Quantitative PCR assay to evaluate ampicillin, ofloxacin, and doxycycline for treatment of experimental leptospirosis

Isolation of Leptospira interrogans Serovar Canicola in a Vaccinated Dog without Clinical Symptoms

More than one million cases of leptospirosis occur across the globe annually, resulting in about 59,000 deaths. Dogs are one of the most important reservoirs of Leptospira species and play an important role in transmitting the pathogen to humans. Many of these infections are controlled by routine vaccination that has reduced the possible reintroduction of leptospiral serovars into the human population. However, it is still not clear how a vaccinated dog can become infected with one or more Leptospira serovars contained in the vaccine formulation and thus against which it should be immunized. Here, we present the case of an asymptomatic dog who developed leptospiral infection despite being vaccinated. This unusual case emphasizes the substantial impact of immunization on mitigating the acute signs of the disease, even while providing limited protection against infection. Further studies will be required to better understand the role of dogs in the environmental circulation of leptospiral serovars in Sardinia. Asymptomatic leptospiral infection in vaccinated dogs should be considered to allow for better diagnosis and management of the infection. This will be essential for preventing Leptospira outbreaks in the future.

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.

Clinical, diagnostic, and epidemiological features of a community-wide outbreak of canine leptospirosis in a low-prevalence region (Maricopa County, Arizona)

OBJECTIVE

To describe clinical, diagnostic, and epidemiological features of an outbreak of leptospirosis in dogs in Maricopa County, Ariz, from January 2016 through June 2017.

ANIMALS

71 case and 281 control dogs.

PROCEDURES

Cases were classified as confirmed, probable, suspect, or not a case on the basis of medical record data that fulfilled clinical, diagnostic, and epidemiological criteria. Potential exposures were assessed by owner survey. For the case-control investigation, control dogs were recruited through owner completion of a July 2017 survey. Summary statistics and ORs for case dog lifestyle factors were reported.

RESULTS

54 dogs were classified as confirmed and 17 as probable cases. For 4 dogs of a household cluster (5 confirmed and 3 probable), the highest microscopic agglutination titer was for serovar Djasiman (Leptospira kirschneri detected by PCR assay), and for 13 dogs of a community outbreak (49 confirmed and 14 probable cases), the highest titer was for serovar Canicola (Leptospira interrogans detected by PCR assay). The 44 case dogs included in the case-control investigation were 7.7 (95% CI, 3.5 to 16.7) and 2.9 times (95% CI, 1.3 to 6.6) as likely as control dogs to have visited dog daycare or to have been kenneled overnight at a boarding facility, respectively, 30 days prior to the onset of clinical signs or diagnosis.

CONCLUSIONS AND CLINICAL RELEVANCE

Diagnostic and epidemiological findings indicated 2 outbreaks. Transmission where dogs congregated likely propagated the community outbreak. Outbreaks of leptospiral infections can occur in regions of low prevalence, and a dog's exposure to areas where dogs congregate should be considered when making Leptospira vaccination recommendations.

Immune-enhanced effect of Iris polysaccharide is protective against leptospirosis

Leptospirosis, caused by pathogenic Leptospira species, is an essential but neglected zoonosis. There are more than 300 serovars of pathogenic Leptospira, while inactivated bacteria offers only short-term serovar-specific protection. Leptospirosis treatment is mainly dependent on the use of antibiotics. However, the side effects of antibiotics and the risk of antibiotic resistance remain major problems. Thus, alternative agents which are fewer side effects on humans and efficient in leptospirosis would be welcome. Many studies have reported that polysaccharides could be used as immunostimulants in treating infection and cancer. In this study, we examined the protective effect of polysaccharides isolated from Iris against leptospirosis. To our knowledge, it is the first time to report Iris polysaccharides (IP) as an immunostimulant in treating infection. The results showed that IP treatment significantly increased the survival rate of hamsters challenged by a lethal dose of leptospires. Besides, the tissue injury and leptospiral load were reduced in IP-treated infection group compared with the untreated infection group at 4 days post-infection (p.i.). Intriguingly, IP treatment sustained intense immune response at 4 days p.i. analyzed by qPCR. The results exhibited that the gene expression of TLR2 and TLR4 was significantly increased in the group coinjected with IP and leptospires than in the infected controls. And the expression of IL-1β and TNF-α were also up-regulated after IP treatment, except the expression of IL-1β in the kidney. Our results not only broaden the medicinal value of Iris, but also provide a competent candidate for the control of Leptospira infection.

Dissemination kinetics and pathology of canine Leptospira icterohaemorrhagiae isolate in a guinea pig infection model

Despite significant progress made in elucidating the mechanism of acute human leptospirosis in different organs, there is a paucity of information in organs such as the heart, pancreas, brain, and adrenal gland. This study was designed to establish leptospire dissemination kinetics and patho-morphological changes associated with these orangs in the guinea pig infection model using cultural isolation (CI), polymerase chain reaction (PCR), Warthin Starry silver stain (WSss), immunohistochemistry (IH), and transmission electron microscopy (TEM). Twenty guinea pigs were inoculated intra-peritoneally with a low dosage of 1 × 10⁷ Leptospira interrogans serovar Icterohaemorrhagiae and 10 as control using distilled water. The guinea pigs were sacrificed at post-infection day (p.i.d.) ½, 1, 3, 5, and 7 followed by the harvest of the brain, pancreas, adrenal gland, heart, lungs, liver, kidneys, and spleen for CI, PCR, HE, WSss, IH, and TEM evaluations. The study revealed early dissemination of Leptospira organism in the brain, heart, pancreas, and adrenal gland and exerted various histopathological changes that were not explicitly elucidated in previous studies. This study revealed that the virulent pathogenic isolate of Leptospira organism obtained from clinically infected dog mimicked the same clinical manifestations, gross and histopathological changes especially in organs that were not previously evaluated.

