Download B anthracis

Brucella
 The genus Brucella consists of six
species, four of which cause human
brucellosis 布鲁菌病： Brucella
melitensis 羊布鲁菌, Brucella suis 猪布
鲁菌, Brucella abortus 牛布鲁菌, and
Brucella canis 犬布鲁菌
 Are all intracellular organisms
 B. neotomae; B. ovis
 Brucella are small (0.4～
0.8 ×0.5～1.5μm), nonmotile, non-capasulate,
gram-negative
coccobacilli.
 The organism is aerobic,
and their nutritional
requirements are
complex.
 All strains grow best in a
medium enrich with
animal serum and
glucose
Antigenic Structure and
classification
 Two main antigen: A and M
 The three main Brucella differ from one
another in the amount or the two main
antigen they have in common :
B.abortus : A:M=20:1
B.melitensis: A:M=1:20
B.suis:
A:M=2:1
B. abortus
 Bacteria is excreted in genital
secretions (including semen), milk,
colostrum.
 Survival time:
Cheese at 4oC: 180 days !!!
Water at 25oC: 50 days
Meat and salted meat: 65 days
Manure at 12oC: 250 days !!!!
 Widespread:
Cattle, Bison, Elk, Deer, Moose,
Horse, Sheep, Goat, Swine, Donkey, Dogs, Birds,
Hares, Fox, Rats, mice, Camels and Human.
B. abortus
 Sources of Human Infection:
Raw milk and products /Direct contact
 Portal of entry: oral mucosa, nasopharynx
and conjunctivae, genital then X in regional
lymph node and spread to RES (nodes of
udder, uterus, erythritol...). Placentitis with
endometritis. Fetus die with edema
/congestion of lung, dissimenated
hemorrhages of epicardium and splenic
capsule. Bacteria in lung and digestive tract
of the fetus.
B. melitensis
 Goat (1886), Sheep,
Cow (1905 in
Malta), Swine,
Hares, Camels,
Buffalo, Impala.
B. suis
 Wild pigs, Rats,
Swine.
 Abortion,metritis,
bursitis,
spondylitis
(Lumbar and
sacral), arthritis,
orchitis, paralysis.
Brucella canis
 Brucella canis was first described as a
cause of abortion in beagles in the USA
 It was subsequently shown to infect
dogs in many other countries,
irrespective of breed
 An occasional cause of brucellosis in
humans
Spread of Brucella in the body
Incubation period
 Acute or subacute disease follows an
incubation period which can vary from 1 week
to 6 or more months.
 In most patients for whom the time of
exposure can be identified, the incubation
period is between 2 and 6 weeks
 The length of the incubation period may be
influenced by many factors
 virulence of the infecting strain
 size of the inoculum
 route of infection
 resistance of the host
Portals of entry
 Oral entry - most common route
 Ingestion of contaminated animal products
(often raw milk or its derivatives)
 contact with contaminated fingers
 Aerosols
 Inhalation of bacteria
 Contamination of the conjunctivae
 Percutaneous infection through skin
abrasions or by accidental inoculation
Clinical Manifestations
 The presentation of brucellosis is




