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Spirochete
螺旋体
Inroduction
•The spirochetes are a large heterogenous group of
bacteria.
•In some respects, this microorganism is similar to
bacteria and protozoa.
•They have cell wall and propagate by binary fission
（二分裂） and move vigorously by the rotation and
twisting of the endoflagella. They are sensitive to
antibiotic.
Single cell dynamics
a. Bacterial cell first can been seen to enlarge
or elongate.
a
b. Then followed by the formation of
transverse membrane and new cell wall.
b
c. The new membrane and cell wall grow
inward from the outer layers.
d. The cell divided into the two daughter cells.
c
d
• Structural characteristics:
◇ They are long, slender and spiral or helical-shaped,
Gram-negative bacilli.
endoflagella
• Structural characteristics:
◇ There are endoflagella located between outer and inner
membrane (envelope) and running parallel to the microbic
body.
Protoplasmic cylinder
Endoflagella
Outer envelope
•
There are three genera whose members are
human pathogens:
I.
Leptospira （钩端螺旋体属）
II. Treponema （密螺旋体属）
III. Borrelia （疏螺旋体属）
I. Leptospira & Leptospirosis
Morphology
•Leptospira are tightly coiled
and flexible (5-15 µm long
and 0.1-0.2 µm wide). One
or two ends are usually bent
to form hook-like shape.
•While stained with silver
stain (Fontana stain), they
show a deep brown color.
Morphology
•They are actively mobile,
which is best seen using a
darkfield microscope.
Can magnify
1000 times
observe living cells
•L. interrogans （问号钩端螺旋体）
• causes human or animal
leptospirosis
diseases
called
• According to the antigenic differences of LPS
and superficial glycoproteins, L. interrogans can
be divided into at least 24 serogroups and 200
serotypes
Culture
•
•
•
•
•
Korthof medium with 10% rabbit serum
The optimal incubating temperature is about 28℃
L. interrogans grows slowly
Sensitive to heating and various chemical agents
Can survive several months in wet soil and water
◇L. interrogans has two chromosomes (one is large
and the other is small).
Transmission
• L. interrogans propagates in the kidney of infected
patients or animals and can be shed in the urine.
• Animal urine from infected rodents, infected farm animals
(usually inapparent infection)
• Contaminate soil and water
• Enters body through healthy or broken skin.
• Human leptospirosis. L. interrogans rapidly enters
bloodstream to cause leptospiremia
Epidemiology
• A common zoonosis（人
畜共患病）:
A disease of animals
that can be transmitted
to humans.
• Extensive animal hosts:
rats, mice, other wild
rodents,
swine,
dog, sheep etc.
cattle,
中华人民共和国地图
黑龙江省
%
新疆维吾尔自治区
内蒙古自治区
辽宁省
甘肃省
青海省
西藏自治区
宁夏回族自治区
$%
%%
北京市
天津市
山西省 E
河北省
山东省
%
$E
$paddy planting area
Leptospirosis area
%
%
江苏省
$
陕西省
E
%E 安徽省%
四川省
$
湖北省$
E
E
%
%E $
%
$ 浙江省
江西省
湖南省
%E$
E
贵州省
% 福建省
E
E
%
$
%
$ E$
$
云南省
$ 广西壮族自治区 E 广东省 % 台湾省
E
E
%
%
%E $ % $
$
河南省
海南省
E
%
$
%
%
吉林省
Pathogenicity
• Virulent factors produced by L. interrogans
LPS: lower toxicity than bacterial LPS
Hemolysin: unknown pathogenesis
Cytotoxicity factor (CTF) and cytopathic effect
(CPE) substance: only show cytotoxicity
• Pathological damage to the capillary endothelium is
the main cause for disease.
Clinical finding
• Leptospirosis affects many internal organs e.g.,
lung, kidney, liver
• The
pathogenicity
of
different
leptospiral
serogroups is distinct. The clinical symptoms are
quite different, from mild influenza-like clinical
signs to death which is usually caused by pulmonary
diffuse hemorrhage (PDH)
• Macrophage can
neutrophils can not
phagocytose
L.
interrogans,
Laboratory Diagnosis
• Peripheral blood in the first week of disease and
urine from the second week on are collected as
samples for detecting leptospire
• Common diagnostic methods in clinic include direct
darkfield microscopy and serological examination
Control
• Penicillin is the first choice drug to
treat leptospirosis
• Multi-valent vaccine composed of
whole dead cells of several leptospiral
serovars（血清群） is available.
