Macrophage Selenoproteins Restrict Intracellular Replication of Francisella tularensis and Are Essential for Host Immunity.

The essential micronutrient Selenium (Se) is co-translationally incorporated as selenocysteine into proteins. Selenoproteins contain one or more selenocysteines and are vital for optimum immunity. Interestingly, many pathogenic bacteria utilize Se for various biological processes suggesting that Se may play a role in bacterial pathogenesis. A previous study had speculated that Francisella tularensis, a facultative intracellular bacterium and the causative agent of tularemia, sequesters Se by upregulating Se-metabolism genes in type II alveolar epithelial cells. Therefore, we investigated the contribution of host vs. pathogen-associated selenoproteins in bacterial disease using F. tularensis as a model organism. We found that F. tularensis was devoid of any Se utilization traits, neither incorporated elemental Se, nor exhibited Se-dependent growth. However, 100% of Se-deficient mice (0.01 ppm Se), which express low levels of selenoproteins, succumbed to F. tularensis-live vaccine strain pulmonary challenge, whereas 50% of mice on Se-supplemented (0.4 ppm Se) and 25% of mice on Se-adequate (0.1 ppm Se) diet succumbed to infection. Median survival time for Se-deficient mice was 8 days post-infection while Se-supplemented and -adequate mice was 11.5 and >14 days post-infection, respectively. Se-deficient macrophages permitted significantly higher intracellular bacterial replication than Se-supplemented macrophages ex vivo, corroborating in vivo observations. Since Francisella replicates in alveolar macrophages during the acute phase of pneumonic infection, we hypothesized that macrophage-specific host selenoproteins may restrict replication and systemic spread of bacteria. F. tularensis infection led to an increased expression of several macrophage selenoproteins, suggesting their key role in limiting bacterial replication. Upon challenge with F. tularensis, mice lacking selenoproteins in macrophages (TrspM) displayed lower survival and increased bacterial burden in the lung and systemic tissues in comparison to WT littermate controls. Furthermore, macrophages from TrspM mice were unable to restrict bacterial replication ex vivo in comparison to macrophages from littermate controls. We herein describe a novel function of host macrophage-specific selenoproteins in restriction of intracellular bacterial replication. These data suggest that host selenoproteins may be considered as novel targets for modulating immune response to control a bacterial infection.

Tick-human interactions: from allergic klendusity to the α-Gal syndrome.

Ticks and the pathogens they transmit, including bacteria, viruses, protozoa, and helminths, constitute a growing burden for human and animal health worldwide. The ability of some animal species to acquire resistance to blood-feeding by ticks after a single or repeated infestation is known as acquired tick resistance (ATR). This resistance has been associated to tick-specific IgE response, the generation of skin-resident memory CD4+ T cells, basophil recruitment, histamine release, and epidermal hyperplasia. ATR has also been associated with protection to tick-borne tularemia through allergic klendusity, a disease-escaping ability produced by the development of hypersensitivity to an allergen. In addition to pathogen transmission, tick infestation in humans is associated with the α-Gal syndrome (AGS), a type of allergy characterized by an IgE response against the carbohydrate Galα1-3Gal (α-Gal). This glycan is present in tick salivary proteins and on the surface of tick-borne pathogens such as Borrelia burgdorferi and Anaplasma phagocytophilum, the causative agents of Lyme disease and granulocytic anaplasmosis. Most α-Gal-sensitized individuals develop IgE specific against this glycan, but only a small fraction develop the AGS. This review summarizes our current understanding of ATR and its impact on the continuum α-Gal sensitization, allergy, and the AGS. We propose that the α-Gal-specific IgE response in humans is an evolutionary adaptation associated with ATR and allergic klendusity with the trade-off of developing AGS.

[Ulceroglandular tularemia after contact with a wild boar : Risk of infection for medical personnel by aerosol inhalation during lymph node resection]. / Ulzeroglanduläre Tularämie nach Kontakt mit Wildschwein : Infektionsrisiko für medizinisches Personal durch Inhalation von Aerosolen bei Lymphknotenresektion.

This article presents a case of ulceroglandular tularemia with local lymph node manifestation in a hobby hunter. An adequate diagnosis and early treatment of tularemia is of crucial importance not only for the patient, as when a surgical intervention is necessary there are also substantial risks for medical personnel. In the diagnosis of tularemia, which is rare but with an increasing incidence in Germany, the anamnesis provides the most important clues. A surgical intervention should only be performed after adequate treatment and duration of treatment.

Francisella tularensis as the cause of protracted fever.

