Bacillus Bacillus

SaprophyticSaprophytic

B.cereus B.cereus

B.subtilisB.subtilis

B.megateriumB.megaterium

B.CirculansB.Circulans

PathogenicPathogenic

B.anthracisB.anthracis

B.anthracisB.anthracis

It is aerobic G+ve, large ,square-ended It is aerobic G+ve, large ,square-ended (rectangular)bacilli with oval central spores, non (rectangular)bacilli with oval central spores, non motile, capsulated, motile, capsulated, arranged singly or in short arranged singly or in short chains, the organism grows well on blood agar.chains, the organism grows well on blood agar. Hemolysis is uncommon with Hemolysis is uncommon with B.anthracis B.anthracis but but common with saprophytic bacilli. common with saprophytic bacilli. If the colonies If the colonies are looked under microscopic lens. They will are looked under microscopic lens. They will appear as apiece of curled hair. The colony is appear as apiece of curled hair. The colony is composed of continuous chain of bacilli. The composed of continuous chain of bacilli. The colony is described as "Medusa- headcolony is described as "Medusa- head", this ", this character is useful for DX & identification of the character is useful for DX & identification of the colony. By G.stain, some spores will be seen in colony. By G.stain, some spores will be seen in between the vegetative cells and these spores between the vegetative cells and these spores appear as empty spaces with out stain. The appear as empty spaces with out stain. The spores usually resist boiling & some chemicals & spores usually resist boiling & some chemicals & dry heat of 140Cdry heat of 140Cْْ but they are destroyed by but they are destroyed by autoclaving (moist heat) for 15 minautoclaving (moist heat) for 15 min..

Biochemical reactionBiochemical reaction

Glucose , sucorose & maltose are Glucose , sucorose & maltose are fermented with production of acid fermented with production of acid only. The bacilli are catalase+ve only. The bacilli are catalase+ve and reduce nitrates to nitritesand reduce nitrates to nitrites..

AntigensAntigens

C.W AgC.W AgCapsular AgCapsular Ag..

Somatic AgSomatic Ag

Types of anthraxTypes of anthraxThere are three clinical types of There are three clinical types of

anthrax based on the route of anthrax based on the route of infectioninfection

11--Skin or coetaneous anthrax Skin or coetaneous anthrax (Malignant pustule)(Malignant pustule)

22 - -Respiratory or pulmonary anthrax Respiratory or pulmonary anthrax (wool sorters' disease)(wool sorters' disease)

33 - -Intestinal anthrax (rare) in primitive Intestinal anthrax (rare) in primitive or poor society. Eat meat of infectedor poor society. Eat meat of infected

animalsanimals

PathogenesisPathogenesisAnthrax is a zoonosis. The portal of entry is the Anthrax is a zoonosis. The portal of entry is the

respiratory tract, a cut in skin or the mouth when respiratory tract, a cut in skin or the mouth when spores enter the human body, spores enter the human body, they lodge in one they lodge in one place & starts to germinate they will produce place & starts to germinate they will produce toxins & enzymes till hemorrhage & oedema are toxins & enzymes till hemorrhage & oedema are producedproduced. .

In susceptible persons, the bacilli resist Φ & In susceptible persons, the bacilli resist Φ & spread to lymphatic to the blood where they spread to lymphatic to the blood where they multiply freely in blood & tissues. multiply freely in blood & tissues. While in While in resistant people, there is more leukocyte response resistant people, there is more leukocyte response with Φ and decapsulation of the microorganismswith Φ and decapsulation of the microorganisms..

Once the organism looses its capsule, it will die Once the organism looses its capsule, it will die easily because it looses its virulenceeasily because it looses its virulence..

Clinical findingsClinical findings Skin anthrax: a papule first develops within 12-Skin anthrax: a papule first develops within 12-

36 hrs after entry of the organisms or spores 36 hrs after entry of the organisms or spores through a scratch. This papule rapidly changes through a scratch. This papule rapidly changes into a vesicle, then a pustule, and finally a into a vesicle, then a pustule, and finally a necrotic ulcer from which the infection may necrotic ulcer from which the infection may disseminate. Giving rise to septicemiadisseminate. Giving rise to septicemia..

Respiratory anthrax:: In inhalation anthrax , Respiratory anthrax:: In inhalation anthrax , early manifestations may be mediastinitis, early manifestations may be mediastinitis, sepsis, meningitis, or hemorrhagic pulmonary sepsis, meningitis, or hemorrhagic pulmonary edema. Hemorrhagic pneumonia with shock is edema. Hemorrhagic pneumonia with shock is a terminala terminal event event..

Intestinal anthrax:: Ingestion of spores cause Intestinal anthrax:: Ingestion of spores cause severe enteritis accompanied by bloody severe enteritis accompanied by bloody diarrhea with high fatalitydiarrhea with high fatality..

Hence, all types of anthrax, if not treated in Hence, all types of anthrax, if not treated in time, progress to septicemia and death occurs time, progress to septicemia and death occurs from overwhelming infectionfrom overwhelming infection..

Lab DXLab DXSpecimens: Pus, Blood, swabs, fluid, Specimens: Pus, Blood, swabs, fluid,

sputumsputumSmearSmear

CultureCulture::11--Medusa headMedusa head

22--fir tree appearancefir tree appearance33--curled haircurled hair

Animal inoculationAnimal inoculationSerodiagnosisSerodiagnosis

TreatmentTreatment

B.anthracisB.anthracis Pencillin, ciprofloxacin, Pencillin, ciprofloxacin,

erythromycin, tetracyclineerythromycin, tetracyclineOther Bacillus sppOther Bacillus spp : :

Vancomycin, ciprofloxacinVancomycin, ciprofloxacin