MEDICAL MICROBIOLOGY LECTURES

2. Sporogenous Bacilli
Aerobic Bacilli
1.Bacillus anthracis
2.Bacillus cereus
3. Anthracoid bacilli
Anaerobic Clostridia
1. Cl.perfringens
2. Cl. tetani
3. Cl.botulinum

3. -First pathogenic bacteria to be observed under microscope
-First bacilli to be isolated in pure culture
-First bacilli in which spores were demonstrated
-First bacterium used for preparation of attenuated vaccine
-First bacterium to be shown cause of disease
-First bacterium that evolved as a potent weapon in bioterrorism

4. Morphology
Cultural characteristics
Biochemical reactions
Resistance
Pathogenicity
Lab diagnosis
Epidemiology
Prophylaxis
Treatment
BIOTERRORISM

5. -One of the largest pathogenic bactera;4-8x1-1.5 mm in size
-Gram +ve, rod shaped, non-motile and non acid-fast
-Bamboo stick appearance of long chains
-Polypeptidal capsule
-Central or sub terminal oval spores

6. -Aerobic ,Facultative anaerobic
-On NA : Colonies are round, grayish white,irregular,raised
with “frosted glass” appearance,2-3 mm in diameter.
Medusa head /Barrister's wig appearance of colonies under
low magnification
-On BA: Non-hemolytic colonies
-Gelatin stab culture: “Inverted fir tree" appearance
-PLET medium: for selective isolation

7. -Glucose, Maltose, Sucrose fermented with ACID production
-Nitrate reduction test
-Gelatin liquefaction test
All positive
-Catalase test
RESISTANCE
-Spores survive for many years(dry state & soil)
-vegetative cells 60 0C x 30 min.
-spores 1000C x 10 min.
-4% FD & KMnO4 kills spores
Duckering: 2% formaldehyde at 30-40 0C for 20 min. disinfects
wool & 0.25% at 60 0C for 6 hrs. for animal hair & bristles.
-Moist heat kills :

8. Virulence factors:
1.Capsular polypeptide – inhibits phagocytosis
2.Anthrax toxin –a complex of 3 fractions:
-Edema factor(OF or Factor I)
whole complex
-Protective antigen factor(PA or Factor II) produces local edema
-Lethal factor(LF or Factor III)
& generalized shock
Edema factor + protective antigen = Edema toxin
Lethal factor + protective antigen = Lethal toxin

10. Clinically three forms of Human anthrax occur
1.Cutaneous anthrax
2.Pulmonary anthrax
3.Intestinal anthrax
Broadly can be classified into
Non Industrial/Agricultural ( Through infected animals):
Cutaneous anthrax
Rarely intestinal anthrax
Industrial Anthrax ( Through animal products):
Mostly through animal products( wools, hair, hides, bones)
Likely to develop Cutaneous and pulmonary anthrax

11. 1.Cutaneous Anthrax(95-99% human anthrax)
•Mainly in professionals( Veterinarian, butcher, Zoo keepers,
persons handling carcasses/hides/hair, loading skin on bare
backs-hide porters disease .
• Spores infect skin- a characteristic gelatinous edema &
congestion develops at the site (Papule- pustule-black
ulcer(eschar) .Later a ring of vesicle containing serous fluid
surrounds eschar termed as Malignant pustule.
•Face ,neck,arms and back are common sites
• 80-90% heal spontaneously ( 2-6wks)
• 10-20% progressive disease – develop fatal septicemia, death

12. Different locations & morphology of lesion in cutaneous anthrax

13. 2.Pulmonar Anthrax- wool sorter's/Ragpicker’s disease:
-Acquired with inhalation of spores(bioterrorism-aerosol)
-Requires very high infective dose(10,000 t0 20,000 spores)
-Inflammatory reaction occurs in trachea, bronchi with
hemorrhagic bronchospasm
-Presents initially with non -specific symptoms but later
with symptoms of severe respiratory infection & severe
respiratory collapse
-Hemorrhagic meningitis sometimes occurs as complication
-Progress to septicemia very rapidly
-Mortality rate is very high

