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V. A. Bacterial Diseases

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V. A. Bacterial Diseases

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  1. V. A. Bacterial Diseases A. Airborne Bacterial Diseases B. Foodborne & Waterborne Bacterial Diseases C. Soilborne Bacterial Diseases D. Arthropodborne Bacterial Diseases E. Sexually Transmitted Bacterial Diseases F. Miscellaneous Bacterial Diseases

  2. V. A. Airborne Bacterial Diseases 1. Streptococcal Diseases 2. Diphtheria 3. Pertussis 4. Meningococcal Infections 5. Haemophilus influenzae Infections 6. Tuberculosis 7. Pneumococcal Pneumonia 8. Primary Atypical Pneumonia 9. Legionellosis Back to Main

  3. V. A. 1. Streptococcal Diseases • Properties of the Genus Streptococcus • General Properties • Gram-positive Cocci in Chains or Pairs • Catalase Negative Back to MainBack to Airborne

  4. V. A. 1. Streptococcal Diseases • Properties of the Genus Streptococcus (cont.) • Hemolytic Reactions • Detected by Blood Agar Cultures • Beta Hemolysis • Complete Hemolysis • Clear Zone Around Colonies on Blood Agar • Alpha Hemolysis • Incomplete Hemolysis • Greenish Zone Around Colonies on Blood Agar • Gamma Reaction • Absence of a Hemolytic Reaction • No Change Around Colonies on Blood Agar Back to MainBack to Airborne

  5. V. A. 1. Streptococcal Diseases • Properties of the Genus Streptococcus (cont.) • Lancefield Groups • Based on Serological Groupings Also may be distinguished by Biochemical Testing or Antibiotic Sensitivity • Group A • Streptococcus pyogenes • The most virulent human pathogen of the genus • Beta hemolytic • Often identified by rapid serological testsor by antibiotic resistance Back to MainBack to Airborne

  6. V. A. 1. Streptococcal Diseases • Properties of the Genus Streptococcus (cont.) • Lancefield Groups (cont.) • Group B • Streptococcus agalactiae • Mildly to moderately virulent; esp. in children & elderly • Usually beta or alpha hemolytic; some strains are gamma • Detected biochemically Back to MainBack to Airborne

  7. V. A. 1. Streptococcal Diseases • Properties of the Genus Streptococcus (cont.) • Lancefield Groups (cont.) • Group D • Includes the fecal streptococci (enterococci) • Normal colon flora in humans & other animals • Genus Enterococcus • Several species; eg. Enterococcus faecalis • Occasionally pathogenic; often in urinary tract infections • Usually gamma reactive • Detected biochemically Back to MainBack to Airborne

  8. V. A. 1. Streptococcal Diseases • Diseases Associated with Streptococcus pyogenes • Respiratory Symptoms • Upper Respiratory Tract • Pharyngitis • Systemic Symptoms • Septicemia • Internal infections • Scarlet feverDue to strains that produce an erythrogenic toxin Back to MainBack to Airborne

  9. V. A. 1. Streptococcal Diseases • Diseases Associated with Streptococcus pyogenes(cont.) • Immune-Related Complications • Rheumatic fever • Glomerulonephritis • Other Conditions/Portals of Entry • Erysipelas • Necrotizing fasciitis • Puerperal sepsis Back to MainBack to Airborne

  10. V. A. 2. Diphtheria • Cause: Corynebacterium diphtheriae • Properties of the Genus Corynebacterium • Gram-positive rods; non-sporeforming • Coryneform (diphtheroid) arrangement • “Snapping division” • Metachromatic Granules • Several different species • Frequently found in soil & in the skin flora • Only virulent strains of Corynebacterium diphtheriaeare considered pathogenic Back to MainBack to Airborne

  11. V. A. 2. Diphtheria • Cause: Corynebacterium diphtheriae • Properties of Corynebacterium diphtheriae • Virulent strains contain a extra gene that encodes for the diphtheria exotoxin • The exotoxin is a cytotoxin that inhibits protein synthesis -- kills host cells Back to MainBack to Airborne