BACKGROUND: Tularemia, a re-emerging, potential life threatening infectious disease, can present itself with nonspecific clinical symptoms including fever, chills and malaise. Taking a detailed history of exposure and a highly raised index of clinical suspicion are necessary to take the appropriate diagnostic and therapeutic steps in this setting. Here, a case report of typhoid tularaemia is presented. CASE PRESENTATION: A 53-year old male forester and farmer with protracted fever, abdominal pain, diarrhoea and loss of weight, who experienced productive cough and a pulmonary infiltrate later in the course of disease, was admitted for further investigation. Tularaemia was suspected only owing to history and confirmed by serologic testing more than three weeks after the beginning of the symptoms. The initial antibiotic therapy with ceftriaxone/doxycycline was switched to ciprofloxacin, resulting in the resolution of fever and symptoms. CONCLUSION: Tularaemia has to be considered as a differential diagnosis in febrile patients, even more in cases with protracted fever. Since tularaemia is expanding geographically, involving more animal hosts and causing larger outbreaks, clinicians have to be aware of this potentially fatal disease.

Tick-Borne Diseases in the United States.

BACKGROUND: Tick-borne diseases are an important cause of human morbidity and mortality in the United States. The past several decades have witnessed an increase in both the number of recognized tick-borne pathogens and the number of tick-borne disease cases, whereas tick surveys have revealed substantial geographic expansions of tick populations throughout the country. Multiple laboratory testing options exist for diagnosis of tick-borne diseases, including serology, microscopy, and molecular-based methods. The preferred approach varies by the specific disease, locally available test options, and the stage of illness at patient presentation. Accurate and timely detection of tick-borne illness is of utmost importance, as prompt treatment is strongly linked to better outcomes. CONTENT: This review covers the clinical manifestations and preferred diagnostic approaches for important bacterial, viral, and parasitic tick-borne diseases in the United States, including Lyme disease, tick-borne relapsing fever, anaplasmosis, ehrlichiosis, spotted fever rickettsioses, and babesiosis. Infection with emerging pathogens such as Borrelia miyamotoi, Powassan virus, Heartland virus, Colorado tick fever virus, and Bourbon virus are also covered. SUMMARY: Our understanding of tick-borne diseases in the United States continues to improve with the detection of novel pathogens and development of new diagnostic modalities. While conventional diagnostic methods, including serology and microscopy, will play an ongoing role in the diagnosis of tick-borne diseases, implementation of advanced molecular diagnostics will further broaden our understanding of these diseases by facilitating detection of emerging pathogens and providing more accurate and timely diagnosis.

Tularemia in a Prosthetic Joint Infection.

Periprosthetic infections occur in approximately 0.8% to 1.9% of all total knee arthroplasties (TKAs). Even with these low rates, it is rare to find a zoonotic bacterium causing a periprosthetic infection. In this case report, the authors identify the second documented case of a total joint infection with Francisella tularensis in the world and the first in the United States. A 58-year-old man underwent a left TKA in 1994 and a right TKA in 1997 for severe primary bilateral knee osteoarthrosis. In 2015, he underwent polyethylene exchange for polyethylene wear. Subsequently, he developed repeated effusion without fever or constitutional signs of infection. One aspiration was sent for culture and grew F tularensis. He was treated with doxycycline for chronic suppression and currently has no signs of infection. Total joint implantation rates are expected to rise, with 3.5 million procedures projected to be performed annually by the year 2030 vs 450,000 procedures performed in 2005. With the increased number of operations, it is likely that zoonotic infections will increase as well. Thus, rare zoonotic bacterial infections as well as chronic outdoor exposure in the presence of persistent joint swelling should be considered when obtaining a patient history. [Orthopedics. 2020; 43(1):e54-e56.].

Development, Characterization, and Standardization of a Nose-Only Inhalation Exposure System for Exposure of Rabbits to Small-Particle Aerosols Containing Francisella tularensis.

