Characterizing interactions of Leptospira interrogans with proximal renal tubule epithelial cells

Impaired functions of human monocyte-derived dendritic cells and induction of regulatory T cells by pathogenic Leptospira

Leptospirosis is a global zoonosis caused by pathogenic Leptospira. The disease outcome is influenced by the interplay between innate and adaptive immune responses. Dendritic cells (DCs) play a crucial role in shaping the adaptive immune response. A recent study revealed that pathogenic Leptospira limited the activation of human monocyte-derived dendritic cells (MoDCs) compared to non-pathogenic Leptospira, but their impact on T-cell responses has not been investigated. Our study is the first to explore how viable pathogenic and non-pathogenic Leptospira affect the interaction between human MoDCs and T cells. We found that MoDCs infected with pathogenic leptospires (L. interrogans serovar Pomona and a clinical isolate, MoDCs-P) exhibited lower levels of CD80 and CD83 expression, suggesting partially impaired MoDC maturation, induced regulatory T cells (Tregs) while failing to induce CD4+ T cell proliferation, compared to MoDCs infected with non-pathogenic leptospires (L. biflexa serovar Patoc and L. meyeri serovar Ranarum, MoDCs-NP). In contrast, non-pathogenic leptospires enhanced MoDC maturation and induced higher T cell proliferation including IFN-γ-producing CD4+ T cells, indicative of a Th1-type response. Furthermore, pathogenic leptospires induced higher MoDC apoptosis through a cysteine aspartic acid-specific protease-3 (caspase-3)-dependent pathway and upregulated expression of the prostaglandin-endoperoxide synthase 2 (PTGS2) gene. Notably, prostaglandin E2 (PGE2), a product of the PTGS2 pathway, was found at higher levels in the sera of patients with acute leptospirosis and in the supernatant of MoDCs-P, possibly contributing to Treg induction, compared to those of healthy donors and MoDCs-NP, respectively. In conclusion, this study reveals a novel immunosuppressive strategy employed by pathogenic Leptospira to evade host immunity by partially impairing MoDC maturation and inducing Tregs. These findings deepen our understanding of leptospirosis pathogenesis in humans and may provide a novel strategy to modulate DCs for the prevention and treatment of the disease.

Proteomic profile of naturally released extracellular vesicles secreted from Leptospira interrogans serovar Pomona in response to temperature and osmotic stresses

Bacterial extracellular vesicles (EVs) are generally formed by pinching off outer membrane leaflets while simultaneously releasing multiple active molecules into the external environment. In this study, we aimed to identify the protein cargo of leptospiral EVs released from intact leptospires grown under three different conditions: EMJH medium at 30 °C, temperature shifted to 37 °C, and physiologic osmolarity (EMJH medium with 120 mM NaCl). The naturally released EVs observed under transmission electron microscopy were spherical in shape with an approximate diameter of 80-100 nm. Quantitative proteomics and bioinformatic analysis indicated that the EVs were formed primarily from the outer membrane and the cytoplasm. The main functional COG categories of proteins carried in leptospiral EVs might be involved in cell growth, survival and adaptation, and pathogenicity. Relative to their abundance in EVs grown in EMJH medium at 30 °C, 39 and 69 proteins exhibited significant changes in response to the temperature shift and the osmotic change, respectively. During exposure to both stresses, Leptospira secreted several multifunctional proteins via EVs, while preserving certain virulence proteins within whole cells. Therefore, leptospiral EVs may serve as a decoy structure for host responses, whereas some virulence factors necessary for direct interaction with the host environment are reserved in leptospiral cells. This knowledge will be useful for understanding the pathogenesis of leptospirosis and developing as one of vaccine platforms against leptospirosis in the future.

Degradation of p0071 and p120-catenin during adherens junction disassembly by Leptospira interrogans

Leptospira interrogans disseminates hematogenously to reach the target organs by disrupting epithelial adherens junctions (AJs), thus causing leptospirosis, which is a globally neglected zoonotic disease. L. interrogans induces E-cadherin (E-cad) endocytosis and cytoskeletal rearrangement during AJ disassembly, but the detailed mechanism remains unknown. Elucidation of AJ disassembly mechanisms will guide new approaches to developing vaccines and diagnostic methods. In this study, we combine proteomic and imaging analysis with chemical inhibition studies to demonstrate that disrupting the AJs of renal proximal tubule epithelial cells involves the degradation of two armadillo repeat-containing proteins, p0071 and p120-catenin, that stabilize E-cad at the plasma membrane. Combining proteasomal and lysosomal inhibitors substantially prevented p120-catenin degradation, and monolayer integrity destruction without preventing p0071 proteolysis. In contrast, the pan-caspase inhibitor Z-VAD-FMK inhibited p0071 proteolysis and displacement of both armadillo repeat-containing proteins from the cell-cell junctions. Our results show that L. interrogans induces p120-catenin and p0071 degradation, which mutually regulates E-cad stability by co-opting multiple cellular degradation pathways. This strategy may allow L. interrogans to disassemble AJs and disseminate through the body efficiently.

