Download General Characteristics of the Organism

Diagnostic microbiology
lecture: 16
Treponema pallidum
Abed ElKader Elottol
MSc. Microbiology
2010
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General Characteristics of the Organism:
1. A thin, motile spiral organism.
2. Can not be cultivated on artificial media.
3. Can not be visualized by light microscope
4. Rabbits could be infected with this organism.
•Are spiral flexible organisms that move without flagella
•Multiply by transverse binary fission.
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Clinical description of the disease:
Syphilis is a chronic granulomatous disease that
characteristically progress by stages of clinically apparent
infections.
Each stage has different manifestation and lesion morphology,
and stages are separated by periods of latency.
The only evidence of infection is a reactive serologic test during
the latency periods.
Except for congenital syphilis which is transmitted from
infected mothers to the fetus across the placenta, syphilis is
almost always transmitted by sexual exposure.
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PRIMARY STAGE:
The primary syphilitic lesion, the chancre, appears.
The chancre is most frequently a painless, ulcer-like lesion with raised
borders and a necrotic base.
The serum (exudate) from the chancre contains T. pallidum and is
highly infectious.
 The chancre heals spontaneously without scaring over a period of 2-3
weeks.
SECONDARY STAGE:
It occur 6 weeks to 6 months after the chancre heals.
 Symptoms of this stage includes, headache and malaise, general
lymphoadenopathy and a variety of skin rashes, hepatitis, meningitis,
glmerulnephritis and nephritis.
 Nephrosis is a result of Antigen antibody complexes deposited in the
kidney.
Secondary lesions heal spontenaneously over a period of several
weeks and then enters in a latent stage number 2. this stage, bone and
teeth deformation may occur.
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TERTIARY STAGE:
The destructive stage of the disease. It may begin 5-20 years after
the initial infection.
Only one third (1/3) of untreated patient develop tertiary which
are of three types:
1. 80% are aneurysms ( : )Leading to dilatation of aortic valve)
2. 15% are CNS disease and meningitis.
3. 5% gummas (Lesions which histologically resemble a tubercle).
At this stage, bone and teeth deformation may occur.
CONGINITAL SYPHILIS:
The fetus may be aborted, stillborn or liveborn or without
clinical evidence of syphilis.
 The lesions of early congenital syphilis are of the secondary
type and may be present at birth.
 Blindness secondary to optic atrophy.
Deformed bones may also occur.
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LABORATORY IDENTIFICATION:
T. pallidum can not be cultivated in the laboratory In-Vitro. Only two
methods are available for the diagnosis of T. pallidum.
1. DARK-FIELD MICROSCOPY: Most specific for infectious syphilis.
• Clean the chancre with gauze moistened with sterile sodium
chloride solution,Dry it.
• Scrap the edges of the chancre several times with the flat side of
a sterile lancet, Do not draw blood.
• Press with dry sterile gauze.
• Remove the swab and wait for a few minutes until a pinkish
serous fluid appear, Draw off the fluid with a Pasteur pipette.
• Place a drop of the fluid on a thin glass slide.
• Examine under the microscope using dark field condenser. Search
for the characteristic morphology of T. pallidum. (Motile thin
spirochetes, rotating around their long axes).
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2. SEROLOGICAL TESTING:
Two types of antigens are used.
A. Non-Treponemal Antigens Test: It utilizes "cardiolipin" as its
antigen, which reacts with IgM or IgG immunoglobulin known as
"reagin" antibody
1. Flocculation test (VDRL): (Venerial Disease Research
Laboratories) This test is based on the fact that particles of the
lipid antigen ( cardiolipin) remains dispersed in normal sera,
but combines with reagin to form visible aggregate within a
few minutes.
Rapid Plasma Reagin test (RPR) is a good modification for rapid
surveys.
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2. Complement fixation test "Wasserman, Kolmer"
This test is based on the fact that, reagin-containing sera
fix complement in the presence of cardiolipin.
NB: Biologic false results may occur with many patients
having:
1. Malaria
2. Leprosy
3. Measles
4. Infectious mononucleosis
5. SLE
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B. Treponemal Antibody Test:
1. Fluorescent Treponema Antibody Absorption Test (FTA-ABS)
This test employs indirect immunofluorescence (Killed T. pallidum +
patient`s serum + labeled anti-human gammaglobulins).
