VibriosVibrios （（弧菌属）

※ Vibrio cholerae （霍乱弧菌） -gastroenteritis

※ Vibrio parahaemolyticus （副溶血性弧菌） -

gastroenteritis, wound infection, bacteremia

※ Vibrio vulnificus （嗜盐弧菌） -wound infection,

bacteremia

Overview

※ ※ G- G- vibrio

※ ※ CCurves or comma shapedurves or comma shaped

※ ※ Non-spore forming Non-spore forming

※ ※ Highly motile-single polar flagella Highly motile-single polar flagella

※ ※ Oxidase Oxidase （（ ++ ）） ※ ※ Facultative anaerobeFacultative anaerobe

※ ※ Tolerate alkaline condition to pH9.0 Tolerate alkaline condition to pH9.0

※ ※ RReadily cultivatedeadily cultivated,, ssimple nutritional requirementsimple nutritional requirements

※ ※ Associated with salt waterAssociated with salt water

CharacteristicsCharacteristicsOverview

two groups two groups

1. 1. non-halophilicnon-halophilic vibrios: including vibrios: including V. choleraeV. cholerae and and

other species that are able to grow in media without other species that are able to grow in media without

added salt.added salt.2. 2. halophilichalophilic （（喜盐的） vibros: species which do not vibros: species which do not grow in media grow in media without added salt.without added salt.

V. choleraeV. cholerae and and V. parahaemolyticusV. parahaemolyticus are pathogens are pathogens

of of humans.humans.

ClassificationClassification

Vibrio choleraVibrio cholera

Cholera

▲ one of the most serious infectious diseases.

▲ also an infectious disease that international quarantine （国 际检疫） .

▲ It is in the second place of the most serious infectious

deseases in the Communicable Disease Prevention Law of

China. So it is also called the No.2 disease in China.

HistoryHistory

▲▲ 1817-1823:1817-1823: First PandemicFirst Pandemic

▲▲ 1829-1850:1829-1850: Second PandemicSecond Pandemic

▲▲ 1852-1860:1852-1860: Third Pandemic Third Pandemic * Pacini* Pacini

▲▲ 1863-1879:1863-1879: Fourth PandemicFourth Pandemic

▲▲ 1881-1896:1881-1896: Fifth Pandemic Fifth Pandemic * Koch* Koch

▲▲ 1899-1923:1899-1923: Sixth PandemicSixth Pandemic

▲▲ 1961-?:1961-?: Seventh PandemicSeventh Pandemic

▲▲ 1992-?:1992-?: Eighth PandemicEighth Pandemic

■ ■ Origins in India, cases reported as early as 1563Origins in India, cases reported as early as 1563

■ ■ About 8 pandemics(About 8 pandemics( 流行病 )to dateto date

Causative Agent DiscoveryCausative Agent Discovery

■ ■ John Snow (1813-1858):John Snow (1813-1858):

■ ■ Water borne transmission Water borne transmission

of Cholera (1855)of Cholera (1855)

DiscoveryDiscovery■ ■ Filippo Pacini (1812-1883)Filippo Pacini (1812-1883)

□ □ 1854: Cholera reaches Florence, 1854: Cholera reaches Florence,

Italy. Pacini discovers causative Italy. Pacini discovers causative

agent.agent.

□ □ Publishes “Microscopical Publishes “Microscopical

Observations and Pathological Observations and Pathological

Deductions on Cholera”Deductions on Cholera”

□ □ 1965: Bacterium named 1965: Bacterium named Vibrio Vibrio

cholerae cholerae Pacini 1854Pacini 1854

■ ■ Robert Koch (1843-1910)Robert Koch (1843-1910)

■ ■ 1884: Rediscovers 1884: Rediscovers Vibrio choleraeVibrio cholerae

DiscoveryDiscovery

History and spread of epidemic choleraHistory and spread of epidemic cholera

※ ※ classic biotypes/classic biotypes/ from 1817 to the early 20th/six global waves from 1817 to the early 20th/six global waves

※ ※ "El Tor" biotype"El Tor" biotype / In 1961 / Philippines /seventh / In 1961 / Philippines /seventh

global/hemolysins global/hemolysins

※ ※ O139 "Bengal" O139 "Bengal" /In 1992/Bangladesh /at least 11 countries in /In 1992/Bangladesh /at least 11 countries in

southern Asiasouthern Asia

Vibrio choleraeVibrio cholerae

▲ ▲ Antigenic structureAntigenic structure

※ ※ Common heat-labile flagellar H antigenCommon heat-labile flagellar H antigen

※ ※ O lipopolysaccharide : O lipopolysaccharide : serologic specificityserologic specificity

△ △ More than 150 O antigen serogroupsMore than 150 O antigen serogroups

△ △ Only O1 and Only O1 and OO139 serogroups cause Asiatic 139 serogroups cause Asiatic

