Isolation of Leptospira from blood culture bottles

Vinetz J. 12 Novel clonal groups of Leptospira infecting humans in multiple contrasting epidemiological contexts in Sri Lanka

Leptospirosis is a ubiquitous zoonotic disease and a major clinical challenge owing to the multitude of clinical presentations and manifestations that are possibly attributable to the diversity of Leptospira, the understanding of which is key to study the epidemiology of this emerging global disease threat. Sri Lanka is a hotspot for leptospirosis with high levels of endemicity as well as annual epidemics. We carried out a prospective study of Leptospira diversity in Sri Lanka, covering the full range of climatic zones, geography, and clinical severity. Samples were collected for leptospiral culture from 1,192 patients from 15 of 25 districts in Sri Lanka over two and half years. Twenty-five isolates belonging to four pathogenic Leptospira species were identified: L. interrogans, L. borgpetersenii, L. weilii, and L. kirschneri. At least six serogroups were identified among the isolates: Autumnalis (6), Pyrogenes (4), Icterohaemorrhagiae (2), Celledoni (1), Grippotyphosa (2) and Bataviae (1). Seven isolates did not agglutinate using available antisera panels, suggesting new serogroups. Isolates were sequenced using an Illumina platform. These data add 25 new core genome sequence types and were clustered in 15 clonal groups, including 12 new clonal groups. L. borgpetersenii was found only in the dry zone and L. weilii only in the wet zone. Acute kidney injury and cardiovascular involvement were seen only with L. interrogans infections. Thrombocytopenia and liver impairment were seen in both L. interrogans and L. borgpetersenii infections. The inadequate sensitivity of culture isolation to identify infecting Leptospira species underscores the need for culture-independent typing methods for Leptospira.

There is a huge diversity in pathogenic Leptospira species worldwide, and our knowledge of the currently circulating species is deficient owing to limited isolation and identification of Leptospira species from endemic countries. This prospective study reveals the wide pathogen diversity that causes human leptospirosis in Sri Lanka, representing four species, more than six serogroups, and fifteen clonal groups. Further, the different geographic and climatic zone distributions and clinical manifestations observed underscores the need for prospective studies to expand the molecular epidemiological approaches to combat leptospirosis.

Isolation and Culture of Leptospira from Clinical and Environmental Samples

Leptospires, the etiological agents of leptospirosis, are fastidious slow-growing organisms. Here we describe the isolation and routine maintenance of leptospires from clinical (blood, urine, or tissue) and environmental (water or soil) samples. Using combinations of filtration, agar plating, and selective agents, leptospires can be isolated in pure cultures even from complex contaminated sources in standard EMJH culture medium.

Laboratory Diagnosis of Leptospirosis

The diagnosis of leptospirosis depends on specific laboratory tests because nonspecific and diverse clinical manifestations make clinical diagnosis difficult and it is easily confused with other infectious diseases in the tropics. Suitable laboratory diagnostic tests vary depending on the stage of the disease, requiring the combination of diagnostic tests using appropriate specimens at each disease stage.

Case Report: Recovery of Pathogenic Leptospira spp. from Routine Aerobic Blood Culture Bottles

Leptospira spp. are fastidious and slow-growing bacteria, making recovery difficult and diagnostic sensitivity in the clinical setting low. However, collection of Leptospira isolates is valuable for epidemiological and laboratory research. Severe leptospirosis cases may present as septic shock, and the differential diagnosis often includes bacterial septicemia, leading clinicians to collect blood cultures. Here, we report the successful isolation of pathogenic Leptospira spp. from blood culture bottles (targeting aerobic bacteria incubated at 37°C) from a 64-year-old man admitted with septic shock. The patient presented with 4 days of fever, severe hypotension, transient atrial fibrillation, jaundice, and oliguric renal failure. After admission, intravenous ceftriaxone plus azithromycin was given with fluid resuscitation, norepinephrine infusion, invasive mechanical ventilation, and renal replacement therapy. He was discharged from the hospital 16 days after admission. Using the blood sample obtained on admission, the diagnosis of leptospirosis was confirmed by multiplex real-time PCR (targeting bacterial 16S rRNA and LipL32 gene). We collected 200 μL from the blood culture bottle to inoculate a 5-mL Ellinghausen, McCullough, Johnson, and Harris media supplemented with 5% fetal bovine serum. After 2 weeks of incubation at 30°C, Leptospira strains were identified and confirmed by real-time PCR. Genotyping was undertaken using the multi-locus sequence typing (MLST) scheme#1. The isolate matched with ST50 isolates in the PUbMLST database. This case provides evidence that in tropical countries, severe leptospirosis should be considered in patients who present with symptoms of sepsis. Pathogenic Leptospira may be successfully isolated from aerobic blood cultures in routine clinical settings.