Inhalation of Francisella tularensis causes pneumonic tularemia in humans, a severe disease with a 30 to 60% mortality rate. The reproducible delivery of aerosolized virulent bacteria in relevant animal models is essential for evaluating medical countermeasures. Here we developed optimized protocols for infecting New Zealand White (NZW) rabbits with aerosols containing F. tularensis We evaluated the relative humidity, aerosol exposure technique, and bacterial culture conditions to optimize the spray factor (SF), a central metric of aerosolization. This optimization reduced both inter- and intraday variability and was applicable to multiple isolates of F. tularensis Further improvements in the accuracy and precision of the inhaled pathogen dose were achieved through enhanced correlation of the bacterial culture optical density and the number of CFU. Plethysmograph data collected during exposures found that respiratory function varied considerably between rabbits, was not a function of weight, and did not improve with acclimation to the system. Live vaccine strain (LVS)-vaccinated rabbits were challenged via aerosol with human-virulent F. tularensis SCHU S4 that had been cultivated in either Mueller-Hinton broth (MHB) or brain heart infusion (BHI) broth. LVS-vaccinated animals challenged with SCHU S4 that had been cultivated in MHB experienced short febrile periods (median, 3.2 days), limited weight loss (<5%), and longer median survival times (∼18 days) that were significantly different from those for unvaccinated controls. In contrast, LVS-vaccinated rabbits challenged with SCHU S4 that had been cultivated in BHI experienced longer febrile periods (median, 5.5 days) and greater weight loss (>10%) than the unvaccinated controls and median survival times that were not significantly different from those for the unvaccinated controls. These studies highlight the importance of careful characterization and optimization of protocols for aerosol challenge with pathogenic agents.

Clinical characteristics in a sentinel case as well as in a cluster of tularemia patients associated with grape harvest.

BACKGROUND: Tularemia is caused by Francisella tularensis and can occasionally establish foodborne transmission. METHODS: Patients were identified by active case detection through contact with the treating physicians and consent for publication was obtained. Clinical data were accumulated through a review of the patient charts. Serology, culture, and PCR methods were performed for confirmation of the diagnosis. CASE CLUSTER: A 46-year-old patient was hospitalised in the University Hospital Frankfurt (a tertiary care hospital) for pharyngitis and cervical lymphadenitis with abscess. A diagnosis of tularemia was made serologically, but treatment with ciprofloxacin initially failed. F. tularensis was detected in pus from the lymph node using a specific real-time PCR. The use of RD1 PCR led to the identification of the subspecies holarctica. Antibiotic therapy with high-dose ciprofloxacin and gentamicin was administered and was subsequently changed to ciprofloxacin and rifampicin. During a must-tasting, five other individuals became infected with tularemia by ingestion of contaminated must. All patients required treatment durations of more than 14 days. CONCLUSIONS: Mechanically harvested agricultural products, such as wine must, can be a source of infection, probably due to contamination with animal carcasses. The clinical course of tularemia can be complicated and prolonged and requires differentiated antibiotic treatment.

Francisella tularensis Transmission by Solid Organ Transplantation, 20171.

In July 2017, fever and sepsis developed in 3 recipients of solid organs (1 heart and 2 kidneys) from a common donor in the United States; 1 of the kidney recipients died. Tularemia was suspected only after blood cultures from the surviving kidney recipient grew Francisella species. The organ donor, a middle-aged man from the southwestern United States, had been hospitalized for acute alcohol withdrawal syndrome, pneumonia, and multiorgan failure. F. tularensis subsp. tularensis (clade A2) was cultured from archived spleen tissue from the donor and blood from both kidney recipients. Whole-genome multilocus sequence typing indicated that the isolated strains were indistinguishable. The heart recipient remained seronegative with negative blood cultures but had been receiving antimicrobial drugs for a medical device infection before transplant. Two lagomorph carcasses collected near the donor's residence were positive by PCR for F. tularensis subsp. tularensis (clade A2). This investigation documents F. tularensis transmission by solid organ transplantation.

Case Report: Atypical Cutaneous Manifestations of Tularemia after Horsefly Bite.

Tularemia is an infectious zoonosis caused by Francisella tularensis, an aerobic, noncapsulated, Gram-negative coccobacillus. It is more common in the northern hemisphere, and there are sporadic reports in non-endemic areas. The bacterium is usually transmitted by the bite or feces of a tick or other arthropods such as mosquitoes and horseflies. We report a case of an Italian patient with tularemia after a horsefly bite.

Human Dose-Response Data for Francisella tularensis and a Dose- and Time-Dependent Mathematical Model of Early-Phase Fever Associated with Tularemia After Inhalation Exposure.