characteristically variable
The onset may be insidious or abrupt
Influenza-like with fever reaching 38 to 40oC
 Limb and back pains are unusually severe,
night sweating and fatigue are marked.
 Anorexia, weakness, severe fatigue and loss
of weight, depression
 Headache
The leukocyte count tends to be normal or
reduced, with a relative lymphocytosis
 Relative leukopenia
On physical examination, splenomegaly may
be the only finding.
COURSE OF BRUCELLOSIS
 If the disease is not treated, the
symptoms may continue for 2 to 4
weeks
 Many patients will then recover
spontaneously
 Others may suffer a series of
exacerbations
 May produce an undulant fever in
which the intensity of fever and
symptoms recur and recede at
about 10 day intervals.
Brucellosis
 Cyprus fever/Gibraltar fever/Malta
fever/Rock fever/Undulant fever
• Most affected persons
recover entirely within
3 to 12 months
• Some will develop
complications
– involvement of various
organs,
– a few may enter an ill-defined
chronic syndrome.
Undulant fever
39.5
37.0
COMPLICATIONS
 Arthritis, often sacroiliitis, and
spondylitis (in about 10 percent of cases)
 central nervous system involvement
including meningitis (in about 5%)
 Uveitis, epididymo-orchitis
 Endocarditis very rare
 In contrast to animals, abortion is not
a feature of brucellosis in pregnant
women.
LARGE JOINTS
SPONDYLITIS脊椎炎
SACROILIITIS 骶髂关节炎
Chronic Brucellosis- Depression
Population risk
 The main source of infection for the general
population is dairy produce prepared from
infected milk.
 B. melitensis presents the greatest hazard.
 The milk of infected sheep and goats may contain
large numbers of viable organisms, which become
concentrated in products such as soft cheeses.
 Indeed, soft cheese has been recognized as a
major vehicle of infection in the Mediterranean
region, the Middle East and Latin America
Occupational hazard
 Infection arises from occupational or domestic
contact with infected animals or with an
environment contaminated by their discharges
 Farmers and their families, abattoir workers,
butchers and veterinarians are particularly at
risk
 Infected animals that have recently aborted or
given birth present the greatest hazard
Extending spectrum of
zoonosis
 The recent isolation of distinctive Brucella strains,
tentatively named Brucella maris, from marine
animals in the United Kingdom and the United
States extends the ecologic range of the genus
and, potentially, its scope as a zoonosis
 seals, sea otters, dolphins and porpoises
 An incident of laboratory-acquired infection
suggests that this type is pathogenic for humans
 Infection could result from occupational contact
with infected seals or cetaceans.
CLINICAL DIAGNOSIS
Sanitary
 Pasteurization of dairy products and use
of protective clothing prevent human
infection. More importantly, systematic
identification and elimination of infected
animals and vaccination of animals
reduces the reservoir.
Prevention
 Eradication of brucellosis in cattle can be
attempted by test and slaughter,active
immunization of heifers with avirulent live strain
19,combined testing,segregation, and
immunization.Cattle are examined by means of
agglutination tests
 Active immunization of humans against brucella
infection is experimental.Control rests on limitation
of spread and possible eradication of animal
infection,pasteurization of milk and milk products,
and reduction of occupational hazards wherever
possible.
Treatment
 Brucella may be susceptible to tetracyclines or
ampicillin.
 Symptomatic relief may occur within a few days
after treatment with these drugs is begun.
 However ,because of their intracellular
location,the organisms are not readily
eradicated completely from the host.
 For best results,treatment must be
prolonged.Combined treatment with
streptomycin and a tetracycline may be
considered
YERSINIA
Enterobacteriaceae
Genus Escherichia
Genus Yersinia
 Y. pestis
 Y. enterocolitica
 Y. pseudotuberculosis
Biological Features
 Small, 0.5-0.8 μm in width
1.0-2.0 μm in length.
 Gram-negative rods.
 Sometimes appearing as
cocco bacilli.
 Bipolar Staining:Retaining
stain at the ends of cells.
Biological Features
 Cultural Features
 Facultative anaerobes.
 Optimal growth temperature range form 28˚C to
30˚C.
 Optimal growth pH: 6.9～7.2.
 Growth is more rapid in media containing blood
or tissue fluids.
 Nonmotile when grow at temperatures above 30
˚C.
Pathogenicity
Transmission:
Flea
Bite
Respiratory Tract
Antigenic Structure
 F1 Antigen:
 V,W Antigen:
 Yersinia Outer membrane Protein (Yop)
 Murine Toxin (MT)
0.3%-0.4% formaldehyde Toxoid
 Endotoxin (LPS)
Ca2+ Dependent
V-W Gene
Gene
Plasmid
W Antigen
V Antigen
F1 Gene
F1 Antigen
Plasmid
LPS
Y. Pestis Virulence factors schematic diagram
Pathogenesis
Invade
Lymph Nodes
In Groin and
Axilla
Phagocyte
Y. pestis
Enter
Pneumonic Plague
Bubonic Plague
Respiratory System
Invade Blood Stream
Septicemic Plague
meningitis
Pathogenicity
 Clinical Forms :
 Bubonic Plague: High fever, Swelling,
Bleeding, Necrosis of lymph nodes
 Pneumonic Plague: chills, cough, respiratory
failure, circulatory collapse ——Black Death
 Septicemic Plague: Fever (39-40 ˚C) , Shock ,
DIC
Y.Enterocolitica & Y.Pseudotuberculosis
 Gram negative, No capsule, No spore,
Facultative anaerobes
 V－W antigen
 More than 50 serotypes of Y.Enterocolitica
6 serotypes of Y.Pseudotuberculosis
 Diseases:
 Gastroenteritis
 terminal ileitis, appendicitis, mesenteric
lymphadenitis,
 dermatitis contusiformia, arthritis
 Septicemia
 Sanitary precautions, Antibiotic
Epidemiology
 Plague
 Probably originated in Asia or central Africa.
 One
of the earliest record pandemics
occurred in 542 B.C.
 Three pandemics in the history.
 1989－1998：5440 cases, 681 dead.
Immunity
Humoral
Immunity
Cellular
Immunity
Antibody To:
1) F1 Ag
2) V,W Ag
Phagocytose
Promote phagocytose , agglutinate and kill bacteria
Diagnosis
 A. Specimens:
 Aspirates of lymph nodes
 Cerebrospinal fluid
 Blood
 Sputum
 B.
Smears:
 Giemsa’s
stain
 immunofluorescent stain
Diagnosis
 C. Culture:
 All materials Cultured on blood agar and
MacConkey’s agar and in infusion broth
 Positive in 24 hours
 Tentatively identified by biochemical
reations Definite identified by
immunofluorescence
CAUTION: All cultures are highly infectious and must be
handled with extreme caution
Diagnosis
 D. Serology:
In patients who have not been
previously vaccinated, a convalescent
serum antibody titer of 1:16 or greater is
presumptive evidence of Y.pestis
infection.A titer rise in two sequential
specimens confirms the serologic
diagnosis.
Treatment
 Streptomycin
 Tetracycline:
alternative drug
combination with streptomycin
essential for control early in disease
 Sulfonamides
Summary of Yersinia infections
12. Spore-Forming GramPositive Bacilli:
Bacillus
Bacillus Species
 At least 48 species are known but only

