Brucellosis: an unusual diagnosis for a seronegative patient with abscesses, osteomyelitis, and ulcerative colitis

NLRP6-associated host microbiota composition impacts in the intestinal barrier to systemic dissemination of Brucella abortus

Brucella abortus is a Gram-negative bacterium responsible for a worldwide zoonotic infection—Brucellosis, which has been associated with high morbidity rate in humans and severe economic losses in infected livestock. The natural route of infection is through oral and nasal mucosa but the invasion process through host gut mucosa is yet to be understood. Studies have examined the role of NLRP6 (NOD-like receptor family pyrin domain-containing-6 protein) in gut homeostasis and defense against pathogens. Here, we investigated the impact of gut microbiota and NLRP6 in a murine model of Ba oral infection. Nlrp6^-/- and wild-type (WT) mice were infected by oral gavage with Ba and tissues samples were collected at different time points. Our results suggest that Ba oral infection leads to significant alterations in gut microbiota. Moreover, Nlrp6^-/- mice were more resistant to infection, with decreased CFU in the liver and reduction in gut permeability when compared to the control group. Fecal microbiota transplantation from WT and Nlrp6^-/- into germ-free mice reflected the gut permeability phenotype from the donors. Additionally, depletion of gut microbiota by broad-spectrum-antibiotic treatment prevented Ba replication in WT while favoring bacterial growth in Nlrp6^-/-. Finally, we observed higher eosinophils in the gut and leukocytes in the blood of infected Nlrp6^-/- compared to WT-infected mice, which might be associated to the Nlrp6^-/- resistance phenotype. Altogether, these results indicated that gut microbiota composition is the major factor involved in the initial stages of pathogen host replication and partially also by the resistance phenotype observed in Nlrp6 -/- mice regulating host inflammation against Ba infection.

Brucella abortus (Ba) is an intracellular bacterium that causes zoonotic and clinical problems worldwide. Although the common route of infection is through oral and nasal, the mechanisms toward the gastrointestinal mucosa response is still unexplored. It is well known that microbiota promotes and maintains host intestinal homeostasis during bacterial infections. However, mechanisms by which the gut microbiota affects the Ba infection have not yet been demonstrated. Here, we provide significant insights into the relationship between gut microbiota and B. abortus oral infection and demonstrate the gut microbiota contribution to the gut permeability and dissemination of Ba. Furthermore, we investigated the participation of the gut microbiota from Nlrp6 deficient mice, on the gut permeability and Ba infection. Substantial experiments performed, mostly in vivo, showed that gut microbiota alterations promote gut barrier disruption, as indicated by increased gut permeability after Ba oral infection. Thus, our work highlights the role of gut mucosal environment through gut microbiota and Nlrp6 molecule involved in host innate immune responses to Ba infection.

Update on treatment options for spinal brucellosis

We evaluated the efficacy and tolerability of antibiotic regimens and optimal duration of therapy in complicated and uncomplicated forms of spinal brucellosis. This is a multicentre, retrospective and comparative study involving a total of 293 patients with spinal brucellosis from 19 health institutions. Comparison of complicated and uncomplicated spinal brucellosis was statistically analysed. Complicated spinal brucellosis was diagnosed in 78 (26.6%) of our patients. Clinical presentation was found to be significantly more acute, with fever and weight loss, in patients in the complicated group. They had significantly higher leukocyte and platelet counts, erythrocyte sedimentation rates and C-reactive protein levels, and lower haemoglobulin levels. The involvement of the thoracic spine was significantly more frequent in complicated cases. Spondylodiscitis was complicated, with paravertebral abscess in 38 (13.0%), prevertebral abscess in 13 (4.4%), epidural abscess in 30 (10.2%), psoas abscess in 10 (3.4%) and radiculitis in 8 (2.7%) patients. The five major combination regimens were: doxycycline 200 mg/day, rifampicin 600 mg/day and streptomycin 1 g/day; doxycycline 200 mg/day, rifampicin 600 mg/day and gentamicin 5 mg/kg; doxycycline 200 mg/day and rifampicin 600 mg/day; doxycycline 200 mg/day and streptomycin 1 g/day; and doxycycline 200 mg/day, rifampicin 600 mg/day and ciprofloxacin 1 g/day. There were no significant therapeutic differences between these antibiotic groups; the results were similar regarding the complicated and uncomplicated groups. Patients were mostly treated with doxycycline and rifampicin with or without an aminoglycoside. In the former subgroup, complicated cases received antibiotics for a longer duration than uncomplicated cases. Early recognition of complicated cases is critical in preventing devastating complications. Antimicrobial treatment should be prolonged in complicated spinal brucellosis in particular.

