Cat-bite-induced Francisella tularensis infection with a false-positive serological reaction for Bartonella quintana

Infectious Complications of Bite Injuries

Animal and human bite injuries are a public health burden. Dog bites outnumber cat bites, but cat bites pose the greatest risk for infection. Skin and soft tissue infections are the most frequent infectious manifestations resulting from bite injury, although invasive infection may occur through direct inoculation or dissemination through the bloodstream. Although contemporary, well-designed trials are needed to inform clinical practice, preemptive antibiotic therapy after a bite injury is warranted for injuries posing high risk for infection and for patients at risk of developing severe infection; antibiotics should target aerobic and anaerobic microbes that comprise the oral and skin flora.

A Rare Case of Spontaneous Splenic Rupture Secondary to Tularemia Following a Cat Bite

Spontaneous splenic rupture is a rare but potentially life-threatening condition. More common infectious causes include infectious mononucleosis, cytomegalovirus (CMV), human immunodeficiency virus (HIV), and malaria. We present a case of a 42-year-old male who was admitted with persistent fevers, myalgia, and a recent ulcerative lesion on the base of his left thumb after a cat bite. He developed abdominal and back pains, left axillary lymphadenopathy, and near syncope. Abdominal computed tomography (CT) scan showed splenomegaly with subcapsular splenic rupture and large hematoma requiring emergent splenic embolization. Infectious work-up revealed tularemia as a cause which was successfully treated with oral doxycycline. Though not a common cat zoonoses, tularemia should be considered in a patient with splenomegaly or spontaneous splenic rupture in the setting of cat bite.

Francisella tularensis, Tularemia and Serological Diagnosis

Tularemia is a zoonotic disease caused by the bacterium Francisella tularensis. The predominant sources, routes of infection, and clinical manifestations of human infections greatly vary according to the geographic area considered. Moreover, clinical suspicion of tularemia is often tricky because of the lack of specificity of the clinical manifestations. Because F. tularensis isolation is tedious and detection of its DNA usually requires removal of infected tissues, serological techniques are most often used for diagnostic confirmation. However, these techniques are varied and poorly standardized. The microagglutination test (MAT), the indirect immunofluorescence assay (IFA), and ELISA tests are currently the most frequently used techniques. These home-made and commercial tests are mainly used for tularemia diagnosis but also seroprevalence studies. ELISA tests detect specific antibodies within two weeks of disease evaluation, compared to 2-3 weeks for MAT and IFA. However, more false-positive results are usually reported with ELISA. The long-term persistence of anti-F. tularensis antibodies in patients with past tularemia infection hampers the diagnostic specificity of all these tests. Also, cross-reacting antibodies have been described (especially with Brucella and Yersinia species), although usually at a low level. The immunoblotting technique can highlight these serological cross-reactions. Tularemia remains an underdiagnosed disease in most endemic areas, and the clinical presentations of this disease are evolving. It is necessary to improve further speed and accuracy of tularemia diagnosis, as well as the standardization of diagnostic procedures.

First European report of Francisella tularensis subsp. holarctica isolation from a domestic cat

Francisella tularensis subsp. holarctica is a select agent causing life-threatening tularemia. It has been isolated from humans and animals, mainly lagomorphs and rodents, rarely other wild carnivore species. Increasing numbers of human tularemia cases have been reported during the last 5 years in Switzerland. Here we report the first isolation of Francisella tularensis subsp. holarctica from a domestic cat in Europe and compare its genome sequence with other Swiss isolates. The cat isolate shows a close phylogenetic relationship with a contemporary hare isolate from close geographic proximity, indicating a possible epidemiological link.

Tularemia: an experience of 13 cases including a rare myocarditis in a referral center in Eastern Switzerland (Central Europe) and a review of the literature

BACKGROUND

Tularemia, a zoonotic disease caused by Francisella tularensis, can cause a broad spectrum of disease in humans including six major clinical presentations: the ulceroglandular, glandular, oculoglandular, oropharyngeal, typhoidal and pneumonic form. The epidemiology and ecology and thus transmission of tularemia are complex, depending on conditions unique to specific locations.

CASE SERIES AND METHODS

Thirteen cases with different forms of the disease and one very rare case of a myocarditis are reported, discussed, and reviewed within the scope of current literature.

CONCLUSION

Tularemia is a rare, but emerging disease in Central Europe with glandular and ulceroglandular disease as its predominant forms. Transmission is mainly caused by contact with lagomorphs, rodents and tick bites. However, domestic cats may play an important role in transmission too. Myocarditis is probably a worldwide, but very rare manifestation of tularemia.