B. anthracis and B. cereus cause defined
diseases in humans.
 B. anthracis is responsible for the disease
anthrax.
 This is a disease primarily of animals (zoonosis) but
humans can acquire via handling, inhaling or ingesting
contaminated animal products.

B. cereus is predominantly responsible for food
poisoning in humans.
 Bacitracin and polymyxin are two well-known
antibiotics obtained from Bacillus species.

Spores of many Bacillus species are resistant to heat, radiation,
disinfectants and desiccation
 It was from studies on anthrax that Koch
established his famous postulates in
1876
 Pasteur (1881) developed a vaccine
against anthrax
B. anthracis Gram stain
demonstrating spores
B. anthracis,
Colony on SBA
“STICKY” Consistency of
B. anthracis’ Colony on SBA
Anthrax infections are classified
by route of entry
• Cutaneous
• Gastrointestinal
• Respiratory
Cutaneous Anthrax





> 95% of naturally occurring cases
Spores enter breaks in skin after contact
with contaminated animal products
Papule丘疹- Vesicle水泡- Ulcer - Eschar焦
痂
Up to 20% case fatality rate if untreated
Mortality with treatment < 1%
 After a 2- to 3-day incubation period, a small
pimple or papule appears at the inoculation
site.
 A surrounding ring of vesicles develops
 Over the next few days, the central
papule ulcerates, dries, and blackens
to form the eschar
Vesicles & Black Eschar
Painless & Edema
 The lesion is painless and is surrounded by marked
edema that may extend for some distance
 Pus and pain appear only if the lesion becomes infected
by a pyogenic organism
 Similarly, marked lymphangitis淋巴管炎and fever
usually point to a secondary infection.
Evolution of an anthrax eschar in
a 4-year-old boy
DAY 6
DAY 10 - 15

