Molecular detection of leptospirosis and melioidosis co-infection: A case report

Bacterial community profiles within the water samples of leptospirosis outbreak areas

Background

Leptospirosis is a water-related zoonotic disease. The disease is primarily transmitted from animals to humans through pathogenic Leptospira bacteria in contaminated water and soil. Rivers have a critical role in Leptospira transmissions, while co-infection potentials with other waterborne bacteria might increase the severity and death risk of the disease.

Methods

The water samples evaluated in this study were collected from four recreational forest rivers, Sungai Congkak, Sungai Lopo, Hulu Perdik, and Gunung Nuang. The samples were subjected to next-generation sequencing (NGS) for the 16S rRNA and in-depth metagenomic analysis of the bacterial communities.

Results

The water samples recorded various bacterial diversity. The samples from the Hulu Perdik and Sungai Lopo downstream sampling sites had a more significant diversity, followed by Sungai Congkak. Conversely, the upstream samples from Gunung Nuang exhibited the lowest bacterial diversity. Proteobacteria, Firmicutes, and Acidobacteria were the dominant phyla detected in downstream areas. Potential pathogenic bacteria belonging to the genera Burkholderiales and Serratia were also identified, raising concerns about co-infection possibilities. Nevertheless, Leptospira pathogenic bacteria were absent from all sites, which is attributable to its limited persistence. The bacteria might also be washed to other locations, contributing to the reduced environmental bacterial load.

Conclusion

The present study established the presence of pathogenic bacteria in the river ecosystems assessed. The findings offer valuable insights for designing strategies for preventing pathogenic bacteria environmental contamination and managing leptospirosis co-infections with other human diseases. Furthermore, closely monitoring water sample compositions with diverse approaches, including sentinel programs, wastewater-based epidemiology, and clinical surveillance, enables disease transmission and outbreak early detections. The data also provides valuable information for suitable treatments and long-term strategies for combating infectious diseases.

Optimal control and cost-effectiveness analysis for the human melioidosis model

In this work, we formulated and investigated an optimal control problem of the melioidosis epidemic to explain the effectiveness of time-dependent control functions in controlling the spread of the epidemic. The basic reproduction number ( R 0 c ) with control measures is obtained, using the next-generation matrix approach and the impact of the controls on R 0 c is illustrated numerically. The optimal control problem is analyzed using Pontryagin's maximum principle to derive the optimality system. The optimality system is simulated using the forward-backward sweep method based on the fourth-order Runge-Kutta method in the MATLAB program to illustrate the impact of all the possible combinations of the control interventions on the transmission dynamics of the disease. The numerical results indicate that among strategies considered, strategy C is shown to be the most effective in reducing the number of infectious classes compared to both strategy A and strategy B. Furthermore, we carried out a cost-effectiveness analysis to determine the most cost-effective strategy and the result indicated that the strategy B (treatment control strategy) should be recommended to mitigate the spread and impact of the disease regarding the costs of the strategies.

Optimal control and cost-effectiveness analysis for leptospirosis epidemic

This paper aims to apply an optimal control theory for the autonomous model of the leptospirosis epidemic to examine the effect of four time-dependent control measures on the model dynamics with cost-effectiveness. Pontryagin's Maximum Principle was used to derive the optimality system associated with the optimal control problem. Numerical simulations of the optimality system were performed for different control strategies and the results were presented graphically with and without controls. The optimality system was simulated using the Forward-Backward Sweep method in the Matlab programme. The numerical results revealed that the combination of all optimal control measures is the most effective strategy for minimizing the spread and impact of disease in the community. Furthermore, a cost-effectiveness analysis was performed to determine the most cost-effective strategy using the incremental cost-effectiveness ratio approach and we observed that the rodenticide control-only strategy is most effective to combat the spread of disease when available resources are limited.

