Transcript Bartonella Prepared by: Ohood R. Sarsour

Bartonella
Prepared by:
Ohood R. Sarsour
Introduction
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Bartonella species (formerly known as
Rochalimaea)
Linked to a number of emerging zoonotic diseases
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B.quintana, B.bacilliformis, B.henselae
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Unique and common feature is ability to cause
vasoproliferative lesions (process of pathological
angiogenesis)
Infection affects function of endothelial cells
resulting in cell invasion, suppression of apoptosis
and induction of proliferation, resulting in
vasoproliferative tumor growth
B. henselae
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Gram negative aerobic rods
Main reservoir is cats
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Transferred to humans through scratches and bites
(fleas/ticks??)
Resulting illness is Cat Scratch Disease (CSD)
About 40% of cats carry B.henselae
Cats are asymptomatic, although bacteria can be
cultivated from their blood for up to 2 years
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This persistent infection due to persistence in red blood
cells
Epidemiology
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Cases of CSD occur worldwide
Higher incidence of Bartenellosis in warmer
and more humid areas of the United States
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More fleas and ticks
Children 2-24 and veterinarians make up
80-90% of human cases
22 000 cases of CSD are diagnosed per year
in the United States
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Most cases occur in late fall and winter
Infections
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CSD is a self-limiting disease characterized by
lymphadenopathy and infection at the site of injury
Lasts 6-12 weeks in healthy individuals and can be
accompanied by headaches, nausea, vomiting and
fatigue
Severity of CSD depends on immune status of the
host
Immunocompromised individuals can develop
Bacillary angiomatosis (BA) and Parinaud’s
oculoglandular syndrome (POS)
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Diagnosis is difficult and is usually based on
exposure to a cat, enlarged lymph nodes and
lack of another appropriate cause
Virulence Factors
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VEGF (vascular endothelial growth factor)
Triggers angiomatosis and has a pathogenic role
in vasoproliferative disorders (such as BA)
 Highly mitogenic to endothelial cells
 B.henselae induces host cell production of VEGF
 This production and subsequent proliferation is
necessary for angiogenesis and BA
 This proliferation also promotes growth of
B.henselae’s own cells
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Pili
Expression of pili allows adhesion and invasion of
host cells
 Pili are also thought to be responsible for the
induction of VEGF as pili- mutants have a
significant decrease in production of VEGF
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Type 4 secretion system (virB-D4)
 Consists of a multiprotein channel that allows
transportation of DNA or protein into the host
cell
 virB operon encodes 10 genes, 8 of which known
to encode a T4SS
 virD4 locus located just downstream
 virB5 encodes a 17kD protein found in patients
with CSD
 Function not known but not found outside
Bartonella species
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Downstream region of virB encodes Bep proteins
that are translocated into the endothelial cells
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These proteins thought to mediate all virB-virD4dependent changes of endothelial cell function
Recent studies have shown that a mutation in
either virB or virD4 prevents intraerythrocytic
infection as well as endothelial cell invasion
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Type 4 Secretion System (Trw)
Second T4SS identified that is active during
endothelial cell infection
 Primary function to establish contact with
erythrocytes through surface expressed T4SS pili
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Deformin
Hydrophobic secreted protein
 Affinity for albumin
 Formation of pits and trenches on red blood cell
membranes that aids in colonization and entry
to the cell
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Outer Membrane Proteins (OMPs)
Induce NFκB-dependent upregulation of Eselectin and ICAM-1
 Leads to increased adhesion molecule expression
 NFκB plays a role in initiation and regulation of
the body’s proinflammatory response
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Persistent Infection
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Endothelial cell interaction
Primary niche
 Most information gathered using HUVEC cells
 Bartonella species can enter endothelial cells by
rearranging actin cytoskeleton
 B.henselae can also enter using “invasome”
mechanism
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Bacterial aggregate formation on cell surface that is
engulfed and internalized through an actindependent process
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Intraerythrocytic persistence
Common theme of Bartonella is prolonged
intraerythrocytic bacteremia associated with
transmission by blood-sucking arthropods
 Adherence mediated by pili and OMPs exposed
on bacterial surface
 Exact mechanism is not known but assumed to
be bacterial-induced endocytosis
 Assisted by deformin secretion
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After invasion intracellular multiplication occurs
 Limited by quorum sensing to prevent hemolysis
Bacteria survive for the duration of the cell life and
remain in the blood stream for several weeks, facilitating
transmission
Bacteria seeded into blood stream every 5 days
Unique persistence is an adaptation to mode of
transmission
Intraerythrocytic bacteremia subsides due to strong IgG
antibody response (in animal models)
Prevention and Treatment
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Proper cat care
Keeping cats indoors
 Using flea products
 Prevent roughhousing with kittens
 Do not let cats like open wounds
 Wash cat wounds out with warm water
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Most healthy people recover without
treatment in anywhere from 3 weeks to
several months
Immunocompromised individuals may
develop more serious complications and
possibly death
If antibiotics are prescribed
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Erythromycin, rifampin, doxycycline
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Antibiotics can not reach intraerythrocytic
bacteria but can prevent new waves of
parasitism
A recent study has shown that cats treated
for bacteremia caused by B.henselae were
resistant to reinfection when challenged
following recovery
B.quintana
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Facultative,intracellular,gram negative rod.
Catalase and oxidase reactions are negative.
The bacterium can be grown on axenic media
When grown on blood agar,rough colonies
embedded in the agar obtained after 12to14 days
Humans are the reservoir of the bacterium,and
the human body louse is its usual vector
The bacterium has atropism for endothelial
cells,leading to angioproliferative
lesions,observed in bacillary angiomatosis.
