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4-c The Bacteria

4-c The Bacteria. And various pages in additional chapters. Relationships Between Bacteria and Clinical Features of Disease. Structure/Function Relationships. Differences exist between human (eukaryotic) and bacterial (prokaryotic) cells.

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4-c The Bacteria

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  1. 4-c The Bacteria And various pages in additional chapters Relationships Between Bacteria and Clinical Features of Disease

  2. Structure/Function Relationships Differences exist between human (eukaryotic) and bacterial (prokaryotic) cells Many of the differences account for disease pathogenesis And, allow exploitation of the differences to develop chemotherapy (antibiotics)

  3. Differences Accounting for Pathogenesis

  4. Toxins Poisonous substances produced by microbes • Transported in blood • Produce fever, cardiovascular disturbances, diarrhea, shock • Inhibit protein synthesis, destroy blood cells & vessels, disrupt nervous system

  5. Two Types

  6. Bacilli, rods Cocci Bacillus anthracis Neisseria gonorrhoea Clostridium botulinum Staphylococcus aureus Clostridium perfringens Streptococci mutans Clostridium tetani Streptococci pneumoniae Corynebacterium diphtheria Curved Escherichia coli Vibrio cholera Klebsiella pneumonia Spirochete Mycobacterium leprae Borrelia burgdorferi Mycobacterium tuberculosis Treponema pallidum

  7. Clinically Significant Bacteria Arrangement: rods, bacilli • Bacillus • Clostridium • Corynebacterium • Escherichia coli • Mycobacterium

  8. Bacillus anthracis • Gram positive, rods • Spore forming • Aerobe or facultative • Found in soil Disease: Fig. 11.17b Bacillus germinating • Anthrax • Pulmonary • Cutaneous • GI • Biological warfare • Ch 23, p 680-1 Ch / Pg

  9. Cutaneous Anthrax • Contact with material containing anthrax endospores • Results in skin lesion covered by a black scab • Diagnosis • New blood test detection Fig. 4.21 Endospore Fig. 23.7 Anthrax lesion

  10. Clostridium • Gram positive, rods • Obligate anaerobe • Endospores • Widely found in soil, GI tracts human, animals • Toxins (neuro) Diseases: Fig. 23.8 gangrene • Botulism • Tetanus • Gas gangrene • Food borne diarrhea Ch / Pg

  11. Gas Gangrene • C. perfringens • If wound is brand new • Prompt cleaning of serious wounds • Antibiotic treatment (penicillin) • Wound is seriously necrotic • Surgery, amputation Fig. 23.9 Hyperbaric chamber

  12. Corynebacterium diphtheriae • Gram positive • Club-shaped, pleomorphic • Aerobic or (facultative anaerobic) • Non-spore forming • Toxin (cyto) • Metachromatic granules • Volutin Fig. 24.5 Corynebacterium Disease: Ch / Pg • Diphtheria

  13. Diphtheria • Airborne transmission • Forms a leathery, grayish membrane in the throat • Sore throat, fever, general malaise, swelling of neck • Diagnosis: • Selective & differential media Fig. 24.6 Diphtheria membrane Part of the DPT immunizations for children

  14. Gram negative, rods • Facultative anaerobe • Toxins • Invasive • Hemorrhagic • Plasmid borne Escherichia coli Diseases: Fig. 4.11 E. coli • Foodborne epidemics • Urinary tract infections (‘travelers diarrhea’) • Gastroenteritis • E. coli O157:H7 Ch / Pg

  15. Gastroenteritis • E. coli (EHEC) • Hemorrhagic colitis (very bloody stools) • Adhere to intestinal mucosa, destroy microvilli • Serotype: O157:H7 • Infective dose 100 bacteria • Diagnosis: rapid methods Fig. 24.6 Enterohemorrhagic E. coli

  16. Mycobacterium • Acid fast, slender rod • Obligate aerobe • Non-spore forming Disease: • Tuberculosis • Leprosy (Hanson’s Disease) Fig. 24.9 Mycobacterium Ch / Pg • Mycobacterium tuberculosis • M. leprae

  17. Tuberculosis • Inhale the bacillus • Lodge in the lung alveoli • Can progress to a lung damaging inflammation • Diagnosis: • TB skin test • Sputum smears • Chest X ray, CT Fig. 24.2 Lower Respiratory System Fig. 24.11 TB skin test

  18. Leprosy • Invades myelin sheath, peripheral nervous system • Cause nerve damage • 12 day generation time • Never grown in culture • Necrosis of tissue • Diagnosis: • Detect acid-fast rods in patient fluids • Lepromin test Fig. 22.9 Leprosy Also called Hansen’s disease