Military health risk assessors, medical planners, operational planners, and defense system developers require knowledge of human responses to doses of biothreat agents to support force health protection and chemical, biological, radiological, nuclear (CBRN) defense missions. This article reviews extensive data from 118 human volunteers administered aerosols of the bacterial agent Francisella tularensis, strain Schu S4, which causes tularemia. The data set includes incidence of early-phase febrile illness following administration of well-characterized inhaled doses of F. tularensis. Supplemental data on human body temperature profiles over time available from de-identified case reports is also presented. A unified, logically consistent model of early-phase febrile illness is described as a lognormal dose-response function for febrile illness linked with a stochastic time profile of fever. Three parameters are estimated from the human data to describe the time profile: incubation period or onset time for fever; rise time of fever; and near-maximum body temperature. Inhaled dose-dependence and variability are characterized for each of the three parameters. These parameters enable a stochastic model for the response of an exposed population through incorporation of individual-by-individual variability by drawing random samples from the statistical distributions of these three parameters for each individual. This model provides risk assessors and medical decisionmakers reliable representations of the predicted health impacts of early-phase febrile illness for as long as one week after aerosol exposures of human populations to F. tularensis.

A case of typhoidal tularemia in a male Japanese farmer.

In Japan, most tularemia cases occur after contact with hares (hunting, cooking) and involve the glandular or ulceroglandular form. Here, we present a case of typhoidal tularemia in a 72-year-old Japanese male farmer who presented with fever, fatigue, and right lower abdominal pain. Computed tomography revealed intestinal wall thickening at the ascending colon, pleural effusion, and ascites. Following an initial diagnosis of bacterial enteric infection, his symptoms deteriorated after a week-long cephalosporin treatment course. The patient lived in an area endemic for scrub typhus; the antibiotic was changed to a tetracycline on suspicion of scrub typhus infection. His symptoms rapidly improved after initiation of minocycline treatment. Later, blood tests revealed marked increases in serological tests against Francisella tularensis exclusively, and the patient was diagnosed with typhoidal tularemia. Typhoidal tularemia may be characterized by any combination of general symptoms, but does not exhibit the local manifestations associated with other forms of tularemia. The patient, in this case, had no direct contact with hares or other wild animals and did not present with local manifestations of tularemia. Physicians should consider this disease, especially when tick-borne disease is suspected in the absence of local wounds, eschar, ulcers, or lymphadenopathy.

Tick Talk: Tick-borne Diseases of South Dakota.

In addition to being a nuisance, ticks can carry disease. This article presents a brief review of ticks and associated tick-borne disease relevant to South Dakota and surrounding regions. Tick-borne diseases of special relevance in South Dakota include tularemia, Rocky Mountain spotted fever, and Lyme disease. A number of others may also be encountered in the state as well. Prompt treatment of suspected cases is important to ensure a successful recovery, and tick-avoidance measures can reduce the risks of acquiring them. Most of these conditions are nationally reportable infectious diseases.

Severe glandular tularemia in a patient treated with anti-tumour necrosis factor for psoriatic arthritis.

A case of severe glandular tularemia in a patient receiving anti-tumour necrosis factor (TNF) therapy is reported here. The patient required prolonged treatment with doxycycline-ciprofloxacin due to early relapse after ciprofloxacin was stopped. Tularemia may have a more severe course in patients receiving anti-TNF. This may thus be an indication for more aggressive treatment.

Clinical Characteristics of Ulceroglandular Tularemia in Two Bulgarian Regions, 2014-2015: a Report of Five Cases.

We present here the first five human cases with tularemia from two regions in South Bulgaria in which there had been no previous report of the infection. The cases occurred over a period of 8 months (December 2014 - August 2015). They were treated at the Department of Infectious Diseases in Stara Zagora University Hospital, Bulgaria. We present the clinical, epidemiological and laboratory data for four men and one woman (age range 52 to 73 years). Three men were hunters, four patients took part in handling, preparing/skinning and cooking the game animals. One man marked agricultural work and contact with straw stems. After a mean incubation period of 4.8±1.4 days ulcers appeared, followed by local painful lymphadenitis. All patients presented with liver enlargement and elevation in acute phase reactants. The etiological diagnosis was made by tube agglutination test in all cases, PCR positive result was found in one. The administered antibacterial treatment was a combination of aminoglycosides and 4-quinolones with the outcome being favorable for all patients. The current report suggests presence of Francisella tularensis in South Bulgaria.

Epidemiological and clinical characteristics and management of oropharyngeal tularemia outbreak.