Transmission
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B.quintana is
transmitted by the
human body louse,
which lives in clothes
Clinical Manifestations
Trench Fever.
 Chronic Bacteremia.
 Endocarditis.
 Bacillary Angiomatosis.
 Lymphadenopathy.
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Diagnosis
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Serologic tests
Western blot and cross-adsorption results in a patient
with Bartonella quintana endocarditis. A) Nonadsorbed. B)
Adsorbed with B. quintana. C) Adsorbed with B. henselae. Lane 1,
B. quintana; lane 2, B. henselae; lane 3, B. elizabethae; lane 4, B.
vinsonii subsp. Berkhoffi; lane 5, B. vinsonii subsp. Arupensis.
Before adsorption (A), antibodies are detected against all species
(1, 2, 3, 4, and 5). After adsorption with B. quintana antigen (B), all
antibodies disappear. After adsorption with B. henselae antigen
(C), antibodies against B. quintana (1) persist. This reaction shows
B. quintana infection.
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Culture.
Molecular Biology.
Immunohistochmistry
and Immunoflurescence.
. Immunohistochemical demonstration of
Bartonella sp
Laser confocal microscopy showing the intraerythrocytic
location of Bartonella quintana.
Antimicrobial drug susceptibility of
B. quintana
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Evaluation of susceptibilities to antimicrobial
drugs has been performed in both axenic media
and cell culture.
Penicillines,cephalosporins,aminoglycosides,chlo
ramphenicol,tetracyclines,rifampin,fluoroquinolo
nes,and cortimonazole.
However only aminoglycosides have
bactericidal effect.
Bartonella bacilliformis
Gram negative aerobic,
pleomorphic, flagellated,
motile, coccobacillary, 2-3
m large and 0,2 - 0,5 m
wide and facultative
intracellular bacterium.
For its isolation, special cultures
are required containing
complemental soy agar,
proteases, peptones, some
essential amino acids and blood.
The optimum growing
temperature is 19-29 ºC.
Suspected vectors:
Phlebotomine sand flies
• Smaller than a
mosquito, larger than a
midge
• Coloration varies from
light brown (sandy or
fawn) to gray or black
• Require humid, not wet,
conditions
• Only female sand flies
take a blood meal
• Nocturnal feeding
behavior
Lutzomyia
verrucarum
Suspected Vectors:
Phlebotomine sand flies
• Sand fies are weak fliers
• Fly only at night unless
disturbed in their
daytime resting site
• Sand flies transmit
Bartonella bacilliformis
from infected to
uninfected hosts by bite
• At least two species
suspected in Peru: Lu.
verrucarum and Lu.
peruensis
Lutzomyia
peruensis
Pathogenesis
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Bartonella bacilliformis is
transmitted by the bite of the
suspected vector Lutzomyia spp
Following transmission, the
bacterium infects red blood cells
and endothelial cells
The physical damage and
introduction of antigens in the
membranes of the red cells
stimulate the Reticuloendothelial
System to produce an intense
erythrophagocytosis by
macrophages and histiocytic cells
resulting in severe extra vascular
hemolytic anemia
The disease
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The clinical symptoms of
bartonellosis are pleomorphic and
some patients may be
asymptomatic
The two classical clinical
presentations are the acute phase
and the chronic phase,
corresponding to the two different
host cell types invaded by the
bacterium
Acute phase: Oroya fever or
Carrion’s disease
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The mean incubation time is 21 days
(range 10 to 270 days)
The diagnostic tests in this phase are:
Diagnostic test
Blood smear
Immunoblot
PCR(16S-23S)
Sensitivity
Specificity
36-73
91-96
70
94
47
98
Values in porcentaje
The diagnosis
The diagnosis in the
acute phase can be
done using the thin
blood film with
Giemsa stain.
It is possible to
observe the bacillus
inside the red blood
cells.
Immunologic technics:
Sonicated immunoblot
20
18
17
14
kDa
kDa
kDa
kDa
A
B
C
D
Lane A: Positive control
pool
Lane Band C:
Bartonella bacilliformispositive serum taken
from a patient in acute
phase
Lane D: Negative
control pool
Molecular technics
M
Base
pairs
1500 bp
600 bp
1
2
3
4
M: DNA ladder (100 bp).
1: B. bacilliformis DNA from
culture extracted by thermal lysis
(100°C, 10 min.) using 16S 23S
primers (positive control).
2: Whole blood extraction from an
acute phase patient, using 16S
23S primers.
3: Whole blood extraction from an
acute phase patient, using primers
for Citrate Synthetase gene.
4: B. bacilliformis DNA from a
culture extraction using primers
for Citrate Synthetase gene.
Chronic Phase: Peruvian wart
(Verruga Peruana)
Mularlesions
Chronic Phase: Peruvian wart
(Verruga Peruana)
Miliary lesions
Chronic Phase: Peruvian wart
(Verruga Peruana)
Miliary lesions with overwhelming infection
Chronic phase: some numbers
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The diagnostic tests in this phase
are blood culture (13% of patients
with verruga have bacteriemia),
culture of the verrugous warts and
Immunoblot with a sensitivity of
70% and specificity of 100%
The IFA has a sensitivity of 82%
and specificity of 92%
Immunity and infection
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One factor that complicates the
clearance of the bacterium is that intraerythrocytic Bartonella are protected
from both humoral and cellular immune
responses due to a lack of major
histocompatibility complex (MHC)
molecules on the surface of the mature
erythrocytes
They are unable to present antigens of
their invaders to the immune system