Design, green synthesis, and quorum sensing quenching potential of novel 2-oxo-pyridines containing a thiophene/furan scaffold and targeting a LasR gene on P. aeruginosa

The current trend in fighting bacteria is attacking the virulence and quorum-sensing (QS) signals that control bacterial communication and virulence factors, especially biofilm formation. This study reports new Schiff bases and tetracyclic rings based on a pyridine pharmacophore by two methods: a green approach using CAN and a conventional method. The structure of designed derivatives was confirmed using different spectroscopies (IR and 1H/13C NMR) and elemental analysis. The designed derivatives exhibited good to moderate inhibition zones against bacterial and fungal pathogens. In addition, six compounds 2a,b, 3a,b, and 6a,b displayed potency against tested pathogens with eligible MIC and MBC values compared to standard antimicrobial agents. Compound 2a displayed MIC values of 15.6 μg mL-1 compared to Gentamicin (MIC = 250 μg mL-1 against K. pneumoniae), while compound 6b exhibited super-potent activity against P. aeruginosa, and K. pneumoniae with MIC values of 62.5 and 125 μg mL-1, as well as MBC values of 31.25 and 15.6 μg mL-1 compared to Gentamicin (MIC = 250 and 125 μg mL-1 and MBC = 62.5 μg mL-1), respectively. Surprisingly, these six derivatives revealed bactericidal and fungicidal potency and remarkable anti-biofilm activity that could significantly reduce the biofilm formation against MRSA, E. coli, P. aeruginosa, and C. albicans. Furthermore, the most active derivatives reduced the LasR gene's production between 10-40% at 1/8 MICs compared with untreated P. aeruginosa. Besides, they demonstrated promising safety profile on Vero cells (normal cell lines) with IC50 values ranging between (175.17 ± 3.49 to 344.27 ± 3.81 μg mL-1). In addition, the in silico ADMET prediction was carried out and the results revealed that these compounds could be used with oral bioavailability with low toxicity prediction when administered as a candidate drug. Finally, the molecular docking simulation was performed inside LasR and predicted the key binding interactions responsible for the activity that corroborated the biological results.

Epidemiological Characteristics and Trends in the Incidence of Leptospirosis in Japan: A Nationwide, Observational Study from 2006 to 2021

During this age of climate change, the incidence of tropical diseases may change. This study compared the epidemiological characteristics and trends of leptospirosis in Japan between the endemic region, Okinawa, and the rest of the country. Infectious Diseases Weekly Reports were used to determine the numbers and crude incidence rates of leptospirosis. Data were stratified by sex, age, the estimated location of the infection, the notified regions, and the reporting month. A joinpoint regression analysis was performed to estimate the annual percentage change (APC). During the 16-year study period (2006-2021), 543 leptospirosis cases were reported, with male dominance (86.2%). Approximately half of these cases were reported from Okinawa (47.1%). The patients were relatively younger in Okinawa (20-29 years, 23.4%; 30-39 years, 20.7%) than outside Okinawa. The frequency of imported cases was significantly higher outside Okinawa (0.4% versus 14.3%). The incidences of leptospirosis in and outside Okinawa were apparently higher during the summer and typhoon seasons. The annual crude incidence ratios were 20-200 times higher in Okinawa than in the rest of the country. The average APCs for the entire study period in Okinawa and the rest of Japan were 1.6% (95% CI: -5.9 to 9.6) and -1.8% (95% CI: -7.8 to 4.6), respectively, without any particular trends. Collectively, the patient profile of leptospirosis differed between Okinawa (younger men) and outside Okinawa (middle- or older-aged men with a history of traveling abroad). The disease remains a neglected tropical disease; continuous surveillance with close monitoring is required.

Case Report: Leptospirosis after a Typhoon Disaster Outside the Endemic Region, Japan

Leptospirosis is a zoonotic disease that primarily affects people in tropical and subtropical areas worldwide. Owing to the temperate climate of Japan, leptospirosis is not endemic across the country. Domestic cases of leptospirosis have been mainly reported in Okinawa and the southwestern subtropical islands, but not in the other regions. Here, we describe a case of leptospirosis that developed and was diagnosed outside the domestically endemic region. Notably, disease onset occurred shortly after the patient experienced a flood after a typhoon disaster. With global warming, the international prevalence of leptospirosis may change. Physicians outside currently endemic areas must be aware of this tropical disease.

