Gastrointestinal infections - bacteriology

975
-1

Published on

This is a series of lectures on microbiology, useful for both undergraduate and post graduate medical and paramedical students... This lecture covers cholera, typhoid, diarrhoea and dysentry

Published in: Health & Medicine, Technology
0 Comments
2 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
975
On Slideshare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
96
Comments
0
Likes
2
Embeds 0
No embeds

No notes for slide
  • Age; EPEC and rotovirus tend you affect young children
    Hygiene: fecooral
    Acidity: protective barrier, low inoculm
    Motility: expel the pathogens. Antimotility assoc with prolonged fever shedding shigella, complication c diff, HUS in ETEC
    Flora: ex cdiff
  • Gastrointestinal infections - bacteriology

    1. 1. Gastrointestinal Infections Dr. Ashish V. Jawarkar, MD (Path)
    2. 2. Overview • Most infections of the g.i.t. are acquired through contaminated food – food poisoning • Food infection – − Bacteria like - Cholera, E. coli, Salmonella, shigella, − viruses like enterovirus, rotavirus, hepatitis A and E − Parasites like G. lamblia • Food intoxication – S. aureus, B. cereus, Cl. Perfringens, Cl. botulinum
    3. 3. Symptoms • Abdominal pain • Diarrhoea • Vomitting • Fever
    4. 4. Factors responsible for spread • Age – children more susceptible • Personal hygiene • Open air defecation • Food at road side stalls • Uncovered food
    5. 5. Vibrio Cholerae • Vibrio – vibrate – vibratory motility • Present in surface waters worldwide
    6. 6. • Morphology • Growth characteristics • Biochemical reactions • Resistance • Pathogenicity and virulence • Epidemiology • Diseases caused • Laboratory diagnosis • Treatment
    7. 7. Morphology • Short, curved comma shaped bacillus • Single polar flagella • Gram negative
    8. 8. • Morphology • Growth characteristics • Biochemical reactions • Resistance • Pathogenicity and virulence • Epidemiology • Diseases caused • Laboratory diagnosis • Treatment
    9. 9. Growth characteristics • Aerobic • Colorless colonies on mac conkey • Special media − Transport media − Enrichment media − Plating media
    10. 10. Transport media • VR medium (Venkatraman, ramkrishnan) • Cary blair medium
    11. 11. Enrichment media • Alkaline peptone water • Monsur’s taurocholate tellurite peptone water
    12. 12. Plating media • TCBS medium – thiosulfate, citrate, bile salts and sucrose
    13. 13. String test • Loopful of colonies mixed with drop of sodium deoxycholate in saline
    14. 14. • Morphology • Growth characteristics • Biochemical reactions • Resistance • Pathogenicity and virulence • Epidemiology • Diseases caused • Laboratory diagnosis • Treatment
    15. 15. Biochemical reactions • Cholera red reaction − Ferments glucose, mannitol, maltose, mannose and sucrose − Produces indole which gives red color
    16. 16. • Morphology • Growth characteristics • Biochemical reactions • Resistance • Pathogenicity and virulence • Epidemiology • Diseases caused • Laboratory diagnosis • Treatment
    17. 17. Resistance • Resistant to cold – refrigerated food may carry vibrio • Donot survive at room temperature / heating • Susceptible to common drugs like doxycycline
    18. 18. • Morphology • Growth characteristics • Biochemical reactions • Resistance • Pathogenicity and virulence • Epidemiology • Diseases caused • Laboratory diagnosis • Treatment
    19. 19. Cholera • Acute diarrhoeal illness • Painless ‘rice water’ stools • Copius vomitting • Fluid loss and dehydration
    20. 20. • Due to two toxins released by bacteria in intestine • Toxin A and B • Cause pouring of water from body into intestines • Extensive water depletion
    21. 21. • Morphology • Growth characteristics • Biochemical reactions • Resistance • Pathogenicity and virulence • Epidemiology • Laboratory diagnosis • Treatment
    22. 22. Epidemiology • Source – infected humans • Mode of transmission – contaminated water/food • Cholera spreads as sporadic/epidemic or pandemic forms • Large movement of people such as during fairs/festivals is associated with cholera spread
    23. 23. Sporadic • Short duration infection limited to a small area
