Brucellosis: unusual presentations in two adolescent boys

When the Going Gets Rough: The Significance of Brucella Lipopolysaccharide Phenotype in Host-Pathogen Interactions

Brucella is a facultatively intracellular bacterial pathogen and the cause of worldwide zoonotic infections, infamous for its ability to evade the immune system and persist chronically within host cells. Despite the frequent association with attenuation in other Gram-negative bacteria, a rough lipopolysaccharide phenotype is retained by Brucella canis and Brucella ovis, which remain fully virulent in their natural canine and ovine hosts, respectively. While these natural rough strains lack the O-polysaccharide they, like their smooth counterparts, are able to evade and manipulate the host immune system by exhibiting low endotoxic activity, resisting destruction by complement and antimicrobial peptides, entering and trafficking within host cells along a similar pathway, and interfering with MHC-II antigen presentation. B. canis and B. ovis appear to have compensated for their roughness by alterations to their outer membrane, especially in regards to outer membrane proteins. B. canis, in particular, also shows evidence of being less proinflammatory in vivo, suggesting that the rough phenotype may be associated with an enhanced level of stealth that could allow these pathogens to persist for longer periods of time undetected. Nevertheless, much additional work is required to understand the correlates of immune protection against the natural rough Brucella spp., a critical step toward development of much-needed vaccines. This review will highlight the significance of rough lipopolysaccharide in the context of both natural disease and host–pathogen interactions with an emphasis on natural rough Brucella spp. and the implications for vaccine development.

Canine Brucellosis: An Update

Canine brucellosis is an infectious and zoonotic disease caused by Brucella canis, which has been reported worldwide, and is a major public health concern due to close contact between dogs and humans. In dogs, canine brucellosis manifests with abortion outbreaks, reproductive failure, enlargement of lymph nodes, and occasionally affects the osteoarticular system, although the occurrence of asymptomatic infections in dogs are not uncommon. In humans, the disease is associated with a febrile syndrome, commonly with non-specific symptoms including splenomegaly, fatigue, and weakness. Infection of dogs occurs mostly by the oronasal route when in contact with contaminated tissues such as aborted fetuses, semen, urine, and vaginal secretions. In humans, contact with contaminated fluids from infected dogs is an important source of infection, and it is an occupational risk for veterinarians, breeders, laboratory workers, among other professionals who deal with infected animals or biological samples. The diagnosis in dogs is largely based on serologic methods. However, serologic diagnosis of canine brucellosis remains very challenging due to the low accuracy of available tests. Molecular diagnostic methods have been increasingly used in the past few years. Treatment of infected dogs is associated with a high frequency of relapse, and should be employed only in selected cases. Currently there are no commercially available vaccines for prevention of canine brucellosis. Therefore, development of novel and improved diagnostic methods as well as the development of efficacious and safe vaccination protocols are needed for an effective control of canine brucellosis and its associated zoonotic risk.

Pulmonary involvement in brucellosis: A case report and literature review

Although pulmonary involvement is rare in brucellosis it should be considered as a causative agent in patients with prolonged fever and arthritis. Also, it should be presented with manifestations resembling systemic juvenile idiopathic arthritis.

MALDI-TOF MS and genomic analysis can make the difference in the clarification of canine brucellosis outbreaks

Brucellosis is one of the most common bacterial zoonoses worldwide affecting not only livestock and wildlife but also pets. Canine brucellosis is characterized by reproductive failure in dogs. Human Brucella canis infections are rarely reported but probably underestimated due to insufficient diagnostic surveillance. To improve diagnostics, we investigated dogs in a breeding kennel that showed clinical manifestations of brucellosis and revealed positive blood cultures. As an alternative to the time-consuming and hazardous classical identification procedures, a newly developed species-specific intact-cell matrix-assisted laser desorption/ionization–time of flight mass spectrometry analysis was applied, which allowed for rapid identification of B. canis and differentiation from closely related B. suis biovar 1. High-throughput sequencing and comparative genomics using single nucleotide polymorphism analysis clustered our isolates together with canine and human strains from various Central and South American countries in a distinct sub-lineage. Hence, molecular epidemiology clearly defined the outbreak cluster and demonstrated the endemic situation in South America. Our study illustrates that MALDI-TOF MS analysis using a validated in-house reference database facilitates rapid B. canis identification at species level. Additional whole genome sequencing provides more detailed outbreak information and leads to a deeper understanding of the epidemiology of canine brucellosis.