Leptospiral cell wall hydrolase (LIC_10271) binding peptidoglycan, lipopolysaccharide, and laminin and the protein show LysM and M23 domains are co-existing in pathogenic species

Leptospirosis, a global reemerging zoonosis caused by the spirochete Leptospira, has severe human and veterinary implications. Cell wall hydrolase (LIC_10271) with LytM (peptidase M23) and LysM domains are found to be associated with various pathogenic bacteria. These domains regulate effects on extracellular matrix and biofilm components, which promote cell wall remodeling and pathogen dissemination in the host. In this study, we present the cloning, expression, purification, and characterization of LIC_10271. To determine the localization of LIC_10271 within the inner membrane of Leptospira, Triton X-114 subcellular fractionation and immunoblot studies were performed. Furthermore, r-LIC_10271 binds with peptidoglycan, lipopolysaccharide, and laminin in a dose-dependent manner. Analysis of the signal peptide, M23, and LysM domains revealed conservation primarily within the P1 group of Leptospira, which encompasses the most pathogenic species. Moreover, the presence of native-LIC_10271 in the inner membrane and the distribution of M23 and LysM domains across pathogenic strains indicates their potential involvement in the interaction between the host and Leptospira.

Double-trouble: A rare case of co-infection with melioidosis and leptospirosis from Sri Lanka

Melioidosis and leptospirosis are two emerging tropical infections that share somewhat similar clinical manifestations but require different methods of management. A 59-year-old farmer presented to a tertiary care hospital with an acute febrile illness associated with arthralgia, myalgia and jaundice, complicated by oliguric acute kidney injury and pulmonary haemorrhage. Treatment was initiated for complicated leptospirosis but with poor response. Blood culture was positive for Burkholderia pseudomallei and microscopic agglutination test (MAT) for leptospirosis was positive at the highest titres of 1:2560, confirming a co-infection of leptospirosis and melioidosis. The patient made a complete recovery with therapeutic plasma exchange (TPE), intermittent haemodialysis and intravenous (IV) antibiotics. Similar environmental conditions harbour melioidosis and leptospirosis, making co-infection a very real possibility. Co-infection should be suspected in patients from endemic areas with water and soil exposure. Using two antibiotics to cover both pathogens effectively is prudent. IV penicillin with IV ceftazidime is one such effective combination.

Distribution, frequency and clinical presentation of leptospirosis and coinfections: a systematic review protocol

INTRODUCTION

Leptospirosis is a zoonotic disease with high prevalence in low-income and middle-income countries and tropical and subtropical regions. The clinical symptoms of the disease are similar to symptoms presented by other endemic infectious diseases that could be present simultaneously. Thus, leptospirosis could be masked by similar infections like dengue, malaria, hantavirus, melioidosis and borreliosis, among others. Therefore, leptospirosis could present itself as an under-reported infection or as a coinfection with another pathogen, as has been reported in the literature. However, there is a lack of documented evidence about the specific risk factors of leptospirosis infection, the symptoms, the coinfection's mortality and the frequency of coinfection. Additionally, leptospirosis coinfections have not been considered a neglected public health concern. Therefore, this systematic review aims to evaluate published articles that show the risk factors associated with leptospirosis infection and coinfection with other pathogens.

METHODS AND ANALYSIS

The search process to identify eligible studies will be conducted including the LILACS, ProQuest, PubMed and Scopus databases with no restriction in terms of publication date. Also, grey literature will be included in the research. Authors will independently screen the title and abstracts of the articles identified from the search using Rayyan free software. Eligibility criteria include peer-reviewed research articles written in English or Spanish, including observational studies, cohorts, case-control, cross-sectional, ecological studies and report cases. The systematic review will include studies that report descriptions of leptospirosis cases with coinfection or co-occurrence. The search will be accomplished by articles from 1950 to May 2022. The data will be extracted in a standard extraction form using an Excel format.

ETHICS AND DISSEMINATION

Results will be published in a peer-reviewed journal. Also, findings will be disseminated through scientific meetings. Ethical approval will not be required as this is a systematic review and primary data will be not collected or included.

PROSPERO REGISTRATION NUMBER

CRD42021234754.

