basis of the results reported in the literature. Spirochetes equipped with Pla activity have been shown to degrade extracellular matrix (ECM) components, in addition to digesting fibrin, facilitating bacterial invasion and dissemination. Pla generation triggers the induction of matrix metalloproteases (MMPs) in a cascade of events that enhances the proteolytic capacity of the spirochetes. These activities in concert with the interference exerted by the Plg/Pla on the complement system - helping the bacteria to evade the immune system - should illuminate our understanding of the mechanisms involved in host infection.

Leptospirosis in humans

Leptospirosis is a widespread and potentially fatal zoonosis that is endemic in many tropical regions and causes large epidemics after heavy rainfall and flooding. Infection results from direct or indirect exposure to infected reservoir host animals that carry the pathogen in their renal tubules and shed pathogenic leptospires in their urine. Although many wild and domestic animals can serve as reservoir hosts, the brown rat (Rattus norvegicus) is the most important source of human infections. Individuals living in urban slum environments characterized by inadequate sanitation and poor housing are at high risk of rat exposure and leptospirosis. The global burden of leptospirosis is expected to rise with demographic shifts that favor increases in the number of urban poor in tropical regions subject to worsening storms and urban flooding due to climate change. Data emerging from prospective surveillance studies suggest that most human leptospiral infections in endemic areas are mild or asymptomatic. Development of more severe outcomes likely depends on three factors: epidemiological conditions, host susceptibility, and pathogen virulence (Fig. 1). Mortality increases with age, particularly in patients older than 60 years of age. High levels of bacteremia are associated with poor clinical outcomes and, based on animal model and in vitro studies, are related in part to poor recognition of leptospiral LPS by human TLR4. Patients with severe leptospirosis experience a cytokine storm characterized by high levels of IL-6, TNF-alpha, and IL-10. Patients with the HLA DQ6 allele are at higher risk of disease, suggesting a role for lymphocyte stimulation by a leptospiral superantigen. Leptospirosis typically presents as a nonspecific, acute febrile illness characterized by fever, myalgia, and headache and may be confused with other entities such as influenza and dengue fever. Newer diagnostic methods facilitate early diagnosis and antibiotic treatment. Patients progressing to multisystem organ failure have widespread hematogenous dissemination of pathogens. Nonoliguric (high output) renal dysfunction should be supported with fluids and electrolytes. When oliguric renal failure occurs, prompt initiation of dialysis can be life saving. Elevated bilirubin levels are due to hepatocellular damage and disruption of intercellular junctions between hepatocytes, resulting in leaking of bilirubin out of bile caniliculi. Hemorrhagic complications are common and are associated with coagulation abnormalities. Severe pulmonary hemorrhage syndrome due to extensive alveolar hemorrhage has a fatality rate of >50 %. Readers are referred to earlier, excellent summaries related to this subject (Adler and de la Peña-Moctezuma 2010; Bharti et al. 2003; Hartskeerl et al. 2011; Ko et al. 2009; Levett 2001; McBride et al. 2005).

Severity markers in severe leptospirosis: a cohort study

We aimed to evaluate parameters for their value as severity markers in hospitalized leptospirosis patients. We recruited 47 informed adult consenting patients and assessed a number of clinical, hematological, biochemical, and biological variables. Patients were sorted according to severity based on fatality or the requirement of mechanical ventilation or dialysis; the parameters studied were compared between groups on inclusion and the next day. Beside septic shock presentation or a high severity score (Simplified Acute Physiology Score; SAPS II), increased lactate, total bilirubin, lipase, and AST/ALT ratio or a decreased cytokines IL-10/TNF-α ratio were all significantly associated with severity. The gene expression of the IL-1 receptor antagonist IL-1ra, IL-1α, and the long pentraxin PTX-3 were also transcribed at higher levels in most severe cases. Patients could rapidly improve or deteriorate, highlighting the need for a new assessment the next day. Our results add to the limited body of knowledge about severity markers in leptospirosis. They also suggest that patients should be reassessed the next day before being possibly discharged from the hospital. Further studies are needed in order to confirm relevant and reliable prognostic parameters in leptospirosis that would be helpful for the purpose of triage.

