1 Anaerobic Bacteria Fundamentals II Stephen A. Moser, Ph.D. 10/19/2011

2 Categories Based Upon Gaseous Requirements  Aerobic bacteria Ø Require oxygen as electron acceptor  Microaerophilic bacteria Ø Require oxygen in reduced quantity  Capnophilic bacteria Ø Require carbon dioxide  Facultative bacteria Ø Grow either with or without oxygen  Anaerobic bacteria Ø Both obligate and aerotolerant

3  Both pH and oxidation-reduction potential are important.  Cytochrome systems absent.  Most lack superoxide dismutase (SOD) and catalase.  Obligate anaerobe - lack cytochrome, SOD and catalase.  Aerotolerant anaerobe - has some SOD and or catalase.  Facultative anaerobe - grow equally well under either aerobic or anaerobic conditions. Physiology And Growth Conditions

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5 Oxidation - Reduction Potential And Anatomic Site

6 Anaerobic Bacteria Of Clinical Importance

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8 Conjunctivitis Conjunctivitis Keratitis Keratitis Dacryocystitis Dacryocystitis Anaerobic Bacteria in Ocular Infections Number of patients Aerobic organisms only Staphylococcus aureus12 Streptoccoccus pneumoniae13 Haemophilus influenzae14 Haemophilus parainfluenzae3 Anaerobic organisms only Peptostreptococcus spp.7 Propionibacterium acnes6 Bifidobacterium spp.2 Prevotella melaninogenica1 Bacteroides fragilis1 Fusobacterium varium 1 Peptostreptococcus spp. + other anaerobic bacteria3 Patients with mixed aerobic and anaerobic organisms Peptostreptococcus spp. + Staphylococcus spp.6 Peptostreptococcus spp. + other anaerobic and aerobic bacteria 7 Propionibacterium acnes + other bacteria12 Brook I. Anaerobic and aerobic bacterial flora of acute conjunctivitis in children. Arch Ophthalmol 1980; 98: 833–835.

9 Vincent Angina

10 Adult Periodontitis Adult Periodontitis

11 Anaerobic Brain Abscess

12 Anaerobic Polymicrobic Cellulitis

13 Bacteroides / Prevotella / Porphyromonas species Bacteroides / Prevotella / Porphyromonas species  Non-spore forming, pleomorphic rods  Normal flora of upper respiratory tract, intestinal and female genital tract  Most important groups - Bacteroides fragilis and Prevotella melaninogenica  Colon associated –group (fragilis)  Upper respiratory tract - P. melaninogica group  Female genital tract - P. bivia and P. disiens  Clinical disease usually abscess formation with mixed anaerobic and facultative anaerobic bacteria. Anaerobic Infections Gram -negative Bacilli

14 Necrotizing Fasciitis Bacteroides fragilis

15 Necrotizing Fasciitis Bacteroides fragilis

16  Fusobacterium  Pleomorphic non-spore forming rods  Usually present in mixed infections but may be the sole agent  Present in both upper respiratory and intestinal tract  F. necrophorum – Lemierre’s syndrome  Jugular vein thrombosis Anaerobic Infections Gram-negative Bacilli

17 Pulmonary Abscess

18 Fusobacterium

19  Actinomyces  Most common is Actinomyces israelii  Slow growing and are difficult to isolate  Cause extensive soft tissue involvement crossing tissue plane and involving multiple organ systems  Can result in draining sinus tracts with “sulfur granules”  Associated with oral, respiratory and female genital tract infections (IUD) Anaerobic Infections Gram-positive Bacilli

20 DACRYOCYSTITIS

21 Actinomycosis “Lumpy Jaw”

22 Actinomycosis

23 “Sulfur” Granules

24 Actinomyces israelii

25  Propionibacterium  Unusual cause of infection  Normal flora of the skin  May be difficult to determine the role of blood isolates in disease  Lactobacillus  Normal flora of the vagina  Rare cause of disease  Eubacterium, Bifidobacterium, Arachnia Anaerobic Infections Gram-positive Bacilli

26  Clostridium  The only genus of anaerobes that forms spores  Tetanus - C. tetani - in vivo toxin production  Tetanospasmin – blocks inhibitory neurotransmitters  Botulism - C. botulinum - ingestion of preformed neurotoxin except for wound and infant botulism  Blocks release of acetylcholine  Gas gangrene - C. perfringens - H 2 & CO 2  Phospholipase C (  -toxin)  Food poisoning - C. perfringens  Enterotoxin  C. septicum - associated with malignancy, neutropenia  Pseudomembranous colitis / antibiotic associated diarrhea - C. difficile Anaerobic Infections Spore forming Gram positive Bacilli

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28 Tetanus

29 Clostridium tetani

30 Gas Gangrene

31 Clostridium perfringens

32 Clostridium perfringens Nagler Test

33 Clostridium difficle Colitis

34 Pathogenesis  Synergy with facultative organisms.  Facultative bacteria such as Enterobacteriaceae function to reduce the oxygen content in the tissue.  Beta-lactamase production.  Capsule of Bacteroides fragilis is antiphagocytic.  Toxin production.

35 DIAGNOSIS OF ANAEROBIC INFECTIONS  Clinical signs  Foul smelling discharge  Proximity to a mucosal surface  Gas in tissue  Abscess formation  Gram stain  May be helpful in the establishment of a mixed infection or the presence clostridia in wounds

36 Gram Stain of Mixed Infection

37 DIAGNOSIS OF ANAEROBIC INFECTIONS  Culture  Sample collection and transport are critical  Require complex medium supplemented with hemin, Vit. K and or blood.  Should include media containing antibiotics (aminoglycoside) to suppress facultative anaerobes, e.g., E. coli  Incubation and work up performed in CO 2 in nitrogen/ hydrogen mix

38 Anaerobic Containers

39 Anaerobe Chamber

40 Bacteroides fragilis

41  Surgical drainage of closed abscess.  Mixed infections - cover for both aerobic and anaerobic component.  Metronidazole, penicillin G, Clindamycin.  Penicillin resistance is common among some species, e.G. P. melaninogenica group, B. fragilis groups.  Aminoglycosides not effective.  Toxin mediated diseases - antitoxin and antibiotics if active infection vs. Intoxication. Treatment Of Anaerobic Infections

42 Etest™ Susceptibility Testing

43 Objectives l Know the different gaseous requirements of bacteria. l Know what special collection and diagnostics methods are required to isolate anaerobes. l Know the epidemiology of anaerobic infections. l Recognize the clinical syndromes associated with anaerobic bacteria.