Outpatient Clinical Trial in Dogs With Leptospirosis Treated With Enrofloxacin Hydrochloride-Dihydrate (ENRO-C)

Pharmacokinetics of enrofloxacin HCl-2H2O (enro-C) in dogs and Monte-Carlo simulations against Leptospira spp. prompted a clinical study to treat the clinically apparent phase of this disease. Leptospirosis was diagnosed by real-time PCR from blood, micro-agglutination titers (MAT), clinical signs and blood parameters of the liver and kidney. In order to determine the clinical ability of the participants to diagnose leptospirosis on the first exam and establish an early treatment to avoid excessive organ damage, patients were clinically classified as: high-risk or medium-risk. Forty-five dogs were included in this trial (from 2017 to early 2019). The treatment consisted of IM injections of a 5% aqueous enro-C suspension (10 mg/kg/day) for 10 days, and subsequently enro-C was administered orally for another 7 days in gelatin capsules. Thirty-four high-risk and 11 medium-risk dogs were treated, including 6 puppies (4 high-risk with ages between 6 to 10 months and 2 medium-risk dogs with an average age of 6 and 7 months). Other ages ranged from 1 to 5 years. Fifteen cases had a history of having received prior treatment with other antibiotics, including all puppies. The clinical diagnostic error was 13.5% (7/52 cases), and only one of the misdiagnosed dogs had been classified as a high-risk patient. Three to 5 days after finishing treatment with enro-C, 82.2% of the dogs were negative to real-time PCR from urine samples and 100% negativity was observed on day 30 after treatment, when antibody titrations dropped to 1:100-1:200. Based on the absence of clinical signs, real-time PCR, and MAT titers, all treated dogs were considered as successful treatments. Within 6-24 months of clinical follow-up, no relapses were recorded. Adverse effects were inconsequential. This study represents the first report of a successful treatment of canine leptospirosis using a fluoroquinolone, and due to its efficacy, it is suggested that enro-C be considered as a viable option for the treatment of this disease.

Persistent Leptospiruria in Five Dogs Despite Antimicrobial Treatment (2000-2017)

In dogs with leptospirosis, doxycycline therapy is recommended as the preferred therapy for its ability to eliminate the organism from all tissues, including the renal tubules. Elimination of organisms from the renal tubules terminates leptospiruria and prevents transmission of the organism. This report describes the discovery of persistent leptospiruria in the face of therapy with doxycycline in four dogs and enrofloxacin in one dog. Leptospiruria was confirmed by polymerase chain reaction testing for pathogenic leptospires in all five dogs. In two dogs, leptospiruria resolved after a change in therapy to enrofloxacin. In three dogs, doxycycline and/or enrofloxacin were ineffective at eliminating leptospiruria, which then resolved after therapy with clarithromycin. Pet owners could be at risk as persistent leptospiruria poses a potential zoonotic risk. The potential reasons for persistent leptospiruria as demonstrated by polymerase chain reaction testing are discussed.

Orchitis and balanoposthitis in a dog with Leptospira interrogans serovar Canicola in Southern California

Leptospirosis is a disease caused by bacteria Leptospira. It can infect multiple species of mammals, including humans, dogs, rats, mice, raccoons, skunks, opossums, cows and pigs. Once infected, mammals may present with a variety of clinical manifestations. While the classical presentation of the disease is easily recognised by experienced clinicians practising in endemic regions, atypical systemic manifestations can be missed. In this case report, we describe the atypical manifestations of orchitis and balanoposthitis in a five-year-old male intact dog from Los Angeles County, California with confirmed leptospirosis. The dog was infected with serovar Canicola, which is uncommon for this region. Awareness of these atypical manifestations would hopefully guide clinicians towards early diagnosis.

Evidence of interspecies transmission of pathogenic Leptospira between livestock and a domestic cat dwelling in a dairy cattle farm

A domestic cat dwelling in a dairy cattle farm with haematuria was referred for a physical examination. The examination showed no abnormalities therefore complementary exams were performed. Leukocytosis with neutrophilia, monocytosis and hyperproteinaemia were detected. The urine analysis showed a bacterial infection without ultrasound findings. Serological titers to Leptospira interrogans serovar Pomona and Autumnalis were detected. Molecular analysis demonstrated the presence of Leptospira spp. in urine. The findings were consistent with subclinical leptospirosis. The cattle herd had evidence of Leptospira infection. The microbiological exams confirmed the presence of the Leptospira spp. in urine and serum. According to the evidence presented in this study, cats that dwell within a dairy farm could play a role in the Leptospira infection epidemiologically. The importance of feline leptospirosis must be evaluated with leptospirosis control in livestock.

Antibiotic susceptibilities of livestock isolates of leptospira

Leptospirosis is the most common zoonotic disease and is endemic worldwide. The antibiotic susceptibilities of Leptospira strains isolated from both humans and animals are poorly documented. This issue is particularly important for isolates from food-producing animals which are regularly exposed to antibiotic treatments. This study assessed the susceptibility of 35 leptospira strains isolated from food-producing animals of diverse geographical origins between 1936 and 2016 to the antimicrobial agents used most commonly in animals. A broth microdilution method was used to determine the susceptibilities of Leptospira strains isolated from livestock to 11 antibiotics. All isolates were susceptible to penicillin, amoxicillin, clavulanate, cephalexin, ceftriaxone, doxycycline, tetracycline, streptomycin, enrofloxacin and spectinomycin, but not polymyxin [minimum inhibitory concentration (MIC) ≥ 4 μg/L]. For tetracycline and doxycycline, the MIC was significantly higher for the recent isolates from Sardinia, Italy than for the other isolates. Antimicrobial susceptibilities were also determined with 10- and 100-fold higher inocula. High inocula significantly diminished the antibacterial effect by at least 10-fold for enrofloxacin (MIC ≥256 μg/L), streptomycin (MIC ≥16 μg/L) and tetracycline (MIC ≥32 μg/L), suggesting selection of resistant strains for high inocula. These findings contribute to the assessment of whether certain antibiotics are potentially useful for the treatment of leptospirosis, and point out the risk of failure for some antibiotics during infection with a high inoculum in both animals and humans. This study strengthens the need to detect and prevent the emergence of antimicrobial resistance of this major emerging zoonotic pathogen.

