1. CLOSTRIDIA Obligate anaerobes: Clostridia G+ spore-forming rods Soft tissue and skin infections Antibiotic-associated colitis & diarrhea Toxins: botulism tetanus gas gangrene pseudomomembranous colitis

2. C. perfringens histotoxics C. difficile pseudomembranous colitis C. tetani tetanus C. botulinum botulism

3. General features of Clostridia large, gram-positive, blunt-ended rods endospore-forming in vegetative cells

4. Physiology utilize pyruvate grow on enriched media of cysteine or thioglycollate (↓ redox) or O 2 -free gaseous atmosphere

5. Epidemiology environment intestinal tract soil, sewage or aquatic persistent survival in environment commensals & contaminants of clinical materials

6. Clostridium perfringens encapsulated vegetative form in GIT and vagina spores in soil anaerobic cellulitis, myonecrosis

7. Pathogenesis C. perfringens secretes exotoxins, enterotoxins and enzymes 12 exotoxins alpha toxin → lysis of endothelial cells, RBC’s WBC’s and platelets Types A → E

8. Enterotoxins: disrupts in transport = loss of fluid and proteins degradative enzymes – proteases (DNAses, hyaluronidase, collagenases

9. Diseases Myonecrosis gas-fermentation of tissue carbohydrates

10. Exudates → increased capillary permeability →exotoxins →circulation →other organs & intravascular hemolysis shock, renal failure →death Anaerobic cellulitis – clostridial infection of connective tissue rapid spread of the infection

11. Food poisoning, nausea, abdominal cramps and diarrhea Enteritis necrosticans Clostridial endometritis

12. Clostridium botulinum flaccid paralysis = toxin pure intoxication = disease

13. Epidemiology Soil and aquatic sediments Spores – vegetables, meat or fish toxin produced during vegetative growth

14. Pathogenesis Toxin: A-G ABE – human disease Serotypes = homologous types of proteins with tetanus toxin Toxin affects peripheral cholinergic Synapses = blocks neuromuscular junction = inhibit release of Ach = prevents contraction = Flaccidity

15. a. Classic botulism – food poisoning s/s difficulties in focusing vision, swallowing, in other CN functions progressive paralysis

16. b. Infant botulism toxin absorbed from the large bowel that is colonized s/s constipation, feeding problems, lethargy, poor muscle tone c. Wound contamination

17. Laboratory identification: Culture by anaerobic methods Treatment: antitoxin (Trivalent horse antiserum) mechanical ventilation

18. Clostridium tetani Epidemiology soils puncture wound foreign bodies, small areas of cell killing = divitalized material umbilical wound

19. Pathogenesis Tetanospasmin – transported by retrograde neuronal flow or by blood. Plasmid – coded exotoxin B fragment – binding to neurons - penetration of A A fragment – blocks neurotransmitter release at inhibitory synapses Result: prolonged muscle spasms

20. A fragment: a protease cleaves synaptobrevin Immunity: None Tetanus – Incubation period: days to weeks s/s trimus or lockjaw painful spasms, convulsions respiratory failure

21. Laboratory identification: clinical diagnosis characteristic morphology: “racquet shaped” bacillus swarming growth

22. Treatment: antitoxin – human horse antitoxin sedatives, muscles relaxants ventilation

23. Prevention: Active immunization with tetanus toxoid DPT – given at 2, 4, 6 & 18 mos.

24. Clostridium difficile

25. may be part of normal flora of the colon proliferates with antibiotic treatment 2 toxic polypeptides A & B Toxin A – enterotoxin Toxin B – cytotoxi

26. Drugs implicated: Ampicillin, Clindamycin, Cephalosporins s/s: diarrhea inflammation fulminant PMC (Pseudomembranous colitis)

27. Laboratory identification: Toxin production ELISA – Enzyme immunoassays Treatment: Oral metronidazole Oral vancomycin

28. B. anthracis enzootic worldwide domestic herbivores (sheep, goats and horses) humans – contact with infected animals products or contaminates dust.

29. Pathogenesis: capsule = D. glutamic acid 2 exotoxins = edema factor lethal toxin

30. Clinical forms: a.Cutaneous anthrax – 95% papule →black eschar → septicemia b. Pulmonary anthrax (“Woolsorter’s” disease) inhalation c. Gastrointestinal form

31. Laboratory identification: blunt-ended bacilli: singly, in pairs or frequently in long chains Spores are oval and centrally located Blood agar: colonies are large, grayish and non-hemolytic

32. Treatment: Penicillin, Doxycycline and Cipofloxacin

33. Listeria Slender, short, gram-positive rods Do not form spores Catalase-positive Tumbling motility in liquid media Can be confused morphologically with streptococci and corynebact.

34. L. monocytogenes widespread among animals in nature, infections usually food-borne capable of growth at 4 O C pregnant women, newborns, fetuses and immunocompromised

35. Pathogenesis L. monocytogenes – facultative, intracellular internalized → escapes the phagocytic vacuole: Listeriolysin O

36. Corynebacterium Bacillus anthracis Corynebacteria small, slender, pleiomorphic do not form spores non-motile and unencapsulated Toxin; A & B fragments

37. NAD & EF-2: ADP-ribosylation Blocks translocation of polypeptidyl-t-RNA from A site to P site The structural gene tox is encoded on the corynecbacterial phage; Β phage

38. Disease manifestations: 1.Upper respiratory tract – local formation of pseudomembrane Respiratory obstruction Cardiac condition defects Myocarditis CHF Neuritis of cranial nerves and parolysis of muscle groups

39. 2. Cutaneous diphtheria Immunity: Antibodies

40. Laboratory identification clinical observation isolation of organism and tested for virulence Tinsdale agar – Methylene blue staining shows characteristic bands and polychromatic granules “Chinese characters”, picket fence

41. Treatment: Antitoxin Penicillin/Erythromycin Prevention: Toxoid