AEROBIC BACILLUSAEROBIC BACILLUS

Lecture (14)Lecture (14)

Dr.Dr. Baha,H,ALBaha,H,AL--AmiediAmiedi

Ph.D.MicrobiologyPh.D.Microbiology

General Characteristics of BacillusGeneral Characteristics of Bacillus

60 species; Gram60 species; Gram--positive or Grampositive or Gram--variablevariablebacillibacilli

Large (0.5 x 1.2 to 2.5 x 10 um)Large (0.5 x 1.2 to 2.5 x 10 um)

Most are saprophytic contaminants or normal floraMost are saprophytic contaminants or normal flora

BACILLUSBACILLUS

BacillusBacillus anthracisanthracisHuman pathogenHuman pathogen

Isolation also considered to be clinically significantIsolation also considered to be clinically significantZoonosisZoonosis

Bacillus cereusBacillus cereusEnvironmental organismEnvironmental organism

Contaminates foodContaminates foodCommon cause of food poisoningCommon cause of food poisoning

BacillusBacillus stearothermophilusstearothermophilusTolerates very high temperaturesTolerates very high temperatures

Used for quality control of autoclavesUsed for quality control of autoclaves

BacillusBacillus anthracisanthracis

BacillusBacillus anthracisanthracis is most important memberis most important member

ProduceProduce endosporesendosporesAerobic orAerobic or facultativelyfacultatively anaerobicanaerobic

CatalaseCatalase positivepositive (most)(most)Rapidly differentiates fromRapidly differentiates from ClostridiumClostridium

BacillusBacillus spp. arespp. are ubiquitousubiquitousC) andC) and°°7575<<((ThermophilicThermophilicSoil, water, and airborneSoil, water, and airborne

C)C)°°88--55(>(>psychrophilicpsychrophilicCan flourish at extremes of acidity & alkalinity (pH 2 to 10)Can flourish at extremes of acidity & alkalinity (pH 2 to 10)

.Bacillus.Bacillus anthracisanthracis

B.B. anthracisanthracis

Diseases Associated with BacillusDiseases Associated with Bacillus

Summary of B.Summary of B. anthracisanthracis InfectionsInfections

Transmission:Transmission:

11--cutaneous anthrax result from contact withcutaneous anthrax result from contact withspores & contact with infected animals &spores & contact with infected animals &animals products.animals products.

22--inhalation anthrax result when spores inhaled.inhalation anthrax result when spores inhaled.

33--Gastrointestinal anthrax result when sporesGastrointestinal anthrax result when sporesare ingested.are ingested.

Virulence factorsVirulence factors

11--A capsule of DA capsule of D--glutamicglutamic acid isacid is antiphagocyticantiphagocyticand helps theand helps the anthracisanthracis to evade the immuneto evade the immunesystem of the host.system of the host.

22--The product ofThe product of exotoxinexotoxin

Mode of toxin actionMode of toxin action

ThreeThree exotoxinsexotoxins subunit are product:subunit are product:

11--protctiveprotctive Antigen(PA):bindsAntigen(PA):binds to toxin receptorto toxin receptoron cell surface of host &facilitates translocationon cell surface of host &facilitates translocationof the two otherof the two other exotoxinsexotoxins,,

22--EdemaEdema Factor(EFFactor(EF): is an): is an adenlyateadenlyate cyclasecyclase thatthatincrease intracellularincrease intracellular cAMPcAMP

StimulatingStimulating effuisioneffuision of fluids &ion that resultof fluids &ion that resultthe edema.the edema.

33--LethalLethal Factor(LF):itFactor(LF):it is ais a mitogenmitogen--activtedactivtedproteinprotein kinasekinase kinase(MAPKKkinase(MAPKK) protease that) protease thatdisrupts signaling causing cell death &tissuedisrupts signaling causing cell death &tissuenecrosisnecrosis

Pathogenesis and clinical presentationsPathogenesis and clinical presentations

CutaneousCutaneous anthraxanthrax

About 20% mortalityAbout 20% mortality

Inhalation anthraxHigh mortality

Gastrointestinal anthraxHigh mortality

Pathogenesis of AnthraxPathogenesis of Anthrax

AnthraxAnthraxCutaneousCutaneousClinical Presentation of AnthraxClinical Presentation of AnthraxAnthraxAnthraxCutaneousCutaneousClinical Presentation of AnthraxClinical Presentation of Anthrax

95% human cases95% human cases areare cutaneouscutaneous infectionsinfections1 to 5 days after contact1 to 5 days after contact

Small,Small, pruriticpruritic, non, non--painful papule at inoculation sitepainful papule at inoculation sitePapule develops into hemorrhagic vesicle & rupturesPapule develops into hemorrhagic vesicle & ruptures

SlowSlow--healinghealing painless ulcerpainless ulcer covered withcovered with blackblackeschareschar surrounded by edemasurrounded by edema

Infection may spread toInfection may spread to lymphaticslymphatics w/ localw/ localadenopathyadenopathy