Ameboma: an unusual cause of gastrointestinal bleeding during severe leptospirosis

Background

Severe leptospirosis occurs mainly in a tropical environment and includes icterus, acute renal failure and hemorrhages. These bleedings, which are mainly a consequence of acute homeostatic disturbances, can also reveal simultaneous diseases. Coinfections with other tropical diseases have been previously reported during leptospirosis. To our knowledge, invasive amebiasis, which can induce gastrointestinal bleedings, has never been described in the course of severe leptospirosis.

Case presentation

In this report, we describe a case of a 60 year-old man living in Reunion Island (Indian Ocean, France) admitted to our intensive care unit for severe Leptospira interrogans serovar icterohaemorrhagiae infection with neurological, renal, liver and hematological involvement. Two lower gastrointestinal bleedings occurred 7 and 15 days after admission. The first episode was promoted by hemostatic disturbances while the second bleeding occurred during low-dose heparin therapy. Colonoscopy revealed a pseudo-tumoral inflammatory mass of the recto-sigmoid junction. Histological examination found trophozoites inside mucinous exudate suggestive of Entamoeba histolytica. Amoebic serology was strongly positive whereas careful detection of cysts or trophozoites on saline-wet mount was negative in three consecutive samples of stools. Amoxicillin followed by metronidazole therapy, combined with supportive care, led to an improvement in the clinical and biological patient’s condition and endoscopic appearances.

Conclusion

Clinicians should be aware that gastrointestinal bleeding during severe leptospirosis could not solely be the consequences of hemostatic disturbances. Careful endoscopic evaluation that may reveal curable coinfections should also be considered.

Factors associated with thrombocytopenia in severe leptospirosis (Weil's disease)

OBJECTIVE

This study was conducted to investigate factors associated with thrombocytopenia in a large cohort of patients with leptospirosis in an endemic area.

METHODS

This retrospective study included 374 consecutive patients with leptospirosis who were admitted to tertiary hospitals in Fortaleza, Brazil. All patients had a diagnosis of severe leptospirosis (Weil's disease). Acute kidney injury was defined according to the RIFLE criteria. Thrombocytopenia was defined as a platelet count <100,000/mm3.

RESULTS

A total of 374 patients were included, with a mean age of 36.1 ± 15.5 years, and 83.4% were male. Thrombocytopenia was present at the time of hospital admission in 200 cases (53.5%), and it developed during the hospital stay in 150 cases (40.3%). The patients with thrombocytopenia had higher frequencies of dehydration (53% vs. 35.3%, p=0.001), epistaxis (5.7% vs. 0.8%, p=0.033), hematemesis (13% vs. 4.6%, p=0.006), myalgia (91.5% vs. 84.5%, p=0.038), hematuria (54.8% vs. 37.6%, p=0.011), metabolic acidosis (18% vs. 9.2%, p=0.016) and hypoalbuminemia (17.8% vs. 7.5%, p=0.005). The independent risk factors associated with thrombocytopenia during the hospital stay were lengthy disease (OR: 1.2, p=0.001) and acute kidney injury (OR: 6.6, p=0.004). Mortality was not associated with thrombocytopenia at admission (12.5% vs. 12.6%, p=1.000) or during the hospital stay (12.6% vs. 11.3%, p=0.748).

CONCLUSIONS

Thrombocytopenia is a frequent complication in leptospirosis, and this condition was present in more than half of patients at the time of hospital admission. Lengthy disease and acute kidney injury are risk factors for thrombocytopenia. There was no significant association between thrombocytopenia and mortality.