Evolution of an anthrax eschar in a 4-year-old boy.
(A&B) the lesion when first seen (day 0).Note the arm swollen from the
characteristic edema.
(C) Day 6. (D) Day 10. (E) Day 15.
Although penicillin treatment was begun immediately and the lesion was sterile by
about 24 hours,
it continued to evolve and resolve as seen.
Cutaneous anthrax
Differential diagnosis
Ecthyma gangrenosum
Rat-bite fever
Pseudomonas aeruginosa
Streptobacillus moniliformis,
Spirillum minor
Ulceroglandular tularemia
Francisella tularensis
Plague
Yersinia pestis
Glanders
Pseudomonas pseudomallei
Rickettsialpox
Rickettsia akari
Orf
Parapoxvirus
Staphylococcal lymphadenitis Staphylococcus aureus
Cutaneous tuberculosis
Myocbacterium tuberculosis
Leprosy
Mycobacterium leprae
Buruli ulcer
Mycobacterium ulcerans
Cutaneous anthrax
For cutaneous and gastrointestinal
anthrax, low-level germination occurs at
the primary site, leading to local edema
and necrosis
Inhalation

Bacillus spores are inhaled and ingested by
alveolar macrophages肺泡巨噬细胞
 These cells carry the bacteria to the
regional lymph nodes, causing necrotic
hemorrhaging which leads to death
Gastrointestinal
 Ingestion of contaminated meat
produces systemic symptoms which can
lead to death
 Mortality by gastrointestinal anthrax
may be 50%
Gastrointestinal and pulmonary
anthrax are both more dangerous
than the cutaneous form
because they are usually
identified too late for treatment
to be effective
PATHOGENESIS
 Anthrax infections result only if the
bacteria produce a
 i) capsule (poly-y-D-glutamic acid
polypeptide)
 ii) exotoxins
 both encoded on plasmids
 three proteins
 protective antigen (PA) (82. 7 kDa)
 lethal factor (LF) (90.2 kDa)
 edema factor (EF) (88.9 kDa)
ANTHRAX TOXINS
20 kDa
PA
PA
LF
EF
Host
Protease
PA
The complex (PA+LF or
PA+EF) is internalized by
endocytosis
acidification of the endosome
HOST CELL
LF
the LF or EF cross the
membrane into the cytosol via
PA-mediated ion-conductive
channels
Effects of anthrax exotoxins on
macrophages
 Edema toxin is a
calmodulin钙调节蛋白dependent adenylate
cyclase that increases
intracellular levels of cyclic
AMP (cAMP) on entry into
most types of cell
 This is believed to alter
water homeostasis
 resulting in massive
edema
Effects of anthrax exotoxins on
macrophages

Lethal toxin is a zinc
metallo-protease that causes
a hyperinflammatory
condition in macrophages
 activating the oxidative burst
pathway
 release of reactive
oxygen intermediates
 production of
proinflammatory cytokines
 responsible for shock
and death.