Leptospiral sphingomyelinase Sph2 as a potential biomarker for diagnosis of leptospirosis

Leptospirosis is an underestimated infectious tropical disease caused by the spirochetes belonging to the genus Leptospira. Leptospirosis is grossly underdiagnosed due to its myriad symptoms, varying from mild febrile illness to severe haemorrhage. Laboratory tests for leptospirosis is an extremely important and potent way for disease diagnosis, as the clinical manifestations are very similar to other febrile diseases. Currently available diagnostic techniques are time-consuming, require expertise and sophisticated instruments, and cannot identify the disease at an early phase of infection. Early diagnosis of leptospirosis is the need of the hour while considering the severe complications after the infection and the rate of mortality after misdiagnosis. Secretion of Leptospira-specific sphingomyelinases in leptospirosis patient's urine within a few days of the onset of infection is quite common and is a virulence factor present only in pathogenic Leptospira species. Herein, the structural and functional importance of leptospiral sphingomyelinase Sph2 in leptospirosis pathogenesis, as well as the potential of screening urinary Sph2 for diagnosis and the scope for developing a rapid and easily affordable point-of-care test for urinary leptospiral sphingomyelinase Sph2 as an alternative to current diagnostic methods are discussed.

The diagnosis of leptospirosis complicated by pulmonary tuberculosis complemented by metagenomic next-generation sequencing: A case report

Leptospirosis is a zoonotic infection caused by the pathogenic Leptospira. Leptospirosis is transmitted mainly through contact with contaminated rivers, lakes, or animals carrying Leptospira. Human leptospirosis has a wide range of non-specific clinical manifestations ranging from fever, hypotension, and myalgia to multi-organ dysfunction, which severely hampers the timely clinical diagnosis and treatment of leptospirosis. Therefore, there is an urgent clinical need for an efficient strategy/method that can be used for the accurate diagnosis of leptospirosis, especially in critically ill patients. Here, we report a case of a 75-year-old male patient with clinical presentation of fever, cough, and diarrhea. Initial laboratory tests and a computed tomography (CT) scan of the chest suggested only tuberculosis. The patient was finally diagnosed with pulmonary tuberculosis (PTB) combined with leptospirosis by sputum Xpert MTB RIF, epidemiological investigations, and delayed serological testing. Furthermore, through metagenomic next-generation sequencing (mNGS) of clinical samples of cerebrospinal fluid (CSF), urine, plasma and sputum, the causative pathogens were identified as Mycobacterium tuberculosis complex and Leptospira spp. With specific treatment for both leptospirosis and tuberculosis, and associated supportive care (e.g., hemodialysis), the patient showed a good prognosis. This case report suggests that mNGS can generate a useful complement to conventional pathogenic diagnostic methods through more detailed etiological screening (i.e., at the level of species or species complex).

Bovine leptospirosis: effects on reproduction and an approach to research in Colombia

Leptospirosis is the most widespread zoonosis worldwide, causing severe effects on beef and dairy cattle farming and other livestock. Colombia geographical location in the tropical zone, high biodiversity, and climatic conditions promote Leptospira growth and prevalence. This review article presents state-of-the-art knowledge about the effects of leptospirosis on bovine reproduction and a critical analysis of the research carried out in Colombia. The analysis of the information allows us to infer a sustained increase in prevalence over the last decade in the densest livestock production areas and a high serovar diversity of circulating pathogenic Leptospira. Given the zoonotic nature of leptospirosis, an inter-institutional effort is required to implement prevention, control, and monitoring programs under one-health concept.

Analysis of human clinical and environmental Leptospira to elucidate the eco-epidemiology of leptospirosis in Yaeyama, subtropical Japan

Background

Leptospirosis, a zoonosis caused by species in the spirochete genus Leptospira, is endemic to the Yaeyama region in Okinawa, subtropical Japan. Species of the P1 subclade “virulent” group, within the genus Leptospira, are the main etiological agents of leptospirosis in Okinawa. However, their environmental persistence is poorly understood. This study used a combination of bacterial isolation and environmental DNA (eDNA) metabarcoding methods to understand the eco-epidemiology of leptospirosis in this endemic region.

