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. Spore forming bacteria Dr. Ashish Jawarkar M.D.
- 2. Types • Aerobic – Bacillus • Anaerobic – clostridia Bacillus – two major species B. Anthracis – causes Anthrax B. Cereus – food poisoning
- 3. B. Anthracis • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
- 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
- 6. Mc fadyean’s reaction • Amorphous purplish material around bacilli • Represent capsular material
- 8. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
- 9. 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
- 10. Frosted glass
- 11. Medusa head
- 12. String of pearls
- 13. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
- 14. 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
- 16. • 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
- 17. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
- 18. Pathogenicity and virulence • Capsule – helps to escape phagocytosis • Toxin – leads to anthrax
- 19. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
- 20. Epidemiology • Seen in animal handlers – those who carry skin/hides on back • Hide porter disease
- 21. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
- 22. Anthrax • Agent for bioterrorism
- 24. • Active outbreak in India – in sheep – near Tamilnadu-Andhrapradesh border • Causes cutaneous infections and meningitis
- 25. Anthrax • Usually an occupational disease – contact with infected animals • Types – cutaneous, pulmonary, intestinal
- 28. • Lesion called malignant pustule • Central area is black due to necrosis – eschar • Resolves spontaneously
- 29. Pulmonary anthrax • Hemmorhagic pneumonia • Hemmorhagic meningitis • Seen in people engaged in sorting wool – wool sorters disease
- 31. Intestinal anthrax • Seen in communities that eat dead animals • Bloody diarrhoea
- 32. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
- 33. Lab diagnosis • Sample – Skin – biopsy/materia – Sputum – Stool • Gram stain • Culture • Special test – direct fluoroscent antibody test • PCR
- 34. • • • • • • • • • Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
- 35. 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
- 36. Clostridia • Gram positive, spore forming • Anaerobic – Cl – Cl – Cl – Cl perfringens – gas gangrene tetani – tetanus botulinum – food poisoning difficile – acute colitis
- 37. • Clostridia – kloster - spindle
- 38. 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
- 39. Clinical features • Increasing pain, edema and tenderness of the affected limb • Accumulation of gas
- 41. Lab diagnosis • Sample – muscle fragments or necrotic debris • Plated on appropriate culture media
- 42. 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
- 43. Different forms of tetanus • Generalized tetanus
- 44. Local tetanus
- 45. Cephalic tetanus • After a head injury or local infection • Trismus – lock jaw
- 46. Neonatal tetanus • Infection follows unhygeinic practices after delivery • Applying cowdung on umbilical stump
- 47. • Diagnosis is clinical – by the time symptoms appear, organism is no longer present in lesion
- 48. Treatment • Human tetanus immunoglobulin – can neutralize toxin
- 50. Cl botulinum • Produces neurotoxin • Causes paralysis • Used in treating wrinkles
- 52. 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
- 53. Cl difficile • Antibiotic associated diarrhoea (clindamycin) • Disrupts normal flora • Psuedo membranous colitis
- 55. Pseudomonas
- 56. P. aeruginosa • Pseudo – false • Monas – mono – single unit • Slender gram negative bacillus with polar flagellum
- 58. • Produces bluish green pigment – pyocyanin on culture
- 59. • Very resistant to common antiseptics and disinfectants like dettol • Susceptible to glutaraldehyde and phenols
- 60. • 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