- Melioidosis is an infectious disease caused by the bacterium Burkholderia pseudomallei found in soil and water in Southeast Asia and northern Australia. It is contracted through contact with contaminated soil or water. - Symptoms range from skin ulcers to pulmonary or disseminated infection. Diagnosis involves culture of the bacteria from clinical samples which grows readily on laboratory media. Treatment requires prolonged use of antibiotics like ceftazidime or cotrimoxazole to which the bacteria is intrinsically resistant. There is currently no vaccine available for melioidosis.

1. MELIOIDOSIS
Pradip Hamal

2. Introduction
• Melioidosis is an infectious disease caused by a Gram-
negative bacterium.
• Burkholderia pseudomallei is the causative agent and
found in soil and water.
• Melioidosis, also called Whitmore's disease, is an
infectious disease caused by the bacterium Burkholderia
pseudomallei.
• Melioidosis is primarily a disease of rats, but also occurs
in guinea pigs and rabbits.

3. • Humans acquire infection either by inhalation of
infected aerosols, inoculation of contaminated
material, or ingestion of food and water
contaminated with excreta of infected animals.
• The infection also may be transmitted by the bite of
hematophagous insects.
• Agricultural workers are highly susceptible to
infection.

4. HISTORY
• The name melioidosis is derived from Greek word ‘melis’
meaning a distemper of asses with suffixes ‘oid’ meaning
similar to and ‘osis’ meaning a condition that is, a condition
similar to glanders.
• Melioidosis was first discovered in Burma (now Myanmar)
by Whitmore and Krishmaswami in 1912.
• After its discovery in Burma, melioidosis was documented in
humans and animals in Malaysia and Singapore from 1913
and then Vietnam from 1923 and Indonesia from 1929.
• Thailand had reported the highest number of cases, with an
estimated 2000 to 3000 cases of melioidosis each year.

5. Morphology
• Burkholderia pseudomallei is an oxidase positive,
aerobic gram-negative bacillus that is straight or
slightly curved.
• It is measures about 2–5 μm in length and 0.4–0.8
μm in diameter.
• It frequently does not show bipolar-staining on
Gram stain, but it is often pleomorphic and usually
stains slightly unevenly.

6. Types of melioidosis
a. Acute melioidosis:
• It is characterized by development of a nodule at the site of
inoculation of the bacteria in the skin.
• The bacteria can subsequently spread, causing secondary
lymphangitis, regional lymphangitis, fever, and myalgia.
• Acute melioidosis may progress rapidly to acute septicemia
with high mortality rate.
• Acute blood stream infection is most commonly seen in
patients with HIV, diabetes, renal failure, etc. The condition
results in septic shock.

7. b. Pulmonary infection:
1. It manifests as mild bronchitis to severe pneumonia.
2. The condition is associated with high fever,
headache, chest pain, anorexia, and general myalgia.
3. Nonproductive or productive cough with normal
sputum is typical manifestation of this condition.
c. Chronic suppurative infection
1. It is associated with multiple caseous or suppurative
foci of infection in several organs including joints,
skin, lymph nodes, spleen, lungs, liver, and brain.
2. Bacteria remain as intracellular pathogens of the
reticuloendothelial system, which contributes to long
latency and reactivation of the infection.

8. Epidemiology
• Melioidosis is predominately a disease of tropical
climates.
• It is endemic in Southeast Asia, northern Australia, and
Brazil.
• Northeast Thailand has the highest incidence of
melioidosis.
• Septicemic meliodosis has high mortality, 87% in
Thailand, 75% in East Malaysia, 39% in Singapore and
19% in Australia.
• Localised melioidosis has lower mortality.
(Mustafa, Murtaza, et al. "Clinical manifestations, diagnosis, and treatment of
Melioidosis." IOSR Journal of Pharmacy 5(2015): 13-19).

