It's not all about flagella - sticky invasion by pathogenic spirochetes.

Pathogenic spirochetes cause a range of serious human diseases such as Lyme disease (LD), syphilis, leptospirosis, relapsing fever (RF), and periodontal disease. Motility is a critical virulence factor for spirochetes. From the mechanical perspective of the infection, it has been widely believed that flagella are the sole key players governing the migration and dissemination of these pathogens in the host. Here, we highlight the important contribution of spirochetal surface-exposed adhesive molecules and their dynamic interactions with host molecules in the process of infection, specifically in spirochetal swimming and crawling migration. We believe that these recent findings overturn the prevailing view depicting the spirochetal body to be just an inert elastic bag, which does not affect spirochetal cell locomotion.

Acute pancreatitis as a rare complication of leptospirosis: A case report and literature review.

Leptospirosis is a zoonotic disease. We present a case of acute pancreatitis associated with leptospirosis. An 88-year-old woman was admitted to the hospital with high fever and severe myalgia of the lower extremities. Based on the clinical presentation, hepatic dysfunction with a mild increase in bilirubin, renal dysfunction, and life history, the possibility of leptospirosis was considered. Plain computed tomography of the trunk on admission revealed no special findings. Appropriate antimicrobial therapy was administered at an early stage. After treatment initiation, the clinical symptoms and blood test abnormalities began to improve, and the patient appeared to be doing well. Although no abdominal or back pain was consistently noted during hospitalization, the serum amylase level increased over time; therefore, the patient underwent another computed tomography scan on the ninth day. Acute pancreatitis, which was absent upon admission, was noted. Appropriate treatment for pancreatitis was administered, and the patient was discharged. A subsequent serum antibody test confirmed the diagnosis of leptospirosis. Herein, we also summarized previous cases of acute pancreatitis associated with leptospirosis. The time of onset for pancreatitis was inconsistent, and there were a few cases of pancreatitis without abdominal or back pain. In contrast, serum amylase or lipase levels were elevated in all patients, which could be an important trigger for suspected complications of pancreatitis. When leptospirosis is suspected, complications of pancreatitis should always be considered, even in the absence of apparent abdominal pain. Regular monitoring of pancreatic enzymes such as amylase and lipase is recommended.

Machine learning-based motion tracking reveals an inverse correlation between adhesivity and surface motility of the leptospirosis spirochete.

Bacterial motility is often a crucial virulence factor for pathogenic species. A common approach to study bacterial motility is fluorescent labeling, which allows detection of individual bacterial cells in a population or in host tissues. However, the use of fluorescent labeling can be hampered by protein expression stability and/or interference with bacterial physiology. Here, we apply machine learning to microscopic image analysis for label-free motion tracking of the zoonotic bacterium Leptospira interrogans on cultured animal cells. We use various leptospiral strains isolated from a human patient or animals, as well as mutant strains. Strains associated with severe disease, and mutant strains lacking outer membrane proteins (OMPs), tend to display fast mobility and reduced adherence on cultured kidney cells. Our method does not require fluorescent labeling or genetic manipulation, and thus could be applied to study motility of many other bacterial species.

Effects of Diazinon Exposure on Urinary Shedding of Leptospira interrogans Serogroup Hebdomadis in Mice.

Wild rodents are natural hosts of Leptospira spp. and are exposed to various pesticides, some of which are immunotoxic. Rodent urine is an important source of infection for humans and other animals. We evaluated the effects of pesticide exposure on Leptospira growth in mice. Diazinon, at doses of 0.2, 1, and 5 mg/kg/day, was orally administered continuously to mice infected with Leptospira interrogans serogroup Hebdomadis for 32 days. The numbers of L. interrogans in urine and kidney tissues were significantly lower in mice exposed to 5 mg/kg/day diazinon than in unexposed mice (p < 0.05). The urinary concentration of 2-isopropyl-6-methyl-4-pyrimidinol, the metabolite of diazinon, was comparable with the concentration at which viability of L. interrogans was decreased in in vitro assay, suggesting that it had toxic effects on L. interrogans in the proximal renal tubules. Diazinon exposure reinforced Leptospira-induced expression of inflammatory cytokine genes in kidney tissues, and an enhanced immune system might suppress Leptospira growth. These results suggest that diazinon exposure may not increase the risk of Leptospira transmission to humans through mice. This novel study evaluated the relationship between pesticide exposure and Leptospira infection in mice, and the results could be useful for risk assessment of leptospirosis.