Immunoprotective properties of recombinant LigA and LigB in a hamster model of acute leptospirosis

Leptospirosis is the most widespread zoonosis and is considered a major public health problem worldwide. Currently, there is no widely available vaccine against leptospirosis for use in humans. A purified, recombinant subunit vaccine that includes the last six immunoglobulin-like (Ig-like) domains of the leptospiral protein LigA (LigA7'-13) protects against lethal infection but not renal colonization after challenge by Leptospira interrogans. In this study, we examined whether the addition of the first seven Ig-like domains of LigB (LigB0-7) to LigA7'-13, can enhance immune protection and confer sterilizing immunity in the Golden Syrian hamster model of acute leptospirosis. Hamsters were subcutaneously immunized with soluble, recombinant LigA7'-13, LigB0-7, or a combination of LigA7'-13 and LigB0-7 in Freund's adjuvant. Immunization with Lig proteins generated a strong humoral immune response with high titers of IgG that recognized homologous protein, and cross-reacted with the heterologous protein as assessed by ELISA. LigA7'-13 alone, or in combination with LigB0-7, protected all hamsters from intraperitoneal challenge with a lethal dose of L. interrogans serovar Copenhageni strain Fiocruz L1-130. However, bacteria were recovered from the kidneys of all animals. Of eight animals immunized with LigB0-7, only three survived Leptospira challenge, one of which lacked renal colonization and had antibodies to native LigB by immunoblot. In addition, sera from two of the three LigB0-7 immunized survivors cross-reacted with LigA11-13, a region of LigA that is sufficient for protection. In summary, we confirmed that LigA7'-13 protects hamsters from death but not infection, and immunization with LigB0-7, either alone or in combination with LigA7'-13, did not confer sterilizing immunity.

Antimicrobial susceptibility of Leptospira spp. isolated from environmental, human and animal sources in Malaysia

Leptospirosis is a zoonosis with worldwide distribution caused by pathogenic spirochetes of the genus Leptospira. The aim of this study was to evaluate the susceptibility of isolates obtained from different hosts. A total of 65 Leptospira isolates from humans (n = 1), zoonoses (rat, n = 60; dog, n = 1; swine, n = 1) and environment (n = 2) were tested against six antibiotics. All the isolates were resistant to trimethoprim and sulphamethoxazole and had high MIC toward chloramphenicol (MIC90: 6.25 μg/ml). All except one environment isolate were sensitive to ampicillin, doxycycline and penicillin G.

Real-Time PCR Reveals Rapid Dissemination of Leptospira interrogans after Intraperitoneal and Conjunctival Inoculation of Hamsters

The pathogen Leptospira interrogans is a highly motile spirochete that causes acute and fulminant infections in humans and other accidental hosts. Hematogenous dissemination is important for infection by the pathogen but remains poorly understood because few animal model studies have used sensitive tools to quantify the bacteria. We evaluated the kinetics of leptospiral infection in Golden Syrian hamsters by a sensitive quantitative real-time PCR (TaqMan) with lipl32 as the target gene. The dissemination and bacterial burden were measured after intraperitoneal infection with a high dose (10(8)) or low dose (2.5 × 10(2)) of leptospires. We also examined the conjunctival challenge route to mimic the natural history of infection. Quantification of leptospires in perfused animals revealed that pathogens were detected in all organs of intraperitoneally infected hamsters, including the eye and brain, within 1 h after inoculation of 10(8) virulent L. interrogans bacteria. Peaks of 10(5) to 10(8) leptospires per gram or per milliliter were achieved in blood and all tissues between day 4 and day 8 after intraperitoneal inoculation of high- and low-dose challenges, respectively, coinciding with macroscopic and histological changes. The conjunctival route resulted in a delay in the time to peak organ burden in comparison to intraperitoneal infection, indicating that although infection could be established, penetration efficiency was low across this epithelial barrier. Surprisingly, infection with a large inoculum of high-passage-number attenuated L. interrogans strains resulted in dissemination to all organs in the first 4 days postinfection, albeit with a lower burden, followed by clearance from the blood and organs 7 days postinfection and survival of all animals. These results demonstrate that leptospiral dissemination and tissue invasion occur. In contrast, development of a critical level of tissue burden and pathology are dependent on the virulence of the infecting strain.

European consensus statement on leptospirosis in dogs and cats

Leptospirosis is a zoonotic disease with a worldwide distribution affecting most mammalian species. Clinical leptospirosis is common in dogs but appears to be rare in cats. Both dogs and cats, however, can shed leptospires in the urine. This is problematic as it can lead to exposure of humans. The control of leptospirosis, therefore, is important not only from an animal but also from a public health perspective. The aim of this consensus statement is to raise awareness of leptospirosis and to outline the current knowledge on the epidemiology, clinical features, diagnostic tools, prevention and treatment measures relevant to canine and feline leptospirosis in Europe.

Antibiotic Efficacy in Eliminating Leptospiruria in California Sea Lions (Zalophus californianus) Stranding with Leptospirosis

Stranded California sea lions (Zalophus californianus) along the California coast have been diagnosed with leptospirosis every year since at least the 1980s. Between September 2010 and November 2011, we followed 14 stranded California sea lions that survived to release and evaluated antibiotic efficacy in eliminating leptospiruria (urinary shedding of leptospires). Leptospiruria was assessed by real-time PCR of urine and urine culture, with persistence assessed using longitudinally collected samples. Serum chemistry was used to assess recovery of normal renal function. Microscopic agglutination testing (MAT) was performed to assess serum anti-Leptospira antibody titers, and the MAT reactivity patterns were consistent with L. interrogans serovar Pomona infection frequently observed in this population. Animals were initially treated for 6 to 16 d (median = 10.5; mean = 10.8) with antibiotics from the penicillin family, with some receiving additional antibiotics to treat other medical conditions. All urine cultures were negative; therefore, the presence of leptospiruria was assessed using PCR. Leptospiruria continued beyond the initial course of penicillin family antibiotics in 13 of the 14 sea lions, beyond the last antibiotic dose in 11 of the 14 sea lions, beyond recovery of renal function in 13 of the 14 sea lions, and persisted for at least 8 to 86 d (median = 45; mean = 46.8). Five animals were released with no negative urine PCR results detected; thus, their total shedding duration may have been longer. Cessation of leptospiruria was more likely in animals that received antibiotics for a greater duration, especially if coverage was uninterrupted. Real-time PCR results indicate that an antibiotic protocol commonly used to treat leptospirosis in rehabilitating California sea lions does not eliminate leptospiruria. It is possible that antibiotic protocols given for a longer duration and/or including other antibiotics may be effective in eliminating leptospiruria. These results may have important human and animal health implications, especially in rehabilitation facilities, as Leptospira transmission may occur through contact with animals with persistent leptospiruria.