Establishment of systemic Brucella melitensis infection through the digestive tract requires urease, the type IV secretion system, and lipopolysaccharide O antigen

Human brucellosis is caused mainly by Brucella melitensis, which is often acquired by ingesting contaminated goat or sheep milk and cheese. Bacterial factors required for food-borne infection of humans by B. melitensis are poorly understood. In this study, a mouse model of oral infection was characterized to assess the roles of urease, the VirB type IV secretion system, and lipopolysaccharide for establishing infection through the digestive tract. B. melitensis strain 16M was consistently recovered from the mesenteric lymph node (MLN), spleen, and liver beginning at 3 or 7 day postinfection (dpi). In the gut, persistence of the inoculum was observed up to 21 dpi. No inflammatory lesions were observed in the ileum or colon during infection. Mutant strains lacking the ureABC genes of the ure1 operon, virB2, or pmm encoding phosphomannomutase were constructed and compared to the wild-type strain for infectivity through the digestive tract. Mutants lacking the virB2 and pmm genes were attenuated in the spleen (P < 0.05) and MLN (P < 0.001), respectively. The wild-type and mutant strains had similar levels of resistance to low pH and 5 or 10% bile, suggesting that the reduced colonization of mutants was not the result of reduced resistance to acid pH or bile salts. In an in vitro lymphoepithelial cell (M-cell) model, B. melitensis transited rapidly through polarized enterocyte monolayers containing M-like cells; however, transit through monolayers containing only enterocytes was reduced or absent. These results indicate that B. melitensis is able to spread systemically from the digestive tract after infection, most likely through M cells of the mucosa-associated lymphoid tissue.

False negative serological tests may lead to misdiagnosis and mismanagement in osteoarticular brucellosis

Non-specific clinical presentations and paraclinical findings in osteoarticular brucellosis may mimic many other diseases and other causes of arthritis which could lead to misdiagnosis and mismanagement. We studied retrospectively the records of 232 patients with osteoarticular brucellosis who were admitted to the three teaching hospitals of Babol Medical Sciences University from April 2001 to September 2006. The distribution of osteoarticular involvement and their management were evaluated to determine if any cases had been misdiagnosed because of false negative serologic tests and who had, as a result, undergone inappropriate surgical interventions. Of 232 patients, 138 (59%) were male and 94 (41%) were female. Polyarthritis, monoarthritis, spondylitis and sacroilitis were seen in 91 (39%), 60 (26%), 43 (18.5%) and 38 (16.5%) patients, respectively. Two hundred and twenty-nine (98.7%) patients were diagnosed correctly and treated successfully; three (1.3%) were misdiagnosed and had been given inappropriate surgical interventions. Of these three patients, two (3.3%) were suffering from monoarthritis (hip joint) and one (2.3%) had spondylitis.

A case of spondylodiscitis with spinal epidural abscess due to Brucella

Brucellosis, a zoonosis with worldwide distribution, is a systemic infection caused by facultative intracellular bacteria of the genus Brucella, which can involve multiple organs and tissues. We report an uncommon case of spondylodiscitis with epidural abscess due to Brucella in a male stockbreeder. Diagnosis was based on clinical history, and supported by Brucella serology and magnetic resonance imaging. Clinical and radiological improvement were observed with a combined antimicrobial therapy of doxycycline, rifampicin, and gentamycin.

[Seroprevalence of brucellosis among risk population in Gyeongsangbuk-do, 2006]

OBJECTIVES

Cases of human brucellosis in Korea have recently increased due to the increasing incidence of bovine brucellosis. The authors conducted this study to elucidate the status of brucellosis through seroepidemiologic study.

METHODS

We selected our study population from a high risk group. We conducted a questionnaire survey and obtained blood samples to determine the seroprevalence of brucellosis antibodies for 10 days in February, 2005. The titers of brucellosis were measured by the combination of standard tube agglutination test (STA) and enzyme-linked immunosorbent assay (ELISA) test.

RESULTS

Our study subjects comprised 1,075 cases: 971 livestock workers, 51 veterinarians, and 53 artificial inseminators. In the STA test, 27 cases (2.5%) had titers of greater than or equal to 1:20. Of 1,068 cases (7 cases were excluded due to previous brucellosis), 7 cases of brucellosis were diagnosed with titers of 1:160, giving a seroprevalence of brucellosis of 0.66%. The seroprevalence in the male group was 0.95%, and that of livestock workers, veterinarians, and artificial inseminators was 0.52%, 4.17%, and 0.00%, respectively. The Spearman's correlation coefficient between the positive rate of bovine brucellosis per capita and household and human brucellosis was 0.806 and 0.744, respectively. The concordance rate between the Korea National Institute of Health and the Gyeongsangbuk-do Institute of Health and Environment by the STA and ELISA tests was 94.7% and 100.0%, respectively.

