Clinicopathological and immunohistochemical features of the severe pulmonary form of leptospirosis

Concurrent colonization of rodent kidneys with multiple species and serogroups of pathogenic Leptospira

Rodents are important reservoir hosts of pathogenic leptospires in the US Virgin Islands. Our previous work determined that trapped rodents were colonized with Leptospira borgpetersenii serogroup Ballum (n = 48) and/or Leptospira kirschneri serogroup Icterohaemorrhagiae (n = 3). In addition, nine rodents appeared to be colonized with a mixed population comprising more than one species/serogroup. The aim of this study was to validate this finding by characterizing clonal isolates derived from cultures of mixed species. Cultures of presumptive mixed species (designated LR1, LR5, LR37, LR57, LR60, LR61, LR68, LR70, and LR72) were propagated in different media including Hornsby-Alt-Nally (HAN) media, incubated at both 29℃ and 37℃, and T80/40/LH incubated at 29℃. Polyclonal reference antisera specific for serogroup Ballum and Icterohaemorrhagiae were used to enrich for different serogroups followed by subculture on agar plates. Individual colonies were then selected for genotyping and serotyping. Of the nine cultures of mixed species/serogroups, a single clonal isolate was separated in five of them: L. borgpetersenii serogroup Ballum in LR1, LR5, and LR37, and L. kirschneri serogroup Icterohaemorrhagiae in LR60 and LR72. In four of the cultures with mixed species (LR57, LR61, LR68, and LR70), clonal isolates of both L. borgpetersenii serogroup Ballum and L. kirschneri serogroup Icterohaemorrhagiae were recovered. Our results definitively establish that rodents can be colonized with more than one species/serogroup of Leptospira concurrently. The identification and characterization of multiple species/serogroups of Leptospira from individual reservoir hosts of infection are essential to understand the epidemiology and transmission of disease to both human and domestic animal populations.IMPORTANCEPathogenic Leptospira, the causative agent of human and animal leptospirosis, comprise a diverse genus of species/serogroups which are inherently difficult to isolate from mammalian hosts due to fastidious growth requirements. Molecular evidence has indicated that reservoir hosts of Leptospira may shed multiple species concurrently. However, evidence of this phenomena by culture has been lacking. Culture is definitive and is essential for comprehensive characterization of recovered isolates by high-resolution genome sequencing and serotyping. In this work, a protocol using recently developed novel media formulations, in conjunction with reference antisera, was developed and validated to demonstrate the recovery of multiple species/serogroups of pathogenic Leptospira from the same host. The identification and characterization of multiple species/serogroups of Leptospira from individual reservoir hosts of infection are essential to understand the epidemiology and transmission of disease to both human and domestic animal populations.

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.

Pulmonary haemorrhage as the earliest sign of severe leptospirosis in hamster model challenged with Leptospira interrogans strain HP358

Background

Severe leptospirosis is challenging as it could evolve rapidly and potentially fatal if appropriate management is not performed. An understanding of the progression and pathophysiology of Leptospira infection is important to determine the early changes that could be potentially used to predict the severe occurrence of leptospirosis. This study aimed to understand the kinetics pathogenesis of Leptospira interrogans strain HP358 in the hamster model and identify the early parameters that could be used as biomarkers to predict severe leptospirosis.

Methodology/Principal findings

Male Syrian hamsters were infected with Leptospira interrogans strain HP358 and euthanized after 24 hours, 3, 4, 5, 6 and 7 days post-infection. Blood, lungs, liver and kidneys were collected for leptospiral detection, haematology, serum biochemistry and differential expression of pro- and anti-inflammatory markers. Macroscopic and microscopic organ damages were investigated. Leptospira interrogans strain HP358 was highly pathogenic and killed hamsters within 6–7 days post-infection. Pulmonary haemorrhage and blood vessel congestion in organs were noticed as the earliest pathological changes. The damages in organs and changes in biochemistry value were preceded by changes in haematology and immune gene expression.

Conclusion/Significance

This study deciphered haemorrhage as the earliest manifestation of severe leptospirosis and high levels of IL-1β, CXCL10/IP-10, CCL3/MIP-α, neutrophils and low levels of lymphocytes and platelets serve as a cumulative panel of biomarkers in severe leptospirosis.

As the severe form of leptospirosis could progress rapidly and be potentially fatal if not treated earlier, deciphering the pathophysiology kinetics of infection is crucial to determine the parameters of disease severity. To understand this, we challenged hamsters with the highly virulent Leptospira interrogans strain HP358. Pulmonary haemorrhage was observed as the earliest pathological change followed by liver and kidneys damages. The increased expression of IL-1β, CXCL10/IP-10, CCL3/MIP-α, high neutrophils and low lymphocytes and platelets production observed in the present study indicate that these parameters could serve as a cumulative panel of biomarkers in severe leptospirosis.

A Scoring Tool to Predict Pulmonary Complications in Severe Leptospirosis with Kidney Failure

Rapid identification of patients likely to develop pulmonary complications in severe leptospirosis is crucial to prompt aggressive management and improve survival. The following article is a cohort study of leptospirosis patients admitted at the National Kidney and Transplant Institute (NKTI). Logistic regression was used to predict pulmonary complications and obtain a scoring tool. The Kaplan-Meir method was used to describe survival rates. Among 380 patients with severe leptospirosis and kidney failure, the overall mortality was 14%, with pulmonary hemorrhage as the most common cause. In total, there were 85 (22.4%) individuals who developed pulmonary complications, the majority (95.3%) were observed within three days of admission. Among the patients with pulmonary complications, 56.5% died. Patients placed on mechanical ventilation had an 82.1% mortality rate. Multivariate analyses showed that dyspnea (OR = 28.76, p < 0.0001), hemoptysis (OR = 20.73, p < 0.0001), diabetes (OR = 10.21, p < 0.0001), renal replacement therapy (RRT) requirement (OR = 6.25, p < 0.0001), thrombocytopenia (OR = 3.54, p < 0.0029), and oliguria/anuria (OR = 3.15, p < 0.0108) were significantly associated with pulmonary complications. A scoring index was developed termed THe-RADS score (Thrombocytopenia, Hemoptysis, RRT, Anuria, Diabetes, Shortness of breath). The odds of developing pulmonary complications were 13.90 times higher among patients with a score >2 (63% sensitivity, 88% specificity). Pulmonary complications in severe leptospirosis with kidney failure have high mortality and warrant timely and aggressive management.

Covid-19 and leptospirosis: Cytokine storm and the use of steroids

The majority of patients with Covid-19 have a good outcome. However, complications principally of acute respiratory distress syndrome (ARDS) and multiple-organ failure can occur rapidly. Leptospirosis, a zoonotic disease, is similar to Covid-19 in that most infections are mild or asymptomatic and only a small number develop ARDS. Cytokine storm is considered to be the main incriminating factor in both. High dose steroids have been used to ameliorate the effects in leptospirosis, and similarly, reports suggest a benefit in Covid-19. SARS CoV-2 and leptospira, one a virus and the other a bacterium, are two species separated by millions of years of evolution, but producing illnesses with similar spectra, with cytokine storm being the common precipitating factor. As data are accrued from around the world, more light may be shed on features analogous to both pathways.