Diagnosis of canine brucellosis: comparison of various serologic tests and PCR

Canine brucellosis is an infectious and contagious disease associated with reproductive losses in breeding kennels. As a zoonotic disease, it poses a risk to human health, especially for veterinarians and breeders who handle materials potentially contaminated with Brucella canis. However, canine brucellosis is a neglected and underestimated disease given the difficulties in establishing a definitive diagnosis. We evaluated the frequency of detection of B. canis in 5 breeding kennels by using various serologic methods and PCR. Circulation of B. canis in these kennels was confirmed by bacterial isolation. The frequency of positive serologic results varied from 6.3% by AGID to 16.5% by dot-ELISA. There was no positive serology for smooth Brucella. PCR testing was positive in 13.9% of samples. The only detection tests with reasonable agreement were PCR and 2ME-MAT. The diagnosis of canine brucellosis remains challenging. The use of a single laboratory method, or even the use of different laboratory methods, may not be sufficient to reach a definitive diagnosis.

Investigation and characterization of Brucella canis infections in pet-quality dogs and associated human exposures during a 2007-2016 outbreak in Michigan

OBJECTIVE To estimate Brucella canis seropositivity rates for purebred dogs being bred by noncommercial breeders, describe epidemiological findings in infected commercial dog-production facilities, and characterize B canis infection in pet dogs and the risk to human health. DESIGN Retrospective descriptive study. SAMPLE 2,799 canine specimens submitted to the Michigan State University Veterinary Diagnostic Laboratory for B canis testing and records of B canis reports provided to the Michigan Department of Agriculture and Rural Development from 2007 through 2016. PROCEDURES Results of B canis laboratory tests and epidemiological findings for reported cases of B canis were reviewed and summarized. Federal and state public health officials were interviewed regarding human B canis infection. State veterinarians were interviewed regarding canine brucellosis reporting and control procedures. RESULTS Estimated B canis seropositivity was 0.4% among purebred Michigan dogs owned by noncommercial breeders. Infection was confirmed in dogs from 17 commercial dog-production facilities, 3 shelters, and 1 rescue agency. Estimated infection prevalence in production facilities ranged from 2 of 22 (9%) to 5 of 6 (83%). Transfer of infected dogs involved 22 Michigan counties and 11 states. Seven of 20 privately owned infected dogs had diskospondylitis; I also had uveitis. Fifty-three veterinary hospital or diagnostic laboratory personnel had inadvertent exposure to the pathogen. Brucella canis was isolated from 1 commercial production facility owner. CONCLUSIONS AND CLINICAL RELEVANCE B canis was uncommon in purebred dogs being bred by noncommercial breeders but endemic in Michigan commercial facilities producing dogs destined to become household pets. Infected pet dogs caused human B canis exposure, and several pet dogs had debilitating disease not associated with the reproductive system.

Seroprevalence of Brucella canis antibodies in dogs entering a Minnesota humane society, Minnesota, 2016-2017

BACKGROUND

Canine brucellosis, caused by the bacterium Brucella canis, is a zoonotic and largely reproductive disease of dogs. The disease is a recognized problem in canine breeding populations, and the risk to individuals assisting with birthing is well described. Prior to 2015, all cases of canine brucellosis reported to the Minnesota Board of Animal Health were in dogs used for breeding. In 2015, canine brucellosis was identified in eight Minnesota rescue dogs, all originating from specific geographic areas in South Dakota. Our objective was to measure the seroprevalence of B. canis in stray and previously owned dogs entering a large Minnesota animal rescue organization to determine if our observations represented a localized or generalized disease issue among rescue dogs.