Adhesins of Leptospira interrogans mediate the interaction to fibrinogen and inhibit fibrin clot formation in vitro

We report in this work that Leptospira strains, virulent L. interrogans serovar Copenhageni, attenuated L. interrogans serovar Copenhageni and saprophytic L. biflexa serovar Patoc are capable of binding fibrinogen (Fg). The interaction of leptospires with Fg inhibits thrombin- induced fibrin clot formation that may affect the haemostatic equilibrium. Additionally, we show that plasminogen (PLG)/plasmin (PLA) generation on the surface of Leptospira causes degradation of human Fg. The data suggest that PLA-coated leptospires were capable to employ their proteolytic activity to decrease one substrate of the coagulation cascade. We also present six leptospiral adhesins and PLG- interacting proteins, rLIC12238, Lsa33, Lsa30, OmpL1, rLIC11360 and rLIC11975, as novel Fg-binding proteins. The recombinant proteins interact with Fg in a dose-dependent and saturable fashion when increasing protein concentration was set to react to a fix human Fg concentration. The calculated dissociation equilibrium constants (K_D) of these reactions ranged from 733.3±276.8 to 128±89.9 nM for rLIC12238 and Lsa33, respectively. The interaction of recombinant proteins with human Fg resulted in inhibition of fibrin clot by thrombin-catalyzed reaction, suggesting that these versatile proteins could mediate Fg interaction in Leptospira. Our data reveal for the first time the inhibition of fibrin clot by Leptospira spp. and presents adhesins that could mediate these interactions. Decreasing fibrin clot would cause an imbalance of the coagulation cascade that may facilitate bleeding and help bacteria dissemination

Leptospirosis is probably the most widespread zoonosis in the world. Caused by spirochaetes of the genus Leptospira, it has greater incidence in tropical and subtropical regions. The disease has become prevalent in cities with sanitation problems and a large population of urban rodent reservoirs, which contaminate the environment through their urine. Understanding the mechanisms involved in pathogenesis of leptospirosis should contribute to new strategies that would help fight the disease. We show in this work that Leptospira strains, virulent, attenuated or saprophytic are capable of binding fibrinogen (Fg). The interaction of leptospires with Fg inhibits the formation of fibrin clot that may result of an imbalance in the haemostatic equilibrium. In addition, we show that plasminogen (PLG)/plasmin (PLA) generation on the surface of leptospires can lead to Fg degradation, showing evidence of possible route of fibrinolysis in leptospirosis. We also present six leptospiral proteins, as novel Fg-binding proteins, capable of inhibiting fibrin clot formation by thrombin-catalyzed reaction, suggesting that in Leptospira these multifunctional proteins could mediate Fg interaction. Our data suggest possible mechanisms that leptospires could employ to affect the coagulation cascade and fibrinolytic system that might lead to bacteria spreading.

Commonly used severity scores are not good predictors of mortality in sepsis from severe leptospirosis: a series of ten patients

Introduction. Severe leptospirosis, also known as Weil's disease, can cause multiorgan failure with high mortality. Scoring systems for disease severity have not been validated for leptospirosis, and there is no documented method to predict mortality. Methods. This is a case series on 10 patients admitted to ICU for multiorgan failure from severe leptospirosis. Data were collected retrospectively, with approval from the Institution Ethics Committee. Results. Ten patients with severe leptospirosis were admitted in the Patras University Hospital ICU in a four-year period. Although, based on SOFA scores, predicted mortality was over 80%, seven of 10 patients survived and were discharged from the hospital in good condition. There was no association between SAPS II or SOFA scores and mortality, but survivors had significantly lower APACHE II scores compared to nonsurvivors. Conclusion. Commonly used severity scores do not seem to be useful in predicting mortality in severe leptospirosis. Early ICU admission and resuscitation based on a goal-directed therapy protocol are recommended and may reduce mortality. However, this study is limited by retrospective data collection and small sample size. Data from large prospective studies are needed to validate our findings.

Comparative study on infection-induced thrombocytopenia among returned travellers

BACKGROUND

Thrombocytopenia is a frequent finding among ill returned travellers and may be caused by a large number of different conditions, including infectious diseases specific or typical for tropical and subtropical regions. In order to assess the diagnostic significance of thrombocytopenia we investigated a large cohort of returned travellers.

METHODS

This was a comparative study in which data collected on 19,473 returned travellers who consulted the outpatient travel clinic of the the University of Munich Hospital between 1999 and 2009 were analysed. Of these, 732 (3.8%) travellers were diagnosed with thrombocytopenia, and their data were compared with those of the remaining 18,741 travellers with normal platelet counts.