14. 3.Intestinal Anthrax
-Rare in man and is found in primitive communities eating
dead carcasses of infected animal
-Presents with serious severe enteritis, bloody or hemorrhagic
diarrhoea,bloody vomit
-Fatality rate is 25-60% depending upon treatment

16. EPIDEMIOLOGY(INDIA)
-Anthrax is enzootic in India
-An epizootic of anthrax in sheep active AP,TN borders
-Largest live stock population in the world
-Pondicherry ( JIPMER) - 30 human cases reported ( Mostly
Cutaneous, Septicemic or Meningeal)
-Vellore ( CMC)- 49 human cases
-Chittor ( Rajasthan)- 30 human cases
-Tirupati ( Andhrapradesh)- 25 human cases
-Midnapur ( WB)- 22 human cases

17. LABORATORY DIAGNOSIS
A. Hematological investigation-not significant
B.Bacteriological investigation:
Specimen- swabs, pus, pustules, blood ,sputum, feces etc.
1.Microscopy:Gram staining & spore staining
Characteristic Mc’ Fadyean’s reaction
Immunofluorescent microscopy

18. 2.Culture: Suitable culture media for selective isolation
3.Animal inoculation : done in guinea pigs, mice & rabbits.
3.Serology(Ascoli’s thermoprecipitation test)
4.Molecular methods : PCR with specific primers
5.Molecular typing: MLVA & AFLL for epidemiological studies

19. PROPHYLAXIS
Humans protected by preventing disease in animals
-Veterinary supervision
-Trade restrictions
-Proper sterilization & disinfection of animal products
-Deep burial or cremation of carcasses
 Improved industry standards
 Safety practices in laboratories
 Post-exposure antibiotic prophylaxis

20. VACCINATION:
-Active immunization with Pasteur’s anthrax vaccine
-Salvo immune serum in serious toxic cases
-Cell free vaccine in high risk groups
-Inactivated /killed vaccine for veterinarians & Agri-workers
-Sterne vaccine used effectively in livestock's
-Alum precipitated toxoid found safe in professionals
 3 doses given intramuscularly
TREATMENT
Effective antibiotics in humans:
Sulphonamides,ciprofloxacin,penicillin,erythromycin,
Vancomycin,doxycyline,chloramphenicol
FDA -approved ciprofloxacin,doxycycline and penicillin

21. BIOTERRORISM-anthrax as a bioweapon
-Anthrax was used by Scandinavian rebels against Russians
-Operation vegetarian by Royal Air Force against Germany in
1944 ,an anti-livestock operation
-In 1997-accidental release of anthrax spores from biological
weapons complex in Russia infected 94 people ,68 died
-In Oct.2001 anthrax attacks in USA termed Amerithrax(FBI)
22 cases- 11 inhalation(5 deaths),11 cutaneous(no deaths)

22. -Important cause of food poisoning
-Distributed widely in nature(soil, vegetables & foods)
-Non-Capsulated but Motile (few non-motile strains )
-Two patterns of food borne disease are produced:
1.Diarrhoeal type: -caused by serotypes 2,6,8,9,10 & 12
-associated with wide range of foods
-characterized by diarrhea & abdominal pain
2.Emetic type(fried rice syndrome) caused by STs 1,3 & 5
- associated with consumption of cooked rice
- characterized by acute nausea & vomiting
For isolation MYPA medium is used
10,00000 bacilli/gram of stool is significant

23. ANTHRACOIS /PSEUDOANTHRAX
-Saprophytic ,spore-forming, non-pathogenic species
-They are most common laboratory contaminants
(e.g. B.subtilis contaminating blood transfusion bottles
-They are opportunistic & may cause septicemia