Pulmonary haemorrhage in Weil's disease

Leptospirosisis a zoonosis caused by spirochaetes from the species Leptospira. The more severe form of leptospirosis, known as Weil’s disease, is characterised by the triad of jaundice, renal impairment and haemorrhages. Pulmonary involvement occurs in 20%–70% of the patients, with severity ranging from non-productive cough to respiratory failure mainly due to pulmonary haemorrhage. Recognition of Weil’s disease in patients presenting with pulmonary symptoms can be difficult. This case illustrates a classic case of pulmonary haemorrhagic involvement in Weil’s disease.

A case of leptospirosis with acute respiratory failure and acute kidney injury treated with simultaneous extracorporeal membrane oxygenation and haemoperfusion

A 47-year-old man with a recent history of wading in floodwaters presented with a 1-week history of cough, myalgia, conjunctival suffusion and decreasing urine output. The patient had uraemia, hypotension, leukocytosis, thrombocytopenia, elevated liver enzymes and oliguria. His condition quickly worsened with haemoptysis, and respiratory distress which subsequently required intubation and mechanical ventilation. Continuous renal replacement therapy was started together with haemoperfusion (HP). The patient initially required norepinephrine and this was discontinued after the first session of HP. He was referred for veno-venous extracorporeal membrane oxygenation (ECMO) due to severe hypoxia and pulmonary haemorrhage. Oxygenation and lung compliance improved, and serum creatinine levels continued to normalise with improved urine output. He was placed off ECMO, extubated and eventually discharged. Patient was diagnosed with severe leptospirosis, acute respiratory failure and acute kidney injury successfully treated with simultaneous ECMO and HP. Blood samples were positive for Leptospira spp. DNA via PCR assay.

Sequel and therapeutic modalities of leptospirosis associated severe pulmonary haemorrhagic syndrome (SPHS); a Sri Lankan experience

BACKGROUND

The emergence of leptospirosis-associated severe pulmonary hemorrhagic syndrome (SPHS) with high case fatality has been reported from many countries. Understanding of clinical disease and sequel of SPHS needs larger studies with adequate numbers. The purpose of this study was to describe the characteristics and sequel by different therapeutic approaches for SPHS in Leptospirosis in Sri Lanka.

METHODS

This study was conducted at Teaching Hospital-Karapitiya (THK), Galle, Sri Lanka from June 2015 to December 2017. THK is the main tertiary care center for the Southern Province. All confirmed-cases of leptospirosis who presented during this period and were admitted to five medical units of THK were included in this study. SPHS was defined as a patient presenting; haemoptysis, arterial hypoxemia (Acute Lung Injury Score < 2.5), haemoglobin drop (10% from the previous value), or diffused alveolar shadows in the chest radiograph, without alternative explanation other than leptospirosis.

RESULTS

Of the 128 MAT confirmed cases of leptospirosis, 111 (86.7%) had acute kidney injury (AKI) whilst SPHS was seen in 80 (62.5%). Patients typically developed SPHS within the first week of illness, mostly on days 4 and 5. The case fatality rate of this study sample was 28.1% (n = 36), while for patients with SPHS, it was 41.5%. Most of the deaths (n = 19) were within the first 3 days of admission (on the same day 8, and within next 48 h 11). Among SPHS patients, 59 received therapeutic plasma exchange (TPE). The survival rate was higher (n = 35, 74.5%) when the TPE was performed within the first 48 h of detecting SPHS compared to patients in whom the procedure was done after 48 h (n = 5, 54.5%). Of the 19 leptosprosis patients with SPHS who did not receive TPE, 17 died (89.5%). However, the group of patients who received TPE was primarily the patients survived beyond day 3.

CONCLUSIONS

We observed that during the study period, SPHS was common and the mortality rate was higher in the study area. The treatment modalities tested need further evaluation and confirmation.

Development and evaluation of latex agglutination test coating with recombinant antigen, LipL32 for serodiagnosis of human leptospirosis

Leptospirosis is a widespread zoonotic disease caused by Leptospira interrogans. Symptoms of disease range from mild symptoms to serious complications including, jaundice, pulmonary hemorrhage, renal and hepatic failure, which may prove fatal. Clinical presentations of this disease are similar with other febrile illness. Therefore, rapid and appropriated laboratory diagnostic tests are needed to aid clinical case identification. As these reasons, objective of this study is to develop and evaluate a simple latex agglutination test coating with recombinant leptospiral antigens, LipL32 for serodiagnosis of human leptospirosis. Firstly, lipl32 gene was amplified from genomic DNA of Leptospira interogans serovar Pyrogenes. Then PCR product of lipl32 gene was ligated with pGEX-2T plasmid, generating pGRK32 recombinant plasmid. Recombinant GST-LipL32 protein was overexpressed and subsequently purified by using Glutathione-Agarose Resin. Recombinant GST-Lipl32 protein was coated on latex beads for development latex agglutination test (LAT). The relative sensitivity, specificity and accuracy of the developed LAT were compared with indirect immunofluorescences assay (IFA) for detection of anti-leptospiral antibodies in 30 human leptospirosis samples, 30 healthy blood donor samples, 10 dengue fever positive samples, 10 scrub typhus positive samples, and 10 melioidosis samples. Results showed that the developed LAT showed sensitivity, specificity and accuracy: 66.66%, 86.66%, and 80.00%, respectively, comparing with IFA method. Moreover, Kappa analysis showed agreement rate of the two methods were 0.421. It concluded that our developed gave compatible result with IFA. Additionally, Our LAT are simple, rapid and suitable for detection in the field. However, for better sensitivity, diagnostic specificity, positive predictive value, negative predictive value, accuracy and Cohen’s kappa comparison should be done in larger amounts of sera samples.

Historical Review of Leptospirosis in the Korea (1945 - 2015)

Leptospirosis is a widespread worldwide zoonosis. Human leptospirosis was first identified in the Korea in 1984 as the cause of “epidemic pulmonary hemorrhagic fever of unknown etiology” that occurred sporadically or in outbreaks. The major outbreaks, leading to some deaths, mainly involved rice field farmers who worked in wet and muddy rice paddies following floods or heavy rainfalls. Leptospirosis was designated a nationally notifiable disease in 1987. The Korean government introduced a supplementary immunization program to control the disease from 1988 to 1997, which provided people at risk in endemic areas with the inactivated vaccine prepared from a local strain Leptospira interrogans serovar Lai. In addition, the continuous promotion of education and awareness in the media played a role in improving personal hygiene management. Since then, the reported incidence of leptospirosis has been low. Leptospirosis is currently considered in the differential diagnosis of acute febrile illnesses occurring in fall. This study historically reviews clinical and epidemiological publications, scientific reports, and public health policies for recognition, identification, and infection control of human leptospirosis in the Korea.