9. Mode of Transmission
1. Inhalation
2. Ingestion
3. Inoculation
4. breast milk
5. perinatal
6.human to human uncommon

10. Clinical manifestations
A shows cutaneous melioidosis in a healthy host.
B shows lung abscesses on the chest radiograph of a patient with acute melioidosis
pneumonia.
C shows the corresponding computed tomographic (CT) scan.
D shows the skin manifestations in a fatal case of disseminated melioidosis.
E shows splenic abscesses on an abdominal CT scan.
F shows aspirated pus in a patient with prostatic and periprostatic abscesses, and
G shows the abscesses on a CT scan from the patient.

11. Clinical manifestation
• Pulmonary infection
• Skin ulceration
• Lymphadenopathy
• Manifestations are exacerbated long after the exposure;
hence called as Vietnam time bomb disease.

12. The infectious Disease Association of Thailand
has summarized 345 cases in these categories,
include:
1. Multifocal infection with septicemia (45% of
caes,87 % mortality
2. Localized infection with septicemia (12% of
cases,17% mortality)
3. Localized infection (42% of cases,9% morality)
4. Transient bacteremia (0.3%)

13. Laboratory diagnosis
• Sample collection
1. Sputum
2. BAL
3. Blood or bone marrow
4. Urine and a
5. Throat swab
6. Pus and
7. Wound swab
8. Skin lesions
9. Rectal swab

14. Gram stain
• Gram stain:
• B. pseudomallei is a
Gram-negative bacillus.
• Measures about 2–5 μm in
length and 0.4–0.8 μm in
diameter.
• It frequently does not
show bipolar-staining on
Gram stain, but it is often
pleomorphic and usually
stains slightly unevenly.

15. Culture
• B. pseudomallei is not fastidious and grows on a
large variety of culture media (blood
agar, Chocolate agar, MacConkey agar, etc.).
• Ashdown's medium may be used for selective
isolation.
• Cultures typically become positive in 24 to 48 hours

16. Colony morphology:
• Smooth, creamy, white colonies on BA at 24 hrs
• Some may be mucoid or become dry and wrinkled
at 48 - 72 hrs
• Pink colonies on MA agar at 24 - 48 hrs or colorless
colonies at 48 hrs

17. Selective medium (Ashdown medium)
• Contains crystal violet and gentamicin as selective
agents.
• It is also enriched with 4% glycerol, which is
required by some strains of B. pseudomallei to
grow.
• It usually produces flat wrinkled purple colonies.
• Colonies will also exhibit an earthy odor.
• The colony appears irregular-edge, rough and pale
purple.

18. Biochemical test
• Catalase = Positive
• Oxidase = Positive
• Indole = Negative
• Motility = Positive
• Triple Sugar Iron (TSI) = K/NC
• Colistin/Polymyxin B = Resistant (no zone)

19. Biochemical Test

20. API 20NE biochemical Kit

21. 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.

22. Latex agglutination test
• Initial screening of suspected colonies from any agar medium
is undertaken by latex agglutination using latex particles
coated with antibodies specific for the 200-kDa
exopolysaccharide of B. pseudomallei.
Method:
• Pipette 10 μl of control and test latex onto a glass slide
• Note: Controls do not have to be tested with every sample but
should be run in tandem on each testing day.
• Using a toothpick, touch the suspected colony and emulsify
the colony in the test latex.
• Rotate the samples to mix to allow the reaction to occur.

23. Interpretation:
• Agglutination (positive) may be rapid or may take
up to 20 secs.
• Observe for at least 2 mins before declaring the
status of the sample as positive or negative.

24. • Indirect hemaggultination test (IHA).
• Various enzyme-linked immunosorbent assays
(ELISA),and other serological assays are also
available.
• PCR (polymerase chain reaction) which has also
been evaluated to detect B. pseudomallei genome in
pus, sputum, and other specimens.

25. Treatment

26. Treatment
• B. pseudomallei is intrinsically resistant to many
antibiotics, including aminoglycosides and early
betalactams (penicillin, ampicillin, first and second
generation cephalosporins, gentamicin, tobramycin,
and streotomycin).

27. Vaccine
• No vaccine are available

28. THANK YOU