chapter 20 other bacteria bacillus, brucella, yersinia disease: anthrax, brucellosis, plague
TRANSCRIPT
Chapter 20 other bacteriaChapter 20 other bacteria
Bacillus , Brucella, Yersinia Bacillus , Brucella, Yersinia
Disease: anthrax, brucellosis, plagueDisease: anthrax, brucellosis, plague
教学大纲教学大纲• 掌握:炭疽杆菌的形态特征、培养特性、掌握:炭疽杆菌的形态特征、培养特性、
致病物质;布鲁菌属的种类、致病物质致病物质;布鲁菌属的种类、致病物质与所致疾病;鼠疫杆菌的形态特性、致与所致疾病;鼠疫杆菌的形态特性、致病物质、特异性菌苗预防;小肠结肠炎病物质、特异性菌苗预防;小肠结肠炎耶氏杆菌的致病性。耶氏杆菌的致病性。
• 熟悉:炭疽临床类型、鼠疫临床类型。熟悉:炭疽临床类型、鼠疫临床类型。
section 4 Bacillus
B. anthracis
anthrax
Biological characterizationBiological characterization
•B. anthracisB. anthracis gram positivegram positive, non-motile , rectangular, rod , non-motile , rectangular, rod
•Have square end, attached by a joint Have square end, attached by a joint to othto other cells.er cells.
•In artificial media, can form long chains as In artificial media, can form long chains as a streptobacillus (a streptobacillus (bamboo-likebamboo-like ), can ), can producproduce sporese spores
•Virulent strain has Virulent strain has capsulecapsule
ColonyColony : 2-5 mm , R: 2-5 mm , R
Wavy marginWavy margin and small projections, called and small projections, called medusa hmedusa headead appearance. (curled-hair) appearance. (curled-hair)
Hemolysis is uncommonHemolysis is uncommon
(common with saprophytic bacilli)(common with saprophytic bacilli)
cultureculture
blood agarblood agar
• Capsule :Capsule :coded coded by plasmids gene, by plasmids gene, anantiphagocytic tiphagocytic
• Exotoxin (anthrax toxin) : Exotoxin (anthrax toxin) : codedcoded by by plasmids gene, consisting of : plasmids gene, consisting of :
protective antigen (PA) protective antigen (PA)
edema factor (EF)edema factor (EF) lethal factor (LF)lethal factor (LF)
pathogenesispathogenesis
Virulence factorsVirulence factors
Anthrax toxinAnthrax toxin
• Be considered “classical” AB toxinBe considered “classical” AB toxin
A (PF) : bind with ATR on host cellA (PF) : bind with ATR on host cell
B (EF or LF): B (EF or LF):
EF :causing elevated intracellular cAEF :causing elevated intracellular cAMP, fluid excretion and edemaMP, fluid excretion and edema
LF: necrosis ,fever, hypoxia ,shockLF: necrosis ,fever, hypoxia ,shock
ANTHRAX TOXINSANTHRAX TOXINS
LF
EF
PA
PA
PA
LF
HostProtease
HOST CELL
20 kDa
• Habitat: animals Habitat: animals ((HerbivoresHerbivores))
• Transmission: by contact with infected aTransmission: by contact with infected animal and animal products , inhalation, dnimal and animal products , inhalation, digestionigestion
Anthrax infections are classified by route of entry
• Cutaneous
• Gastrointestinal
• Respiratory
Clinical findingClinical finding
Cutaneous Anthrax
• > 95%> 95% • Spores enter breaks in skin after Spores enter breaks in skin after contact contact
with contaminated animal productswith contaminated animal products• Papule- Vesicle- Ulcer - EscharPapule- Vesicle- Ulcer - Eschar• Up to 20% Up to 20% case fatality ratecase fatality rate if untreated if untreated• Mortality with treatment < 1%Mortality with treatment < 1%
In hand , forearm or headIn hand , forearm or head
Vesicles & Black Eschar
•
Cutaneous anthrax
local edema and necrosis
Pulmonary anthrax
• Bacillus spores are inhaled and ingested by alveolar macrophages
• These cells carry the bacteria to the regional lymph nodes, causing necrotic hemorrhaging which leads to death
Fever, malaise, myalgia, nonproductive cFever, malaise, myalgia, nonproductive cough.ough.
Intestinal anthrax
• Ingestion of contaminated meat produces systemic symptoms which can lead to death
• Mortality may be 50%
Protective immunity
• Abs against protective antigen
Handling of carcasses动物尸体
• forbid postmortem examination of animals when anthrax is suspected
• animals that die suddenly should be handled cautiously
(cremation or deep burialcremation or deep burial )
• Livestock should be vaccinated annually.