Role of Plasmapheresis and Extracorporeal Membrane Oxygenation in the Treatment of Leptospirosis Complicated with Pulmonary Hemorrhages

Introduction

Leptospirosis is an emerging infectious disease associated with multiorgan involvement and significant morbidity and mortality. Although pulmonary hemorrhage due to leptospirosis has a high fatality, specific treatment options are limited and their efficacy is not adequately proven. We opted to find out the current evidence on plasmapheresis and extracorporeal membrane oxygenation (ECMO) in pulmonary hemorrhages due to leptospirosis.

Methods

The first search was conducted in PubMed, OVID, Google Scholar, and Cochrane clinical trial registry using keywords "leptospirosis" OR "Leptospira" OR "Weil's disease" AND "plasmapheresis" OR "plasma exchange" AND "pulmonary hemorrhage" OR "alveolar hemorrhage" OR "lung hemorrhage" and the second search was done using keyword "leptospirosis" OR "Leptospira" OR "Weil's disease" AND "ECMO" OR "Extracorporeal membrane oxygenation." The searches were not limited by study design or the date of publication. Only articles written in English were reviewed. Although we intended to include only clinical trials, it was decided later to include other information such as case reports and case series which addressed these treatment modalities. Two authors selected articles independently in a blinded manner using a set of inclusion and exclusion criteria and discrepancies were solved after discussions.

Results

The information found was very limited. This included one clinical trial which showed a significant survival benefit with plasmapheresis but the study design had many limitations. Two case reports described the benefit of plasmapheresis in severe leptospirosis with pulmonary hemorrhages. There were eight case reports where ECMO was performed and out of all only one patient has died. One retrospective study on patients with severe leptospirosis mentioned that four out of five patients with pulmonary hemorrhages survived after being treated with ECMO.

Conclusions

Current evidence is insufficient to recommend the routine use of plasmapheresis or ECMO for patients presenting with pulmonary hemorrhages due to leptospirosis. ECMO may be a promising mode of treatment in acute respiratory failure in leptospirosis related pulmonary hemorrhages. These treatment modalities, however, can be applied based on the availability of resources and expertise at the discretion of the clinician in charge, considering patient related factors such as cardiovascular stability and derangement of coagulation profile. Clinical trials conducted adhering to standard procedures are urgently required to establish the efficacy of these treatment modalities.

Severe pulmonary haemorrhage syndrome in leptospirosis in a returning traveller

Clinical presentation of leptospirosis ranges from asymptomatic infection to fulminant, life-threatening disease. Pulmonary involvement in terms of severe pulmonary haemorrhage syndrome (SPHS) has recently become a more frequently reported facet of leptospirosis and correlates with high mortality rates. It has not yet been described in returning German travellers. We present a case of a healthy young man developing massive pulmonary haemorrhage and severe ARDS requiring mechanical ventilation and high-dose catecholamines after travelling to Indonesia. Leptospirosis was verified by blood PCR as well as serology and treated with high-dose, intravenous penicillin. Outcome was favourable, the patient recovered completely. Leptospirosis and SPHS should be taken into account as an emerging infectious disease in patients with fever and lung involvement.

A Case of Leptospirosis-Associated Severe Pulmonary Hemorrhagic Syndrome Successfully Treated with Venovenous Extracorporeal Membrane Oxygenation

Background

In patients with leptospirosis-associated severe pulmonary hemorrhagic syndrome (SPHS), hypoxemia is the most common cause of death despite maximal mechanical ventilation.

Case

A 50-year-old male sushi chef who had never traveled outside Japan presented with a 2-day history of fever and muscle pain. On admission, the patient had thrombocytopenia, renal insufficiency, and jaundice. His condition continued to deteriorate, with decreasing platelet count, worsening renal function, hyperbilirubinemia, hypotension, and respiratory distress. On day 5 after onset of symptoms, he required intubation and mechanical ventilation. Bronchoscopy showed diffuse endobronchial bleeding. His respiratory status worsened rapidly with a partial pressure of arterial oxygen to fraction of inspired oxygen ratio of 70, necessitating venovenous extracorporeal membrane oxygenation (V-V ECMO) and treatment with an inotrope, renal replacement therapy, and broad-spectrum antibiotics including benzylpenicillin. Anticoagulation was maintained at the minimum level. His condition improved, and he was weaned off ECMO on day 15 and discharged on day 19 after onset of symptoms. The leptospirosis diagnosis was confirmed by leptospiral DNA detection in urine samples by polymerase chain reaction and the results of paired serum antibody titer testing.

Conclusions

V-V ECMO may prevent mortality in patients with leptospirosis-induced SPHS that does not respond to conventional therapy.

Leptospirosis among the self-supporting convicts of Andaman Island during the 1920s--the first report on pulmonary haemorrhage in leptospirosis?

Several researchers had carried out investigations on the possibility of existence of Weil's disease in Andaman Islands during early 20 th century. The first report of a series of confirmed cases of leptospirosis that occurred during 1929 was published in 1931.There were several reports during 1995 to 2009 that described detailed account of leptospirosis including various clinical syndromes. The possibility of pulmonary involvement in leptospirosis being a manifestation historically overlooked rather than newly emerged during the past two decades is examined in this review in the context of Andaman Islands. Two case series of leptospirosis, one occurred in 1929 and the other in 1996-1997 were reviewed with special emphasis on pulmonary involvement and haemorrhagic manifestations. The similarities and differences in the clinical profile of patients of the two case series were analysed. The review shows that respiratory system involvement and pulmonary haemorrhage as evidenced by presence of haemoptysis as a complication of leptospirosis was occurring during 1920s in Andaman Islands. The incidence of pulmonary involvement, however, rose from 9.4 per cent during 1929 to 52 per cent in 1996-1997. The case fatality ratio in patients with pulmonary involvement, which was 50 per cent during 1929 and 42.9 per cent during 1996-1997, was higher than that in cases without pulmonary involvement.Fever, conjunctival congestion, jaundice, vomiting, diarrhoea, hepatomagaly, haemoptysis, haematemesis and subconjunctival haemorrhage were common in both series. The case series in Andaman Islands in 1929 was probably the first report of pulmonary haemorrhage as a manifestation of leptospirosis. The increase in the incidence of pulmonary involvement in leptospirosis in the recent past is probably due to the increase in the density and diversity of its animal vectors,the broadening of the range of circulating serovars and the interactions between the vector and the agent. An increased virulence of Leptospira through gene acquisition and loss on an evolutionary time scale and the resulting change in the gene content, gene order and gene expression cannot be ruled out.