  12. V. A. 2. Diphtheria • Transmission & Symptoms • Airborne; contact with infected persons • Upper Respiratory Infection • Pseudomembrane Formation • May Spread into Bloodstream • Cardiovascular damage • Vaccination with diphtheria toxoid vaccine Back to MainBack to Airborne

  13. V. A. 3. Pertussis • Cause: Bordetella pertussis • Gram-negative aerobic rod • Found among the respiratory flora of humans & other animals • Transmission and Symptoms • Airborne contact with infected persons • Upper respiratory tract infection; may be severe in children & elderly • Difficulty breathing; staccato cough (“whooping cough”) • Usually does not spread into bloodstream Back to MainBack to Airborne

  14. V. A. 4. Meningococcal Infections • Cause: Neiserria meningitidis • Properties of the Genus Neiserria • Gram-negative cocci in pairs • Several species;some of which are normal colon flora • Fastidious nutritional requirementsGrow best on chocolate agar • Notable pathogenic species • Neiserria meningitidis • Neiserria gonorrhoeae Back to MainBack to Airborne

  15. V. A. 4. Meningococcal Infections • Transmission & Symptoms • Airborne contact with infected persons • Often associated with children& with persons in close or crowded quarterseg. schools, daycare, etc. • Upper respiratory tract symptoms • Septicemia • Meningitis • Headache and stiff neck • Listlessness; dizziness; disorientation • Seizures; coma; death Back to MainBack to Airborne

  16. V. A. 5. Haemophilus influenzae Infections • Cause: Haemophilus influenzae • Properties of the genus Haemophilus • Gram-negative rod • Facultatively anaerobic • Fastidious -- requires chocolate agarfor growth • Several species; common among the respiratory flora Back to MainBack to Airborne

  17. V. A. 5. Haemophilus influenzae Infections • Cause: Haemophilus influenzae (cont.) • Notable species • Haemophilus influenzae: Several strains; common in the upper respiratory tract. Type b is associated with some cases of bacterial meningitis; type III is sometimes the cause of certain eye infections • Haemophilus ducreyii: Causative agent of chanchroid Back to MainBack to Airborne

  18. V. A. 5. Haemophilus influenzae Infections • Transmission & Symptoms • Infections most frequently associated with the virulent strain, type b • Upper respiratory tract symptoms • Rhinitis and Sinusitis • Otitis media • Epiglottitis • Septicemia and Meningitis • Prevented by HIB vaccine Back to MainBack to Airborne

  19. V. A. 6. Tuberculosis • Cause: Mycobacterium tuberculosis • Properties of the genus Mycobacterium • Acid-fast rods • Grow slowly; some species are difficult to culture • Several species;some found in soil and among skin flora • Major pathogenic species: • Mycobacterium tuberculosis • Mycobacterium avium-intracellulare • Mycobacterium cheloni • Mycobacterium scrofulaceum • Mycobacterium leprae Back to MainBack to Airborne

  20. V. A. 6. Tuberculosis • Transmission & Symptoms • Transmission • Airborne Contact • Prolonged Exposure • Occasionally via skin contactor wounds Back to MainBack to Airborne

  21. V. A. 6. Tuberculosis • Transmission & Symptoms (cont.) • Symptoms • Lung Infection • Destruction of alveoli • Cough; sputum • Tubercle Formation • May remain dormant for yearsand then become active again • May spread to other areas of the body:Miliary TB Back to MainBack to Airborne

  22. V. A. 6. Tuberculosis • Transmission & Symptoms (cont.) • Detection: • Microscopic examination • Chest X-Ray • Culture • Tuberculin Skin Test • TB Vaccination Back to MainBack to Airborne

  23. V. A. 7. Pneumococcal Pneumonia • Cause: Streptococcus pneumoniae • Properties of the Genus -- See Earlier Notes • Formerly Known as Diplococcus pneumoniae • No Lancefield classification • Gram-positive diplococci;virulent strains are encapsulated • Alpha Hemolytic • A common cause of secondary bacterial pneumonia Back to MainBack to Airborne