METHODS

A stratified random sample of stray and previously owned dogs entering the largest Minnesota animal rescue organization between November 1, 2016 and November 7, 2017, was tested for B. canis antibodies by the 2-Mercaptoethanol Rapid Slide Agglutination Test (2ME-RSAT) (Zoetis d-TEC^® CB kit). Sample sizes for each strata were calculated using previously published seroprevalence estimates. Blood from selected dogs was collected, serum harvested, and transported to the Minnesota Veterinary Diagnostic Laboratory for testing. Positive samples in the 2ME-RSAT were shipped to Cornell University for confirmation by Agarose Gel Immunodiffusion (AGID) testing. Demographics, state and setting of origin, and health status were collected on study-dogs.

RESULTS

Of the 10,654 dogs accepted by AHS during the study period, 943 (8.9%) were selected for testing. Most study dogs arrived from Oklahoma (28%), Alabama (18%), and Minnesota (12%). The median age of study dogs was 1.5 years; 303 (32%) were intact males and 294 (31%) were intact females. Most study dogs were strays (n = 716, 76%). Of the total, 22 (3.1%) stray and eight (3.5%) owner-surrendered dogs were presumptively positive by RSAT; one (0.11%) of the stray dogs was positive by 2ME-RSAT and confirmed by AGID. The positive dog was a healthy-appearing 1 year-old neutered male beagle from Texas.

CONCLUSIONS

The seroprevalence of canine brucellosis in dogs entering Minnesota for adoption from multiple states was low. Never-the-less, care must to be taken to consider all potential risks and outcomes of interstate and international dog trade, including the spread of infectious diseases such as canine brucellosis.

Tissue distribution and cell tropism of Brucella canis in naturally infected canine foetuses and neonates

Brucella canis infection is an underdiagnosed zoonotic disease. Knowledge about perinatal brucellosis in dogs is extremely limited, although foetuses and neonates are under risk of infection due to vertical transmission. In this study, immunohistochemistry was used to determine tissue distribution and cell tropism of B. canis in canine foetuses and neonates. Diagnosis of B. canis in tissues of naturally infected pups was based on PCR and sequencing of amplicons, bacterial isolation, and immunohistochemistry, whose specificity was confirmed by laser capture microdissection. PCR positivity among 200 puppies was 21%, and nine isolates of B. canis were obtained. Tissues from 13 PCR-positive puppies (4 stillborn and 9 neonates) presented widespread immunolabeling. Stomach, intestines, kidney, nervous system, and umbilicus were positive in all animals tested. Other frequently infected organs included the liver (92%), lungs (85%), lymph nodes (69%), and spleen (62%). Immunolabeled coccobacilli occurred mostly in macrophages, but they were also observed in erythrocytes, epithelial cells of gastrointestinal mucosa, renal tubules, epidermis, adipocytes, choroid plexus, ependyma, neuroblasts, blood vessels endothelium, muscle cells, and in the intestinal lumen. These results largely expand our knowledge about perinatal brucellosis in the dog, clearly demonstrating a pantropic distribution of B. canis in naturally infected foetuses and neonates.

Treatment of pulmonary brucellosis: a systematic review

INTRODUCTION

Pulmonary involvement is a rare, focal complication of human brucellosis. The aim of this review is to describe clinical and radiologic features, treatment administered and clinical course of these patients. Areas covered: We conducted a systematic search of scientific reports of brucellosis with pulmonary involvement published from January 1985 to July 2016. Four main patterns of disease were observed: pneumonia, pleural effusion, nodules and interstitial pattern. Cough and fever were the most common symptoms. Brucella spp. culture was obtained from blood (50%) or pleural fluid. Treatment is based on the same antibiotics and combinations of antibiotics as for patients with acute no complicated brucellosis. The most frequent antimicrobial combination was doxycycline and rifampin for six weeks. The clinical course was favorable in most reports, and mortality was remarkably low (<1%). Expert commentary: Non-specific clinical and radiological manifestations were the main reason for the delay in proper treatment. Difficulty in distinguishing Brucellosis from other pulmonary infections, such as tuberculosis, sometimes posed an added diagnostic challenge.