BACKGROUND/AIM: The purpose of this study was to determine the epidemiological and clinical characteristics of patients diagnosed with tularemia and the effectiveness of the administered treatments. MATERIALS AND METHODS: Patients treated in our hospital between January 2009 and March 2011 and diagnosed with tularemia were evaluated retrospectively. Patients' epidemiological and clinical characteristics, administered treatments, and posttreatment findings were recorded on patient monitoring forms. RESULTS: At anamnesis, 29% of patients used water from wells and 71% used water from the network supply; moreover, 48.4% had a history of contact with animals and 87.1% a history of lethargy. At physical examination, 96.8% had a mass in the neck and 90.3% had fever. Gentamycin + doxycycline therapy was administered to 45.2% of patients, while levofloxacin, gentamycin, and streptomycin were used for the other patients. After treatment, neck masses persisted in 48.4% of patients and complaints of lethargy and fever in 6.5%. Treatment of these patients was initiated once tularemia had been diagnosed, as test results were announced about 3 weeks later. Lymphadenopathy excision was performed on 19.4% of patients in whom neck mass persisted. CONCLUSION: Appropriate empiric antibiotherapy should be commenced in patients presenting with neck mass, fever, and lethargy in regions with tularemia epidemics.

[Tularemia: are hunters really a risk group?]. / Tularemi: Avcilar Gerçekten Bir Risk Grubu mu?

The aim of this study was to investigate the tularemia seroprevalence among hunters mainly hunting in districts with emerging tularemia cases in Yozgat province located at the Central Anatolia region of Turkey. A total of 64 serum samples were collected from the subjects (all were male; age range: 18-67 years; mean age: 42.7 years) registered to Hunting and Shooting Clubs in Yozgat province and it's two districts, during January-April 2010 and anamnestic data were obtained using a questionnaire. The presence of Francisella tularensis antibodies in serum samples were screened by microagglutination test (MAT), and the positive samples were also confirmed by a commercial ELISA kit (Serazym, Germany). Four (6.3%) out of 64 were found to be seropositive for tularemia with titers of 1/160 in three cases, and 1/2560 in one case. All of the MAT positive samples yielded positive results with ELISA test and all seropositive cases had negative brucella agglutination result. No tularemia compatible clinical history were determined in two hunters with 1/160 antibody titer. However, one of the cases had defined symptoms consistent with oropharyngeal form. The hunter with 1/2560 antibody titer developed acute oropharyngeal tularemia and treated with 14 days of ciprofloxacin therapy. Evaluation of risk factors in seropositive cases revealed consumption of spring water as a risk factor. In conclusion, our results indicated a considerable exposure of hunters to F.tularensis in Yozgat province and reflected a high prevalence of the pathogen around Yozgat, which coincided with the high notification rate of tularemia in this region.

[A water-borne tularemia outbreak caused by Francisella tularensis subspecies holarctica in Central Anatolia region]. / Iç Anadolu Bölgesinde Francisella tularensis alt tür halorctica'ya Bagli Su Kaynakli Bir Tularemi Salgini

In this study, we investigated a waterborne tularemia outbreak occured in Kadiozu, a village of Cerkes county of Cankiri province (located in North-west part of central Anatolia, Turkey) between 18 November 2009-24 December 2009. Active surveillance was conducted to determine clinical characteristics and risk factors of cases after two patients from the same village had been diagnosed as oropharyngeal tularemia. All villagers were examined, and clinical specimens from cases and water samples which may be the source of outbreak in the field investigations were taken. Cases were in the form of oropharyngeal, glandular and pneumonic. Polymerase chain reaction (PCR) and cultures were conducted from lymph node aspirates, throat swabs taken from cases and samples from water sources of epidemic zone. All serum samples taken from the villagers were screened for F.tularensis antibodies with microagglutination test (MAT). Oropharyngeal tularemia was diagnosed in 11 patients, glandular form in 3 patients and pneumonic form in one patient according to clinical and laboratory results. Age of the patients ranged between 6-75 years old (mean age: 52.5 years) and thirty one of them (54.7%) were female. MAT titers ranged between 1/160 and 1/5120 in cases of tularemia. Causative agent was grown in the cultures of two patients (including a throat swab and a lymph node aspirate). F.tularensis DNA was shown by PCR in a throat swab and four lymph node aspirates. F.tularensis was also detected by PCR in the water sample obtained from one of the spring water commonly used by villagers. Only one of the lymph node samples obtained from two different patients, was positive by direct fluorescent antibody method. Causative agent was defined as F.tularensis subsp. holarctica by conventional and also molecular methods. Patients were treated with aminoglycoside (streptomycin, gentamicin, amikacin) or quinolone (ciprofloxacin, levofloxacin) antibiotics. Treatment failure was observed in five patients, due to the delay in initiating treatment. Comparison of characteristics and risk factors for tularemia cases versus controls yielded age and contact with rodent excreta at home as potential risk factors (p= 0.001 and 0.002, respectively). The epidemic was controlled after cleaning the tank collecting spring water and chlorination of the water. Tularemia which is an emerging disease in Turkey is spreading to non-endemic regions and represent a significant threat for public health.