The test serum is added to the antigen (killed T. pallidum) which is
fixed on a glass slide, incubated and then washed to remove excess
serum.
Conjugate (Labeled antihuman gammaglobulin) is added ,
incubated and then washed. This test is read microscopically with
an ultraviolet light source.
2. T. pallidum immobilization test (TPI):
Specific antibodies in the patient serum after the second week of
infection could be demonstrated by their ability to immobilize
actively motile T. pallidum, extracted from the chancre of infected
rabbits. The test is read microscopically with an dark field
microscope.
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3. T. pallidum-Hemagglutination test (TP-HA):
Red cells are treated to adsorb treponemal antigens on their
surface.
When mixed with serum containing antitreponemal
antibodies, the cells become clumped.
Clumping is considered as positive results.
NB: VDRL and FTA-ABS tests can also be performed on spinal
fluids. Antibodies do not reach the CSF from the blood stream
but are probably formed in CNS in response to syphylitic
infection.
TREATMENT:
Penicillin is the treatment of choice of syphilis
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Diseases Related to Treponema:
1. Yaws: (Frambesia):
is a tropical infection of the skin, bones and joints caused by T.
pertenue.
2. Pinta
is a human skin disease endemic to Mexico, Central America, and
South America.
 It is caused by infection with a spirochete, Treponema carateum,
which is morphologically and serologically indistinguishable from the
organism that causes syphilis.
Pinta initially presents as a raised papule, followed by a generalized
eruption of flat, reddened areas, and is followed by the development of
bluish coloration and a subsequent loss of pigmentation.
 Unlike syphilis, it is transmitted by nonsexual skin contact, often
between children living in conditions of poor hygiene.
 The disease can be treated with penicillin, tetracycline, or
chloramphenicol, and can be prevented through contact tracing by
public
health officials.
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LEPTOSPIRA INTERROGANS
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Causative agent of Leptospirosis : A zoonotic disease
Habitat : Infected domestic live-stock ‫ & مواشي‬pets ‫اليف‬.
The organism settles in the kidney and excreted in urine.
Mode of Infection
Direct Contact with:
•Urine of infected animal
•Water & soil recently contaminated with infected urine
The organism enters body through:
•Skin lesions
•Conjunctival mucus membrane
•Ingestion.
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High-Risk Groups
•Farmers
•Sewer‫ بالوعة‬workers
LEPTOSPIROSIS
Pathogenesis
Incubation period : 1-2 weeks.
Bacteremia : organisms multiply in liver, spleen,
kidney, meninges, conjunctiva
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Clinical Features
Influenza-like followed by hepatitis & meningitis
Weil’s Disease (severe leptospirosis) severe headache, pain in
pack, prostration, jaundice
Jaundice, hemorrhage, renal failure
Lab Diagnosis
Dark field Microscopy of blood & CSF
Sero-diagnosis
Leptospira can be cultured in Ellinghausen-McCulloughJohnson-Harris medium(EMJH), which is incubated at 28 to
30 °C.
The median time to positivity is three weeks with a
maximum of 3 months.
Treatment & Prevention
Penicillin
Animal immunization
Proper treatment and disposal of contaminated water
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BORRELIA RECURRENTIS
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Can be stained with Giemsa stain in blood film.
 Can grow in media containing serum & tissue extracts.
 High frequency of antigenic variation in major surface protein
and is responsible for :
Organism can escape immune system
Relapses of disease
Disease : Relapsing Fever
Transmission :
Tick-borne ‫ قراد‬Relapsing Fever
From infected rodents to human
Louse-borne ‫ قمل‬Relapsing Fever
From infected human to human
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Clinical Features
Bacteremia : Infect various organs.
A non-pruritic rash at bite site.
Fever, rigors (shaking occurring during a high fever) and
headache for weeks to months.
Weeks to months later: Cardiac and neurological symptoms.
Predominant arthritis.
One of the causes of Pyrexia of Unknown Origin PUO.
Lab Diagnosis
Giemsa staining of blood smear.
Detection of IgM OR rising titer of IgG.
PCR.
Treatment & Prevention
Amoxycillin
Louse, tick & rodent control
Hygienic measures
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End of Lecture
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