  24. V. A. 7. Pneumococcal Pneumonia • Transmission & Symptoms • A frequent cause of secondary bacterial pneumonia • Airborne transmission • Lower Respiratory Tract Infection • Pneumonia • Fluid Buildup in Lung Back to MainBack to Airborne

  25. V. A. 8. Primary Atypical Pneumonia • Cause: Mycoplasma pneumoniae • Properties of the Genus Mycoplasma • Small, irregular cells • Naturally cell wall deficient • Several species • Common among respiratory flora in humans & other animals Back to MainBack to Airborne

  26. V. A. 8. Primary Atypical Pneumonia • Transmission & Symptoms • Airborne Transmission • May be opportunistic • Frequently causes mild cases of primary pneumonia • Mycoplasma pneumoniae may also cause severe secondary pneumonia in immunocompromised patients Back to MainBack to Airborne

  27. V. A. 9. Legionellosis • Cause: Legionella pneumophila • Properties of the genus Legionella • Gram-negative rods • Strictly aerobic • Found in highly aerated, moist environmentseg. streams • May parasitize certain aquatic protozoa • Can contaminate building ventilation systems, air filters, etc. Back to MainBack to Airborne

  28. V. A. 9. Legionellosis • Transmission & Symptoms • Airborne • Contact with infected persons or environments • Mild to Moderate Pneumonia Back to MainBack to Airborne

  29. V. B. Foodborne & Waterborne Bacterial Diseases 1. Foodborne Intoxications vs Infections 2. Botulism 3. Staphylococcal Food Poisoning 4. Clostridial Food Poisoning 5. Typhoid Fever 6. Salmonellosis 7. Shigellosis 8. Cholera 9. Diseases associated with Escherichia coli 10. Camphylobacteriosis and Helicobacteriosis Back to Main

  30. V. B.1. Foodborne Intoxications vs Infections • Foodborne intoxications: Caused by the exotoxin secreted by bacteria in contaminated food • Foodborne infections: Caused by the ingestion of live bacteria that colonize the digestive tract Back to MainBack to Food- and Waterborne

  31. V. B.2. Botulism • Cause: Clostridium botulinum • Properties of the genus Clostridium • Gram-positive rod • Strictly anaerobic • Spore-former • Widely distributed, especially in soil • Important species: • Clostridium botulinum • Clostridium perfringins • Clostridium tetani Back to MainBack to Food- and Waterborne

  32. V. B.2. Botulism • Transmission & Symptoms • Transmitted via contaminated food • Botulinum toxin: • A neurotoxic exotoxin • Heat sensitive • Inhibits synaptic transmission at motor neuron end plates • Causes flaccid paralysis • Very deadly: Death due to respiratory & cardiac failure • Treatment: Administration of antitoxin Back to MainBack to Food- and Waterborne

  33. V. B.2. Botulism • Transmission & Symptoms (cont.) • Other mechanisms of transmission: • Wound botulism • Animal botulism • Infant botulism Back to MainBack to Food- and Waterborne

  34. V. B.3. Staphylococcal Food Poisoning • Cause: Staphylococcus aureus • Properties of the genus Staphylococcus • Gram positive coccus in clusters • Catalase positive • Two major species • Staph. aureus is more virulent & is coagulase positive • Staph epidermidis is more common & is coagulase negative • Both are common skin & upper RT flora Back to MainBack to Food- and Waterborne

  35. V. B.3. Staphylococcal Food Poisoning • Transmission & Symptoms • Certain strains of Staph. aureus: Produce staphylococcal enterotoxin • Toxin is secreted in contaminated food • Causes abdominal pain, nausea, diarrhea, for a few hours • Staph. aureus enterotoxin is unusually heat-resistant Back to MainBack to Food- and Waterborne

  36. V. B.4. Clostridial Food Poisoning • Cause: Clostridium perfringins • Certain strains secrete an enterotoxic exotoxin • Transmission & Symptoms • Similar to staphylococcal food poisoning, except that the clostridial enterotoxin is not as heat-stable Back to MainBack to Food- and Waterborne