Human Brucella canis Infection and Subsequent Laboratory Exposures Associated with a Puppy, New York City, 2012

Human Brucella canis infection incidence is unknown. Most identified cases are associated with pet dogs. Laboratory-acquired infections can occur following contact with Brucella spp. We identified a paediatric B. canis case, the source and other exposed persons. A 3-year-old New York City child with fever and dyspnoea was hospitalized for 48 h for bronchiolitis. After her admission, blood culture grew B. canis, she was prescribed anti-microbials and recovered. B. canis was also isolated from blood of the child's pet dog; these isolates were genetically similar. The dog originated from an Iowa breeding facility which was quarantined after identification of the dog's infection. Additionally, 31 laboratory workers were exposed and subsequently monitored for symptoms; 15 completed post-exposure prophylaxis. To our knowledge, this is the first report strongly suggesting B. canis zoonotic transmission to a child in the United States, and highlights the need for coordinated control policies to minimize human illness.

Brucella arteritis: clinical manifestations, treatment, and prognosis

Brucellosis is the most common bacterial zoonosis, and causes a considerable burden of disease in endemic countries. Cardiovascular involvement is the main cause of mortality due to infection with Brucella spp, and most commonly manifests as endocarditis, peripheral and cerebrovascular aneurysms, or arterial and venous thromboses. We report a case of brucellosis presenting as bacteraemia and aortic endarteritis 18 years after the last known exposure to risk factors for brucella infection. The patient was treated with doxycycline, rifampicin, and gentamicin, and underwent surgical repair of a penetrating aortic ulcer, with a good clinical recovery. We review the signs and symptoms, diagnostic approach, prognosis, and treatment of brucella arteritis. We draw attention to the absence of consensus about the optimum therapy for vascular brucellosis, and the urgent need for additional studies and renewed scientific interest in this major pathogen.

Brucella canis causing infection in an HIV-infected patient

From the blood culture of an HIV-positive patient with a febrile syndrome (CD4 count 385 cells/microL and viral load nondetectable), Brucella canis was isolated. The patient was presumptively infected from his dogs, which tested positive, and showed good outcome after the therapy with doxycycline-ciprofloxacin, and the HIV infection would seem not to have been influenced by brucellosis. To our knowledge, no other case of B. canis in the setting of HIV infection has been reported in the literature, and the emerging zoonotic potential of the disease in urban areas should be considered.

Brucella canis endophthalmitis in 3 dogs: clinical features, diagnosis, and treatment

OBJECTIVE

To describe historical, clinical and diagnostic features of dogs with Brucella canis endophthalmitis and the response to medical therapy.

ANIMALS STUDIED

Three dogs with naturally acquired B. canis endophthalmitis.

PROCEDURE

Dogs were treated symptomatically with topical ophthalmic anti-inflammatories and a novel antimicrobial protocol that included doxycycline, enrofloxacin, rifampin and streptomycin.

RESULTS

All dogs presented with chronic or recurrent uveitis in the absence of overt systemic disease. Clinical ophthalmologic abnormalities were unilateral in each dog and included mild-to-moderate anterior uveitis, iris hyperpigmentation, marked vitreal infiltrates, and multifocal chorioretinitis. Dogs were diagnosed with canine brucellosis serologically and by blood culture (n = 2 dogs) or polymerase chain reaction of aqueous humor and blood (n = 1 dog). Active ocular inflammation resolved in all dogs during treatment, with preservation of vision in 2 dogs. Following treatment, B. canis could not be cultured from blood samples and serological values declined with seronegativity achieved in all dogs after a median of 96 weeks (range: 36-112 weeks) of therapy.

