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)