  37. V. B.5. Typhoid Fever • Cause: Salmonella typhi • Properties of the genus Salmonella • A member of the family Enterobacteriaceae • Colon flora; sometimes carried asymptomatically • Gram negative rods • Facultatively anaerobic • Salmonella typhi • Most virulent member of the genus Back to MainBack to Food- and Waterborne

  38. V. B.5. Typhoid Fever • Transmission & Symptoms • Transmission via oral route • often associated with contact with infected persons, either symptomatic or carriers • sewage • flies Back to MainBack to Food- and Waterborne

  39. V. B.5. Typhoid Fever • Transmission & Symptoms • Invades intestinal epithelium tissue • ulceration • bloody stools but little diarrhea • Blood invasion • fever; delirium • blood vessel hemorrhaging • rose-colored spots on the abdomen • bowel perforation • gall-bladder infection Back to MainBack to Food- and Waterborne

  40. V. B.6. Salmonellosis • Cause: Salmonella serotypes • Serotypes of the genus Salmonella other than S. typhi • Hundreds of serotypes; species names exist but are often not reported • Examples • Salmonella enteriditis • Salmonella gallinarum • Salmonella typhimurum Back to MainBack to Food- and Waterborne

  41. V. B.6. Salmonellosis • Transmission & Symptoms • Contaminated food • Meat • Poultry products • Dairy products • Gastroenteritis • Cramps • Nausea • Vomiting • Diarrhea Back to MainBack to Food- and Waterborne

  42. V. B.7. Shigellosis • Cause: Shigella species • Genus Shigella • A member of the family Enterobacteriaceae • Colon flora; sometimes carried asymptomatically • Gram negative rods • Facultatively anaerobic • Species • Shigella sonnei • Shigella dysenteriae • Shigella flexneri • Shigella boydii Back to MainBack to Food- and Waterborne

  43. V. B.7. Shigellosis • Transmission & Symptoms • Transmission: • Similar to salmonellosis • Gastroenteritis • Often with watery diarrhea • Sometimes with bloody stools: Dysentery Back to MainBack to Food- and Waterborne

  44. V. B.8. Cholera • Cause: Vibrio cholerae • Genus Vibrio • Gram-negative curved bacteria • comma-shaped • facultatively anaerobic • Normal flora in many animals • Notable Pathogenic Species • Vibrio cholerae • Vibrio parahaemolyticus Back to MainBack to Food- and Waterborne

  45. V. B.8. Cholera • Transmission & Symptoms • Transmission: • Contaminated food • shellfish • vermin • livestock Back to MainBack to Food- and Waterborne

  46. V. B.8. Cholera • Transmission & Symptoms (cont.) • Gastroenteritis with extensive severe diarrhea • Cholera enterotoxin • Toxin blocks water reabsorption by inhibiting the anion active transport mechanism in large intestinal epithelium • “Rice water” stools • Dehydration & death • Recent epidemic due to spread of new drug-resistant strain Back to MainBack to Food- and Waterborne

  47. V. B.9. Diseases associated with Escherichia coli • Cause: Escherichia coli • Family Enterobacteriaceae • Gram-negative rods • Facultatively anaerobic • Widely distributed among humans & animals • Normal colon flora • Used as indicator of water & food contamination Back to MainBack to Food- and Waterborne

  48. V. B.9. Diseases associated with Escherichia coli • Transmission & Symptoms • Oral route • Extremely common normal flora • Different strains in different geographical regions • Colonize gut in infancy • Infantile diarrhea • Traveler's diarrhea Back to MainBack to Food- and Waterborne

  49. V. B.9. Diseases associated with Escherichia coli • Transmission & Symptoms (cont.) • E. coli strain O157:H7 • A rare, particular virulent & deadly strain • Hemorrhagic E. coli disease • Kidney damage in children Back to MainBack to Food- and Waterborne

  50. V. B.10. Camphylobacteriosis and Helicobacteriosis • Camphylobacter jejuni • Gram-negative spirillum • Microaerophilic • Normal flora of colon • Common cause of mild to moderate gastroenteritis Back to MainBack to Food- and Waterborne