Findings

Polymerase chain reaction (PCR) characterized twelve human clinical L. interrogans isolates belonging to the P1 subclade “virulent” subgroup and 11 environmental soil isolates of the P1subclade “low virulent” subgroup (genetically related to L. kmetyi, n = 1; L. alstonii, n = 4; L. barantonii, n = 6) from the Yaeyama region targeting four virulence-related genes (lipL32, ligA, ligB and lpxD1). Clinical isolates were PCR positive for at least three targeted genes, while all environmental isolates were positive only for lipL32. Analysis of infected renal epithelial cells with selected clinical and environmental strains, revealed the disassembly of cell-cell junctions for the Hebdomadis clinical strain serogroup. Comparison of leptospiral eDNA during winter and summer identified operational taxonomic units corresponding to the species isolated from soil samples (L. kmetyi and L. barantonii) and additional P2 subclade species (L. licerasiae, L. wolffii-related, among others) that were not detected by soil cultivation. Total Leptospira read counts were higher in summer than in winter and the analysis of leptospiral/animal eDNA relationship suggested Rattus spp. as a potential reservoir animal.

Conclusion

Our study demonstrated high environmental Leptospira diversity in the Yaeyama region, particularly during summer, when most of the leptospirosis cases are reported. In addition, several Leptospira species with pathogenic potential were identified that have not yet been reported in Yaeyama; however, the environmental persistence of P1 subclade species previously isolated from human clinical cases in this region was absent, suggesting the need of further methodology development and surveillance.

Leptospirosis is a widespread bacterial zoonosis and one of the most important acute febrile infectious disease in tropical and subtropical regions, which is difficult to differentiate from other infectious diseases common in these regions. Leptospirosis is endemic to Okinawa prefecture, the southernmost prefecture of Japan, where the infection occurs mainly after recreational activities in rivers in the northern part of Okinawa Main Island and the Yaeyama region. This study combined several methods such as bacterial isolation from soil and environmental DNA metabarcoding from river water samples to understand the persistence of Leptospira outside the human host, leptospiral diversity in the environment, and their potential reservoir animals in the wild environment of the Yaeyama region. Although this study didn’t confirm the environmental persistence of Leptospira species previously isolated from clinical cases, several newly reported Leptospira species with pathogenic potential from the Yaeyama region suggested the need for continual surveillance to improve leptospirosis control and prevention in this region.

Infectious Uveitis in Horses and New Insights in Its Leptospiral Biofilm-Related Pathogenesis

Uveitis is a sight-threatening eye disease in equids known worldwide that leads to considerable pain and suffering. By far the most common type of uveitis in Germany and neighboring countries is classical equine recurrent uveitis (ERU), which is caused by chronic intraocular leptospiral infection and is the main cause of infectious uveitis in horses. Other infectious causes are extremely rare and are usually clinically distinguishable from ERU. ERU can be treated very effectively by vitreous cavity lavage (vitrectomy). For proper indications of this demanding surgery, it is necessary to differentiate ERU from other types of uveitis in which vitrectomy is not helpful. This can be conducted on the basis of anamnesis in combination with ophthalmologic findings and by aqueous humor examination. During vitrectomy, vitreous material is obtained. These vitreous samples have historically been used for numerous etiologic studies. In this way, a chronic intraocular leptospiral infection has been shown to be the cause of typical ERU and, among other findings, ERU has also been recognized as a biofilm infection, providing new insights into the pathogenesis of ERU and explaining some thus far unexplainable phenomena of ERU. ERU may not only have transmissible aspects to some types of uveitis in humans but may also serve as a model for a spontaneously occurring biofilm infection. Vitreous material obtained during therapeutically indicated vitrectomy can be used for further studies on in vivo biofilm formation, biofilm composition and possible therapeutic approaches.

Evaluation by polymerase chain reaction assay of persistent shedding of pathogenic leptospires in the urine of dogs with leptospirosis

BACKGROUND

Persistent leptospiruria in naturally infected dogs occurs despite appropriate antibiotic treatment.

HYPOTHESIS/OBJECTIVES

To determine the frequency of persistent leptospiruria in naturally infected dogs and the association of persistent leptospiruria with different antibiotic treatments.

ANIMALS

Thirty-two dogs of varying age and breed diagnosed with leptospirosis via urine polymerase chain reaction assay (PCR).

METHODS

A prospective observational study of dogs diagnosed with leptospirosis was undertaken to determine the frequency of persistent leptospiruria as determined by PCR. Clinical presentation of leptospirosis, antibiotic treatment, serum creatinine concentration, and outcome were recorded.