Age-specific epidemiology of human leptospirosis in New Caledonia, 2006-2016

With over one million cases worldwide annually and a high fatality in symptomatic forms, human leptospirosis is a growing public health concern for the most vulnerable populations, especially in the context of global warming and unplanned urbanization. Although the Asia-Pacific region is particularly affected, accurate epidemiological data are often lacking. We conducted an eleven-year retrospective laboratory-based epidemiological survey of human leptospirosis in New Caledonia. From 2006 to 2016, 904 cases were laboratory-confirmed, including 29 fatalities, corresponding to an average annual incidence of 30.6/100,000 and a case fatality rate of 3.2%. Over the period, there was a major shift from indirect serological diagnosis by MAT to direct diagnosis by real-time PCR, a more specific and sensitive test when performed early in the course of the disease. The systematic implementation of genotyping informed on the variety of the infective strains involved, with a predominance of serogroups Icterohaemorrhagiae and Pyrogenes. The epidemiological pattern showed a marked seasonality with an annual peak in March-April. Interestingly, the seasonal peak in children of school age was significantly earlier and corresponded to school holidays, suggesting that attending school from February on could protect children from environment-borne leptospirosis.

Leptospirosis in an asplenic patient -case report

Background

The presentation of clinical leptospirosis has been historically associated with animal workers, slaughterhouse workers and medical veterinarians. This association has shifted to be related to flooding events and outdoor activities; few cases are related to high-risk factors found in immunosuppressed patients. Scarcely a handful of cases have serological evidence of immune response against Leptospira serovar Bratislava representing serogroup Australis, a serovar associated with poor reproductive performance in swine and horses, and recently with cats.

Case presentation

Herein, we describe a rare clinical presentation of disseminated Leptospira infection in an immunosuppressed 65-year-old woman. She was admitted to the emergency room with fever, bacteraemia, bilateral uveitis and pulmonary involvement. The patient denied outdoor activities; she only had wide exposure to faeces and urine from cats living in her home. Her medical history included idiopathic thrombocytopenic purpura (ITP) diagnosed at the age of 18. She did not respond to medical treatment, and a splenectomy was performed. At age 60, she was diagnosed with Chronic Myeloid Leukemia (CML), and was treated with a tyrosine kinase inhibitor (TKI) –Imatinib. The patient voluntarily discontinued the treatment for the last 6 months. After extensive workup, no microorganisms were identified by the commonly used stains in microbiology. The diagnosis was performed through dark-field microscopy, microagglutination test (MAT), Leptospira genus-specific PCR, the IS1500 PCR for identification of pathogenic species, and 16S based sequencing for the genus identification.

Conclusion

Immunosuppressed patients may acquire uncommon infections from ubiquitous microorganisms. In this case, serology evidence of exposure to Leptospira serovar Bratislava by MAT and the presence of the Leptospira genus were identified. It should be on mind for the diagnosis in otherwise healthy patients, and thoroughly search on splenectomised patients exposed to animals. Additionally, this report highlights the usefulness of PCR for diagnosis of this potentially life-threatening illness.

Biodiversity of Environmental Leptospira: Improving Identification and Revisiting the Diagnosis

Leptospirosis is an important environmental disease and a major threat to human health causing at least 1 million clinical infections annually. There has recently been a growing interest in understanding the environmental lifestyle of Leptospira. However, Leptospira isolation from complex environmental samples is difficult and time-consuming and few tools are available to identify Leptospira isolates at the species level. Here, we propose a polyphasic isolation and identification scheme, which might prove useful to recover and identify environmental isolates and select those to be submitted to whole-genome sequencing. Using this approach, we recently described 12 novel Leptospira species for which we propose names. We also show that MALDI-ToF MS allows rapid and reliable identification and provide an extensive database of Leptospira MALDI-ToF mass spectra, which will be valuable to researchers in the leptospirosis community for species identification. Lastly, we also re-evaluate some of the current techniques for the molecular diagnosis of leptospirosis taking into account the extensive and recently revealed biodiversity of Leptospira in the environment. In conclusion, we describe our method for isolating Leptospira from the environment, confirm the usefulness of mass spectrometry for species identification and propose names for 12 novel species. This also offers the opportunity to refine current molecular diagnostic tools.

Isolation and characterization of pathogenic leptospires associated with cattle

Pathogenic leptospires colonize the renal tubules of reservoir hosts of infection, including cattle, and are excreted via urine. In order to identify circulating serovars of pathogenic leptospires in beef cattle, and their associated rates of urinary excretion, a cross sectional study was performed. Fifty urine samples were collected one day each month over 12 consecutive months (N = 600), directly from the bladder of beef cattle at a single slaughter facility and assessed for the presence of leptospires by culture and the fluorescent antibody test (FAT). Where possible, a matched serum sample was also collected for the microscopic agglutination test (MAT). Forty-three urine samples were either culture positive or FAT positive, indicating that 7.2% of sampled beef cattle were actively excreting leptospires in urine. Twenty-three urine samples were culture positive. Sequence analysis of 16S ribosomal DNA and secY indicated that all isolates were Leptospira borgpetersenii. Typing by serology indicated that all isolates were serogroup Sejroe. An overall seroprevalence of 20% (MAT ≥ 1:25) was determined; positive bovine sera was most reactive to serogroup Sejroe (serovar Hardjo) (8.1%), and serogroup Australis (serovar Bratislava) (6.7%). There was poor correlation between seroprevalence and excretion of leptospires since 18/43 (41.9%) cattle, which were positive by culture or FAT, were seronegative. The virulence of two selected isolates of L. borgpetersenii was confirmed by experimental infection in small animal models of infection. Results confirm that L. borgpetesenii continues to circulate in beef cattle and that multiple diagnostic assays are required to detect active shedding. These findings also highlight beef cattle as a reservoir host for the potential zoonotic transmission of leptospires.