Anaerobic  Bacteriology Lecture
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Anaerobic Bacteriology Lecture

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    Anaerobic  Bacteriology Lecture Anaerobic Bacteriology Lecture Presentation Transcript

    • ANAEROBIC BACTERIOLOGY Dr. Ma. Ellery M. Mendez FPAMS , FPAAM, DPSMAP
      • Anaerobes generate energy by fermentation
      • Lack the capacity to utilize O2 as a terminal hydrogen acceptor
      • Some are sensitive to O2 concentration as low as 0.5% O2
      • Most can survive in 3%-5% O2
      • A few can grow poorly in the presence of air  aerotolerant anaerobes
      • Many are members of the normal flora
      •  created by presence of facultative
      • anaerobes
    • FACTORS THAT INHIBIT THE GROWTH OF ANAEROBES BY OXYGEN
      • 1. Toxic compounds are produced
      • e.g. H2O2 , Superoxides
      • 2. Absence of catalase & Superoxide
      • dismutase
      • 3. Oxidation of essential sulfhydyl groups in enzymes without sufficient reducing power to regenerate them
    • FACTORS RESPONSIBLE FOR THEIR VIRULENCE
      • 1. Lipopolysaccharide
      • - promotes abscess formation, enhanced coagulation
      • 2. Polysaccharide capsule
      • - correlated with abscess production
      • 3. Enzymes
      • a. Collagenase
      • b. Heparinase
      • * develop thrombophlebitis & septic emboli
      • 4. Short chained fatty acids
      • a. Butyrate- seen in dental plaque
      • b. succinic acid – reduces phagocytic killing
    • Multiplication of the opportunistic pathogens is facilitated by:
      • 1. inhibition of phagocytosis & intracellular killing
      • by PMN in the presence of Bacteroides by:
      • a. competition of opsonins
      • b. inhibition by capsular materials
      • 2. protection of antibiotic susceptibility strains in
      • mixtures thru destruction by the ß-lactamases
      • 3. utilization of O2 by facultative species that aids in
      • producing a suitable environment for growth of
      • anaerobe
    • Anaerobic Bacteria of Medical Interest MORPHOLOGY GRAM STAIN GENUS Sporeforming (+) Clostridium Non-sporeforming bacilli (+) (-) Actinomycetes, Bifidobacterium,Eubacte-rium,Propionibacerium, Mobilncus,Lactobacillus Bacteroides,Fusobacterium Prevotella,Porphyromonas Non-sporefoming cocci (+) (-) Peptococcus, Pepto-streptococcus Streptococcus Veilonella
    • CLINICAL MANIFESTATION
      • Clinical hints
      • 1. odor
      • 2. tissue
      • 3. location
      • 4. necrotic tissue
      • 5. endocarditis with (-) blood culture
      • 6. infection associated with malignancy
      • 7. black discoloration
      • 8. blood containing exudates
      • 9. associated with sulfur granules
      • 10. Bacteremic feature with jaundice
      • 11. human bites
    • Sites and Infection produced by Anaerobes
    •  
    • LABORATORY DIAGNOSIS
      • A. COLLECTION
      • Anaerobes are endogenous in nature
      • I. Appropriate specimens for anaerobic
      • culture :
      • 1. pus
      • 2. pleural fluid
      • 3. urine
      • 4. pulmonary secretions
      • 5. uterine secretions or sinus tract material
      • II. Collection by needle aspiration is preferrable than swab culture because of
      • a. better survival of pathogen
      • b. greater quantity of specimen
      • c. less contamination with extraneous
      • organism are often achieved
    • B. HANDLING
      • If a swab must be used, a 2 tube system
      • must be used
      •  1 st tube contains swab in O2 free CO2
      •  2 nd tube contains PRAS (pre-reduced
      • anaerobically steilized culture media)
      • Specimen should be placed in anaerobic transport device with gas mixture
    • C. Isolation
      • Gram stain should be done in the
      • laboratory :
      • a. choice of appropriate media &
      • methods for culture
      • b. quality control for the types of
      • bacteria that laboratory culture
      • reveal
    • A solid or liquid medium maybe used & must provide an anaerobic environment  Anaerobic Culture System
      • ANAEROBIC JAR
      • 1. Candle Jar
      • - reduces O2 environment
      • - only ↑ CO2 tension
      • 2. Gas Pak Jar
      • a. Palladium aluminum coated pellets
      • - catalyst
      • - chemically reduces O2
      • - reacts with residual O2 in the presence of H2 to form
      • H2O
      • b. Gas Pak envelope
      • - generates CO2 & H2 gases
      • c. Methylene blue strip
      • - indicator
      • blue -> (+) O2
      • white -> (-) O2
      • II. Anaerobic Glove Chamber
      • - close system
      • - used for premature babies
      • - e.g. incubator
      • III. Roll Tube
      • - has a pedal  gas ( CO2 & H2 ) would come out
      • - place test tube directly to the outlet
    • D. IDENTIFICATION
      • Plates are checked at
      • > 18-24 hours for faster growing species like
      • Cl. Perfringens & B.fragilis & daily thereafter up to
      • > 5-7 days for slowly growing species like
      • Actinomyces, Eubacterium & propionibacterium
      • Genus is determined by
      • - gram stain, cellular morphology, Gas-liquid
      • chromotography
      • Species determination is based on fermentation of sugars & other biochemical determination
    • TREATMENT
      • - Susceptibility testing should be done
      • - surgical drainage & resection of necrotic tissue
      • - most are resistant to aminoglycosides
      • - for Bacteroides gr oup, if resistant to Penicillin & Cephalosporin, they may use:
      • a. Clindamycin
      • b. Metronidazole
      • c. Chloramphenicol
      • THE END