RESULTS

Fifteen of 32 dogs had a negative urine PCR on the first submission in the study, 5 of 15 received only an aminopenicillin. The remaining 17 dogs had a negative urine PCR on the second (n = 6 dogs), third (n = 5), fourth (n = 5), and eighth (n = 1) submissions. Acute kidney injury was reported in 32/32 dogs. Two of 32 dogs developed chronic kidney disease.

CONCLUSIONS AND CLINICAL IMPORTANCE

Persistent leptospiruria is common despite treatment with antibiotics frequently recommended for treatment. Follow-up urine PCR to confirm clearance of the organism is recommended in all dogs. In dogs with persistent leptospiruria, chronic kidney disease can develop after acute kidney injury.

Comparative Genomic Analysis and a Novel Set of Missense Mutation of the Leptospira weilii Serogroup Mini From the Urine of Asymptomatic Dogs in Thailand

Leptospira weilii belongs to the pathogenic Leptospira group and is a causal agent of human and animal leptospirosis in many world regions. L. weilii can produce varied clinical presentations from asymptomatic through acute to chronic infections and occupy several ecological niches. Nevertheless, the genomic feature and genetic basis behind the host adaptability of L. weilii remain elusive due to limited information. Therefore, this study aimed to examine the complete circular genomes of two new L. weilii serogroup Mini strains (CUDO6 and CUD13) recovered from the urine of asymptomatic dogs in Thailand and then compared with the 17 genomes available for L. weilii. Variant calling analysis (VCA) was also undertaken to gain potential insight into the missense mutations, focusing on the known pathogenesis-related genes. Whole genome sequences revealed that the CUDO6 and CUD13 strains each contained two chromosomes and one plasmid, with average genome size and G+C content of 4.37 Mbp and 40.7%, respectively. Both strains harbored almost all the confirmed pathogenesis-related genes in Leptospira. Two novel plasmid sequences, pDO6 and pD13, were identified in the strains CUDO6 and CUD13. Both plasmids contained genes responsible for stress response that may play important roles in bacterial adaptation during persistence in the kidneys. The core-single nucleotide polymorphisms phylogeny demonstrated that both strains had a close genetic relationship. Amongst the 19 L. weilii strains analyzed, the pan-genome analysis showed an open pan-genome structure, correlated with their high genetic diversity. VCA identified missense mutations in genes involved in endoflagella, lipopolysaccharide (LPS) structure, mammalian cell entry protein, and hemolytic activities, and may be associated with host-adaptation in the strains. Missense mutations of the endoflagella genes of CUDO6 and CUD13 were associated with loss of motility. These findings extend the knowledge about the pathogenic molecular mechanisms and genomic evolution of this important zoonotic pathogen.

Understanding the Renal Fibrotic Process in Leptospirosis

Leptospirosis is a neglected infectious disease caused by pathogenic species of the genus Leptospira. The acute disease is well-described, and, although it resembles other tropical diseases, it can be diagnosed through the use of serological and molecular methods. While the chronic renal disease, carrier state, and kidney fibrosis due to Leptospira infection in humans have been the subject of discussion by researchers, the mechanisms involved in these processes are still overlooked, and relatively little is known about the establishment and maintenance of the chronic status underlying this infectious disease. In this review, we highlight recent findings regarding the cellular communication pathways involved in the renal fibrotic process, as well as the relationship between renal fibrosis due to leptospirosis and CKD/CKDu.

Leptospira interrogans biofilm formation in Rattus norvegicus (Norway rats) natural reservoirs

Rattus norvegicus (Norway rat) is the main reservoir host of pathogenic Leptospira, the causative agent of leptospirosis, in urban environments. Pathogenic Leptospira forms biofilms in the environment, possibly contributing for bacterial survival and maintenance. Nonetheless, biofilms have not yet been studied in natural animal reservoirs presenting leptospiral renal carriage. Here, we described biofilm formation by pathogenic Leptospira inside the renal tubules of R. norvegicus naturally infected and captured in an urban slum endemic for leptospirosis. From the 65 rats carrying Leptospira in their kidneys, 24 (37%) presented biofilms inside the renal tubules. The intensity of leptospiral colonization in the renal tubules (OR: 1.00; 95% CI 1.05–1.1) and the type of occlusion pattern of the colonized renal tubules (OR: 3.46; 95% CI 1.20–9.98) were independently associated with the presence of Leptospira biofilm. Our data showed that Leptospira interrogans produce biofilms during renal chronic colonization in rat reservoirs, suggesting a possible role for leptospiral biofilms in the pathogenesis of leptospirosis and bacterial carriage in host reservoirs.