Leptospirosis in humans

Leptospirosis is a widespread and potentially fatal zoonosis that is endemic in many tropical regions and causes large epidemics after heavy rainfall and flooding. Infection results from direct or indirect exposure to infected reservoir host animals that carry the pathogen in their renal tubules and shed pathogenic leptospires in their urine. Although many wild and domestic animals can serve as reservoir hosts, the brown rat (Rattus norvegicus) is the most important source of human infections. Individuals living in urban slum environments characterized by inadequate sanitation and poor housing are at high risk of rat exposure and leptospirosis. The global burden of leptospirosis is expected to rise with demographic shifts that favor increases in the number of urban poor in tropical regions subject to worsening storms and urban flooding due to climate change. Data emerging from prospective surveillance studies suggest that most human leptospiral infections in endemic areas are mild or asymptomatic. Development of more severe outcomes likely depends on three factors: epidemiological conditions, host susceptibility, and pathogen virulence (Fig. 1). Mortality increases with age, particularly in patients older than 60 years of age. High levels of bacteremia are associated with poor clinical outcomes and, based on animal model and in vitro studies, are related in part to poor recognition of leptospiral LPS by human TLR4. Patients with severe leptospirosis experience a cytokine storm characterized by high levels of IL-6, TNF-alpha, and IL-10. Patients with the HLA DQ6 allele are at higher risk of disease, suggesting a role for lymphocyte stimulation by a leptospiral superantigen. Leptospirosis typically presents as a nonspecific, acute febrile illness characterized by fever, myalgia, and headache and may be confused with other entities such as influenza and dengue fever. Newer diagnostic methods facilitate early diagnosis and antibiotic treatment. Patients progressing to multisystem organ failure have widespread hematogenous dissemination of pathogens. Nonoliguric (high output) renal dysfunction should be supported with fluids and electrolytes. When oliguric renal failure occurs, prompt initiation of dialysis can be life saving. Elevated bilirubin levels are due to hepatocellular damage and disruption of intercellular junctions between hepatocytes, resulting in leaking of bilirubin out of bile caniliculi. Hemorrhagic complications are common and are associated with coagulation abnormalities. Severe pulmonary hemorrhage syndrome due to extensive alveolar hemorrhage has a fatality rate of >50 %. Readers are referred to earlier, excellent summaries related to this subject (Adler and de la Peña-Moctezuma 2010; Bharti et al. 2003; Hartskeerl et al. 2011; Ko et al. 2009; Levett 2001; McBride et al. 2005).

Host response to leptospira infection

Pathogenic Leptospira has the capacity to infect a broad range of mammalian hosts. Leptospirosis may appear as an acute, potentially fatal infection in accidental hosts, or progress into a chronic, largely asymptomatic infection in natural maintenance hosts. The course that Leptospira infection follows is dependent upon poorly understood factors, but is heavily influenced by both the host species and bacterial serovar involved in infection. Recognition of pathogen-associated molecular patterns (PAMPs) by a variety of host pattern recognition receptors (PRRs) activates the host immune system. The outcome of this response may result in bacterial clearance, limited bacterial colonization of a few target organs, principally the kidney, or induction of sepsis as the host succumbs to infection and dies. This chapter describes current knowledge of how the host recognizes Leptospira and responds to infection using innate and acquired immune responses. Aspects of immune-mediated pathology and pathogen strategies to evade the host immune response are also addressed.

Live imaging of bioluminescent leptospira interrogans in mice reveals renal colonization as a stealth escape from the blood defenses and antibiotics

Leptospira (L.) interrogans are bacteria responsible for a worldwide reemerging zoonosis. Some animals asymptomatically carry L. interrogans in their kidneys and excrete bacteria in their urine, which contaminates the environment. Humans are infected through skin contact with leptospires and develop mild to severe leptospirosis. Previous attempts to construct fluorescent or bioluminescent leptospires, which would permit in vivo visualization and investigation of host defense mechanisms during infection, have been unsuccessful. Using a firefly luciferase cassette and random transposition tools, we constructed bioluminescent chromosomal transformants in saprophytic and pathogenic leptospires. The kinetics of leptospiral dissemination in mice, after intraperitoneal inoculation with a pathogenic transformant, was tracked by bioluminescence using live imaging. For infective doses of 10⁶ to 10⁷ bacteria, we observed dissemination and exponential growth of leptospires in the blood, followed by apparent clearance of bacteria. However, with 2×10⁸ bacteria, the septicemia led to the death of mice within 3 days post-infection. In surviving mice, one week after infection, pathogenic leptospires reemerged only in the kidneys, where they multiplied and reached a steady state, leading to a sustained chronic renal infection. These experiments reveal that a fraction of the leptospiral population escapes the potent blood defense, and colonizes a defined number of niches in the kidneys, proportional to the infective dose. Antibiotic treatments failed to eradicate leptospires that colonized the kidneys, although they were effective against L. interrogans if administered before or early after infection. To conclude, mice infected with bioluminescent L. interrogans proved to be a novel model to study both acute and chronic leptospirosis, and revealed that, in the kidneys, leptospires are protected from antibiotics. These bioluminescent leptospires represent a powerful new tool to challenge mice treated with drugs or vaccines, and test the survival, dissemination, and transmission of leptospires between environment and hosts.

Leptospirosis is a worldwide neglected disease caused by the pathogenic bacterium named Leptospira interrogans. Some rodents, such as rats, do not get sick from leptospirosis and constitute a reservoir. They carry leptospires in their kidneys and excrete the bacteria in the environment. L. interrogans are mobile and penetrate their hosts through abraded skin or mucosa. Infected humans may develop mild to severe leptospirosis, potentially leading to death. Leptospires are difficult to cultivate and to genetically manipulate, impairing the study of leptospirosis. Here, we constructed bioluminescent leptospires, and monitored infection in live mice by tracking bioluminescence. In the first days after infection, a rapid dissemination and growth of bacteria was observed in the blood circulation, followed around one week after the infection by their apparent disappearance. However, the leptospires reemerged and multiplied in the kidneys, to reach sustained levels three weeks after infection. The use of antibiotics showed that antibiotic-susceptible L. interrogans are very difficult to eradicate once they are settled in the kidneys. Mice infected with bioluminescent leptospires represent a pertinent model to study leptospirosis. These bioluminescent leptospires are novel tools that will be useful to test the efficacy of treatments or vaccines against leptospirosis.