Analysis of Adhesion and Surface Motility of a Spirochete Bacterium.

Spirochetes are Gram-negative bacteria with helical or flat wave morphology and move using flagella residing beneath the outer membrane. Most commonly, flagellated bacteria swim in liquid. Meanwhile, some species of spirochete not only swim but keep moving after adhering to solid surfaces, and such amphibious motility is believed to be significant for pathogenicity. This chapter focuses on the zoonotic spirochete Leptospira and describes the method for measuring the spirochete adhesion and surface motility.

Case Report: An Imported Case of Severe Leptospirosis with Septic Cardiomyopathy Requiring Venoarterial Extracorporeal Membrane Oxygenation in Japan.

A 29-year-old Japanese man presenting with fever, joint pain, and diarrhea was admitted to the intensive care unit for cardiogenic and distributive shock. We suspected leptospirosis based on conjunctival hyperemia, skin rash, elevated bilirubin, and renal involvement; a travel history to Laos was also suggestive. We confirmed the diagnosis with blood and urine polymerase chain reaction and microscopic agglutination tests using paired serum samples. His hemodynamics were unstable, and his echocardiogram showed diffuse and severe left ventricular systolic dysfunction on day 2. He initially required venoarterial extracorporeal membrane oxygenation (V-A ECMO) support but responded and recovered on antimicrobial therapy. His cardiac function and hemodynamics improved on day 5. Severe leptospirosis may cause jaundice, renal failure, pulmonary hemorrhage, acute respiratory distress syndrome, and central nervous system involvement; however, few studies have reported severe cardiac manifestations. Herein, we report the first case of septic cardiomyopathy secondary to leptospirosis that was successfully managed with V-A ECMO. Leptospirosis should be included in the differential diagnosis when a patient returning from an endemic area presents with cardiogenic shock. Furthermore, intensive care management with prompt initiation of V-A ECMO should be considered to reverse septic cardiomyopathy.

Serological Surveillance of Zoonotic Pathogens in Rats in Markets in Bogor, Indonesia.

Background: Rats are a major carrier of several pathogens, including zoonotic pathogens that can cause fatal diseases in humans. Indonesia has one of the fastest growing populations, with high infestation of rats in urban areas. Therefore, this study aims to assess the seropositivity of zoonotic pathogens in rats from four markets in Bogor, Indonesia. Materials and Methods: A total of 80 brown rats (Rattus norvegicus) were captured from the markets and screened for the presence of some zoonotic pathogens, specifically hantavirus, Leptospira spp., Orientia tsutsugamushi, tick-borne encephalitis virus (TBEV), and lymphocytic choriomeningitis virus (LCMV) antibodies, using indirect fluorescence assay or enzyme-linked immunosorbent assay. Results: Among the 80 rats, 40% were seropositive for hantavirus, 36.3% for Leptospira spp., 11.3% for O. tsutsugamushi, 6.3% for TBEV, and 0% for LCMV. Conclusion: Overall, these results indicate that rats in Bogor pose a potential zoonotic risk to humans.

Leptospirosis with multiple organ dysfunction in a mongoose-scat-detection dog infected with Leptospira interrogans serogroup Hebdomadis, Okinawa, Japan.

A 2-year-old male mongoose-scat-detection dog was diagnosed with leptospirosis by urine PCR. The patient developed acute renal failure, hepatic dysfunction, and disseminated intravascular coagulation. Treatment with antibiotics was administered, including ampicillin and doxycycline, and supportive care management was provided. Seroconversion against serogroup Hebdomadis was observed on day 8. The leptospiral gene flaB was detected only in urine collected on day 1, from which Leptospira interrogans ST329 was identified by multilocus sequence typing using seven housekeeping genes. L. interrogans serogroup Hebdomadis ST329 has been isolated from mongooses and humans in Okinawa, Japan. This patient received early treatment with antibiotics, which may have contributed to the early recovery of renal function and removal of L. interrogans from kidney tissue.

