Melioidosis.
Burkholderia pseudomallei
Dr.T.V.Rao MD
Burkholderia pseudomallei
Melioidosis.

Burkholderia pseudomallei causes an
infectious disease called melioidosis. This
bacteria is most commonly found in
Southeast Asia, especially in Thailand and
in Northern Australia. It was first
discovered in Australia in far northern
Queensland in 1962, but has now spread
progressively to the west and south.
What is Melioidosis?

Melioidosis, also called Whitmore's
disease, is an infectious disease caused by
the bacterium Burkholderia pseudomallei.
Melioidosis is clinically and pathologically
similar to glanders disease, but the
ecology and epidemiology of melioidosis
are different from glanders.
An environmental Bacteria

Burkholderia
pseudomallei is found
in the soil, rice
paddies, and muddy
waters of these areas.
 Polluted and
contaminate
atmosphere
contributes for
spread
Spread of B.pseudomallei
Infections

B.pseudomallei is a facultative intracellular
pathogen. It is pathogenic because of its
ability to invade, resist factors in serum,
and survive intracellularly. It is easily
contracted by inhaling dust containing the
bacteria or by having contact between
contaminated soil and cuts or scrapes of
the skin
How Melidiosis is spread

Humans and animals, like sheep, goats
and horses are believed to acquire the
infection by inhalation of dust, ingestion of
contaminated water and contact with
contaminated soil especially through skin
abrasions. Melioidosis can also spread
from person to person by contact with the
body fluids of an infected person.
Human Infections initiated
Human infections are
initiated with
contamination of
skin abrasions.
 By Ingestion
 By inhalation.

Morphology





B.pseudomallei is a small,
motile, aerobic Gram –ve
Grows on standard
bacteriological medium
The colines vary from
muciod and smooth to
rough wrinkled.
The color of the colonies
vary from cream to
orange.
Grows at even 420c
Can be Epizootic Infection
Sheep, horses, Goats, swine, can harbor
the infection
 However animals are unlikely to be
primary reservoirs of infection

It is a gram negative bacteria with
a safety pin like appearance.
Growth on Standard Medium

Grows on Standard
Bacteriological media,
colonies become
rough and wrinkled
on prolonged
incubation
Colonies of B.pseudomallei on
Ashdown media

Ashdown's medium is a
selective culture medium for
the isolation and
characterisation of
Burkholderia pseudomallei. the
medium contains crystal violet
and Gentamycin as selective
agents to suppress the growth
of other bacteria. Colonies of
B. pseudomallei also take up
neutral red which is present in
the medium, Ashdown's agar
needs to be incubated for a
minimum of 96 hours instead
of 48 hours.
Pathogenesis
The disease can manifest as Acute, Sub
acute, and Chronic disease
 Incubation may be as short as 2 – 3 days
 Latent infections can occurs after months
to years

Progress of Infection
The infection starts with non specific
lesion at the inoculum, where there can be
break in the skin.
 Lead to septicemia
 Most common form is pulmonary infection
 Can lead to suppurative infection and
bacterimia

Respiratory Infection





The most dangerous
infection can be
associated with
respiratory infection
Can lead to suppurative
lesions.
Consolidations of upper
lobe of the lung
Can mimic tuberculosis.
Progressive illness can
produce cavities
Spreading lesions
Systemic infections
spread from the
primary lesions on the
skin.
 Can spread to lungs,
Myocardium, Liver
and Bone.
 Can present with
unexplained systemic
disease.

Latent Infection in Melidiosis
The latent infection can reactivate as
result of immuno supression
 A high level of suscipicion in endemic
areas is gratifying.
 Any unexplained clinical symptoms and
signs should be explored for infections.

Who are at risk

Individuals with diabetes are at a higher risk for
contracting melioidosis. About 40% of
meliodiosis patients are diabetic. Other factors
that may increase the risk of contracting
meliodiosis are excessive alcohol consumption,
chronic renal disease, and chronic lung
disease. However, even though these factors do
increase the risk of contracting melioidosis,
cases of infection can still occur in healthy adults
and children occasionally.
Clues to Respiratory infection

Pulmonary infection: This form of the
disease can produce a clinical picture of
mild bronchitis to severe pneumonia. The
onset of pulmonary melioidosis is typically
accompanied by a high fever, headache,
anorexia, and general muscle soreness.
Chest pain is common, but a nonproductive or productive cough with
normal sputum is the hallmark of this form
of melioidosis.
Immuno supression can be
leading cause

Acute bloodstream infection: Patients with
underlying illness such as HIV, renal failure, and
diabetes are affected by this type of the disease,
which usually results in septic shock. The
symptoms of the bloodstream infection vary
depending on the site of original infection, but
they generally include respiratory distress,
severe headache, fever, diarrhea, development
of pus-filled lesions on the skin, muscle
tenderness, and disorientation. This is typically
an infection of short duration, and abscesses will
be found throughout the body.
Diagnosis

Melioidosis is
diagnosed by isolating
Burkholderia
pseudomallei from the
blood, urine, sputum,
or skin lesions.
Detecting and
measuring antibodies
to the bacteria in the
blood is another
means of diagnosis
Bacteriological Diagnosis
Gram stain of the
material from skin
lesions, sputum.
 Small gram-ve bacilli
with specific Bipolar
staining can be
leading clue.
 In all suspected cases
staining with Wright's
stain and methylene
blue

Serology


Strains of B.pseudomallei
are identified serologically
by agglutination tests,
rapid slide or tube
agglutination
Recently ELISA based on
monoclonal antitoxin is
avialble for rapid
diagnosis in endemic
areas of melioidosis.
Treatment
As the disease carries high mortality, a
prompt and effective treatment is highly
essential
 A surgical drainage of organized surgical
lesions.
 Tetracyclnes, Sulfonamides, TrimethoprimSulphmethoxazole are effective.
 Ceftazidime is highly effective

Duration of Antibiotic
Treatment
The duration of treatment should lost at
least 8 weeks.
 The treatment lasting 6moths to 1 year
are considered in immunosuppressive
conditions.
 No Vaccines are available

Bio Hazard and B.pseudomallei



Human laboratory
acquired infection with,
B.pseudomallei and
P.mallei is a hazard
Both organisms are
included in category A
pathogen.
Included in category 3
and to be handled with
greatest care and strict
and designated isolation
conditions.
Created for Medical and
paramedical students in
Developing world
Dr.T.V.Rao MD
Email
doctortvrao@gmail.com