  19. Clinically Significant Bacteria Arrangement: cocci • Neisseria gonorrhoea • Staphylococcus aureus • Streptococci

  20. Neisseria gonorrhoea • Gram negative • Diplococcus • Obligate aerobe • Non-spore forming Disease: • STD: Gonorrhea • Meningitis Fig. 22.4 Neisseria meningitis, pharynx Ch / Pg

  21. Gonorrhea • Attaches via fimbriae • Leads to inflammation • Leucocytes move to infected area • Characteristic pus forms • In women, only the cervix is infected • Diagnosis: • Stained pus smears Fig. 26.7 A smear of pus, patient with gonorrhea

  22. Staphylococcus aureus • Gram positive, cocci • Grape-like clusters • Facultative anaerobe • Toxin Fig. 11.18 Staphylococcus aureus Diseases (many): • Surgical wounds (nosocomial) • TSS (toxic shock syndrome) • Skin infections (impetigo, scalded skin) • Endocarditis Ch / Pg

  23. Acute Bacterial Endocarditis • Gain access to bloodstream • Leads to infection • Forms fibrin-platelet vegetations • Rapid destruction of heart valves within the endocardium • Diagnosis: • Echocardiogram Fig. 23.4 Bacterial endocarditis

  24. Clinical Ramifications, 2 types • S. aureus and S. epidermidis can be divided into 2 groups • Slime layer allows S. epidermidis to colonize catheters Fig. 21.3a, b. Coagulase negative staphylococci

  25. Streptococcus • Gram positive, cocci, chains • Facultative anaerobe • alpha, beta, gamma hemolytic • Secrete toxins Diseases (many): • Pneumonia • Strep throat • Scarlet fever • Skin infections • Rheumatic fever Fig. 11.19 Streptococcus Ch / Pg

  26. Skin Infection - Erysipelas • Most important b-hemolytic species • S. pyogenes • Reddish patches on skin - dermal layer • Tissue destruction • Pus generated • Enter bloodstream cause sepsis Fig. 21.6 Lesion of erysipelas

  27. Q’s What is seen at the ends of the cells of Clostridium tetani in this micrograph? • Very thick flagella • Endospores • The cells are undergoing division • These cells are pleomorphic, accounting for this shaped cell • Budding cells

  28. Q’s Which of these is NOT correctly matched? • Escherichia coli – gastroenteritis • Staphylococcus aureus – TSS • Clostridia tetani – gangrene • Bacillus anthracis – anthrax • Which of following is not true about fimbriae? • They are composed of protein • They may be used for attachment • They are composed of pilin • They may be used for motility • They are found on Gram negative cells

  29. Q’s The formation of a tough grayish membrane in the throat is characteristic of: • Tuberculosis • Scarlet fever • Diphtheria • Streptococcal pharyngitis • A positive tuberculin skin test indicates that an individual: • Has an active case of tuberculosis • May have been vaccinated with BCG • Has immunity to TB due to an earlier infection • Any of the above is possible

  30. Q’s Which of these is an infection of the lower respiratory tract: • Botulism • Diphtheria • Tuberculosis • Streptococcal pharyngitis • An acid-fast stain of a patient’s sputum reveals acid-fast rods. This indicates infection with: • Staphylococcus aureus • Mycobacterium tuberculosis • Corynebacterium diphtheria • Any of the above is possible

  31. Q’s Which of these diseases is also known as Hanson’s disease: • Botulism • Leprosy • Tuberculosis • Gangrene • Anthrax • Staphylococcus aureus is responsible for all of the following except: • Acne • Impetigo • Toxic shock syndrome • Scalded skin syndrome

  32. Q’s The diagram shows the structure of a: • Gram-negative cell wall • Gram-positive cell wall • Eukaryotic cell wall

  33. Q’s The antibiotic Gentamicin binds the 30S ribosome subunit. This will interfere with: • Protein synthesis in eukaryotic cells • Protein synthesis in prokaryotic cells • Cell division in eukaryotic cells • Cell division in prokaryotic cells

  34. 1. Bacillus 2. Streptococcus 3. Klebsiella 4. Escherichia 5. Neisseria 6. Staphylococcus 7. Mycobacterium 8. Clostridium 9. Corynebacterium Q’s Disease Bacteria • Leprosy • Diphtheria • Anthrax • Strep throat • Botulism • Hemorrhagic colitis • Pneumonia • Scarlet fever • Skin infections • Tetanus • Meningitis • Tuberculosis • Acute endocarditis • Food borne diarrhea • Gas gangrene • UTI

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