BACILLUS ANTHRAX A overview of SlideShare

A overview of bacillus anthrax morphology cultural characteristics pathogenesis with simple form

1. VIVEKANANDHA ARTS AND SCIENCE COLLEGE FOR WOMEN VEERCHIPALYAM-637303,SANKAGIRI,SALEM Dt.,TAMILNADU,INDIA. AFFILIATED TO PERIYAR UNIVERSITY,SALEM;RECOGNISED UNDER SECTION 2(F)&12(B) OF THE UGC ACT 1956) SUBJECT INCHARGE; Dr.R.MYTHILI, HEAD OF THE DEPARTMENT Assistant professor, Department of Microbiology, VIAAS,Sankagiri. DEPARTMENT OF MICROBIOLOGY SUBJECT : MEDICAL BACTERIOLOGY SUBMITTED BY; JEEVANI RAJU, III B.SC.MICROBIOLOGY, DEPARTMENT OF MICROBIOLGY, VIAAS,Sankagiri. TITLE : BACILLUS ANTHRAX

2. GENERAL CHARACTERS: They are rod shaped,sporogenous classified into two groups : 1) Aerobic bacillus 2) Anaerobic clostridia Aerobic bacilli are gram-positive,non-motile,spore bearing bacilli occurring in chains. They are thick with truncated or convex ends. They include psychrophilic,mesophilic and thermophilic species. The salt tolerance varies from less than 2 to 25 percent of NaCl. Bacillus anthrax is the only pathogenic species causing anthrax.

3. History; First pathogenic bacterium to be seen under microscope-pollender,1849 First communicable disease shown to be transmitted by inoculation of infected blood-davaine,1850 First bacillus to be isolated in pure culture and shown to possess spores-koch,1876 First used for the preparation of an attenuated vaccine-pasteur,1881

4. Bacillus anthrax It remains in parasitic from in cattle and sheep. Infection in man is the result of accidently contact with infected animal.

5. morphology Its non-motile, non-acid fast,gram positive measuring 1×3 to 4 µ. They may be arranged singly or in short chains. The entire chain may be surrounded by capsule. Capsule is polypeptide in nature (D-Glutamic acid). Capsule production depends upon a 60 megadalton plasmid,p×O2.

6. In culture bacilli are arranged end to end in chains. The chain of bacilli presents bamboo stick appearance. Spores are formed in soil only in presence of oxygen and not in animal body. Sporulation may be brought about by; 1) distilled water. 2) 2 % of NaCl. 3) growth on oxalated agar shows spores which are central , oval and of the same width as the bacillary boy.

7. b.Anthrax on media;

8. Cultural characters; Its aerobic growing at optimum temperature of 37°c ( range being 12ºc to 45ºc).the optimum for spore formation is 25ºc to 30ºc. Growth may occur on ordinary media, a) Nutrient broth: there may be floccular turibidity or no turbidity. b) Agar plate : colony is irregular ,around 2 to 3mm in diameter,raised,dull opaque,greyish white with a frosted glass appearance and cut glass appearance ( in transmitted light). Virulent capsulated strain forms rough colonies whereas a virulent forms smooth colonies .

9. Blood agar : The colony is non-hemolytic. Gelatin stab: A characteristics “inverted tree” appearance is seen with slow liquefication starting from the top. Selective media (PLET)

10. Glucose ,maltose and sucrose are fermented with acid production only. Nitrates are reduced to nitrite, catalase is liquefied. RESISTANCE: Vegetative form is killed within 30 minutes at 56°c. Anthrax spore rema2ins viable for years in dry state. Dry heat at 4o°c requires 3 hours and steam 5 to 0 minutes for sterilization. They survive in 5% of phenol for weeks. They are killed in 4 percent potassium permanganate and destroyed in 2 percent formaldehyde. They are susceptible to penicillin,sulfonamide,erythromycin,streptomycin,tetracycline and chromamophenol.

11. Antigenic structure ; 3 antigens have been recongnized, Capsular antigen is found in virulent strain. It consists of polypeptide of high molecular weight composed of D-Glutamic acid. It is a hapten. Antibodies against this antigen are not protective. Somatic polysaccharides are found as a complex in cell wall. It cross reacts with capsular polysaccharide of type 14 pneumococcus. Antibody to this antigen is not protective . Somatic protein ( protective antigen) is present in edema fluid of anthrax lesion. It is heat labile. Its antibody is protective.

12. Toxin: Bacillus anthrax produces substances having exotoxin like properties. They are: Protective antigen or protein. Edema factor. Lethal factor. The specific toxin is lethal,edema producing and is produced to virulent stain. This toxin seems to have an affinity for cell of reticuloendothelial system.

13. Pathogenicitty: In susceptile animals,the organisms proliferate at the site of entry. The capsules remain intact, and the organisms are surrounded by a large amount of proteinaceous fluid containing few leukocytes from which the rapidly disseminate and reach bloodstream. In resistant animals,the organisms proliferate for a few hours by which time there appears massive accumulation of the leukocytes. The capsule gradually disintegrates and disappears. Thus organisms remain localized.

14. In nature anthrax is primarily is disease of cattle and sheep,less often of horses and swine. Experimentally fatal infection can be produced in mouse,guinea pig ,rabbits,etc.

15. Route of infection:

16. Laboratory diagnosis; Hematological investigation: leukocytosis occur when tissues are invaded otherwise total leukocyte count is within normal limits. Bacteriological investigations: 1)Microscopic examination; smear prepared from exudate, sputum, etc. on gram’s staining shows gram-positive, non –sporing bacilli occuring in chain. 2) Culture; The material is inoculated on nutrient agar plate. Smear shows gram-positive spore bearing bacilli. 3)Animal inoculation; A small amount of exudate or isolated culture from infected subcutaneously in guinea pig. Guinea pig dies within 36 to 48 hours. Smear from heart blood and spleen shows typical gram-positive bacilli.

17. Serological test; It is a precipitation test. Its is used in making rapid diagnosis. The infected tissues are grouped in saline, boiled for 5 minutes and filtered. This tissue extract is layered over anthrax antiserum. Zone of precipitate at the junction of tissue extract and antiserum. zone of precipitate at the junction of tissue extract and antiserum within 5 minutes at room temperature means test is positive . It is called ASCOLIC TEST. McFadyean reaction : when bloods films containing anthrax bacilli are stained with polychrome methylene blue for a seconds and examined under the microscope, amorphous purplish material is seen around bacilli. This represents the capsular material and is characteristics of anthrax bacilli. Polymerase chain reaction: using this technique bacillus anthracis may be confirmed.02

18. treatment Penicillin Erythromycin Antitoxins-in emergency cases ANIMAL VACCINE- 1)Steam vaccine HUMAN VACCINE – 1) Alum precipitated toxoid- 3 doses intramuscularly at intervals of 6 weeks and 6 months booster dose after one year.

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