Leptospirosis is an infectious disease caused by pathogenic Leptospira bacteria. The main reservoir hosts of Leptospira are the brown rats (Rattus norvegicus), which are chronically colonized in the kidneys. Leptospires form biofilms, which are communities of microorganisms embedded in an extracellular polysaccharidic matrix. Leptospira pathogenesis in reservoir hosts is poorly understood. We captured 87 brown rats from an impoverished urban community that is endemic for leptospirosis. To investigate the biofilm in the rats’ kidneys, we co-localized leptospires and saccharides of the biofilm extracellular matrix in the renal tubules, using immunohistochemistry anti-Leptospira and carbohydrate staining, respectively. We quantified Leptospira using molecular tools and characterized the biofilm using electron microscopy. We analysed demographic data to identify variables correlated with renal carriage. We found that Leptospira infected 78 rats. From those, 65 were positive for immunohistochemistry in the kidneys and 24 (37%) were biofilm-positive. We found significant positive correlation between the intensity of colonization and the presence of biofilm in the kidneys. The intensity of colonization was also associated with the rats’ gender and age. Biofilm formation by Leptospira in the kidneys of natural reservoir rats fills a gap into the knowledge of leptospirosis pathogenesis.

In Vivo Biofilm Formation of Pathogenic Leptospira spp. in the Vitreous Humor of Horses with Recurrent Uveitis

Equine recurrent uveitis (ERU) causes painful inflammatory attacks and oftentimes blindness in the affected eyes. The disease is considered a late sequela of systemic leptospirosis. The most effective therapy is the surgical removal of the vitreous (vitrectomy), which is not only therapeutic, but provides vitreous material that can be assessed diagnostically. For example, the lipL32 gene, culturable Leptospira spp., and anti-Leptospira antibodies have all been detected in vitreous samples obtained from eyes with chronic ERU. Despite this clear evidence of leptospiral involvement, the systemic administration of antibiotics in infected horses is ineffective at resolving ERU. This syndrome of chronic recurrent inflammation, which is unresponsive to antibiotic therapy, combined with apparent bacteria evading the immune response, is consistent with a biofilm-associated infection. The purpose of this study, therefore, was to detect the in vivo biofilm formation of Leptospira spp. in vitreous samples collected during vitrectomy and examined using a Warthin-Starry silver stain and immunohistochemistry. All known steps of biofilm formation were visualized in these samples, including individual Leptospira spp., leptospiral microcolonies and dense roundish accumulations of Leptospira spp. In many instances spirochetes were surrounded by an extracellular substance. Taken together, data from the present study show that ERU is a biofilm-associated intraocular leptospiral infection, which best explains the typical clinical course.

Leptospirosis and Coinfection: Should We Be Concerned?

Pathogenic Leptospira is the causative agent of leptospirosis, an emerging zoonotic disease affecting animals and humans worldwide. The risk of host infection following interaction with environmental sources depends on the ability of Leptospira to persist, survive, and infect the new host to continue the transmission chain. Leptospira may coexist with other pathogens, thus providing a suitable condition for the development of other pathogens, resulting in multi-pathogen infection in humans. Therefore, it is important to better understand the dynamics of transmission by these pathogens. We conducted Boolean searches of several databases, including Google Scholar, PubMed, SciELO, and ScienceDirect, to identify relevant published data on Leptospira and coinfection with other pathogenic bacteria. We review the role of the host-microbiota in determining the synanthropic interaction of Leptospira sp. with other bacteria, thus creating a suitable condition for the leptospira to survive and persist successfully. We also discuss the biotic and abiotic factors that amplify the viability of Leptospira in the environment. The coinfection of leptospira with pathogenic bacteria has rarely been reported, potentially contributing to a lack of awareness. Therefore, the occurrence of leptospirosis coinfection may complicate diagnosis, long-lasting examination, and mistreatment that could lead to mortality. Identifying the presence of leptospirosis with other bacteria through metagenomic analysis could reveal possible coinfection. In conclusion, the occurrence of leptospirosis with other diseases should be of concern and may depend on the success of the transmission and severity of individual infections. Medical practitioners may misdiagnose the presence of multiple infections and should be made aware of and receive adequate training on appropriate treatment for leptospirosis patients. Physicians could undertake a more targeted approach for leptospirosis diagnosis by considering other symptoms caused by the coinfected bacteria; thus, more specific treatment could be given.

Acute kidney injury with partial Fanconi syndrome in a patient with leptospirosis: a case report

Background

Leptospirosis is an underdiagnosed bacterial infection with nonspecific symptoms, hence, a diagnostic challenge. Identifying a case of leptospirosis in Switzerland is uncommon. Although kidney complications are frequent in severe forms, including tubular dysfunction, observing this complication is rare in our country. We report the case of a patient with leptospirosis and kidney dysfunction, which was notable for proximal tubulopathy. This case report describes the diagnosis and management of this patient’s tubular dysfunction.