    24. 24. Epidemic • Suddenly many cases are seen over a large area
    25. 25. Pandemic • Cases seen over a long period of time over continents • Till 19th century, cholera was mainly confined to India – mainly area of Ganga plains – Bengal • Total seven pandemics have been identified.
    26. 26. Seventh pandemic
    27. 27. • Morphology • Growth characteristics • Biochemical reactions • Resistance • Pathogenicity and virulence • Epidemiology • Laboratory diagnosis • Treatment
    28. 28. Lab diagnosis • Sample – stool – before administering antibiotics • Use transport medium • Dark field microscopy can be done for darting motility
    29. 29. • Plated on TCBS medium • Slide agglutination test • String test
    30. 30. • Morphology • Growth characteristics • Biochemical reactions • Resistance • Pathogenicity and virulence • Epidemiology • Laboratory diagnosis • Treatment
    31. 31. Treatment • More important is replacement of lost fluid • Antibiotics are of secondary importance • Doxycycline
    32. 32. Enterobacteria • Flora of large intestine • Classified on basis of growth on Mac Conkey’s medium − Lactose fermenters – E. coli, Klebsiella − Late lactose fermenters – shigella − Non lactose fermenters - Salmonella
    33. 33. Diarrhoea causing E. Coli ETEC Toxin causes release of water into intestinal lumen Watery diarrhoea EIEC Invade intestinal wall Dysentry Entero invasive E Coli Blood and mucous in stools EHEC Does not invade Bloody diarrhoea Entero hemorrhagic Toxin release Colitis Entero toxicogenic E Coli EPEC Entero pathogenic Infant watery diarrhoea
    34. 34. Gram negative rods
    35. 35. • E coli cause − − − − UTI Diarrhoea Pyogenic infections Septicemia • Spread – feco oral route
    36. 36. Salmonella – Enteric Fever - Typhoid • Also causes gastroenteritis • Motile gram negative rods • Peritrichous flagella
    37. 37. Salmonella – Enteric Fever - Typhoid • Also causes gastroenteritis • Motile gram negative rods • Peritrichous flagella
    38. 38. Growth characteristics • Colorless colonies on Mac conkey – Non lactose fermenters • Jet black colonies on Wilson and Blair due to production of H2S
    39. 39. Growth characteristics • Enrichment media − Selenite F broth − Tetrathionate broth
    40. 40. Diseases caused • Enteric fever • Gastroenteritis • Septicemia
    41. 41. Enteric Fever (Typhoid) • Pathogenesis
    42. 42. Clinical course • Gradual onset with fever, abdominal pain and constipation/diarrhoea • Step ladder fever with bradycardia • Spleen and liver are enarged • Rose spots on skin in second week
    43. 43. Complications • Intestinal perforation • Hemorrhage • Shock • Cholecystitis • Osteomyelitis
    44. 44. Epidemiology • Source – food handlers/cooks − Carriers – • Convalescent carriers – shed bacilli for 3 weeks to 3 months after cure • Chronic carriers – more than 3 months after clinical cure
    45. 45. Typhoid Mary • New york cook – infected more than 200 persons – caused atleast 7 outbreaks
    46. 46. Lab diagnosis • Cases – Widal test, blood culture • Carriers – isolation from bile
    47. 47. Widal test
    48. 48. Blood culture / Bile culture • Take 45ml patient blood in bile broth • Send to lab • Cultured on Mac Conkey • Lactose non fermenting colonies
    49. 49. Treatment • Chloramphenicol • Ampicillin • Co trimoxazole
    50. 50. Prophylaxis • Best is improved sanitation • Live oral vaccine – typhoral • Injectable vaccine – typhim vi • Protection lasts 3 years, booster required afterwards
    51. 51. Shigella – BACILLARY DYSENTRY • DYSENTRY – bacillary (shigella) and amebic (parasitic) • Also caused by EIEC, Campylobacter
    52. 52. • Gram negative rods • Lactose non fermenters on Mac conkey • Classified according to mannitol fermentation − Sh dysenteriae – mannitol non fermenter − Sh flexneri, sh bodydii and sh sonnei – mannitol fermeters
    53. 53. Bacillary dysentry • Bacilli infect intestinal epithelial cells • Spread to submucosa • Inflammatory reaction with capillary thrombosis • Sloughing and necrosis of mucosa • Ulcers
    1. A particular slide catching your eye?

      Clipping is a handy way to collect important slides you want to go back to later.

    ×