Case Report: Leptospirosis by Wild Rat Bite in Winter in Tokyo Metropolitan Area, Japan.

We report a case of leptospirosis in Tokyo in winter due to a rat bite, an uncommon cause of Leptospira infection. In Japan, many cases due to exposure to fresh water have been reported from domestic southwest islands in summer. However, a previous report on leptospirosis in Tokyo documented several cases occurring in winter. The main route of infection in the Tokyo metropolitan area during winter was attributed to the increased chance of direct rat exposure. Rapid and feasible diagnostic methods are needed to elucidate its epidemiology and provide prompt treatment.

A prospective observational study of community-acquired bacterial bloodstream infections in Metro Manila, the Philippines.

Community-acquired bacterial bloodstream infections are caused by diverse pathogens with changing antimicrobial-resistance patterns. In low-middle income countries in Southeast Asia, where dengue fever is endemic and a leading cause of fever, limited information is available about bacterial bloodstream infections due to challenges of implementing a blood culture service. This study describes bacterial bloodstream pathogens and antimicrobial-resistance patterns in Metro Manila, the Philippines. We aimed to identify the proportion of patients with a positive blood culture, the bacteria isolated and their antimicrobial resistance patterns, and the clinical characteristics of these patients, in this dengue endemic area. We conducted a prospective observational study in a single hospital enrolling febrile patients clinically suspected of having a community-acquired bacterial bloodstream infection between 1st July 2015 and 30th June 2019. Each patient had a blood culture and additional diagnostic tests according to their clinical presentation. We enrolled 1315 patients and a significant positive blood culture was found in 77 (5.9%) including Staphylococcus aureus (n = 20), Salmonella enterica Typhi (n = 18), Escherichia coli (n = 16), Streptococcus pneumoniae (n = 3) and Burkholderia pseudomallei (n = 2). Thirty-four patients had meningococcal disease diagnosed by culture (n = 8) or blood PCR (n = 26). Additional confirmed diagnoses included leptospirosis (n = 177), dengue virus infection (n = 159) and respiratory diphtheria (n = 50). There were 79 (6.0%, 95%CI 4.8%-7.4%) patients who died within 28 days of enrollment. Patients with a positive blood culture were significantly more likely to die than patients with negative culture (15.2% vs 4.4%, P<0.01). Among S. aureus isolates, 11/20 (55%) were methicillin-resistant (MRSA) and ST30: USA1100 was dominant sequence type (88.9%). Antimicrobial-susceptibility was well preserved in S. enterica Typhi. Among hospitalized patients with clinically suspected community-acquired bacterial bloodstream infection in Metro Manila, the Philippines, 5.9% had a blood culture confirmed infection of whom 15.6% died. S. aureus, including a significant number of MRSA (USA1100 clones), S. enterica Typhi, E.coli and Neisseria meningitidis were frequently identified pathogens.

Comparative genomic analysis of Leptospira spp. isolated from Rattus norvegicus in Indonesia.