[ˌeɪʃi'ætɪk][ˌeɪʃi'ætɪk] choleracholera

■ Three serotypes: Ogawa ■ Three serotypes: Ogawa 小川型 , Inaba, Inaba 稻叶型 , ,

HikojimaHikojima 彦岛型

■ ■ Two biovars : classic and El Tor Two biovars : classic and El Tor

Antigenic structure

Ag

O antigen

H antigen ——non-specificity

O1 serogroupsserogroups

Non-O1 serogroupsserogroups ： O2 ~O155 serogroupsserogroups

El Tor biovarsbiovars

classicclassic biovarsbiovars

The identification of classic biovar andand El Tor El Tor biovar

characteristics Classic biovarClassic biovar El TorEl Tor biovarbiovar

V-P test －－ ＋＋ (( －－ ))

Sheep RBC hemolysis test －－ ＋＋ (( －－ ))

Chicken erythrocyte agglutination test －－ (( ＋＋ ) ) ＋＋

Polymyxin B （多粘菌素B ） susceptibility test

SensitiveSensitive Insensitive

Group phage lysis testⅣ ＋＋ －－ (( ＋＋ ))

小川型

稻叶型

彦岛型

小川型

稻叶型

彦岛型

O1 serogroups serogroups V. choleraeV. cholerae

Vibrio choleraeVibrio cholerae

※ ※ PathogenesisPathogenesis

▲ ▲ Ingest 10Ingest 1088-10-101010 organisms organisms

▲ ▲ Non invasive infection of small intestineNon invasive infection of small intestine

▲ ▲ Organisms secrete enterotoxinOrganisms secrete enterotoxin

▲ ▲ Watery diarrhea and vomitingWatery diarrhea and vomiting

Pathogenesis

1. cholera toxin: coded by ctxA and ctxB gene in Prophage

2. flagella and pili

3. other toxic factors ： such as Hly A(hemolytic-cytolytic A),

hap (hemagglutinin/protease), capsule and Special LPS

toxicity epitopes in O139 serogroups.

4. Enzymes: such as IgA1 Protease, mucinase ['mjuːsɪneɪs] 粘

蛋白酶

Major pathogenic substances

Virulence factors of Virulence factors of V.choleraeV.cholerae O1 and O139 O1 and O139

Virulence factorVirulence factor Biological effectBiological effect

Cholera toxinCholera toxin Hypersecretic of electrolytes and waterHypersecretic of electrolytes and water

Coregulated pilusCoregulated pilus Adherence to mucosal cells adhesinAdherence to mucosal cells adhesin

Accessory colonization factorAccessory colonization factor adhesinadhesin

Hemagglutination proteaseHemagglutination protease Releases bacteria from mucosal cellsReleases bacteria from mucosal cells

Zona occludens Zona occludens （（闭锁小

带）） Exotoxin Exotoxin

Accessory cholera enterotoxinAccessory cholera enterotoxin Exotoxin Exotoxin

Flagellum Flagellum Motility Motility

Siderophores Siderophores （（铁载体）） Iron sequestration Iron sequestration （（螯合作

用））

PathogenesisCholera ToxinCholera Toxin

Cholera toxin activates the Cholera toxin activates the

adenylate [ə'denɪleɪt]adenylate [ə'denɪleɪt]

cyclasecyclase

in cells of the intestinal in cells of the intestinal

mucosa leading to mucosa leading to

increased increased levels of levels of

intracellular intracellular cAMPcAMP, and , and

the secretion of Hthe secretion of H220, 0,

NaNa+sodium+sodium, K, K++, Cl, Cl-chlorine-chlorine, and , and

HCOHCO33-- into the lumen of the into the lumen of the

small intestinesmall intestine

The toxin has been The toxin has been

characterized and contains characterized and contains 5 5

binding (B) subunitsbinding (B) subunits of of

11,500 daltons, an 11,500 daltons, an active active

(A1) subunit(A1) subunit of 23,500 daltons, of 23,500 daltons,

and and a bridging piece (A2)a bridging piece (A2) of of

5,500 daltons that links A1 5,500 daltons that links A1

to the 5B subunits.to the 5B subunits.