Efficacy of cefepime, ertapenem and norfloxacin against leptospirosis and for the clearance of pathogens in a hamster model

Animals and humans with severe leptospirosis may require empirical treatment. Although many antibiotics are active against multiple leptospira serovars in vitro, their efficacy in vivo is limited. We evaluated the efficacy of cefepime (daily dose: 2, 5, 10, and 20 mg/kg), ertapenem (daily dose: 2.5, 5, and 10 mg/kg) and norfloxacin (daily dose: 20, 40, and 80 mg/kg) for the treatment of leptospirosis and the ability to clear leptospira in target organs (liver, kidney, lung, heart, and spleen) in a lethal hamster model using Leptospira interrogans serovar Autumnalis. The histopathology of infected kidney, lung and liver was also evaluated using hematoxylin and eosin stain (H&E stain). All untreated animals, serving as a negative control, died with leptospira existing in the target organs between the 5th and 7th day after infection. All of the treated groups displayed improved survival compared to the untreated group and demonstrated a dose-dependent decrease in the presence of leptospira in the target organs. Cefepime showed survival benefit comparable to the standard treatment, doxycycline. We conclude that all of the antibiotics tested in vivo produce a statistically significant survival advantage, alleviate tissue injury and decrease the abundance of leptospira in target organs.

Kinetics of Leptospira interrogans infection in hamsters after intradermal and subcutaneous challenge

BACKGROUND

Leptospirosis is a zoonosis caused by highly motile, helically shaped bacteria that penetrate the skin and mucous membranes through lesions or abrasions, and rapidly disseminate throughout the body. Although the intraperitoneal route of infection is widely used to experimentally inoculate hamsters, this challenge route does not represent a natural route of infection.

METHODOLOGY/PRINCIPAL FINDINGS

Here we describe the kinetics of disease and infection in hamster model of leptospirosis after subcutaneous and intradermal inoculation of Leptospira interrogans serovar Copenhageni, strain Fiocruz L1-130. Histopathologic changes in and around the kidney, including glomerular and tubular damage and interstitial inflammatory changes, began on day 5, and preceded deterioration in renal function as measured by serum creatinine. Weight loss, hemoconcentration, increased absolute neutrophil counts (ANC) in the blood and hepatic dysfunction were first noted on day 6. Vascular endothelial growth factor, a serum marker of sepsis severity, became elevated during the later stages of infection. The burden of infection, as measured by quantitative PCR, was highest in the kidney and peaked on day 5 after intradermal challenge and on day 6 after subcutaneous challenge. Compared to subcutaneous challenge, intradermal challenge resulted in a lower burden of infection in both the kidney and liver on day 6, lower ANC and less weight loss on day 7.

CONCLUSIONS/SIGNIFICANCE

The intradermal and subcutaneous challenge routes result in significant differences in the kinetics of dissemination and disease after challenge with L. interrogans serovar Copenhageni strain Fiocruz L1-130 at an experimental dose of 2×106 leptospires. These results provide new information regarding infection kinetics in the hamster model of leptospirosis.

Acquired nephrogenic diabetes insipidus in a dog with leptospirosis

A 5 year old male neutered Cairn Terrier was evaluated for signs of polyuria and polydipsia. Initial hematology and chemistry panels were unremarkable and urinalysis showed a persistent hyposthenuria. Eleven days later, the dog became lethargic, inappetent and had developed acute renal failure. The dog was ultimately euthanized due to a poor response to treatment. Microscopic agglutination titres were consistent with a diagnosis of leptospirosis. The initial hyposthenuria in this case was consistent with acquired nephrogenic diabetes insipidus. This is an uncommon presentation of leptospirosis that has not previously been described to progress to acute renal failure. Leptospirosis should be considered as a differential diagnosis in any dog presenting with polyuria and polydipsia and these patients should be treated as a zoonotic risk.

Utility of quantitative polymerase chain reaction in leptospirosis diagnosis: association of level of leptospiremia and clinical manifestations in Sri Lanka

BACKGROUND

Quantitative polymerase chain reaction (qPCR), despite cost and logistical challenges, has the potential to provide accurate and timely diagnosis for leptospirosis at the point-of-care in endemic areas. We studied optimal sample types for qPCR, timing of sampling, and clinical manifestations in relation to quantitative leptospiremia.

METHODS

A new qPCR assay using pathogenic Leptospira-specific 16S ribosomal RNA (rRNA) gene Taqman primers and an optimized temperature stepdown protocol was used to analyze patient blood samples. Serum was compared with whole blood as sample source. Quantitative leptospiremia was compared with clinical manifestations of leptospirosis and outcome.

RESULTS

The diagnostic sensitivity of qPCR of whole blood and serum was 18.4% (95% confidence interval [CI]: 9.97%-31.4%) and 51.0% (95% CI: 37.5%-64.4%) respectively. The qPCR on suspected cases confirmed infection in 58 of 381 cases (15.2%). Of these, 6 cases confirmed by nested polymerase chain reaction (PCR) and sequencing were serologically negative using a standard but not regionally optimized microscopic agglutination test panel. The bacterial load in serum/blood ranged from 10(2) to 10(6) Leptospira/mL. Median leptospiral load for uncomplicated, renal failure, myocarditis, and multi-organ failure patients were 8616, 11007, 36100, and 15882 Leptospira/mL respectively. The qPCR window of positivity ranged from day 2 to day 15; sensitivity of qPCR was not affected by the length of the interval between the onset of symptoms and sample collection (P = .328).

CONCLUSIONS

Quantitative PCR shows potential as a valid diagnostic test with a wider window of positivity than previously thought. Quantitative leptospiremia in serum/whole blood samples did not directly correlate with clinical manifestations of outcome in this patient population.

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

Background

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

Methods

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

Results

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

Conclusion

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

Leptospirosis with transient paraparesis and thrombocytopenia: a case report

Leptospirosis is the most widespread zoonosis in the world. We present an unusual case of leptospirosis in a 44-year-old man with severe thrombocytopenia and transient paraparesis. The diagnosis of leptospirosis was confirmed by blood nested polymerase chain reaction, seroconversion of Leptospira IgM and the microscopic agglutination test. Nerve conduction studies were suggestive of early polyneuropathy involving the right peroneal nerve and bilateral sural nerves. Peripheral nerve palsy is a potential clinical feature of leptospirosis.

Leptospira as an emerging pathogen: a review of its biology, pathogenesis and host immune responses

Leptospirosis, the most widespread zoonosis in the world, is an emerging public health problem, particularly in large urban centers of developing countries. Several pathogenic species of the genus Leptospira can cause a wide range of clinical manifestations, from a mild, flu-like illness to a severe disease form characterized by multiorgan system complications leading to death. However, the mechanisms of pathogenesis of Leptospira are largely unknown. This article will address the animal models of acute and chronic leptospire infections, and the recent developments in the genetic manipulation of the bacteria, which facilitate the identification of virulence factors involved in pathogenesis and the assessment of their potential values in the control and prevention of leptospirosis.