Recent advances in canine leptospirosis: focus on vaccine development

Leptospirosis is a global infection of humans and animals caused by pathogenic Leptospira spp. Leptospirosis is a major zoonosis, with infection acquired from wild and domestic animals. It is also a significant cause of morbidity, mortality, and economic loss in production and companion animals. Leptospirosis in dogs is prevalent worldwide and as well as a cause of canine disease, it presents a zoonotic risk to human contacts. Canine leptospirosis does not differ greatly from the syndromes seen in other animal species, with hepatic, renal, and pulmonary involvement being the main manifestations. While the pathogenesis of disease is well documented at the whole animal level, the cellular and molecular basis remains obscure. Killed, whole-cell bacterin vaccines are licensed worldwide and have not changed greatly over the past several decades. Vaccine-induced immunity is restricted to serologically related serovars and is generally short-lived, necessitating annual revaccination. The appearance of new serovars as causes of canine leptospirosis requires constant epidemiological surveillance and tailoring of vaccines to cover emerging serovars. At the present time, there is no realistic prospect of alternative, non-bacterin vaccines in the foreseeable future.

Detection of urinary biomarkers in reservoir hosts of leptospirosis by capillary electrophoresis-mass spectrometry

PURPOSE

Pathogenic leptospires colonize the renal tubules of reservoir hosts of infection and are excreted via urine into the environment. Asymptomatic reservoir hosts include a wide range of domestic and wild animal species and include cattle, dogs, and rats that can persistently excrete large numbers of pathogenic leptospires over many months. A similar presentation has been observed in humans categorized as "long-term asymptomatic individuals" as they excreted leptospires in the absence of any clinical symptoms or positive serology.

EXPERIMENTAL DESIGN

In the current study, the urine of experimentally infected rats, which showed no clinical signs or positive serology, was analyzed by CE-MS to identify urinary biomarkers of chronic infection.

RESULTS

A discriminating peptide pattern of 43 polypeptides provided a sensitivity of 93%, a specificity of 83%, and an accuracy of 90% for the identification of urine from chronically infected rats (p < 0.05, AUC > 90%). The majority of discriminating peptides were decreased in abundance in urine of chronically infected rats, including a peptide derived from neprilysin, a membrane metalloendopeptidase, the expression of which has previously been shown to be diminished in infected urine.

CONCLUSION AND CLINICAL RELEVANCE

Results highlight the diagnostic capabilities of urinary biomarkers to identify reservoir hosts of leptospirosis using CE coupled to MS.

Comparative proteomic analysis of lung tissue from guinea pigs with leptospiral pulmonary haemorrhage syndrome (LPHS) reveals a decrease in abundance of host proteins involved in cytoskeletal and cellular organization

Leptospiral pulmonary haemorrhage syndrome (LPHS) is a particularly severe form of leptospirosis. LPHS is increasingly recognized in both humans and animals and is characterized by rapidly progressive intra-alveolar haemorrhage leading to high mortality. The pathogenic mechanisms of LPHS are poorly understood which hampers the application of effective treatment regimes. In this study a 2-D guinea pig proteome lung map was created and used to investigate the pathogenic mechanisms of LPHS. Comparison of lung proteomes from infected and non-infected guinea pigs via differential in-gel electrophoresis revealed highly significant differences in abundance of proteins contained in 130 spots. Acute phase proteins were the largest functional group amongst proteins with increased abundance in LPHS lung tissue, and likely reflect a local and/or systemic host response to infection. The observed decrease in abundance of proteins involved in cytoskeletal and cellular organization in LPHS lung tissue further suggests that infection with pathogenic Leptospira induces changes in the abundance of host proteins involved in cellular architecture and adhesion contributing to the dramatically increased alveolar septal wall permeability seen in LPHS.

BIOLOGICAL SIGNIFICANCE

The recent completion of the complete genome sequence of the guinea pig (Cavia porcellus) provides innovative opportunities to apply proteomic technologies to an important animal model of disease. In this study, the comparative proteomic analysis of lung tissue from experimentally infected guinea pigs with leptospiral pulmonary haemorrhage syndrome (LPHS) revealed a decrease in abundance of proteins involved in cellular architecture and adhesion, suggesting that loss or down-regulation of cytoskeletal and adhesion molecules plays an important role in the pathogenesis of LPHS. A publically available guinea pig lung proteome map was constructed to facilitate future pulmonary proteomics in this species.

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).

Acute Respiratory Distress Syndrome Manifested by Leptospirosis Successfully Teated by Extracorporeal Membrane Oxygenation (ECMO)

Leptospirosis is recognized as a zoonotic disease that is emerging worldwide. Severe manifestations are associated with high morbidity and mortality rates and may therefore pose an important risk to public health, especially in certain high prevalence areas like Taiwan. The severe pulmonary form of leptospirosis is a lesser known entity and is characterized by intra-alveolar hemorrhage and can lead to acute respiratory failure with resistant hypoxemia, which leads to high mortality rates despite maximally invasive mechanical ventilation and adequate treatment. We herein present a case of severe leptospirosis complicated by massive pulmonary hemorrhage, which was successfully managed by extra corporeal membrane oxygenation.

Post-translational modification of LipL32 during Leptospira interrogans infection

Background

Leptospirosis, a re-emerging disease of global importance caused by pathogenic Leptospira spp., is considered the world's most widespread zoonotic disease. Rats serve as asymptomatic carriers of pathogenic Leptospira and are critical for disease spread. In such reservoir hosts, leptospires colonize the kidney, are shed in the urine, persist in fresh water and gain access to a new mammalian host through breaches in the skin.

Methodology/Principal Findings

Previous studies have provided evidence for post-translational modification (PTM) of leptospiral proteins. In the current study, we used proteomic analyses to determine the presence of PTMs on the highly abundant leptospiral protein, LipL32, from rat urine-isolated L. interrogans serovar Copenhageni compared to in vitro-grown organisms. We observed either acetylation or tri-methylation of lysine residues within multiple LipL32 peptides, including peptides corresponding to regions of LipL32 previously identified as epitopes. Intriguingly, the PTMs were unique to the LipL32 peptides originating from in vivo relative to in vitro grown leptospires. The identity of each modified lysine residue was confirmed by fragmentation pattern analysis of the peptide mass spectra. A synthetic peptide containing an identified tri-methylated lysine, which corresponds to a previously identified LipL32 epitope, demonstrated significantly reduced immunoreactivity with serum collected from leptospirosis patients compared to the peptide version lacking the tri-methylation. Further, a subset of the identified PTMs are in close proximity to the established calcium-binding and putative collagen-binding sites that have been identified within LipL32.

Conclusions/Significance

The exclusive detection of PTMs on lysine residues within LipL32 from in vivo-isolated L. interrogans implies that infection-generated modification of leptospiral proteins may have a biologically relevant function during the course of infection. Although definitive determination of the role of these PTMs must await further investigations, the reduced immune recognition of a modified LipL32 epitope suggests the intriguing possibility that LipL32 modification represents a novel mechanism of immune evasion within Leptospira.