CONCLUSIONS

The study results indicated in higher seroprevalence rate among veterinarians than among livestock workers and artificial inseminators. Because veterinarians may be exposed to this high risk, effective working guidelines for veterinarians to guard against brucellosis must be developed. Moreover, more extensive epidemiologic research for laboratory workers and meat handlers is needed.

Protean clinical manifestations and diagnostic challenges of human brucellosis in adults: 16 years' experience in an endemic area

A prospective study was carried out to elucidate the clinical, epidemiological and laboratory features of human brucellosis. A total of 26 948 blood samples (from adults aged 15 years and above) were screened for serological evidence of brucellosis over a period of 16 years. The slide agglutination/Rose Bengal plate agglutination test gave positive results in 517 patients, of which 509 had detectable titres by the standard tube agglutination test (SAT). The diagnosis of brucellosis was documented in 495 (1.8 %) patients based on diagnostic titres (> or = 1 : 160, 490 cases) and rising titres from insignificant titres (four cases) by serology and for one case by blood-culture isolation alone. Blood cultures were carried out in 345 cases, of which 191 cases (55.3 %) yielded Brucella melitensis. In 77/79 cases undertaken for follow up, there was a steady fall in 2-mercaptoethanol (2ME) agglutination titres along with clinical improvement (P < 0.01). SAT titres remained detectable in most cases for a longer period in spite of an effective antimicrobial therapy and clinical recovery. A substantial number of patients (84.2 %) presented with fever, this being the only complaint in 51.1 % of the cases. Complications were present in 8.8 % of the patients (arthritis excluded): this included the unusual complications of hydrocele (two cases), Stevens-Johnson syndrome (one case) and urinary tract infection (one case). Brucella agglutinins were demonstrated in synovial, testicular, hydrocele and cerebrospinal fluids. There was no clinical suspicion of brucellosis in 439 cases (88.7 %) and the diagnosis was made only by routine serology. A two-drug regimen for 42-84 days with a follow-up 2ME test resulted in lower levels of relapse. These results suggest that, in endemic areas of the world, it should be mandatory to screen routinely for brucellosis due to protean clinical manifestations.

Surgical treatment of spinal brucellosis

We retrospectively reviewed 10 patients with spinal brucellosis of the thoracic and lumbar spine who were treated successfully with a combination of surgery and antibiotics. All patients had back pain; six patients had radiculopathy and one patient had paraparesis. Patients with spondylodiscitis without epidural abscesses (n = 3) had transpedicle discectomy and drainage. Epidural abscesses in the lumbar area caused by spondylodiscitis (n = 3), spondylitis (n = 2), and discitis with infected disc herniation (n = 1), were drained using a posterior approach combined with posterolateral fusion in two patients with spondylodiscitis and discectomy in the patient with a herniated disc. One patient presented with a pathologic fracture and neural compression and was treated with anterior corpectomy and reconstruction. Antibiotic treatment was given for 3 to 9 months. Mean followup was 3 years. Back pain improved soon after surgery. Recovery from radiculopathy and paraparesis was complete. One patient had recurrence of infection 9 months after initial treatment. Clinical manifestation of spinal brucellosis can include spondylitis, spondylodiscitis, discitis, epidural abscess, paraspinal abscess, and vertebral collapse. Transpedicle drainage allows tissue diagnosis and facilitates treatment. Because brucellosis usually responds to antibiotics, surgery is considered as the last resort in treating spinal brucellosis, but severe neurologic deficit and incapacitating back pain often necessitate surgical intervention.

LEVEL OF EVIDENCE

Therapeutic study, level IV (case series). Please see the Guidelines for Authors for a complete description of levels of evidence.

Buttock abscess brucellosis

Human brucellosis is a multisystem disease that may present with a broad spectrum of clinical manifestations, and its complications can affect almost all organs and systems with varying incidence. Soft-tissue infection due to Brucella species is a rare complication of brucellosis. This report presents a case of a 30-y-old previously healthy woman whose right buttock abscess culture grew Brucella spp. The patient was treated successfully with abscess drainage and antibiotic therapy.