2010 ACVIM small animal consensus statement on leptospirosis: diagnosis, epidemiology, treatment, and prevention

This report offers a consensus opinion on the diagnosis, epidemiology, treatment, and prevention of leptospirosis in dogs, an important zoonosis. Clinical signs of leptospirosis in dogs relate to development of renal disease, hepatic disease, uveitis, and pulmonary hemorrhage. Disease may follow periods of high rainfall, and can occur in dogs roaming in proximity to water sources, farm animals, or wildlife, or dogs residing in suburban environments. Diagnosis is based on acute and convalescent phase antibody titers by the microscopic agglutination test (MAT), with or without use of polymerase chain reaction assays. There is considerable interlaboratory variation in MAT results, and the MAT does not accurately predict the infecting serogroup. The recommended treatment for optimal clearance of the organism from renal tubules is doxycycline, 5 mg/kg PO q12h, for 14 days. Annual vaccination can prevent leptospirosis caused by serovars included in the vaccine and is recommended for dogs at risk of infection.

In vitro sensitivity and resistance of 46 Leptospira strains isolated from rats in the Philippines to 14 antimicrobial agents

The in vitro susceptibilities of 46 Leptospira isolates from rats to 14 antimicrobial agents were tested. All of the strains were found to be sensitive to ampicillin, cefotaxime, ciprofloxacin, norfloxacin, doxycycline, erythromycin, and streptomycin. In contrast, the tested isolates showed resistance to amphotericin B, 5-fluorouracil, fosfomycin, trimethoprim, sulfamethoxazole, neomycin, and vancomycin. These findings will help in selecting effective and ineffective antimicrobials for treatment of leptospirosis and for the development of new selective media, respectively.

Differential cytokine gene expression according to outcome in a hamster model of leptospirosis

Background

Parameters predicting the evolution of leptospirosis would be useful for clinicians, as well as to better understand severe leptospirosis, but are scarce and rarely validated. Because severe leptospirosis includes septic shock, similarities with predictors evidenced for sepsis and septic shock were studied in a hamster model.

Methodology/Principal Findings

Using an LD50 model of leptospirosis in hamsters, we first determined that 3 days post-infection was a time-point that allowed studying the regulation of immune gene expression and represented the onset of the clinical signs of the disease. In the absence of tools to assess serum concentrations of immune effectors in hamsters, we determined mRNA levels of various immune genes, especially cytokines, together with leptospiraemia at this particular time-point. We found differential expression of both pro- and anti-inflammatory mediators, with significantly higher expression levels of tumor necrosis factor α, interleukin 1α, cyclo-oxygenase 2 and interleukin 10 genes in nonsurvivors compared to survivors. Higher leptospiraemia was also observed in nonsurvivors. Lastly, we demonstrated the relevance of these results by comparing their respective expression levels using a LD100 model or an isogenic high-passage nonvirulent variant.

Conclusions/Significance

Up-regulated gene expression of both pro- and anti-inflammatory immune effectors in hamsters with fatal outcome in an LD50 model of leptospirosis, together with a higher Leptospira burden, suggest that these gene expression levels could be predictors of adverse outcome in leptospirosis.

Leptospirosis is a widespread bacterial infection that is transmitted by soil or water contaminated by the urine of infected animals, or directly from these animals. It has highly diverse clinical presentations, making its differential diagnosis difficult. Though most cases are minor and self-resolving, there are also severe forms that include a sepsis pattern and multiple organ failure, and have possible fatal outcomes. Predictors of disease evolution and outcome are scarce, yet they would be very valuable to clinicians as well as to better decipher disease pathogenesis. In this study, we used a hamster model of leptospirosis to evaluate if immune genes were differentially expressed between individuals and if their expression levels could help forecast the outcome of the disease. We found that hamsters that later died from leptospirosis had significantly higher expression levels of both pro- and anti-inflammatory mediators compared to survivors. These results suggest that expression levels of these immune effectors might be helpful predictors of outcome in leptospirosis and that septic shock contributes to fatal leptospirosis.

Use of quantitative real-time PCR for studying the dissemination of Leptospira interrogans in the guinea pig infection model of leptospirosis

The dynamics of leptospirosis infection have been poorly studied. The purpose of this study was to determine the LD50, rate of bacterial dissemination, histopathology and antibody responses against leptospira following inoculation with the highly virulent Leptospira interrogans Fiocruz L1-130 strain in a guinea pig model of leptospirosis. Three routes of infection (intraperitoneal, conjunctival and subcutaneous inoculation) were used to establish disease in guinea pigs. The size and kinetics of leptospiral burdens in the blood and tissues of infected animals were determined over a 1 week course of infection using quantitative real-time PCR (qPCR). Bacteraemia peaked at day 5 post-infection reaching more than 5×104 leptospires ml−1. The highest spirochaetal load was found in the liver and kidneys, and was associated with alterations in organ tissues and a decline in liver and kidney functions. In contrast, lesions and bacteria were not detected in guinea pigs infected with an avirulent strain derived from a high-passage-number in vitro-passaged variant of the Fiocruz L1-130 strain. The use of qPCR supports the findings of earlier studies and provides an easy and reliable method for the quantification of L. interrogans in the tissues of infected animals. qPCR will be used in future studies to evaluate the efficacy of vaccine candidates against leptospirosis and the virulence of selected L. interrogans mutants relative to the parental strain.

The efficacy of tetracyclines in peripheral and intracerebral prion infection

We have previously shown that tetracyclines interact with and reverse the protease resistance of pathological prion protein extracted from scrapie-infected animals and patients with all forms of Creutzfeldt-Jakob disease, lowering the prion titre and prolonging survival of cerebrally infected animals. To investigate the effectiveness of these drugs as anti-prion agents Syrian hamsters were inoculated intramuscularly or subcutaneously with 263K scrapie strain at a 10⁻⁴ dilution. Tetracyclines were injected intramuscularly or intraperitoneally at the dose of 10 mg/kg. A single intramuscular dose of doxycycline one hour after infection in the same site of inoculation prolonged median survival by 64%. Intraperitoneal doses of tetracyclines every two days for 40 or 44 days increased survival time by 25% (doxycycline), 32% (tetracycline); and 81% (minocycline) after intramuscular infection, and 35% (doxycycline) after subcutaneous infection. To extend the therapeutic potential of tetracyclines, we investigated the efficacy of direct infusion of tetracyclines in advanced infection. Since intracerebroventricular infusion of tetracycline solutions can cause overt acute toxicity in animals, we entrapped the drugs in liposomes. Animals were inoculated intracerebrally with a 10⁻⁴ dilution of the 263K scrapie strain. A single intracerebroventricular infusion of 25 µg/ 20 µl of doxycycline or minocycline entrapped in liposomes was administered 60 days after inoculation, when 50% of animals showed initial symptoms of the disease. Median survival increased of 8.1% with doxycycline and 10% with minocycline. These data suggest that tetracyclines might have therapeutic potential for humans.