CONCLUSIONS

Brucella canis infection should be included in the differential diagnosis for dogs with intraocular inflammation, regardless of previous history or neuter status. This is the first report of apparently successful medical therapy of canine brucellosis with ocular involvement.

Infected abdominal aortic aneurysm caused by Brucella abortus: a case report

This case report describes an infected aneurysm caused by Brucella abortus. To the best of our knowledge, this case represents the first reported occurrence of an infected abdominal aortic aneurysm caused by this pathogen. The clinical findings included mild fever, fatigue, cold sweats, and abdominal pain. The diagnosis was reached by computed tomography scanning. The patient was treated by urgent surgery, which consisted of resection of the aneurysmal sac, prosthetic graft replacement, and omental wrapping. Antibiotics were administrated for 3 months. A bacteriologic specimen was isolated from the blood culture. At 1 year 10 months after surgery, the patient remains in good health.

Diagnosis of human brucellosis caused by Brucella canis

The transmission ofBrucella canisto man commonly occurs through contact with infected dogs or their secretions, or through direct laboratory exposure. The disease is underdiagnosed due to a general lack of serological testing facilities and misconceptions concerning its prevalence. This report shows the potential use of an indirect ELISA (IELISA) for the diagnosis of human brucellosis caused byB. canisin a population of patients negative by smooth-Brucellaantigen tests but positive by rapid slide agglutination test (RSAT). One hundred and ten sera from asymptomatic people found negative by tests using smoothBrucella abortusantigen and by RSAT showed an IELISA specificity of 100 % when a cut-off value of 27 % positivity (%P) was selected. For 17 sera from patients with positiveB. canisculture or in close contact with culture-positive dogs, the IELISA sensitivity was 100 % with the same cut-off value. The positive patients presented clinical symptoms similar to brucellosis caused by other species ofBrucellaand some of them received antibiotic treatment and made good progress. Using this cut-off value, we studied 35 patients with negative blood cultures but positive RSATs, and IELISA detected 18 as positive; of the 17 IELISA-negative, two were RSAT-positive at dilution 1 : 2 and 15 were weakly positive with pure serum. These samples were probably from patients at an early stage of infection or indicate false-positive results. No cross-reaction was observed among the sera from nine cases with a diagnosis other than brucellosis, but cross-reactivity was evident in sera from patients infected with smooth-Brucellaspecies. Since routine brucellosis diagnosis does not includeB. canisinvestigation, infection with this species may be more widespread than is currently suspected. The RSAT could be a suitable screening test for the diagnosis ofB. canishuman brucellosis, and a supplementary technique, such as IELISA, performed on all positive RSAT samples that were negative byB. abortusantigen could ensure diagnostic specificity and confirm the diagnosis.

Popliteal artery pseudoaneurysm: a rare complication of brucellosis

Brucellosis is still a public health problem, particularly in developing countries. After the primary infection subsides, a chronic stage characterized by nonspecific manifestations can develop, during which it may not be possible to isolate Brucella organisms and agglutination test titers may or may not be high. We present the case of a 49-year-old man who had only nonspecific symptoms and a 2-month history of a pulsatile painful swelling in his right popliteal region. He had no history of trauma or surgery in that region, but he did ingest unpasteurized milk products. The patient's agglutination test titers were high, and Brucella melitensis was isolated from a bone marrow culture. Color Doppler sonography, T2-weighted MRI, and digital subtraction angiography were performed. Treatment with ultrasound-guided compression of the pseudoaneurysm failed because of high blood flow in its neck. Aneurysmectomy was undertaken, and the excised material was consistent with that from a mycotic pseudoaneurysm. Although both MRI and angiography provided useful information, the color Doppler sonography findings were characteristic of a pseudoaneurysm in the popliteal artery, and only that modality could detect the flow dynamics within the pseudoaneurysm.

Imaging of osteomyelitis in children

Imaging approach to osteomyelitis in children should aim toward a timely and accurate diagnosis in view of the need for prompt therapy to prevent sequelae. One must take advantage of the specific value of each imaging modality and adopt a strategy that works best for a given child in a given institution.