Leptospirosis, caused by pathogenic Leptospira spp., constitutes an increasing global public health threat. Humans are accidental hosts, and acquire the disease primarily from contact with water sources that have been contaminated with urine from infected animals. Rats are asymptomatic carriers of infection and are critical for disease transmission to humans, particularly in urban slum environments. In this study, investigation of Leptospira directly isolated from the urine of infected rats showed acetylation or tri-methylation of the highly abundant leptospiral lipoprotein, LipL32. In comparison, Leptospira grown in culture did not result in any LipL32 lysine modifications. A synthetic peptide derived from LipL32 that incorporated a tri-methylated lysine modification exhibited less reactivity with serum from leptospirosis patients compared to an unmodified version of the peptide, suggesting LipL32 modifications may alter protein recognition by the immune response. This study reports, for the first time, modification of a Leptospira protein during infection, and suggests these modifications may have a functional consequence that contributes to bacterial persistence during infection.

Leptospira Interrogans induces fibrosis in the mouse kidney through Inos-dependent, TLR- and NLR-independent signaling pathways

Background

Leptospira (L.) interrogans are bacteria responsible for a worldwide reemerging zoonosis. Rodents carry L. interrogans asymptomatically in their kidneys and excrete bacteria in the urine, contaminating the environment. Humans get infected through skin contact and develop a mild or severe leptospirosis that may lead to renal failure and fibrosis. L. interrogans provoke an interstitial nephritis, but the induction of fibrosis caused by L. interrogans has not been studied in murine models. Innate immune receptors from the TLR and NLR families have recently been shown to play a role in the development and progression of tissue fibrosis in the lung, liver and kidneys under different pathophysiological situations. We recently showed that TLR2, TLR4, and NLRP3 receptors were crucial in the defense against leptospirosis. Moreover, infection of a human cell line with L. interrogans was shown to induce TLR2-dependent production of fibronectin, a component of the extracellular matrix. Therefore, we thought to assess the presence of renal fibrosis in L. interrogans infected mice and to analyze the contribution of some innate immune pathways in this process.

Methodology/principal findings

Here, we characterized by immunohistochemical studies and quantitative real-time PCR, a model of Leptospira-infected C57BL/6J mice, with chronic carriage of L. interrogans inducing mild renal fibrosis. Using various strains of transgenic mice, we determined that the renal infiltrates of T cells and, unexpectedly, TLR and NLR receptors, are not required to generate Leptospira-induced renal fibrosis. We also show that the iNOS enzyme, known to play a role in Leptospira-induced interstitial nephritis, also plays a role in the induction of renal fibrosis.

Conclusion/significance

To our knowledge, this work provides the first experimental murine model of sustained renal fibrosis induced by a chronic bacterial infection that may be peculiar, since it does not rely on TLR or NLR receptors. This model may prove useful to test future therapeutic strategies to combat Leptospira-induced renal lesions.

Leptospirosis is a bacterial disease transmitted by asymptomatic rodents to humans. The symptoms may be mild, or severe with kidney failure. Renal fibrosis, occurring during inflammatory situations, is characterized by the pathological accumulation of extra-cellular matrix components and can compromise the kidney functions of patients with leptospirosis. Recent research revealed that both innate and adaptive immune responses are involved in the establishment of fibrosis, in several organs and in different pathophysiological situations. In the present study, we characterized a mouse model of chronic infection with Leptospira that provokes mild renal fibrosis. We show that fibrogenesis requires the presence of live Leptospira in the kidney and that B and T cells from the adaptive immune response do not participate in the induction of renal fibrosis. Unexpectedly, we also found that innate immune receptors, TLRs and NLRs, are not involved in the Leptospira-induced fibrosis. Finally, we show that the enzyme responsible for NO production, iNOS, known to participate in renal inflammatory lesions induced by Leptospira, is also involved in renal fibrosis. Our work provides a novel mouse model to study fibrosis occurring due to leptospirosis.

Severe Pulmonary Involvement in Leptospirosis: Alternate antibiotics and systemic steroids

Pulmonary complications in leptospirosis, though common, are often unrecognized in a non-endemic area. We report here a patient with leptospirosis and severe pulmonary involvement who was treated with meropenem (1 g every 8 hours), moxifloxacin (400 mg once daily), and high doses of corticosteroids. Systemic steroids were continued for 3 months because of persistent pulmonary lesions.

Anicteric leptospirosis-associated severe pulmonary hemorrhagic syndrome: a case series study

In leptospirosis, severe pulmonary hemorrhagic syndrome has replaced Weil's disease as the main cause of mortality, with rates of up to 75%. Four men, all farmers, were admitted to the intensive care unit between August 2009 and July 2010 with a diagnosis of acute respiratory distress syndrome. All patients presented with fever, hemoptysis, bilateral pulmonary infiltrates in chest radiographs, and thrombocytopenia and had compatible epidemiological history with leptospirosis; 3 patients had anemia, 3 had renal failure, 2 had increased creatine kinase, whereas bilirubin was slightly increased in only 1 patient. Leptospirosis was diagnosed serologically in all cases. Empirical therapy with ceftriaxone was administered immediately to all patients, while implementation of ARDSnet protective mechanical ventilation approach combined with an early goal-directed hemodynamic approach led to a relatively low mortality rate (25%). Acute Physiology and Chronic Health Evaluation II, Simplified Acute Physiology Score II and Sepsis-Related Organ Failure Assessment scoring systems were unable to predict the outcome of the patients with leptospirosis-associated severe pulmonary hemorrhagic syndrome.

Pulmonary manifestations of leptospirosis

Leptospirosis has a spectrum of presentation which ranges from mild disease to a severe form comprising of jaundice and renal failure. Involvement of the lung can vary from subtle clinical features to deadly pulmonary hemorrhage and acute respiratory distress syndrome. Of late, it has been identified that leptospirosis can present atypically with predominant pulmonary manifestations. This can delay diagnosis making and hence optimum treatment. The purpose of this review is to bring together all the reported pulmonary manifestations of leptospirosis and the recent trends in the management.

Establishment of a leptospirosis model in guinea pigs using an epicutaneous inoculations route

Background

Leptospires are presumed to enter their host via small abrasions or breaches of the skin. The intraperitoneal route, although commonly used in guinea pig and hamster models of leptospirosis, does not reflect conditions encountered during natural infection. The aim of this study is to develop a novel leptospirosis guinea pig model through epicutaneous route and to elucidate the pathogenesis of leptospirosis in experimental guinea pigs by comparing the data from other studies using different infection routes.