Leptospiral pneumonias

PURPOSE OF REVIEW

Pulmonary involvement in leptospirosis has been reported to be increasing in the last few years and is emerging as a serious life threat and the main cause of death due to leptospirosis in some countries. In this review, we present the main clinical and pathological manifestations of pulmonary involvement in leptospirosis, and recent data on the pathophysiology of lung damage and therapeutic implications.

RECENT FINDINGS

Although previous reports have emphasized the increasing incidence of pulmonary manifestations in patients with leptospirosis worldwide, pulmonary involvement in leptospirosis is still under-recognized. Experimental models have been used to address new aspects of the pathogenesis of the disease, including determination of novel outer membrane proteins, characterization of dysregulation of sodium transporters of alveolar epithelial cells, and provision of new data on the role of innate immunity in the development of severe disease, thereby making major progress in understanding the mechanisms underlying lung injury.

SUMMARY

Pulmonary hemorrhage represents the main cause of death in severe forms of leptospirosis. Although the mechanism of pulmonary impairment is still poorly understood, recent experimental studies have brought new insights to the pathogenesis of lung injury and provide new perspectives on treatment of critically ill patients.

Efficacy of fluoroquinolones against Leptospira interrogans in a hamster model

Ciprofloxacin, gatifloxacin, and levofloxacin were evaluated for their abilities to prevent mortality in hamsters infected with a lethal inoculum of Leptospira interrogans serovar Portlandvere. Each agent produced a statistically significant survival advantage compared to no treatment and demonstrated survival similar to that seen with doxycycline therapy.

Antimicrobial therapy of leptospirosis

PURPOSE OF REVIEW

Leptospirosis is an important but often overlooked zoonotic disease that can cause significant morbidity and mortality. The optimal antimicrobial treatment for this disease has not been established. This review summarizes the most recent literature pertaining to the use of antimicrobial agents in the treatment of leptospirosis.

RECENT FINDINGS

Leptospira are highly susceptible to a wide variety of antimicrobials in vitro. Despite this, it is not clear what the best choice of antimicrobial agents is for human disease. Based on the best available literature, the current choices of treatment for leptospirosis include penicillin, doxycycline, cefotaxime, ceftriaxone and azithromycin. Penicillin has long been considered the treatment of choice. Doxycycline is a reasonable alternative, but concerns exist regarding its use in all patients. Recent trials have demonstrated that cefotaxime and ceftriaxone are also acceptable agents. For a variety of reasons, these may be the preferred agents at this time. Azithromycin appears promising for the treatment of less severe disease. Another option for treating leptospirosis is the fluoroquinolone antimicrobials, although adequate human trials are lacking to fully support their use.

SUMMARY

Leptospirosis is an important cause of morbidity and mortality worldwide. Despite this, the optimal treatment is not fully defined.

Optimal treatment of leptospirosis: queries and projections

Although the global burden of leptospirosis remains enormous and new aspects of the disease are constantly recognised, little progress has been achieved in the field of leptospirosis therapeutics and queries regarding the utility of antibiotics in the late severe form of the disease remain. From the currently existing data, conclusions on the efficacy of antibiotic administration in severe or late disease cannot easily be drawn, since clinical trials have different selection criteria and may focus on Leptospira serovars with different virulence. However, as a rule the benefit of the doubt should apply. Moreover, new options, such as ceftriaxone, have a superior safety profile to penicillin. In vitro studies have outlined potential antimicrobial candidates such as macrolides and ketolides. Development of a globally accepted subunit vaccine for humans is warranted but is not expected in the near future.

Hamster model of leptospirosis

This unit describes the techniques involved in the hamster model of leptospirosis. Hamsters are exquisitely susceptible to infection with pathogenic Leptospira species. The LD(50) of virulent Leptospiral strains by intraperitoneal inoculation of 3- to 4-week-old hamsters is as low as a single organism. The pathogenesis of severe leptospirosis in the hamster is a model of accidental infections observed in nature in many mammals, including humans. Animal husbandry issues and the reproducibility of the hamster model make it the animal model of choice for Leptospiral vaccine and antibiotic treatment studies.

Proinflammatory and immunomodulatory cytokine mRNA time course profiles in hamsters infected with a virulent variant of Leptospira interrogans

In order to quantify in vivo the mRNAs of cytokines which play important roles in leptospirosis, we have developed quantitative real-time PCR assays for interleukin-2 (IL-2), IL-4, IL-10, IL-12p40, tumor necrosis factor alpha (TNF-alpha), gamma interferon (IFN-gamma), transforming growth factor beta, and two housekeeping genes (encoding beta-actin and hypoxanthine phosphoribosyltransferase). We used a lethal hamster model reflecting severe leptospirosis in humans. The LightCycler system was used to quantify the gene expression levels with the SYBR green I detection format using external standard curves for each target. We compared the expression levels of cytokine mRNA in the peripheral blood mononuclear cells of both control (uninfected) hamsters and Leptospira interrogans-inoculated hamsters from 1 to 24 h and then 1 to 4 days postinfection. In this kinetic study, there was pronounced expression of Th1 cytokine mRNA (TNF-alpha, IFN-gamma, and IL-12), with transcripts being detected as early as 1 h postinfection. Expression of anti-inflammatory cytokines, such as IL-4 and IL-10, was prominent in delayed samples from 1 to 4 days postinfection in response to infection with Leptospira interrogans. Our data are the first to establish that pathogenic leptospires can stimulate in vivo the production of type 1 cytokines involved in cellular immunity by using this informative animal model. Measuring and assessing cytokine profiles may provide a useful method for accurate study of the mechanisms of anti-Leptospira immunity, indications of prognosis factors, and prospective evaluation of leptospirosis vaccine efficacy in humans.