Case presentation

A 34-year-old Caucasian male known for alcohol and drug abuse presented to our emergency department suffering from severe pain in the lower limbs, jaundice, and fever with flu-like symptoms. Physical examination was not contributory. Blood tests showed cytopenia, elevated inflammatory markers, acute kidney injury, and altered liver function tests with predominant cholestasis. Urinalysis showed proteinuria and significant glycosuria without concomitant hyperglycemia. Leptospirosis was suspected and confirmed by both positive serum polymerase chain reaction and elevated immunoglobulin M for Leptospira interrogans. The patient was treated with intravenous amoxicillin–clavulanate and doxycycline for 7 days. After antibiotic treatment, symptoms disappeared, and kidney dysfunction completely resolved.

Conclusion

Our case focuses on the description of leptospirosis-related acute kidney injury with proximal tubular dysfunction, which is a rare finding in Switzerland.

Detection and characterization of Leptospira spp. in dogs diagnosed with kidney and/or liver disease in Selangor, Malaysia

Leptospirosis is a serious bacterial disease that affects both humans and animals. A wide range of symptoms have been described in humans; the disease in dogs is commonly associated with kidney and/or liver disease. In Malaysia, information about the common serovars infecting dogs is limited. Therefore, we investigated the occurrences of leptospirosis in 124 pet dogs diagnosed with kidney and/or liver disease. Blood, urine, abdominal effusion, and/or kidney and liver were collected from the dogs. Based on microscopic agglutination testing, 53 of 124 (42.7%) dogs were seropositive for leptospiral exposure. Sera were frequently positive to serovars Bataviae (n = 12), Javanica (n = 10), and Icterohaemorrhagiae (n = 10). Direct detection using PCR showed that 42 of 124 (33.9%) of the whole blood and 36 of 113 (31.9%) urine samples were positive for pathogenic Leptospira spp. By PCR, 2 of 23 (9.1%) kidney and 2 of 23 (9.1%) liver were positive for pathogenic Leptospira spp. Abdominal effusion from 4 dogs were PCR-positive for pathogenic Leptospira spp. The species detected were L. interrogans, L. borgpetersenii, L. kirschneri, and L. kmetyi by partial 16S rRNA sequencing. We further identified and characterized 11 Leptospira spp. isolates from 8 dogs as serovars Bataviae, Javanica, and Australis. The mortality rate of the Leptospira-infected dogs was high (18 of 53; 34%).

Disassembly of the apical junctional complex during the transmigration of Leptospira interrogans across polarized renal proximal tubule epithelial cells

Bacterial pathogens have evolved multiple strategies to disassemble epithelial cell apical junctional complexes (AJCs) and infect epithelial cells. Leptospirosis is a widespread zoonotic infection, mainly caused by Leptospira interrogans, and its dissemination across host cell barriers is essential for its pathogenesis. However, the mechanism of bacterial dissemination across epithelial cell barriers remains poorly characterised. In this study, we analysed the interaction of L. interrogans with renal proximal tubule epithelial cells (RPTECs) and found that at 24 hr post‐infection, L. interrogans remain in close contact with the plasma membrane of the RPTEC by extracellularly adhering or crawling. Leptospira interrogans cleaved E‐cadherin and induced its endocytosis with release of the soluble N‐terminal fragment into the extracellular medium. Concomitantly, a gradual decrease in transepithelial electrical resistance (TEER), mislocalisation of AJC proteins (occludin, claudin‐10, ZO‐1, and cingulin) and cytoskeletal rearrangement were observed. Inhibition of clathrin‐mediated E‐cadherin endocytosis prevented the decrease in TEER. We showed that disassembly of AJCs in epithelial cells and transmigration of bacteria through the paracellular route are important for the dissemination of L. interrogans in the host.