Methods

The guinea pigs were inoculated with 5 × 10⁸ Leptospira interrogans strain Lai onto either shaved-only or abraded skin. The guinea pigs were sacrificed at 2, 8, 24, 48, 72, 96 and 144 h post-infection (p.i.) followed by harvest of the lungs, liver, kidneys, spleen, and the skin around the inoculated sites for further examinations. Hematoxylin and eosin (HE) staining and electron microscopy were used to detect the pathologic changes. Real time PCR and immunohistochemistry staining were performed to detect dynamic distribution of leptospires in blood and tissues, respectively.

Results

In the guinea pigs with abraded skin inoculations, leptospires were detected in blood as early as 2 h post infection (p.i.) and then disseminated to the liver, lungs and kidneys of almost all animals within 96 h p.i.. Leptospires were also detected engulfed in the swelling vascular endothelial cells and were frequently aggregated around the capillaries in the dermis and subcutaneous tissue under the inoculated site. For the guinea pigs with abraded skin inoculations, hemorrhage at the dermis around the inoculated site was found before the appearance of internal organs hemorrhage, severe lesions such as hemorrhages in the lungs, nephritis, jaundice, haematuria were also observed, and two of seven guinea pigs died at 144 h p.i. while no lesions and leptospires were detected in the shaved-only guinea pigs using the same dose of strain Lai.

Conclusion

Intact keratinocyte layer is a very efficient barrier against leptospires, and intact skin can prevent the infiltration of leptosipres to the host. Leptospires can penetrate abraded skin and quickly establish a systemic infection by crossing tissue barriers. We have successfully established a novel leptospirosis guinea pig model through epicutaneous inoculations route, which replicates a natural course of infection and appears to be an alternative way to investigate the pathogenesis of leptospirosis, especially in terms of early stage of host-pathogen interactions. This novel model may also be advantageous for studies of the mechanisms involved in cutaneous barriers and epidermal interactions with this organism.

The emergence of severe pulmonary hemorrhagic leptospirosis: questions to consider

Since the 1980s, the incidence of severe pulmonary hemorrhage caused by Leptospira spp. infection has increased. The mild, non-specific symptoms or the more classical form of severe disease with hepatorenal manifestations, Weil's syndrome, predominate world-wide. However, several regions of the world have seen increases in numbers of patients with pulmonary hemorrhage attributed to leptospirosis. The reasons behind the emergence of this syndrome, which carries a high mortality rate, are not known. Several avenues for future research may shed light on the mechanisms involved in development of pulmonary hemorrhage, and inform targeted therapeutics to improve outcomes. Possibilities to consider include: (1) emergence of new bacterial strains, (2) acquisition of virulence traits by strains in the endemic regions, (3) changes in underlying health of the affected human populations, and (4) increased recognition of the syndrome and better record keeping by the medical and veterinary communities. Determining the causes of emerging clinical manifestations presents challenges and opportunities for potentially life-saving research into the pathogenesis of a number of infectious diseases, including leptospirosis.

Leptospirosis prevalence in Chinese populations in the last two decades

Leptospirosis is a common zoonotic disease in China. From 1991 to 2010, its average annual incidence was 0.70 cases per 100,000 population. During these two decades, three major outbreaks of leptospirosis occurred due to flooding and heavy rainfall. Leptospira interrogans serogroup Icterohaemorrhagiae serovar Lai is the predominant leptospire responsible for at least 60% of Chinese cases, and Apodemus agrarius serves as the major animal host. Based on the differences in predominant leptospiral serovars, epidemic features and incidence, there are three leptospirosis-prevalent regions in China. However, the incidence has significantly decreased in the last ten years.

Thrombocytopenia in leptospirosis and role of platelet transfusion

Aim:

The study was designed to find out the incidence of thrombocytopenia in leptospirosis and to correlate thrombocytopenia with other parameters like renal failure, hepatic failure and bleeding manifestation like adult respiratory distress syndrome and to assess the role of platelet transfusion.

Materials and Methods:

50 cases of leptospirosis during the month of July and August 2005 were retrospectively analyzed. Criteria for selection were Lepto Tek Dri - dot test positive cases of the clinically suspected cases of Leptospirosis. Degree of thrombocytopenia was categorized as severe, moderate and mild. Presence of thrombocytopenia was clinically correlated with parameters like renal dysfunction, hepatic dysfunction and hemorrhagic manifestations (mainly ARDS). Role of platelet transfusion was assessed with reference to presence and degree of thrombcytopenia and hemorrhagic manifestations.

Results:

Out of total 50 patients 26 were male and 24 were females. Major bleeding manifestation in the form of ARDS was seen in 15 (30%) of patients. 28 (56%) patients had thrombocytopenia and 22 (44%) patients had normal platelet counts. Total number of patients with renal dysfunction was 24 (48%). Only four (18.18%) patients with normal platelet counts had renal dysfunction while 20 (71.42%) patients with thrombocytopenia had renal dysfunction. Only two (9.09%) patients with normal platelet counts and 48 (46.42%) patients with thrombocytopenia had hepatorenal dysfunction. Total number of patients with ARDS was 15 (30%). Of these two (13.33%) had normal platelet count while 13 (86.6%) patients were thrombocytopenic. Total 47 units of platelets were transfused to 12 patients in our study. Of these seven patients with severe thrombocytopenia required total 28 units, two patients with moderate thrombocytopenia required total seven units and patients with mild thrombocytopenia were transfused total 12 units of platelets.

Conclusion:

It is important to anticipate and recognize thrombocytopenia early in the course of leptospirosis so that appropriate steps can be taken to prevent it and to treat it with platelet transfusion when it develops

Pulmonary hemorrhage in horses seropositive to leptospirosis

The aim of this study was to verify the occurrence and severity of pulmonary hemorrhage (PH) in horses seropositive or not to leptospirosis. A total of 84 training horses were tested for anti-Leptospira antibodies and submitted to endoscopy of the upper airways 30-60 minutes after exercise. Forty-nine (46.4%) horses were seropositive (titer>100) to serovar Copenhageni. Seventeen horses (20.2%) presented PH in different grades, significantly more commonly observed in seropositives (34.7%) than seronegatives (8.6%) (p<0.05), and also more severe in the first. Additionally, a seropositive horse is 4.26 times more likely (OR) to present PH than a seronegative one. Fifteen days after specific antibiotic treatment for leptospirosis a significant improvement in grade of hemorrhage was observed. Therefore it is suggested that leptospirosis may potentiate the severity of PH and that specific antibiotic treatment directed towards leptospirosis may help to control the disease.

Potent innate immune response to pathogenic leptospira in human whole blood

Background

Leptospirosis is caused by pathogenic spirochetes of the genus Leptospira. The bacteria enter the human body via abraded skin or mucous membranes and may disseminate throughout. In general the clinical picture is mild but some patients develop rapidly progressive, severe disease with a high case fatality rate. Not much is known about the innate immune response to leptospires during haematogenous dissemination. Previous work showed that a human THP-1 cell line recognized heat-killed leptospires and leptospiral LPS through TLR2 instead of TLR4. The LPS of virulent leptospires displayed a lower potency to trigger TNF production by THP-1 cells compared to LPS of non-virulent leptospires.