Natural infection of leptospirosis and melioidosis in long-tailed macaques (Macaca fascicularis) in Thailand

This study aimed to determine the incidence of leptospirosis and melioidosis in long-tailed macaques (Macaca fascicularis) in Thailand. Serum samples from 223 monkeys were subjected to the Lepto Latex Test and indirect hemagglutination (IHA) test to detect antibodies against Leptospira spp. and Burkholderia pseudomallei. The microagglutination test (MAT) was used to identify serovars of Leptospira spp. Conventional PCR for the LipL32 gene of L. interogans and the BPSS0120 and btfc-orf18 genes of B. pseudomallei was used for molecular detection. The overall seroprevalence of leptospirosis and melioidosis was 2.69% (95% CI: 0.99-5.76%) and 14.35% (95% CI: 10.03-19.65%), respectively. Six samples that showed positive MAT results were also positive for IHA. The serovars of Leptospira were Ranarum (5/6), Shermani (6/6), and both (5/6). Conventional PCR for the LipL32 gene of Leptospira spp. was positive in 10.31% of the samples (95% CI: 5.56-13.51%). However, there were no positive results for BPSS0120 and btfc-orf18 in B. pseudomallei. Active infection was detected only for leptospirosis; however, it can be assumed that pathogen exposure occurred in this group of animals because immunity could be detected. The routes of infection and elimination pathways of both bacteria remain unclear, and the mechanism of protection in non-human primates needs to be elucidated in further studies. Moreover, this health issue should be considered to prevent human infections in monkeys and their environment.

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.

Duplex TaqMan Hydrolysis Probe-Based Molecular Assay for Simultaneous Detection and Differentiation of Burkholderia pseudomallei and Leptospira spp. DNA

Melioidosis and leptospirosis, caused by two different bacteria, Burkholderia pseudomallei and Leptospira spp., are potentially fatal infections that share a very similar spectrum of clinical features and cause significant mortality and morbidity in humans and livestock. Early detection is important for better clinical consequences. To our knowledge, there is no diagnostic tool available to simultaneously detect and differentiate melioidosis and leptospirosis in humans and animals. In this study, we described a duplex TaqMan probe-based qPCR for the detection of B. pseudomallei and Leptospira spp. DNA. The performance of the assay was evaluated on 20 B. pseudomallei isolates, 23 Leptospira strains, and 39 other microorganisms, as well as two sets of serially diluted reference strains. The duplex qPCR assay was able to detect 0.02 pg (~ 4 copies) Leptospira spp. DNA and 0.2 pg (~ 25.6 copies) B. pseudomallei DNA. No undesired amplification was observed in other microorganisms. In conclusion, the duplex qPCR assay was sensitive and specific for the detection of B. pseudomallei & Leptospira spp. DNA and is suitable for further analytical and clinical evaluation.

First co-infection case of melioidosis and Japanese encephalitis in China

BACKGROUND

Melioidosis is endemic in Southeast Asia and northern Australia. Infection usually follows percutaneous inoculation or inhalation or ingestion of the causative bacterium, Burkholderia pseudomallei, which is present in soil and surface water in endemic regions. Japanese encephalitis (JE) is a vector-borne viral zoonosis caused by Japanese encephalitis virus (JEV), leading to epidemic encephalitis in Southeast Asia. Both B. pseudomallei and JEV have spread dominantly in the Hainan and Guangdong provinces in China. Here we reported the first case of co-infection of B. pseudomallei and JEV, which was discovered in Huizhou in the Guangdong province in June 2016.

CASE PRESENTATION

A 52-year-old man was admitted to the hospital with acute febrile illness and headache, diagnosed as respiratory infection, central nervous system (CNS) infection, septicemia, and hepatic dysfunction. Based on B. pseudomallei-positive blood and cerebrospinal fluid (CSF) cultures, the patient was diagnosed with melioidosis and treated aggressively with antibiotics. However, the patient failed to make a full recovery. Further laboratory tests focused on CNS infection were conducted. The co-infection of B. pseudomallei and JEV was confirmed after the positive IgM antibodies of JEV were detected in both CSF and blood. After diagnosis of co-infection with B. pseudomallei and JEV, the patient was provided supportive care in hospital and recovered after approximately 3 weeks.

CONCLUSION

Given the possibility of co-infection of B. pseudomallei and JEV, as well as variable case presentations, it is critical to enhance the awareness, detection, and treatment of co-infection in regard to melioidosis.