High incidence of asymptomatic leptospirosis among urban sanitation workers from Kota Kinabalu, Sabah, Malaysian Borneo

Leptospirosis is a public health challenge in Sabah State of Malaysian Borneo. Rapid urbanization, rural-to-urban migration, and undocumented immigration in Sabah have increased the pressure on the urban garbage disposal system. Rodents and other small animals thrive under these conditions. We hypothesized that urban sanitation workers would be at risk of developing leptospirosis. In total, 303 urban sanitation workers with a mean age of 42.6 years were enrolled in this study. The serum samples collected from these workers were subjected to the microscopic agglutination test (MAT), PCR and nucleotide sequencing of the amplicons to confirm the presence of Leptospira. The phylogenetic analysis using the neighbor joining method was performed to assess whether they were pathogenic. In this study 43.8% (133/303) of the samples were MAT-seropositive and among them, 29 (21.8%) were positive by PCR. Nucleotide sequencing of the amplicons confirmed the presence of Leptospira. Phylogenetic analysis showed that our strains belonged to the pathogenic group of Leptospira. A high proportion of urban sanitation workers were seropositive for leptospirosis, and a considerable number were PCR positive for Leptospira, thereby indicating asymptomatic infections. Further research is needed to confirm whether this is a transient phenomenon or antibiotic therapy is required.

Serological Survey and Molecular Typing Reveal New Leptospira Serogroup Pomona Strains among Pigs of Northern Italy

Swine act as both maintenance and incidental hosts of pathogenic Leptospira spp. Here, a serological test was performed on 131,660 pig sera collected between 2002 and 2017 from 4715 farms in Northern Italy. A positivity rate of 13.05% was determined. Australis was the most frequently identified serogroup (77.29%), followed by Pomona (18.47%), Tarassovi (1.51%) and Icterohaemorrhagie (1.40%). Culture isolation and real-time Polymerase chain reaction (PCR) were carried out on 347 kidneys and 470 clinical samples, respectively. Overall, 133 strains were cultured successfully and 43 randomly chosen isolates were identified as serogroup Pomona. Multi-locus sequence typing (MLST) revealed that 41 isolates and 8 DNA extracted from biological samples belonged to sequence type 140. Using a multiple-locus, variable-number tandem repeat analysis, 43 samples produced identical profiles but, after 2014, three new Leptospira interrogans serogroup Pomona genotypes were observed. Interestingly, two isolates showed new MLST profiles and an unclassified identification by monoclonal antibodies. The 16S rRNA gene sequencing clustered them into L. kirschneri species and a core genome MLST analysis revealed an allelic identity of 96% compared with Mozdok strains. Genotyping allowed us to discriminate leptospires and to identify new emerging strains. The accurate identification of infective strains is required for formulating preventive methods and intervention strategies.

Environmental DNA metabarcoding to detect pathogenic Leptospira and associated organisms in leptospirosis-endemic areas of Japan

Leptospires, which cause the zoonotic disease leptospirosis, persist in soil and aqueous environments. Several factors, including rainfall, the presence of reservoir animals, and various abiotic and biotic components interact to influence leptospiral survival, persistence, and pathogenicity in the environment. However, how these factors modulate the risk of infection is poorly understood. Here we developed an approach using environmental DNA (eDNA) metabarcoding for detecting the microbiome, vertebrates, and pathogenic Leptospira in aquatic samples. Specifically, we combined 4 sets of primers to generate PCR products for high-throughput sequencing of multiple amplicons through next-generation sequencing. Using our method to analyze the eDNA of leptospirosis-endemic areas in northern Okinawa, Japan, we found that the microbiota in each river shifted over time. Operating taxonomic units corresponding to pathogenic L. alstonii, L. kmetyi, and L. interrogans were detected in association with 12 nonpathogenic bacterial species. In addition, the frequencies of 11 of these species correlated with the amount of rainfall. Furthermore, 10 vertebrate species, including Sus scrofa, Pteropus dasymallus, and Cynops ensicauda, showed high correlation with leptospiral eDNA detection. Our eDNA metabarcoding method is a powerful tool for understanding the environmental phase of Leptospira and predicting human infection risk.

Chronology of emergence of the genus Leptospira and over-representation of gene families enriched by vitamin B2, B12 biosynthesis, cell adhesion and external encapsulating structure in L. interrogans isolates from asymptomatic dogs

The spirochete species Leptospira interrogans is the most common cause of leptospirosis, producing acute to chronic infections in most mammalian species. This pathogenic bacterium has an ability to evolve in many ways to occupy various environments and hosts. In this study, we performed chronology analysis to look for insight into the emergence of Leptospira species, focusing on L. interrogans, and investigated gene gain and loss related to their adaptation in strains isolated from asymptomatic dogs. Chronology analysis revealed that the emergence of L. interrogans was around 53.7 million years ago (MYA), corresponding to the Paleogene period that coincided with an optimal climatic temperature and the evolution of suitable mammalian hosts. Gene families encoding for vitamin B2, B12 biosynthesis, cell adhesion and external encapsulating structure were found to be enriched in L. interrogans isolated from the urine of asymptomatic dogs. The activity of these gene families may have favored adaptations resulting in chronic infections.