Leptospirosis is one of the most prevalent zoonotic diseases caused by pathogenic spirochetes of Leptospira spp. The disease has become a public health concern in urban localities in the tropics, where rats serve as significant reservoir animals for leptospirosis transmission. In Indonesia, the occurrence of leptospirosis is underestimated, and information on the causative Leptospira genotypes and serotypes is limited. This study reports the isolation of Leptospira spp. from rats captured in urban areas of Bogor, Indonesia. Serogroups and genotypes, sequence types (STs), or multiple-locus variable-number tandem repeat analysis (MLVA) types using 11 loci, were determined for the isolates. Furthermore, whole genome sequencing (WGS) was performed on 11 Indonesian isolates and 24 isolates from other Asian countries. Ninety small mammals, including 80 Rattus norvegicus and ten Suncus murinus, were captured and, 25 Leptospira spp. were isolated solely from R. norvegicus (31.3%). The isolates were identified as Leptospira borgpetersenii serogroup Javanica with ST 143 (four strains) and Leptospira interrogans serogroup Bataviae with the same MLVA type as isolates from other Asian countries (19); the serogroup of the two L. interrogans with ST252 could not be identified. The core genome SNP-based phylogenetic tree revealed that Indonesian isolates were genetically related to L. borgpetersenii serogroup Javanica strains widely distributed in Asian countries but formed a different cluster from other strains. The phylogenetic tree of L. interrogans serogroup Bataviae isolates from Indonesia, the Philippines, Taiwan, and Vietnam revealed that isolates were grouped into five clusters based on their geographic locations. This study discovered a high carriage rate of Leptospira spp. among R. norvegicus in Bogor, Indonesia, indicating a potential risk of rat-borne leptospirosis in the area. Besides L. borgpetersenii serogroup Javanica, WGS on L. interrogans serogroup Bataviae illustrated the geographical structuring of genetic diversity in Leptospira spp.

Light dependent synthesis of a nucleotide second messenger controls the motility of a spirochete bacterium.

Nucleotide second messengers are universally crucial factors for the signal transduction of various organisms. In prokaryotes, cyclic nucleotide messengers are involved in the bacterial life cycle and in functions such as virulence and biofilm formation, mainly via gene regulation. Here, we show that the swimming motility of the soil bacterium Leptospira kobayashii is rapidly modulated by light stimulation. Analysis of a loss-of-photoresponsivity mutant obtained by transposon random mutagenesis identified the novel sensory gene, and its expression in Escherichia coli through codon optimization elucidated the light-dependent synthesis of cyclic adenosine monophosphate (cAMP). GFP labeling showed the localization of the photoresponsive enzyme at the cell poles where flagellar motors reside. These findings suggest a new role for cAMP in rapidly controlling the flagella-dependent motility of Leptospira and highlight the global distribution of the newly discovered photoactivated cyclase among diverse microbial species.

Carrier Status of Leptospira spp. in Healthy Companion Dogs in Sri Lanka.

Dogs are asymptomatic chronic carriers of Leptospira spp. and excrete these bacteria in their urine, resulting in environmental contamination and potentially leading to zoonotic transmission. Although a previous study in Sri Lanka detected anti-Leptospira antibodies in companion dogs, the urinary shedding of Leptospira spp. and the Leptospira species and serogroups prevalent in them remain unclear. Thus, the current study identified the prevalent Leptospira serogroups and the carrier status of Leptospira spp. in apparently healthy, client-owned dogs in the Kandy District of Sri Lanka. Serum and urine samples were collected from 96 unvaccinated and 82 vaccinated dogs. Anti-Leptospira antibodies and Leptospira DNA in urine were detected using the microscopic agglutination test (MAT) and nested PCR that targeted the pathogenic leptospiral gene, flaB. The flaB sequences were compared with those of Leptospira spp. using the public databases. MAT detected anti-leptospiral antibodies in 15.6% (15/96) of the unvaccinated dogs, and the reactive serogroups were observed to be Sejroe (11.5%), Canicola (2.1%), Icterohemorrhagiae (1.0%), and Javanica (1.0%). Furthermore, MAT results revealed that 11.0% (9/82) of the vaccinated dogs tested positive for the anti leptospira antibodies and the only reactive serogroup was Sejroe. Leptospira DNA was detected in 15.6% (15/96) and 15.9% (13/82) of urine samples collected from unvaccinated and vaccinated dogs, respectively, and phylogenetic analysis revealed that the animals were infected with L. borgpetersenii, L. interrogans, L. kmetyi, and L. weilii. The L. interrogans sequence detected in the canine sample was identical to the one that was previously reported in a human sample from the Kandy District. This study demonstrated that both unvaccinated and vaccinated dogs excrete various pathogenic Leptospira spp. in their urine, suggesting that they may play an important role in environmental contamination that poses a health risk to the dog owners and the general public.