RESULTS

Thrombocytopenia was significantly more frequent among patients with malaria (63%), acute human immunodeficiency virus infection (48%), dengue fever/dengue haemorrhagic fever (DF/DHF; 47%), Epstein-Barr virus infectious mononucleosis (23%), paratyphoid/typhoid fever (14%), and rickettsiosis (12%). Malaria and DF/DHF caused 25% of all cases of thrombocytopenia (platelet count <140,000/μl) and 75% of all cases of severe thrombocytopenia (platelet count <30,000/μl). Sex, age, country of origin, duration and type of travel were not significantly correlated with thrombocytopenia. The most frequent travel destinations were Asia (42%), Africa (33%), and Latin America (14%). Travellers to Sub-Saharan Africa (high risk for malaria) and to South/South-east Asia (high risk for DF/DHF) had the highest relative risk for thrombocytopenia.

CONCLUSION

Platelet count among returned travellers is an essential screening parameter, as thrombocytopenia is highly correlated with important infectious diseases, particularly with malaria and DF/DHF.

Recovery from intracranial hemorrhage due to leptospirosis

Intracranial hemorrhage is a rare and fatal presentation of leptospirosis. In this paper we present the case of a 51-year-old male farmer who lives in northern Iran. He came to our hospital with a severe headache. A paraclinical evaluation showed clear signs of thrombocytopenia, and a brain MRI revealed left temporoparietal hemorrhage. Our preliminary diagnosis was Leptospirosis, and after 26 days of hospital care the patient was discharged in good condition. This paper will educationally help physicians in better diagnosis and treatment of leptospirosis.

Fulminant Leptospirosis (Weil's disease) in an urban setting as an overlooked cause of multiorgan failure: a case report

Introduction

Leptospirosis has recently come to international attention as a globally important re-emerging infectious disease. Our case is unusual given the season, location and setting in which leptospirosis occurred. According to the New York City Board of Health, there were only two other cases of leptospirosis in New York City in the year that our patient was diagnosed.

Case presentation

A 49-year-old healthy Chinese man presented to our hospital with sepsis and multiorgan failure. The patient did not respond to antibiotics and his multiorgan failure worsened. His workup did not show any significant findings except for a positive nasopharyngeal swab result for influenza A. Later the patient developed hemoptysis with evidence of bilateral infiltrates on radiography. His status mildly improved after he was started on steroids. Eventually, a microagglutination test confirmed the presence of antibodies against Leptospira icterohaemorrhagiae. The patient subsequently recovered after a course of intravenous antibiotics.

Conclusion

The case of fulminant leptospirosis presented here should serve to alert health care providers and the general public to the clinical importance of this severe, sometimes fatal, disease. Leptospirosis should be considered early in the diagnosis of any patient with acute, non-specific febrile illness with multiorgan system involvement or high fever in a returning traveler. In addition, not only should it be considered in tropical and rural areas between late summer to early fall, but also in any location or time if the risk factors are present.

Leptospirosis-associated disturbances of blood vessels, lungs and hemostasis

The frequency of massive pulmonary hemorrhages seems to be increasing in different geographic areas; however, there is no clear explanation for this trend. Although data on the pathogenesis of such complications are scarce, recent research indicates a potential role of autoimmunity and/or multifactorial mechanisms. However, much information is already available on the disturbance of hemostasis and blood vessels in leptospirosis-related literature, even if some contradictory concepts coexist. The purpose of this review is to integrate both new and classical information from human and animal studies on severe pulmonary forms of leptospirosis and disorders of hemostasis and blood vessels. We propose that the involvement of blood vessels in leptospirosis must be understood as a sepsis-like, diffuse process of endothelial activation/damage rather than as a classical systemic vasculitis. Pulmonary hemorrhages are most likely multifactorial and there has recently been evidence against the role of autoimmunity; however, further investigation of strain variations, exposure to hydrocarbons and association with renal dysfunction is required. Thrombocytopenia is a consistent feature of leptospirosis but it is not clear whether it is attributable to sepsis-related mechanisms. In addition, further investigation is required to define whether platelet function is activated or inhibited during severe leptospirosis.