Anaerobic Bacteria Neglected but Important
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Anaerobic Bacteria Neglected but Important
- 3. Neglected in diagnostic labs- but they outnumber the aerobic bacteria including most sites of human and animal body. Mouth and skin -10-30 times more frequent than aerobic bacteria. The numbers of anaerobes have been estimated to be 10 4-10 5/ml in small intestine,10 8/ml in saliva and 10 11/g in the colon
- 4. Earlier-coloney morphology,biochemical reactions and antibiotic sensitivity pattern. Current classification-based on DNA base composition and analysis of fatty acids, end products of metabolism
- 5. Aerobes and facultative anaerobes have metabolic systems listed below, whereas anaerobic bacteria do not ▪ Cytochrome system of metabolism of oxygen. ▪ Superoxide dismutase, which catalyses the following reaction: ▪ O-2+O-2----H2O2+O2 ▪ Catalase, which catalyses the following reaction. ▪ 2H2O2----2H2O+O2 (gas bubbles).
- 7. Anaerobic bacteria do not have cytochrome systems for metabolism. Less fastidious anaerobes have low levels of superoxide dismutase and may not have catalase. Obligate anaerobes usually lack superoxide dismutase and catalase and are susceptible to lethal effects of oxygen radicals. Most human infections are caused by moderately obligate anaerobes. Ability to tolerate oxygen varies from species to species.
- 11. They cause following infections Divided into Graminfections,wound Genital positive and Gram negative cocci infections,gangrenous Peptococci,peptostreptococci.-cocci small appendicitis,urinary tract size 0.2-2.5 µ. Many aerotolerent. infections,osteomyelitis,absc Normal flora of vagina,intestinesand mouth. ess in the brain,lungs and Peptostreptococcusorgans other internal anaerobicuspuerperal sepsis. P.magnus-Abscess
- 12. GNC of varying sizes occurring as diplococci,short chains or groups They are normal inhabitants of mouth,intestinal and genital tract All anaerobic cocci are generally sensitive to penicillin,chloramphenicol,and metronidazole and resistant to streptomycin and gentamicin
- 13. BACTERIAL VAGINOSIS Eubacterium- periodintitis POLYMICROBIAL INFECTION OF Lactobacillus usually non CHARACTERIZED BY THIN VAGINA pathogenic MALODOUROUS VAGINAL L.catenaformae-bronchopulmonary DISCHARGE KOH TEST infections VAGINAL PH IS MORE THAN 4.5 CLUE CELL SEEN Bifidobacterium-branching MICROSCOPICALLY IN FRAM STAINED SMEARSMobiluncus-M.mulieris,M.curtisii-Bacterial vaginosis. What is bacterial vaginosis?
- 16.
- 17. Large group of GNB appear as slender rods or cocobacilli. Normal commensal of intestine. Normal stool-1011 B.fragilis/gram. Commonly isolatedB.fragilis,B.ovatus,B.distasonis,B.vulgatus,B. thetaiotamicron and others. Contamination by contents of colon where they may cause suppuration-perotinitis
- 18. Constitutes less than 10% of Bacteroides species in the normal colon, however, is the most common isolate of anaerobes. Major virulence factor: capsular polysaccharides, which may cause abscess formation when injected into the rat abdomen. Resistant to penicillin.
- 19. Classification is based on colonial and biochemical features and characteristic short chain fatty acid patterns in gas liquid chromatography. Associated with anaerobic coccipeptostreptococci and others.
- 20. GNB-slender rods and cocobacilli Common-P.melaninogenica. Found in lung and brain abscess,in empyema and in pelvic inflammatory diseases,and tuboverian abscess. Often polymicrobial – peptostreptococci,anaerobic gram positive rods and fusobacterium species. Black colonies produced by this. Colonies show-red fluorescence in UV rays
- 21. Normal oral commensal. Gingival, periapical tooth infections. More commonly-breast,axillary,perianal and male genital infections
- 22. Pleomorphic GNB. Most species produce butyric acid and convert threonine to propionic acid. Isolated from mixed bacterial infections-oral infection pleuropulmonary sepsis.
- 23. L.buccalis-vincent’s fusiform bacillusfusobacterium fusiformae It causes Vincents angina-oropharyngitis
- 24. Now-a-days techniques are simplified for their isolation & identification. Endogenous infections. Trauma, tissue Precipitating factors are there. necrosis,foregin Anaerobicdiabetes, malnutrition, body, infections-polymicrobial malignancy, prolonged treatment with aminoglycosides
- 25. Site and type of infection Bacteria commonly responsible Central nervous system-brain abscess B.fragilis,peptostreptococcus ENT-chronic sinusitis,otitis media,mastoiditis,orbital cellulitis Fusobacteria Mouth and jaw-ulcerative gingivitis,dental abscess,cellulitis,abscess or sinus of jaw Fusobacteria,spirochetes,mouth anaerobes,actinomycetes, Respiratory-aspiration pneumonia,lung abscess,bronchiectasis,empyema Fusobacteria,P.melaninogenica,anaerobic cocci,B.fragilis Abdominal-shbphrenic,hepatic abscess,appenditicitis,peritonitis,ischiorec tal abscess,wound infection after colorectal surgery B.Fragilis Female genitialia-purperal sepsis etc P.melaninogenica,anaerobic cocci,B.fragilis Skin and soft tissue Anaerobic cocci
- 27. Interpretation should be done cautiously. Avoid resident flora contamination. Avoid or minimise the exposure with oxygen. In laboratory exposure should me limited to minimum Gram staining shows large variety of different organisms and numerous pus cells Occasionally-brain abscess-single organism. UV examination-bright red fluorescence? Gas liquid chromatography
- 30. Freshly prepared blood agar with neomycin,yeast extract,hemin and vitamin K is adequate Incubated at 37oC with 10%CO2. Gas pak Jar is used Examine plates after 24-48 hrs Parallel aerobic cultures shd. Be always put.
- 31. Methods for excluding oxygen 1. Fluid media containing fresh animal tissue or 0.1% agar containing a reducing agent, thioglycollate. 2. Anaerobic jar 3. Anaerobic glove chamber