However side effect of the vaccine is
relatively serious
II. Treponema pallidum and Syphilis
梅毒螺旋体&梅毒
Morphology of Treponema pallidum
• Moves with endoflagella
• There are 16 to 18 bends
• Shows a deep brown color by silver stain.
• Can be cultured in rabbit testicle（睾丸） but can not
grow in vitro
• Sensitive to temperature and dryness
Treponema pallidum
in testis of infected rabbit
•
Transmission
–
–
–
•
via sexual contact
via placenta or during birth
via blood transfusion
Disease
–
–
Acquired syphilis （后天性梅毒）
Congenital syphilis （先天性梅毒）
I. Acquired Syphilis
• Syphilis is the a most common STD in our
country
• This disease appears chronic and slowly
progressive
• Syphilis undergoes 3 stages
Stage 1: Primary Syphilis
• Chancre （ 硬 性 下 疳 ）
appears
(an
area
of
ulceration/inflammation)
usually in genital areas
• The patient has influenzalike symptoms
• The local lesion will heal
within 4-6 weeks but the
microbe spread systemically
Stage 2: Secondary Syphilis
• Pale red rash (syphilid) appears on the palms
or soles or over the entire body
• The sores around the genitals or anus secrete
extremely infectious fluids
• This stage will last 3-6 months
Syphilid
Abdominal part
palms
soles
Stage 3: Latency Stage
• No obvious symptoms and usually occurs 2-10
years after initial infection and last 3-6 months.
• The infectious ability is decreased.
• Later the complications in the skin, bones,
central nervous system, heart and blood vessels
appear, which frequently cause death.
• The
basic
pathological
lesion
granuloma (肉芽肿，Gumma).
is
chronic
• Gumma (syphiloma)
lesion in the heart
• Gumma (syphiloma)
lesion in the skin
II. Congenital Syphilis
• The disease can cause
fetal death.
• In infants, multi-organ
deformity
or
latent
infection are present.
Runny nose
I. Early Congenital
Syphilis
Vesicular rash
Osteochondritis
Saw-teeth
II. Late congenital
Syphilis
Sabre shins
Frontal bossing and saddle nose
Laboratory diagnosis
• Samples
– the secretions from chancre in Stage I and
from syphilid in Stage II
– the patient’s serum
Laboratory diagnosis
Darkfield microscopy and fluorescence microscopy
RPR (rapid plasma reagin)
• Use cattle cardiolipin as the antigen to detect reagin (syphilis
non-specific antibodies) in the serum
TPPA (T. pallidum particle agglutination assay) or
TPHA (T. pallidum hemagglutination assay)
• micro-hemoagglutination assays for the detection of antibodies
to Treponema pallidum
Treatment & Prevention
• Penicillin
•
Tetracycline
Erythromycin
•
No vaccine
III.Borrelia burgdorferi /Lyme disease
伯氏疏螺旋体&莱姆病
• Lyme disease is an emerging zoonosis mainly
caused by Borrelia burgdorferi. In 1975, the disease
was firstly found in a town named Lyme in the U.S.A.
• Human is infected by bite of ticks carrying Borrelia
burgdorferi.
• The clinical characteristic is erythema chronicum
migrans (ECM，慢性游走性红斑 ) at the bite site.
• Borrelia burgdorferi can invade host cells, resist
phagocytosis and produce endotoxin-like substance.
Pathogenesis is considered to be closely associated
with immunopathological injury because rarely the
pathogen can be found in vivo.
• Borrelia burgdorferi is a spiral microorganism. The microbe
has variable numbers (7-11) of endoflagella to move actively.
Inn tick（硬蜱 pi2）
A kind of tick to transmit Borrelia burgdorferi to human
Erythema chronicum migrans (ECM)
Lyme Disease
erythematous rash
Erythema chronicum migrans (ECM) at the bite site.
Diagnosis & Treatment
•Lyme disease is diagnosed based on clinical symptoms (e.g.,
ECM) and the possibility of exposure to infected ticks.
•PCR and serological assays are helpful for clinical diagnosis.
•Most of Lyme disease cases can be treated successfully with
a few weeks of antibiotics (penicillin or tetracycline).