Brucellosis is a zoonotic infection transmitted to
contact with fluids from infected animals (sheep,
cattle, goats, pigs, or other animals)
derived food products such as unpasteurized milk
and cheese .
The disease is rarely, if ever, transmitted between
Brucella spp are small gram-negative aerobic
coccobacilli lacking a capsule, flagella, endospores,
or native plasmids.
Oxidase and catalase tests are positive for most
members of the genus Brucella.
Some species require CO2 enrichment for primary
isolation in the laboratory.
Other methods for the identification and
speciation of Brucella include:
production of urease and H2S
sensitivity to dyes, basic fuchsin, thionin, and
use of specific antisera
Brucellosis occurs worldwide; major endemic
areas include countries of the Mediterranean
basin, Arabian Gulf, the Indian subcontinent, and
parts of Mexico, Central and South America
Human Infection:B. melitensis is the species that
infects humans most frequently.
The incubation period ranges from a few days to a
The disease is manifested as fever accompanied by
a wide array of other symptoms.
Methods of transmission
Direct inoculation through cuts and skin abrasions
from handling animal carcasses, placentas, or
contact with animal vaginal secretions
Direct conjunctival inoculation
Inhalation of infectious aerosols
Ingestion of contaminated food such as raw milk,
cheese made from unpasteurized (raw) milk, or
Venereal transmission has been suggested, but the
data are not conclusive
1 week to several months
Patients may have a multitude of complaints
without objective findings except fever.
Often fits one of the three pattern:
febrile illness resembling typhoid,less severe
fever & acute monoarthritis (hip/knee),young child
long lasting fever,LBA,hip pain,older man
Travel to an endemic area
Consumption of unpasteurized milk
Physical manifestations may be absent.
Osteoarticular disease, especially sacroileitis — 20
to 30 percent and vertebral spondylitis. Large
joints are affected most commonly in children
Genitourinary disease, especially epididymo-
orchitis — 2 to 40 percent of males
Neurobrucellosis, usually presenting as meningitis
— 1 to 2 percent.
Less common neurologic complications include
papilledema, optic neuropathy, radiculopathy,
stroke, and intracerebral hemorrhage
Endocarditis — 1 percent.Most cases of
endocarditis are left-sided, and about two-thirds
occur on previously damaged valves.
Hepatic abscess — 1 percent
Other less common complications include
pneumonitis, pleural effusion, empyema,, or
abscess involving the spleen, thyroid, or epidural
A few cases of Brucella infection involving
prosthetic devices such as pacemaker wires and
prosthetic joints have been reported
Patients with undiagnosed and untreated
brucellosis can be symptomatic for months. In
addition, previously treated patients may present
with relapsed infection.
The presence of granulomatous hepatitis, hepatic
microabscesses, bone marrow granulomas, and/or
hemophagocytosis should prompt further
diagnostic evaluation for brucellosis.
Relapse — About 10 percent of patients relapse
About 10 percent of patients relapse after therapy.
Most relapses occur within three months following
therapy and almost all occur within six months.
Risk factors for relapse include inadequate initial
therapy, duration of the initial illness of less than
10 days, male sex, bacteremia, and
CSF/Body fluid analysis-Lymphocytosis,low glucoce
Biopsied samples of lymph node,liver-non caseating
granuloma without acid fast bacilli.
Polymerase chain reaction (PCR) shows promise
for rapid diagnosis of Brucella spp in human blood
Positive PCR at the completion of treatment is not
predictive of subsequent relapse
PCR testing for fluid and tissue samples other than
blood has also been described
Most serological studies for diagnosis of
Brucellosis are based on antibody detection
Serum agglutination (standard tube agglutination)
ELISA Rose Bengal agglutination
It is generally agreed that a titer of >1:160 in the
presence of a compatible illness supports the
diagnosis of brucellosis.
Demonstration of a fourfold or greater increase or
decrease in agglutinating antibodies over 4 to 12
weeks provides even stronger evidence for the
ELISA is probably the second most common
The sensitivity of the ELISA was 100 percent when
compared with blood culture but only 44 percent
compared with serologic tests other than ELISA
The Specificity was >99 percent.
In a study including 75 patients with brucellosis,
five patients with positive ELISA had a negative
tube agglutination test
In the setting of Brucella arthritis, the synovial
fluid white blood cell count does not generally
exceed 15,000 cells/microL.
In brucellosis, lymphocytes frequently
predominate (in contrast to septic arthritis due to
other bacteria, in which polymorphonuclear
leukocytes frequently predominate.
Patients with spine symptoms MRI examination
to rule out spinal cord compromise.
Plain radiographs, radionuclide bone scintigraphy,
CT scanning, and joint sonography.
Radiology of Spine
Site Lumbar Dorso lumbar
Vertebrae Multiple,contigous Contigous
Diskitis Late Early
Body Intact until late Morphology lost early
Canal compression Rare common
Osteophyte Anterolateral unusual
Deformity Wedging uncommon Anterior wedging
Recovery Sclerosis Variable
Paravertebral abscess Small well localized Common,discrete
Psoas Abscess Rare More likely
Localized snowflake calcification in chronic
hepatosplenic brucellosis only specific
There are two major regimens:
Regimen A: Doxycycline 100 mg orally twice daily for
6 weeks + Streptomycin 1 gram intramuscularly
once daily for the first 14 to 21 days
Regimen B: Doxycycline 100 mg orally twice daily
plus rifampin 600 to 900 mg (15 mg/kg) orally
once daily for six weeks.
Patients with focal disease have a less favorable
prognosis. In a study of 530 patients (including
170 patients with focal disease); those with focal
disease had a greater likelihood of therapeutic
failure, relapse, or death.
Indications for Surgery
Endocarditis where valve replacement or valve
debridement is required
Drainage or excision of abscesses, especially those
that have not responded to antimicrobials
Spinal epidural abscess
Removal of infected foreign bodies, eg, pacemaker
wires, prosthetic joints
Resection of mycotic aneurysms
Procurement of tissue for diagnostic purposes
Chronic hepatosplenic suppurative brucellosis
may require surgery in addition to antibiotics to
Patients with Brucella spondylitis appear to
respond better to doxycycline-streptomycin or a
three-drug regimen (doxycycline-streptomycin-
rifampin) than to doxycycline-rifampin.
The duration of therapy is generally prolonged
individualized according to clinical signs and
Continued until cerebrospinal fluid parameters
have returned to normal
Antimicrobial therapy alone may be attempted
absence of heart failure, valvular destruction,
abscess, or a prosthetic valve.
A combination of three or four antimicrobials, eg,
a tetracycline, rifampin, and an aminoglycoside
plus or minus trimethoprim-sulfamethoxazole.
Therapy is usually given for six weeks to six
The aminoglycoside component is usually
administered for two to four weeks in an effort to
Relapse should prompt assessment for a focal
lesion, especially hepatosplenic abscess
Most relapses can be treated successfully with a
repeat course of a standard regimen.
Should resistance or a second or third relapse
occur, an alternative regimen should be devised.
Premature labor and fetal wastage
Rifampin — 900 mg once daily for six weeks
Rifampin — 900 mg once daily plus trimethoprim-
sulfamethoxazole(TMP-SMX; 5 mg/kg of the
trimethoprim component twice daily) for four