Use of ceftriaxone in patients with severe leptospirosis

The optimal treatment of severe and late leptospirosis, and even the need for antibiotic treatment in such clinical settings, remains a subject of debate. Twenty-two patients with severe late leptospirosis were treated with intravenous ceftriaxone 2g daily. Twenty-one patients recovered and one patient passed away due to respiratory complications of the disease. The adverse effect profile and the convenience of the regimen were superior to penicillin regimens reported in other clinical trials. Ceftriaxone may be a reasonable alternative in severe leptospirosis as an efficient, convenient and safe regimen. Large multicentre studies may further define the optimal interventions in severe leptospirosis as well as possible variations in the pathogenic and clinical parameters of respiratory leptospirosis.

Quantitative assessment of protection in experimental syphilis

Protection in experimental rabbit syphilis has been previously assessed by lesion development following intradermal challenge with Treponema pallidum. We have recently reported that passive immunization using monoclonal antibody M131 conveys partial protection as evidenced by significant lesion delays following intradermal challenge. To determine whether such delays in time to lesion appearance corresponded to decreases in the numbers of spirochetes, we used real-time PCR to quantitate T. pallidum genomic DNA copy numbers in lesion biopsies taken throughout the course of lesion development. Three groups of animals were given one prechallenge passive immunization with immune rabbit serum (IRS), M131, or control monoclonal antibody (CMAb) and then challenged with treponemal admixtures of IRS or monoclonal antibody in normal rabbit serum (NRS). As compared to the CMAb NRS controls, delays in the mean time to lesion appearance of 5.8 days for IRS and 8.8 days for M131 were observed. At the earliest time point (10 days postchallenge), real-time PCR showed a mean T. pallidum DNA copy number per mug of rabbit DNA in the CMAb NRS group of 7.65 x 10(3) copies, while no T. pallidum DNA could be detected in the M131 group. At approximately the mean time to lesion appearance in the IRS and M131 groups (17 and 20 days, respectively), the numbers of T. pallidum DNA copies were still 5- and 30-fold less, respectively, than those in the control group at these times. By 30 days postchallenge, the T. pallidum DNA copy numbers were similar in all three groups. These findings indicate that the delays in appearance of syphilitic lesions conferred by IRS and M131 corresponded to a marked decrease in treponemal numbers during the course of lesion development.

A rapid and quantitative method for the detection of Leptospira species in human leptospirosis

Prompt laboratory diagnosis of leptospirosis infection facilitates patient management and initiation of therapy. A cost effective real-time PCR assay using SYBR Green I was developed for detection of pathogenic leptospires in serum specimens. Specific PCR products were obtained only with DNA of pathogenic Leptospira genomospecies. LightCycler PCR ability to distinguish between species was possible using melting curves, providing an approach for identification with a specific Tm assigned to a single species or set of species. Assay sensitivity was approximately 50 leptospires/ml, corresponding to one to two genome copies in a PCR mixture. Fifty-one patients who had clinical symptoms consistent with leptospirosis were tested both with a previously described rrs amplification and our real-time assay. Our LFB1 real-time assay confirmed the diagnosis for 25 patients (49%, 25/51) and revealed an estimated density of 8.0x10(1)-3.9x10(4) leptospires/ml of blood. The total assay time for 12 clinical samples from sample to data analysis was less than 3 h. These data illustrate the potential of our LFB1 real-time assay for the rapid detection of leptospires in serum samples and their subsequent quantification in a single run.

[Eleven cases of leptospirosis: clinical and microbiological features]

OBJECTIVE

The authors had for aim, to describe clinical and biological features of 11 cases of leptospirosis observed in Lorraine between 1996 and 2002, and to assess the interest of diagnostic methods.

PATIENTS AND METHODS

A retrospective study was performed. The inclusion criteria was positive serological test for Leptospira.

RESULTS

The contamination was mainly linked to water sports, during the summer holidays. The main symptom was fever, associated with moderate increase of aminotransferase serum level. Leptospira icterohaemorragiae was the most frequently identified serogroup. One 17-year-old male patient died after infection during water sports practice.

CONCLUSION

Preventive measures should be considered for people exposed to Leptospira when practicing water sports.

The management of leptospirosis

How to quickly identify patients who should be treated for leptospirosis is a challenge. The interest of polymerase chain reaction (PCR) assays is currently being evaluated and rapid tests which can be used outside of the specialised laboratory, have recently been developed. Leptospires are sensitive to many antibiotics and few clinical studies have been made to compare different treatment options. Doxycycline is standard therapy in early leptospirosis treatment and chemoprophylaxis. Intravenous penicillin has been considered the drug of choice in late and severe disease, although it is now challenged by ceftriaxone, which use is easier. Ciprofloxacin may be combined with standard therapy in uveitis. Adjunctive therapies proposed in the management of severe forms of leptospirosis and Jarisch-Herxheimer reactions, are reviewed.

Leptospirosis: a zoonotic disease of global importance

In the past decade, leptospirosis has emerged as a globally important infectious disease. It occurs in urban environments of industrialised and developing countries, as well as in rural regions worldwide. Mortality remains significant, related both to delays in diagnosis due to lack of infrastructure and adequate clinical suspicion, and to other poorly understood reasons that may include inherent pathogenicity of some leptospiral strains or genetically determined host immunopathological responses. Pulmonary haemorrhage is recognised increasingly as a major, often lethal, manifestation of leptospirosis, the pathogenesis of which remains unclear. The completion of the genome sequence of Leptospira interrogans serovar lai, and other continuing leptospiral genome sequencing projects, promise to guide future work on the disease. Mainstays of treatment are still tetracyclines and beta-lactam/cephalosporins. No vaccine is available. Prevention is largely dependent on sanitation measures that may be difficult to implement, especially in developing countries.

Leptospirosis. A re-emerging zoonotic disease

Leptospirosis is a re-emerging infectious disease that occurs in dogs in urban and rural environments. It is caused by a filamentous spiral bacterium that has a predilection for renal tubules. Acute renal failure, hepatic dysfunction, and hemorrhagic diathesis are the most common clinical signs. Treatment with antibiotics and supportive care can manage a high percentage of cases successfully. Newer vaccines developed in response to the change in frequency of certain serovars may decrease the incidence of clinical disease. Leptospirosis affects a wide variety of species and is zoonotic.