Septicemia may developSepticemia may develop20% mortality20% mortality inin untreateduntreated cutaneouscutaneous anthraxanthrax

Anthrax:Anthrax: CutaneousCutaneous

Anthrax:Anthrax: CutaneousCutaneous

Anthrax:Anthrax: CutaneousCutaneous

Anthrax:Anthrax: CutaneousCutaneous

Inhalation AnthraxInhalation AnthraxClinical Presentation of AnthraxClinical Presentation of Anthrax

Virtually 100% fatal (pneumonic)Virtually 100% fatal (pneumonic)

Meningitis may complicateMeningitis may complicate cutaneouscutaneous and inhalationand inhalationforms of diseaseforms of disease

Pharyngeal anthraxPharyngeal anthrax

FeverFever

PharyngitisPharyngitis

Neck swellingNeck swelling

Inhalational AnthraxInhalational Anthrax

MediastinalMediastinal Widening and Pleural EffusionWidening and Pleural Effusionon Chest Xon Chest X--Ray in Inhalational AnthraxRay in Inhalational Anthrax

GastrointestinalGastrointestinalClinical Presentation of AnthraxClinical Presentation of Anthrax(Ingestion) Anthrax(Ingestion) Anthrax

Virtually 100% fatalVirtually 100% fatal

Abdominal painAbdominal pain

HemorrhagicHemorrhagic ascitesascites

ParacentesisParacentesis fluid may reveal gramfluid may reveal gram--positive rodspositive rods

Epidemiology of BacillusEpidemiology of Bacillus anthracisanthracis

Enzootic in certain foreign countries (e.g.,Enzootic in certain foreign countries (e.g.,Turkey, Iran,Turkey, Iran, Pakistan,andPakistan,and Sudan)Sudan)

AnthraxAnthrax spores infectious for decadesspores infectious for decades

Epidemiology of Anthrax in Animal andEpidemiology of Anthrax in Animal andHuman HostsHuman Hosts

B.B. anthracisanthracis

..Bacillus cereusBacillus cereus

Pre formed Large, motile, saprophytic HeatPre formed Large, motile, saprophytic Heatresistant sporesresistant spores

heat and acid stable toxin (Emetic syndrome)heat and acid stable toxin (Emetic syndrome)

bacillusbacillus

Heat labileHeat labile enterotoxinenterotoxin ((DiarrhoealDiarrhoeal disease)disease)

Lab diagnosisLab diagnosis –– DemonstationDemonstation of large numberof large numberof bacilli in foodof bacilli in food

GastroenteritisGastroenteritisGastroenteritis

DIARRHOEAL FORMEMETIC FORM

Incubation period < 6 hoursSevere vomitingLasts 8-10 hours

Incubation period > 6 hoursDiarrhoea

Lasts 20-36 hours

::AnthraxAnthrax..BBLaboratory diagnosisLaboratory diagnosis

11--Microscopic ExaminationMicroscopic Examination

Smear prepared from exudates ,sputum showSmear prepared from exudates ,sputum showgram positive bacilli nongram positive bacilli non-- occur in chainoccur in chain

22--Macfadyen test; it is special stain for capsularMacfadyen test; it is special stain for capsularof bacilliof bacilli

33--Seriological test (Ascoli test): it is rapidSeriological test (Ascoli test): it is rapidprecipitate diagnosis test.precipitate diagnosis test.

Ascoli testAscoli test

,the infected,the infectedanthraxanthrax..BBIt is rapid diagnosis ofIt is rapid diagnosis oftissues are grounded in saline boiled for 5tissues are grounded in saline boiled for 5minutes & filtered. extracted tissue is layeredminutes & filtered. extracted tissue is layeredover anthrax antiserum.over anthrax antiserum.

Zone of precipitate at the junction of tissueZone of precipitate at the junction of tissueextract and antiserum within 5 minutes at roomextract and antiserum within 5 minutes at roomtemperature means test is positive.temperature means test is positive.

44--Cultur ;On blood agarCultur ;On blood agar

Large, spreading, grayLarge, spreading, gray--white colonies, with irregularwhite colonies, with irregularmargins (margins (MedosaMedosa head shape)head shape)

Many are betaMany are beta--hemolytic (helpful inhemolytic (helpful in differentiatingdifferentiatingvariousvarious BacillusBacillus species fromspecies from B.B. anthracisanthracis))

Spores seen after several days of incubation in centralSpores seen after several days of incubation in centralby smear gram stain examine,by smear gram stain examine,

55--Animal inoculation: injected guineaAnimal inoculation: injected guineapig subcutaneously which die withinpig subcutaneously which die within3636--4848 hours,smearhours,smear fromfrom

Heart blood &spleen show gramHeart blood &spleen show grampositive bacilli.positive bacilli.

TreatmentTreatment

TreatmentTreatment

Antibiotic suchAntibiotic such ciprofloxinciprofloxin ,,doxcyclinedoxcycline &other are&other areused for treatmentused for treatment