★ ★ Cholera toxinCholera toxin

▲ ▲ Enterotoxin-cholera toxin-CtxABEnterotoxin-cholera toxin-CtxAB

△ △ Encoded by a prophageEncoded by a prophage

△ △ Molecular mass of 84,000 daltonsMolecular mass of 84,000 daltons

△ △ A subunit: ADP-ribosylating toxinA subunit: ADP-ribosylating toxin

△ △ B subunit:bind GM1-gangliosides on enterocytesB subunit:bind GM1-gangliosides on enterocytes

△ △ A subunit ADP ribosylates Gs-alpha which regulates A subunit ADP ribosylates Gs-alpha which regulates

activation of adenlyate cyclaseactivation of adenlyate cyclase

△ △ Result is persistent increase in cAMP levelsResult is persistent increase in cAMP levels

△ △ Hyper secretion of NaHyper secretion of Na ＋＋ , Cl, Cl －－ , K, K ＋＋ , bicarbonate and , bicarbonate and

HH2200

Pathogenesis

PathogenesisColonizationColonization

Determinants of the colonization :Determinants of the colonization :

※※ adhesinsadhesins: fimbriae Tcp pili, : fimbriae Tcp pili,

hemagglutinin ,hemagglutinin ,

acf (accessory colonization acf (accessory colonization

factor) , and so on. factor) , and so on.

※※ motilitymotility: polar flagella: polar flagella

※ ※ LPS and capsuleLPS and capsule

※ ※ EmzymesEmzymes

Vibrio choleraeVibrio cholerae--Clinical manifestationsClinical manifestations

▲ ▲ Asymptomatic colonization to fatal diarrheaAsymptomatic colonization to fatal diarrhea

▲ ▲ Onset 2-3 days after ingestionOnset 2-3 days after ingestion

▲ ▲ Abrupt onset of watery diarrhea and vomitingAbrupt onset of watery diarrhea and vomiting

▲ ▲ Rice water stoolsRice water stools

▲ ▲ Severe fluid and electrolyte loss-dehydration, metabolic Severe fluid and electrolyte loss-dehydration, metabolic

acidosis [ˌæsɪ'doʊsɪs]acidosis [ˌæsɪ'doʊsɪs] （（酸中毒 ), hypovolemic , hypovolemic

[haɪpɒ'vəʊlemɪk]shock([haɪpɒ'vəʊlemɪk]shock( 血容量减少性休克） , renal , renal

failurefailure

▲ ▲ Death 60% if untreated, 1% if treated for fluid lossDeath 60% if untreated, 1% if treated for fluid loss

Clinical Manifestations

"rice-water stool"

Immunity to CholeraImmunity to Cholera

※ ※ Secretory IgA, as well as IgG and IgM in serum exudate, Secretory IgA, as well as IgG and IgM in serum exudate,

can be detected in the intestinal mucosa of immune can be detected in the intestinal mucosa of immune

individuals. individuals.

※ ※ Vibriocidal antibodies reach a peak 8-10 days after the Vibriocidal antibodies reach a peak 8-10 days after the

onset of clinical illness, and then decrease, returning to onset of clinical illness, and then decrease, returning to

the baseline 2 - 7 months later.the baseline 2 - 7 months later.

Bacteriological DiagnosisBacteriological Diagnosis

■ ■ Specimens: stool, vomitus.Specimens: stool, vomitus.

■ ■ MethodsMethods

□ □ hanging drop testhanging drop test

□ □ Stained smearStained smear

□ □ Culture: alkaline peptone water or alkaline peptoneCulture: alkaline peptone water or alkaline peptone

agar plate, and thiosulfate [ˌθaɪoʊ'sʌlfeɪt]agar plate, and thiosulfate [ˌθaɪoʊ'sʌlfeɪt] –citrate––citrate–

bile-salts (TCBS) agar plate.bile-salts (TCBS) agar plate.

□ □ Quick immunological methods: Quick immunological methods:

immunofluorescent “ball” test; PCR, etc.immunofluorescent “ball” test; PCR, etc.

※ ※ Rapid intravenous fluid and electrolyteRapid intravenous fluid and electrolyte replacement replacement

※ ※ Most antibiotics and chemotherapeutic agents have Most antibiotics and chemotherapeutic agents have

no value in cholera therapy.no value in cholera therapy.

TreatmentTreatment

Prevention & ControlPrevention & Control■ ■ ImmunizationImmunization

▲ ▲ Active Immunity induced by:Active Immunity induced by:

△ △ A parenteral [pə'rentərəl]A parenteral [pə'rentərəl] 肠胃外的肠胃外的 vaccine of whole vaccine of whole

killed bacteria has been used widelykilled bacteria has been used widely

△ △ attenuated attenuated V. choleraeV. cholerae

△ △ Toxoid (not good antigen)Toxoid (not good antigen)

■ ■ Preventing contamination of food and water e.g. boiling Preventing contamination of food and water e.g. boiling

water, covering foodwater, covering food

■ ■ Strengthen health educationStrengthen health education ：： Personal and domestic Personal and domestic

hygienehygiene

■ ■ Prevention of contamination of water suppliesPrevention of contamination of water supplies

▲ ▲ Improvement of sewage systemsImprovement of sewage systems

■■ Antibiotic prophylaxisAntibiotic prophylaxis

Exercises:

1. Please briefly describe the mechanism of cholera toxin