Methodology/Principal Findings

We investigated the host response and killing of virulent and non-virulent Leptospira of different serovars by human THP-1 cells, human PBMC's and human whole blood. Virulence of each leptospiral strain was tested in a well accepted standard guinea pig model. Virulent leptospires displayed complement resistance in human serum and whole blood while in-vitro attenuated non-virulent leptospires were rapidly killed in a complement dependent manner. In vitro stimulation of THP-1 and PBMC's with heat-killed and living leptospires showed differential serovar and cell type dependence of cytokine induction. However, at low, physiological, leptospiral dose, living virulent complement resistant strains were consistently more potent in whole blood stimulations than the corresponding non-virulent complement sensitive strains. At higher dose living virulent and non-virulent leptospires were equipotent in whole blood. Inhibition of different TLRs indicated that both TLR2 and TLR4 as well as TLR5 play a role in the whole blood cytokine response to living leptospires.

Conclusions/Significance

Thus, in a minimally altered system as human whole blood, highly virulent Leptospira are potent inducers of the cytokine response.

An emerging pulmonary haemorrhagic syndrome in dogs: similar to the human leptospiral pulmonary haemorrhagic syndrome?

Severe pulmonary haemorrhage is a rare necropsy finding in dogs but the leptospiral pulmonary haemorrhagic syndrome (LPHS) is a well recognized disease in humans. Here we report a pulmonary haemorrhagic syndrome in dogs that closely resembles the human disease. All 15 dogs had massive, pulmonary haemorrhage affecting all lung lobes while haemorrhage in other organs was minimal. Histologically, pulmonary lesions were characterized by acute, alveolar haemorrhage without identifiable vascular lesions. Seven dogs had mild alveolar wall necrosis with hyaline membranes and minimal intraalveolar fibrin. In addition, eight dogs had acute renal tubular necrosis. Six dogs had a clinical diagnosis of leptospirosis based on renal and hepatic failure, positive microscopic agglutination test (MAT) and/or positive blood/urine Leptospira-specific PCR. Leptospira could not be cultured post mortem from the lungs or kidneys. However, Leptospira-specific PCR was positive in lung, liver or kidneys of three dogs. In summary, a novel pulmonary haemorrhagic syndrome was identified in dogs but the mechanism of the massive pulmonary erythrocyte extravasation remains elusive. The lack of a consistent post mortem identification of Leptospira spp. in dogs with pulmonary haemorrhage raise questions as to whether additional factors besides Leptospira may cause this as yet unrecognized entity in dogs.

Clinical and imaging manifestations of hemorrhagic pulmonary leptospirosis: a state-of-the-art review

Leptospirosis, a spirochetal zoonosis, is frequently unrecognized due to its manifestation as an undifferentiated fever. It is an emerging infectious disease that has changed from an occupational disease of veterinarians, farmers, butchers, and other animal handlers to a cause of epidemics in poor and decayed urban communities in developing countries. Humans are infected when mucous membranes or abraded skin come into direct contact with the urine of infected animals, especially rats and dogs. Mortality from severe leptospirosis is high, even when optimal treatment is provided. The diagnosis of leptospirosis is based on clinical findings, history of direct or indirect exposure to infected animals in endemic areas, and positive serological tests. It should be considered in the differential diagnosis of patients with febrile illnesses associated with pneumonitis and respiratory failure, especially when hemoptysis is present. Severe pulmonary involvement in leptospirosis consists primarily of hemorrhagic pneumonitis. In advanced cases, adult respiratory distress syndrome and massive pulmonary hemorrhage may occur. Chest radiographs show bilateral alveolar infiltrates and/or resemble viral pneumonia, bronchopneumonia, tuberculosis, adult respiratory distress syndrome, and other causes of pulmonary hemorrhage such as Goodpasture syndrome. High-resolution computed tomography scans may show nodular infiltrates, areas of consolidation, ground-glass attenuation, and crazy-paving patterns. Bronchoalveolar lavage and autopsy studies have suggested that ground-glass opacities and air-space consolidations are secondary to pulmonary hemorrhage. Although not specific, the presence of these computed tomography findings in a febrile patient with an appropriate history should suggest a diagnosis of leptospirosis.

[Respiratory functional characteristics of human leptospirosis]

INTRODUCTION

Respiratory impairment may be the main clinical manifestation of human leptospirosis.

METHODS

With the aim of describing the respiratory functional characteristics of this disease, 21 patients were evaluated using pulse oximetry and spirometry at two times: an initial evaluation and after around 28 days.

RESULTS

Two (9.5%) patients presented peripheral oxygen saturation of less than 95%. Normal spirometric patterns were observed in eight (38.1%); cases restrictive ventilatory disorders were inferred in seven (33.3%), obstructive disorders with reduced forced vital capacity in four (19%), and nonspecific disorders in two (9.5%). Abnormal spirometry findings were associated with worse APACHE II scores (p = 0.02) and abnormalities on chest x-ray (p = 0.05). After clinical resolution, significant functional gain was observed (p < 0.05) in the group of patients with abnormal spirometry findings.

CONCLUSIONS

It was concluded that respiratory functional abnormalities were detected during the course of the disease and were associated with greater clinical severity and higher frequency of chest radiographic abnormalities.

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.

Leptospirosis in a European intensive care unit

We report the first series of indigenous European patients with severe leptospirosis in need of intensive care because of acute respiratory distress syndrome, coma and shock. The all-cause hospital mortality was 16.7%, and may have been influenced by relatively early diagnosis, indicating the need for heightened clinical suspicion in Europe.

Leptospirosis pulmonary haemorrhage syndrome is associated with linear deposition of immunoglobulin and complement on the alveolar surface

Leptospirosis is a zoonotic infection associated with severe diseases such as leptospirosis pulmonary haemorrhage syndrome (LPHS). The cause of pulmonary haemorrhage is unclear. Understanding which mechanisms and processes are involved in LPHS will be important in treatment regimens under development for this life-threatening syndrome. In the present study, we evaluated 30 lung specimens from LPHS patients and seven controls using histology and immunohistochemistry (detection of IgM, IgG, IgA and C3) in order to describe the pathological features associated with this syndrome. Immunoglobulin deposits were detected on the alveolar surface in 18/30 LPHS patients. Three staining patterns were observed for the immunoglobulins and C3 in the lung tissues of LPHS patients: AS, delicate linear staining adjacent to the alveolar surface, which was indicative of a membrane covering the luminal surface of type I and II pneumocyte cells; S, heterogeneous staining which was sporadically distributed along the alveolar septum; and IA, weak, focal intra-alveolar granular staining. Human LPHS is associated with individual and unique histological patterns that differ from those of other causes of pulmonary haemorrhage. In the present study, it was found that the linear deposition of immunoglobulins (IgA, IgG and IgM) and complement on the alveolar surface may play a role in the pathogenesis of pulmonary haemorrhage in human leptospirosis.

