1. Pathogenic anaerobes

2. Anaerobic bacteria are widely distributed in nature in oxygen-free habitats. Many members of the indigenous human flora are anaerobic bacteria, including Spirochete Gram-positive cocci and bacilli Gram-negative cocci and bacilli

3. Normal places for anaerobics: Colon: contains large populations of anaerobic bacteria, exceeding 10 11 organisms/gr of colon content. Gingival crevices Tonsillar crypts Nasal folds Hair follicles UrethraVagina Tooth surfaces

5. Ecology of anaerobic in the body Anaerobic indigenous flora components are potentially pathogenic if displaced from their normal habitat. Proliferation of anaerobic bacteria in tissue depends on the absence of oxygen. Oxygen is excluded from the tissue when the local blood supply is impaired by trauma, obstruction, or surgical manipulation.

6. Anaerobes multiply well in dead tissue. Multiplication of aerobic or facultative organisms in association with anaerobes in infected tissue also diminishes oxygen concentration. Ecology of anaerobic in the body

7. The types of anaerobic infections Intra-abdominal infections 1. Intra-abdominal infections Abscesses Postoperative wound infections Generalized peritonitis Occur as a consequence of bowel perforation during surgery or injury.

8. Pulmonary infections 2. Pulmonary infections Anaerobic lung infections may originate in the bronchi or the blood. Aspirations from the upper respiratory tract are responsible for initiating infection in the bronchi. Pelvic infections 3. Pelvic infections Due to gynecologic surgery or in association with malignancy of pelvic organs.

10. Brain abscesses 4. Brain abscesses (The infecting organisms usually originate in the upper respiratory tract.) Meningitis Brain abscesses

11. Skin and soft tissue infections 5. Skin and soft tissue infections Combination of anaerobes, aerobes, and facultative organisms often act synergistically Oral and dental infections 6. Oral and dental infections These local infections frequently extend to the face and neck and sometimes to other areas of the body such as the brain.

12. Bacteremia and endocarditis 7. Bacteremia and endocarditis Endocarditis, an inflammation of the endothelial lining of the heart cavities is occasionally caused by anaerobic bacteria, especially anaerobic streptococci.

16. The list of anaerobic bacteria Bacilli Gram positive: Clostridia Gram Negative: Bacteroides, porphyromonas, Fusobacterium Cocci Gram positive: Peptostreptococcus Gram negative: Veillonella, Acidominococcus Megosphora Spirochetes: includes both aerobic and anaerobic species

17. Bacteroides Important properties: Anaerobic, non-spore-forming, Gram negative rods. Of 22 species, 3 are human pathogens: 1. Bacteroides fragilis 2. Bacteroides melaninogenicus 3. Bacteroides corrodens

18. Members of the B. fragilis group are the predominant organisms in the human colon, numbering approximately 10 11 /g of feces, and are found in the vagina of approximately 60% of women. B. melaninogenicus and B. corrodens are normal oral flora but found in lung abscesses.

19. Pathogenesis and Epidemiology Local mucosal abscesses due to a break in a mucosal surface Metastatic abscesses by hematogenous spread to distant organs Lung abscesses by aspiration of oral flora.

20. Virulence factors Virulence factors of B. fragilis  The polysaccharide capsule  No exotoxin have been found.

21. Clinical finding B. fragilis The B. fragilis is frequently associated with: - Peritonitis - Localized abscesses - Pelvic abscesses - Bacteremia

22. Culture on blood agar containing kanamycin and vancomycin to inhibit unwanted organisms. Identification by biochemical reactions (eg. Sugar fermentations) and by production of certain organic acids (eg. Formic, acetic, and propionic acids) which are detected by gas chromatography. Laboratory diagnosis

23. Treatment for members of B. fragilis Clindamycin is the drug of choice Resistant to penicillin, first generation of cephalosporins and aminoglycosides. Aminoglycosides treat the facultative gram-negative rods in mixed infections. Seurgical drainage of abscesses

24. Treatment for B. melaninogenicus Highly susceptible to penicillin G Seurgical drainage of abscesses

25. Prevention No vaccine Per-operative administration of a cephalosporins (frequently cefoxitin) for abdominal or pelvic surgery.