Detection of Trypanosoma lewisi DNA from Rattus norvegicus and Rattus rattus in Hanoi, Vietnam.

Trypanosoma lewisi is a worldwide nonpathogenic parasite that is exclusively found in rats. In general, T. lewisi infection in humans is an opportunistic infection from rats to humans through fleas. However, recently, infection with T. lewisi in humans, including a fatal case, has been reported. Notably, rats living close to a human settlement showed a higher prevalence of infection with T. lewisi than those living in other places. It is possible that the urbanization is associated with the prevalence of T. lewisi in rats and enhances the risk of T. lewisi transmission to humans through fleas. In this study, a total of 88 rats were captured from hospitals, markets, and a cargo station, of which 81 were identified as Rattus norvegicus and 7 as Rattus rattus in Hanoi, the urbanizing city of Vietnam. Of these, 55 rats (62.5%) harbored T. lewisi, of which 52 were R. norvegicus and 3 were R. rattus.

Rat trade and leptospirosis: Molecular epidemiology of Leptospira species in rats exported from Cambodia to Vietnam.

Rats are an important maintenance host of Leptospira spp., the causative agents of leptospirosis, a zoonotic disease with worldwide distribution. Rats are traded as food in the Mekong Delta, where Cambodia exports tons of rats to Vietnam. Handling wild rats is a potential health risk, but the information on Leptospira spp. carried by rats traded in the region remains limited. In this study, we investigated the carriage of Leptospira spp. in rats exported from Cambodia to Vietnam using bacterial culture, nested PCR and DNA sequencing. Isolates were then assessed using serological analysis and whole-genome sequencing (WGS), and Leptospira DNA detected in rat kidney tissues was also analysed by multilocus sequence typing (MLST). Seventy-two rats (2 Bandicota indica, 57 Rattus argentiventer, 11 R. losea, 1 R. norvegicus and 1 R. rattus) were subjected to bacterial culture, and three L. borgpetersenii serogroup Javanica isolates were obtained from R. argentiventer (5.3%). WGS revealed that although Cambodian isolates were genetically related to L. borgpetersenii serogroup Javanica strains widely distributed in East and South-East Asian countries, they formed a different cluster from other strains. In addition to the three L. borgpetersenii sequences, the flaB sequence of L. interrogans was detected in 18 R. argentiventer and 7 R. losea kidney tissue samples (38.9%) using nested PCR followed by DNA sequencing. The L. interrogans flaB-positive samples were further analysed by MLST, revealing that seven housekeeping genes (glmU, pntA, sucA, tpiA, pfkB, mreA and caiB) contained novel sequences with distinct lineages from other sequence types. This study revealed a high prevalence of Leptospira spp. among rats exported from Cambodia to Vietnam, indicating a potential risk to people engaging in rat trade and demonstrating that a fastidious L. interrogans strain circulates among Cambodian rats.

Laboratory diagnostic, epidemiological, and clinical characteristics of human leptospirosis in Okinawa Prefecture, Japan, 2003-2020.

BACKGROUND: Leptospirosis is considered an endemic disease among agricultural workers in Okinawa Prefecture, which is the southernmost part of Japan and has a subtropical climate, but data on the current status and trend of this disease are scarce. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a retrospective study of clinically suspected leptospirosis patients whose sample and information were sent to the Okinawa Prefectural Institute of Health and Environment from November 2003 to December 2020. Laboratory diagnosis was established using culture, nested polymerase chain reaction (PCR), and/or microscopic agglutination test (MAT) with blood, cerebrospinal fluid, and/or urine samples. Statistical analyses were performed to compare the epidemiological information, clinical features, and sensitivities of diagnostic methods among laboratory-confirmed cases. Serogroups and the species of Leptospira isolates were determined by MAT using 13 antisera and flaB sequencing. A total of 531 clinically suspected patients were recruited, among whom 246 (46.3%) were laboratory confirmed to have leptospirosis. Among the confirmed cases, patients aged 20-29 years (22.4%) and male patients (85.7%) were the most common. The most common estimated sources of infection were recreation (44.5%) and labor (27.8%) in rivers. Approximately half of the isolates were of the L. interrogans serogroup Hebdomadis. The main clinical symptoms were fever (97.1%), myalgia (56.3%), and conjunctival hyperemia (52.2%). Headache occurred significantly more often in patients with Hebdomadis serogroup infections than those with other serogroup infections. The sensitivities of culture and PCR exceeded 65% during the first 6 days, while the sensitivity of MAT surpassed that of culture and PCR in the second week after onset. PCR using blood samples was a preferable method for the early diagnosis of leptospirosis. CONCLUSIONS/SIGNIFICANCE: The results of this study will support clinicians in the diagnosis and treatment of undifferentiated febrile patients in Okinawa Prefecture as well as patients returning from Okinawa Prefecture.