Brucellar spondylitis: review of 35 cases and literature survey

Thirty-five patients aged 14-74 years (average, 54 years) who had brucellar spondylitis were treated between January 1991 and December 1997. The time from onset of symptoms to diagnosis of spondylitis ranged from 1 week to 8 months (median, 9 weeks). Back or neck pain (100% of patients), fever (66%), and constitutional symptoms (57%) were the most common symptoms. Cultures of blood specimens from 26 patients (74%) were positive for Brucella melitensis. The duration of antimicrobial therapy (median, 120 days; range, 45-535 days) varied according to clinical response and the presence of epidural and paravertebral masses. One of the 35 patients underwent surgical treatment of a spinal epidural abscess. Therapy failed for 9 patients (26%; 95% confidence interval [CI], 12%-43%), and 5 (14%; 95% CI, 5%-30%) had a relapse. There were no deaths or severe sequelae in this study. Brucellar spondylitis causes considerable suffering and absenteeism from work, but long-term clinical responses are favorable.

Recurrent subcutaneous abscess of the sternal region in ulcerative colitis

An 18-yr-old female patient with extensive ulcerative colitis suffered from several episodes of recurrent aseptic subcutaneous abscesses of the sternal region with a course paralleling that of her colitis. The abscess seemed to occur secondarily to osteomyelitis of the sternum, which is a manifestation of the synovitis, acne, pustulosis, hyperostosis, and osteomyelitis (SAPHO) syndrome.

Brucellosis: an overview

Brucellosis remains a major zoonosis worldwide. Although many countries have eradicated Brucella abortus from cattle, in some areas Brucella melitensis has emerged as a cause of infection in this species as well as in sheep and goats. Despite vaccination campaigns with the Rev 1 strain, B. melitensis remains the principal cause of human brucellosis. Brucella suis is also emerging as an agent of infection in cattle, thus extending its opportunities to infect humans. The recent isolation of distinctive strains of Brucella from marine mammals has extended its ecologic range. Molecular genetic studies have demonstrated phylogenetic affiliation to Agrobacterium, Phyllobacterium, Ochrobactrum, and Rhizobium. Polymerase chain reaction and gene probe development may provide more effective typing methods. Pathogenicity is related to production of lipopolysaccharides containing a poly N-formyl perosamine O chain, CuZn superoxide dismutase, erythrlose phosphate dehydrogenase, stress-induced proteins related to intracellular survival, and adenine and guanine monophosphate inhibitors of phagocyte functions. Protective immunity is conferred by antibody to lipopolysaccharide and T-cell-mediated macrophage activation triggered by protein antigens. Diagnosis still centers on isolation of the organism and serologic test results, especially enzyme immunoassay, which is replacing other methods. Polymerase chain reaction is also under evaluation. Therapy is based on tetracyclines with or without rifampicin, aminoglycosides, or quinolones. No satisfactory vaccines against human brucellosis are available, although attenuated purE mutants appear promising.

Bacterial infections: osteoarticular brucellosis

Osteoarticular brucellosis has been documented extensively from the Middle East and Spain in the last 5 years, but it has only been reported infrequently from the UK and USA. Brucella melitensis from goat and sheep is the most frequently isolated organism. Peripheral articular pain, particularly of the large joints, is the commonest osteoarticular manifestation, while effusions that seldom yield organisms on culture, also occur frequently. Sacroiliitis which most frequently is unilateral, often presents acutely and dramatically with severe pain that is poorly localized to the lower back and buttock, leading to difficulty in walking and even standing. Tapping the heel and springing the sacrum is probably the best way of localizing the pain to the sacroiliac joint in this acute stage. Lack of awareness of this pattern of presentation could lead to misdiagnosis. Spondylitis is the third major manifestation of osteoarticular brucellosis. It occurs in older patients and is insidious and chronic in onset and course. The lumbar spine is most frequently involved, although cervical involvement is frequently associated with more complications, particularly compressive neurological deficits. Osteomyelitis occurs unusually. Several large series have been reported among children. In them peripheral large joint involvement in association with systemic features predominate while sacroiliitis may occur unusually. Plain X-rays often demonstrate vertebral damage, involving the upper anterior margin most frequently. CT scans define better vertebral damage that is characterized by bony sclerosis and the less frequently encountered extradural extension and para-vertebral abscess formation. Technetium bone scan is the most sensitive technique for detecting acute sacroiliitis and other sites of early osteoarticular involvement. A four-fold rise in Brucella agglutination titre is the most frequently utilized diagnostic aid. A 6 week culture in a CO2-enriched medium is recommended for growing Brucella. Tetracycline or doxycycline 200 mg per day for 6 weeks is the mainstay of most medical treatment schedules. Combination with streptomycin for 3 weeks or rifampicin for 6 weeks is recommended, to reduce significantly the failure and relapse rate. Spinal involvement is associated with an increased failure and relapse rate while they occurred least among those with no osteoarticular involvement. Surgical intervention to stabilize the spine and relieve neurological compression may become necessary. With the use of these various measures, the outlook for complete recovery is good.