MAPKK denotes mitogenactivated protein kinase
kinase
•Endospores
are
phagocytosed
by
macrophages
and germinate
•Macrophages
containing
bacilli detach
and migrate to
the regional
•Vegetative anthrax bacilli grow in the lymph node, creating
regional hemorrhagic lymphadenitis
•Bacteria spread through the blood and lymph and increase to
high numbers, causing severe septicemia
•High levels of exotoxins are produced that are responsible for
overt symptoms and death.
•In a small number of cases, systemic anthrax can lead to
meningeal involvement by means of lymphatic or hematogenous
spread
•In pulmonary anthrax, peribronchial hemorrhagic lymphadenitis
blocks pulmonary lymphatic drainage
• leading to pulmonary edema
Once they have been released from the
macrophages, there is no evidence that an
immune response is initiated against
vegetative bacilli
Protective immunity
 Antibodies against protective antigen
 Both the noncellular human vaccines
and live-spore animal vaccines confer
protection by eliciting antibodies to
protective antigen
 The poly-g-D-glutamic acid capsule of B
anthracis is poorly immunogenic, and
antibodies to the polysaccharide and
other components of the cell wall are
not protective.
Species differences
 Anthrax has been documented in a wide
variety of warm-blooded animals
 Some species, such as rats, chickens,
and dogs, are quite resistant to the
disease
 Others (notably herbivores such as
cattle, sheep, and horses) are very
susceptible
 Humans have intermediate
susceptibility.
reservoir of B anthracis is
contaminated soil
 Spores remain viable for long periods
 Herbivores, the primary hosts, become
infected when foraging in a contaminated
region
 Because the organism does not depend on
an animal reservoir, it cannot readily be
eradicated from a region
 anthrax remains endemic in many
countries
 Humans become infected almost exclusively
Cycle of infection in nature
 As a susceptible animal with anthrax approaches
death, its blood contains as many as 109 bacilli/ml
 Necrosis of the walls of small blood vessels
during the acute phase of the illness leads to
hemorrhages and to characteristic bloody
exudations from the mouth, nose, and anus, a
highly diagnostic sign
 These exudates carry vast numbers of the bacilli
 sporulate on exposure to air
 produce a heavily contaminated environmental
site
 potentially capable of infecting other animals for
many years
Handling of carcasses动物尸体
 Sporulation of B anthracis requires oxygen
 therefore does not occur inside a closed
carcass
 regulations in most countries forbid
postmortem examination of animals when
anthrax is suspected
 The vegetative cells in the carcass are killed
in a few days by the process of putrefaction.
 In endemic areas, animals that die suddenly
should be handled cautiously
 Livestock should be vaccinated annually.
Do I look
that I am going
to die?
Non-Industrial vs Industrial
Anthrax
 Nonindustrial anthrax
 usually affects people who work with animals or
animal carcasses
 farmers, veterinarians, butchers
 almost always cutaneous
 Industrial anthrax
 acquired from handling contaminated hair, hides,
wool, bone meal, or other animal products
 higher chance of being pulmonary as a result of the
inhalation of spore-laden dust
Transmission
Clinical syndrome
Who is at risk
Injured skin or mucous
membranes inoculated
by spores from the soil
or a contaminated
animal or carcass
Skin infection begins as a
raised itchy bump and
within 1-2 days develops
into a vesicle and then a
painless ulcer, usually 1-3
cm in diameter, with a
characteristic black
necrotic area in the center.
Lymph glands in the
adjacent area may swell.
Intestinal
anthrax
The ingestion of poorly
cooked meat or milk
from infected animals
Initial signs of nausea,
loss of appetite, vomiting,
and fever are followed by
abdominal pain,
vomiting of blood, and
severe diarrhea.
People in endemic
areas in contact with
infected animals of
contaminated soils;
people who work with
animals materials
(hides, fur, wool, hair)
imported from endemic
area, such as farmers,
veterinarians, knackers,
butchers and
laboratorians.
Pulmonary
anthrax
Inhalation of sporecontaining dust where
animal hair or hides
are being handled
begins abruptly with high
fever and chest pain,
progresses rapidly to a
systemic hemorrhagic
pathology
Cutaneous
anthrax
Bacillus Cereus蜡样芽胞杆菌
 B. cereus food poisoning results from the
ingestion of preformed enterotoxins,
producing predominantly vomiting and
diarrhea.
 The vomiting form is most often associated
with ingestion of a heat stable toxin from
contaminated rice, while the diarrheal form is
most often associated with ingestion of a heat
labile toxin from contaminated meat or
vegetables
B cereus virulence factors
 A 38 to 46-kDa protein complex has been shown in animal
models:
 to cause necrosis of the skin or intestinal mucosa
 to induce fluid accumulation in the intestine
 a lethal toxin
 Responsible for the necrotic and toxemic nature of severe B
cereuscereus
infections
and for the
form of food poisoning
Bacillus
also produces
twodiarrheal
hemolysins
Phospholipases produced by B cereus may act as exacerbating
factors
by degrading host cell membranes following exposure of their
phospholipid substrates in wounds or other infections
Bacillus Food Poisoning
Two Distinct Types
 Diarrheal type
 diarrhea and abdominal pain
 8 to 16 hours after consumption of the contaminated
food
 Associated with a variety of foods, including meat
and vegetable dishes, sauces, pastas, desserts, and
dairy products
 Emetic呕吐 disease
 nausea and vomiting begin 1 to 5 hours after the
contaminated food is eaten
 Boiled rice that is held for prolonged periods at
ambient temperature and then quick-fried before
serving is the usual offender, although dairy products
or other foods are occasionally responsible.