Unique characteristics of new complete blood count parameters, the Immature Platelet Fraction and the Immature Platelet Fraction Count, in dengue patients.

The advanced platelet parameters Immature Platelet Fraction and Immature Platelet Fraction Count have been implemented in clinical practice as measures of thrombopoietic activity, mainly in hematologic disorders that cause thrombocytopenia. The purpose of this observational study was to examine thrombopoiesis as reflected by these 2 new CBC parameters in patients infected with dengue. The study was conducted in infectious disease referral hospital in Metro Manila, the Philippines. We enrolled hospitalized patients at admission who were diagnosed with acute dengue or community acquired bacterial infection (CABI). Immature Platelet Fraction (IPF) and Immature Platelet Fraction Count were evaluated at admission and during hospitalization. A total of 606 patients were enrolled from May 1, 2017 to June 1, 2018. The participants consisted of 152 patients with dengue infection, 180 confirmed CABI, and 274 suspected CABI patients. At admission, the percent IPF (IPF%) of the patients with dengue was significantly higher than that of the confirmed CABI patients (median 3.7% versus 1.9%; p <0.001). In a time course evaluation, there was no significant difference of IPF% between the patients with dengue infection and the confirmed CABI patients in the febrile phase (median 1.9% versus 2.4%; p = 0.488), however, the IPF% of the patients with dengue infection increased to be significantly higher than that of the confirmed CABI patients in the critical phase (median 5.2% versus 2.2%; p <0.001). Our study elucidated the unique characteristics and time-course trends of IPF percent and number (IPF#) in the patients with dengue infection. IPF% and IPF# are potentially valuable parameters in dengue and further investigation is required for the optimal use in clinical practice.

Complete Genome Sequence of Leptospira kobayashii Strain E30, Isolated from Soil in Japan.

The spirochete bacterium Leptospira kobayashii is a recently designated species of the genus Leptospira. Here, we report the complete genome sequence of L. kobayashii strain E30, consisting of two circular chromosomes and two plasmids.

Identification of Novel Rodent-Borne Orthohantaviruses in an Endemic Area of Chronic Kidney Disease of Unknown Etiology (CKDu) in Sri Lanka.

We reported the genetic evidence of circulating hantaviruses from small mammals captured in a chronic kidney disease of unknown etiology (CKDu) hotspot area of Sri Lanka. The high seroprevalence of anti-hantavirus antibodies against Thailand orthohantavirus (THAIV) has been reported among CKDu patients and rodents in Sri Lankan CKDu hotspots. We captured 116 small mammals from CKDu endemic regions in the Polonnaruwa District of Sri Lanka. Seven animals (five out of 11 Mus booduga and two out of 99 Rattus rattus) were PCR-positive for the hantavirus. A rat-borne sequence was grouped with a THAIV-like Anjozorobe virus. In contrast, Mus-borne sequences belonged to the THAIV lineage, suggesting a novel orthohantavirus species according to the phylogenetic analyses and whole-genome comparisons. Our genetic evidence indicates the presence of two THAIV-related viruses circulating in this CKDu endemic area, suggesting a basis for further investigations to identify the infectious virus in patients with CKDu and the CKDu induction mechanism of these viruses.