• Patients: antibioticsPatients: antibiotics
controlcontrol
Brucella
• brucellosis
• Brucella melitensis 羊 Brucella suis 猪 Brucella abortus 牛 Brucella canis 犬• Are all intracellular organisms
• Brucella are small (0.4 ~ 0.8 ×0.5 ~ 1.5μm), non-motile, non-spore, G- coccobacilli.
• aerobic
• Medium: enrich with animal serum and glucose
• 5-10% carbon dioxide
• Growth is slow
Antigenic Structure and classification
• Two main antigen: A and M
• The three main Brucella differ from one another in the amount
B.abortus 牛 : A:M=20:1
B.melitensis 羊 : A:M=1:20
B.suis 猪 : A:M=2:1
Pathogenesis
• Bacteria is animal pathogens, excreted in genital secretions (including semen), milk, colostrum of animals.
• Widespread: Cattle, Bison, Elk, Deer, Moose, Horse, Sheep, Goat, Swine, Donkey, Dogs, Birds, Hares, Fox, Rats, mice, Camels and Human.
Spread of Brucella in the body
Portals of entry
– Ingestion of contaminated animal products (often raw milk) via alimentary tract
– Inhalation of bacteria via respiratory tract
–Via skin abrasions
Brucellosis
• undulant fever 波浪热
Undulant fever
39.5
37.0
**Abortion occurs Abortion occurs only in cows and only in cows and goat.goat.
Clinical Manifestations
• Influenza-like with fever reaching 38 to 40oC–Limb and back pains, night
sweating , fatigue . –Anorexia (loss of appetite),
weakness, loss of weight, depression–Headache
Occupational hazard
• FarmersFarmers, , abattoir workersabattoir workers, , butchersbutchers
and and veterinariansveterinarians are particularly at are particularly at
riskrisk
PreventionPrevention• Eradication of brucellosis in cattle
• Active immunization of humans against brucella infection
• pasteurization of milk and milk products
TreatmentTreatment
• tetracyclines or ampicillin.
• Y. pestisY. pestis
• Y. enterocoliticaY. enterocolitica
• Y. pseudotuberculosisY. pseudotuberculosis
Yersinia
Epidemiology• Plague
– Probably originated in Asia or central Africa.– One of the earliest record pandemics occurre
d in 542 B.C.– Three pandemics in the history.– 1989 - 1998 : 5440 cases, 681 dead.– 2003: 2118 cases2003: 2118 cases
Biological Features
Small, G- rods or cocco bacilli.
–Bipolar Staining:Retaining stain at the ends of cells.
–Nonmotile ,non-sporing, but has capsule
Y. pestisY. pestis
• Cultural Features–Facultative anaerobes.
–30˚C.
– in media containing blood or tissue fluids.
Pathogenicity
Transmission:Transmission:
FleaFleaRespiratory Tract Respiratory Tract
BiteBite
– 临床表现为发热、显著的毒血症症状和出血倾向。
鼠鼠
鼠蚤鼠蚤人蚤人蚤
人人呼吸道呼吸道 人人
鼠鼠
Epidemiology
Virulent factors
• Envelope(F1 Antigen) : antiphagocytic
• V,W Antigen: rapid proliferation and septicemia
• Endotoxin (LPS)
• Outer membrane proteins (Yop)
• Murine toxin
Pathogenesis
Y. pestis Phagocyte
Lymph Nodes
In Groin and Axilla
Enter
Respiratory System
Invade
Pneumonic Plague Bubonic Plague
Invade Blood StreamSepticemic 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
Bubonic plagueBubonic plague
Diagnosis• Specimens:Specimens:
– Aspirates of lymph nodesAspirates of lymph nodes– Cerebrospinal fluidCerebrospinal fluid– BloodBlood– SputumSputum
Smears and staining; culture Serological test:
Treatment
• Streptomycin
• Tetracycline:
alternative drug
combination with streptomycin
essential for control early in disease
• Sulfonamides
Latest progress
• B.anthracis: study of rapidly detecting anB.anthracis: study of rapidly detecting and identifying methods; search for new vad identifying methods; search for new vaccineccine
• Y.pestis: manufacture better vaccineY.pestis: manufacture better vaccine
summary• B.anthracisB.anthracis: morphology and stain, struc: morphology and stain, struc
ture; culture , pathogenesis (transmission ture; culture , pathogenesis (transmission and diseases) and diseases)
• BrucellaBrucella: stain, pathogenesis (transmissio: stain, pathogenesis (transmission and diseases) n and diseases)
• Y.pestisY.pestis: morphology and stain, special st: morphology and stain, special structure, pathogenesis (transmission and ructure, pathogenesis (transmission and diseases) diseases)