Spore forming bacteria - bacillus and clostridia

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This is a series of lectures on microbiology, useful for undergraduate medical and paramedical students

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Spore forming bacteria - bacillus and clostridia

  1. 1. Spore forming bacteria Dr. Ashish Jawarkar M.D.
  2. 2. Types • Aerobic – Bacillus • Anaerobic – clostridia Bacillus – two major species B. Anthracis – causes Anthrax B. Cereus – food poisoning
  3. 3. B. Anthracis • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
  4. 4. Morphology • • • • Gram positive bacilli in chains Bacilli have characteristic squared ends Bamboo stick appearance Entire chain surrounded by polypeptide capsule • Spores donot stain by ordinary stain • They are central – donot cause bulging
  5. 5. Mc fadyean’s reaction • Amorphous purplish material around bacilli • Represent capsular material
  6. 6. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
  7. 7. Growth charcteristics • Aerobe • On culture – raised, dull opaque, grayish white colonies – frosted glass appearance • Edge of colony is composed of interlacing chains of bacilli looking like matted hair – medusa head appearance • When grown with Penicillin added – the cells become large, spherical and look like string of pearls
  8. 8. Frosted glass
  9. 9. Medusa head
  10. 10. String of pearls
  11. 11. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
  12. 12. Resistance • Bacilli stay in bone marrow and skin of dead animals for about a week • Normal heat fixation may not kill bacteria in blood smears
  13. 13. • Spores are highly resistant to chemical and physical agents • Found in soil after 60 years • Resistant to dry heat at 140 deg for 3 hours • Resistant to boiling for 10 min • They survive in 5% phenol for weeks
  14. 14. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
  15. 15. Pathogenicity and virulence • Capsule – helps to escape phagocytosis • Toxin – leads to anthrax
  16. 16. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
  17. 17. Epidemiology • Seen in animal handlers – those who carry skin/hides on back • Hide porter disease
  18. 18. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
  19. 19. Anthrax • Agent for bioterrorism
  20. 20. • Active outbreak in India – in sheep – near Tamilnadu-Andhrapradesh border • Causes cutaneous infections and meningitis
  21. 21. Anthrax • Usually an occupational disease – contact with infected animals • Types – cutaneous, pulmonary, intestinal
  22. 22. Cutaneous anthrax
  23. 23. • Lesion called malignant pustule • Central area is black due to necrosis – eschar • Resolves spontaneously
  24. 24. Pulmonary anthrax • Hemmorhagic pneumonia • Hemmorhagic meningitis • Seen in people engaged in sorting wool – wool sorters disease
  25. 25. Intestinal anthrax • Seen in communities that eat dead animals • Bloody diarrhoea
  26. 26. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
  27. 27. Lab diagnosis • Sample – Skin – biopsy/materia – Sputum – Stool • Gram stain • Culture • Special test – direct fluoroscent antibody test • PCR
  28. 28. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
  29. 29. B. Cereus • Cause of food poisoning • Found in milk, cereals, spices, meat and poultry • Two types of food poisoning – Acute – chinese fried rice – vomitting in 1-5 hrs after meal – Chronic – After 8 hrs of ingestion • Illnesses are mild – require no treatment
  30. 30. Clostridia • Gram positive, spore forming • Anaerobic – Cl – Cl – Cl – Cl perfringens – gas gangrene tetani – tetanus botulinum – food poisoning difficile – acute colitis
  31. 31. • Clostridia – kloster - spindle
  32. 32. Gas gangrene • Caused by Cl perfringens type A • It is a rapidy spreading necrosis of muscles • Usually seen after extensive muscle damage (contaminated) secondary to trauma – road accidents, battle field injury
  33. 33. Clinical features • Increasing pain, edema and tenderness of the affected limb • Accumulation of gas
  34. 34. Lab diagnosis • Sample – muscle fragments or necrotic debris • Plated on appropriate culture media
  35. 35. Tetanus • Characterised by tonic muscular spasms, commencing at site and slowly becoming generalised • Disease follows injury too trivial to be noticed • Due to tetanospasmin toxin produced by Cl tetani
  36. 36. Different forms of tetanus • Generalized tetanus
  37. 37. Local tetanus
  38. 38. Cephalic tetanus • After a head injury or local infection • Trismus – lock jaw
  39. 39. Neonatal tetanus • Infection follows unhygeinic practices after delivery • Applying cowdung on umbilical stump
  40. 40. • Diagnosis is clinical – by the time symptoms appear, organism is no longer present in lesion
  41. 41. Treatment • Human tetanus immunoglobulin – can neutralize toxin
  42. 42. Prevention • DPT vaccine
  43. 43. Cl botulinum • Produces neurotoxin • Causes paralysis • Used in treating wrinkles
  44. 44. types • Food borne botulism – eating food with pre formed toxin – After 12 hrs of taking food – Vomitting, constipation, difficulty in swallowing, speaking, breathing – Respiratory failure • Wound botulism – No gi manifestations • Infant botulism – Infants below 6 months – Honey is an agent – Poor feeding, pooling of oral secretions, loss of head control
  45. 45. Cl difficile • Antibiotic associated diarrhoea (clindamycin) • Disrupts normal flora • Psuedo membranous colitis
  46. 46. Pseudomembranous colitis
  47. 47. Pseudomonas
  48. 48. P. aeruginosa • Pseudo – false • Monas – mono – single unit • Slender gram negative bacillus with polar flagellum
  49. 49. • Produces bluish green pigment – pyocyanin on culture
  50. 50. • Very resistant to common antiseptics and disinfectants like dettol • Susceptible to glutaraldehyde and phenols
  51. 51. • Most common infection – otitis media • In hospitals – wound infection, bed sores, UTI following catheterisation • Seen in equipments such as respirators, endoscopes, bed pans, lotions, eye drops

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