Chemokines expression during Leptospira interrogans serovar Copenhageni infection in resistant BALB/c and susceptible C3H/HeJ mice

The role of innate immune responses in protection against leptospirosis remains unclear. We examined the expression of the chemokines CCL2/JE (MCP-1), CCL3/MIP-1 alpha (MIP-1 alpha) and CXCL1/KC (IL-8) regarding resistance and susceptibility to leptospirosis in experimental mice models BALB/c and C3H/HeJ, respectively. A virulent strain of Leptospira interrogans serovar Copenhageni was used in this study. Twenty-five animals of each mouse strain of C3H/HeJ and BALB/c, were infected intraperitoneally with 10(6) cells. Five un-infected animals of each strain were kept as control. Mortality of C3H/HeJ mouse was observed while BALB/c mice were asymptomatic. The presence of leptospire DNA in tissues of infected animals was demonstrated by PCR. Chemokines were measured in serum, spleen, liver, kidney and lung of both strains of animals using immunoenzymatic assay (ELISA). Elevations in the levels of chemokines MCP-1 and IL-8 occurred in all organs and sera of C3H/HeJ and BALB/c infected mice. The levels of MIP-1 alpha were lower when compared to MCP-1 and IL-8 in all analyzed organs, with a slight increase in liver and kidney. Our results indicate that the expression of inflammatory mediators can vary greatly, depending on the tissue and mouse strains. It is possible that the resistance to Leptospira can be partially correlated to the increase of MIP-1 alpha observed in BALB/c mice, while an increasing and a sustained expression of MCP-1 and IL-8 in the lungs of C3H/HeJ mice can be correlated to the severity and progression of leptospirosis.

Crystal structure of LipL32, the most abundant surface protein of pathogenic Leptospira spp

Spirochetes of the genus Leptospira cause leptospirosis in humans and animals worldwide. Proteins exposed on the bacterial cell surface are implicated in the pathogenesis of leptospirosis. However, the biological role of the majority of these proteins is unknown; this is principally due to the lack of genetic systems for investigating Leptospira and the absence of any structural information on leptospiral antigens. To address this, we have determined the 2.0-A-resolution structure of the lipoprotein LipL32, the most abundant outer-membrane and surface protein present exclusively in pathogenic Leptospira species. The extracellular domain of LipL32 revealed a compact, globular, "jelly-roll" fold from which projected an unusual extended beta-hairpin that served as a principal mediator of the observed crystallographic dimer. Two acid-rich patches were also identified as potential binding sites for positively charged ligands, such as laminin, to which LipL32 has a propensity to bind. Although LipL32 shared no significant sequence identity to any known protein, it possessed structural homology to the adhesins that bind components of the extracellular matrix, suggesting that LipL32 functions in an analogous manner. Moreover, the structure provides a framework for understanding the immunological role of this major surface lipoprotein.

Hemorrhagic pulmonary leptospirosis: three cases from the Yucatan peninsula, Mexico

Three leptospirosis cases with lung involvement are reported from the Yucatan Peninsula, Mexico. All three patients were admitted to the intensive care unit due to acute respiratory failure. Treatment with antibiotics resulted in favorable evolution despite the negative prognosis. Leptospirosis should be included in the differential diagnosis of patients with fever and lung involvement.

Proteomic analysis of Leptospira interrogans shed in urine of chronically infected hosts

Leptospirosis is a global zoonotic disease. The causative agent, pathogenic Leptospira species, survives in the renal tubules of chronically infected hosts, from where leptospires are shed via urine into the environment. Infection of new hosts can present as an array of acute and chronic disease processes reflecting variations in host-pathogen interactions. The present study was designed to reproduce the carrier phase of infection in Rattus norvegicus, thus facilitating shedding of leptospires in urine. Leptospires shed in urine were collected for proteomic analysis because these organisms reflect a naturally virulent form of Leptospira associated with infection of new hosts. Experimentally infected rats remained clinically asymptomatic but shed leptospires in urine for several months at concentrations of up to 10(7) leptospires/ml of urine. Proteomic analysis of rat urine-isolated leptospires compared to in vitro-cultivated leptospires confirmed differential protein and antigen expression, as demonstrated by two-dimensional gel electrophoresis and immunoblotting. Furthermore, while serum from chronically infected rats reacted with many antigens of in vitro-cultivated Leptospira, few antigens of rat urine-isolated Leptospira were reactive. Results confirm that differential protein expression by Leptospira during chronic infection facilitates its persistence in the presence of a specific host antibody response.

LipL32 is an extracellular matrix-interacting protein of Leptospira spp. and Pseudoalteromonas tunicata

LipL32 is the major outer membrane protein in pathogenic Leptospira. It is highly conserved throughout pathogenic species and is expressed in vivo during human infection. While these data suggest a role in pathogenesis, a function for LipL32 has not been defined. Outer membrane proteins of gram-negative bacteria are the first line of molecular interaction with the host, and many have been shown to bind host extracellular matrix (ECM). A search for leptospiral ECM-interacting proteins identified the major outer membrane protein, LipL32. To verify this finding, recombinant LipL32 was expressed in Escherichia coli and was found to bind Matrigel ECM and individual components of ECM, including laminin, collagen I, and collagen V. Likewise, an orthologous protein found in the genome of Pseudoalteromonas tunicata strain D2 was expressed and found to be functionally similar and immunologically cross-reactive. Lastly, binding activity was mapped to the C-terminal 72 amino acids. These studies show that LipL32 and an orthologous protein in P. tunicata are immunologically cross-reactive and function as ECM-interacting proteins via a conserved C-terminal region.

Severe pulmonary haemorrhage accompanying hepatorenal failure in fulminant leptospirosis

Leptospirosis is a re-emerging spirochetal zoonosis with a worldwide distribution affecting both animals and humans. The clinical syndromes may vary from a subclinical infection to a severe illness. Although it may potentially have a fulminant and fatal course, leptospirosis usually remains as an underdiagnosed cause of multiorgan failure. In this study, we report a patient with leptospirosis who presented with a fulminant course of diffuse alveolar haemorrhage and hepatorenal failure. His clinical condition deteriorated, despite appropriate antibiotic therapy and haemodialysis. However, he showed prompt clinical improvement when corticosteroids and plasma exchange were instituted in addition to the original therapy. We conclude that leptospirosis should be considered in any case presenting with pulmonary haemorrhage and hepatorenal failure. Plasma exchange and corticosteroids may be a choice of treatment in selected patients unresponsive to conventional therapy. Potential benefits of plasma exchange and corticosteroids may be based on a toxin- and/or cytokine-mediated pathogenesis of the disease.