Anaerobes Non Spore Forming

Bacteriology ANAEROBES NON-SPOREFORMING GENERAL CHARACTERISTICS 1. Include cocci, bacilli, comma-shaped, spirochetes; often pleomorphic 2. Lack catalase and superoxide dismutase 3. Usually require 5-10% C02 environment for culture growth 4. Nutritionally very fastidious 5. Culture systems a. Anaerobic jar b. Roll tube c. Anaerobic glove box 6. May grow slowly DETERMINANTS OF PATHOGENICITY 1. Specific virulence factors a. Lipopolysaccharide b. Capsule c. Enzymes 2. Synergy CLINICAL INFECTION 1. Causative organisms usually part of normal indigenous flora 2. Usually develop slowly 3. Characteristic putrid odor produced 4. Gas may be present 5. Abscess formation and tissue necrosis common 6. Clindamycin, metronidazole, and chloramphenicol are usually the most effective antimicrobials BACTEROIDES species B. fragilis group a. Species include B. fragilis, B. thetaiotaomicron, B. distasonis, B. vulgatus, and B. ovatus b. Most common clinical infectious isolate although present in relatively lower concentrations in normal fecal isolates c. Grows more rapidly than other non-sporeforming anaerobes d. Unlike other group members, 8. fragilis may contain polysaccharide capsule, conferring added virulence Black pigmented Bacterioides species a. Formerly all B. melaninogenicus subspecies, now separated into separate species i.B.ASACCHAROLYTICUS, found in non-oral infections ii.B.GINGIVALlS, associated with severe periodontal disease iii.B.DENTICOLA, B. MELANINOGENICUS, and B. LOESCHEII predominantly oral isolates iv.B.CORPORIS, found in gastrointestinal and urogenital tracts v.B.INTERMEDIUS, found in oral and other body sites b. Colonies appear tan to black in 2-14 days c. Usually appear as small coccobacilli usually with longer rods d. Important agents in oral, gynecologic, obstetric, and pulmonary infections Therapy a. Antibiotics as mentioned above b. Surgical debridement and drainage E. FUSOBACTERIUM

F. nucleatum a. Most common isolate b. Important agent in oral infections, lung abscess, and other pleuropulmonary infections F. necrophorum a. Important animal pathogen b. In humans, important association with intra-abdominal infections and liver abscesses Most isolates are susceptible to penicillin and cephalosporins ANAEROBIC GRAM-POSITIVE BACILLI 1. Eubacterium lentum of unknown pathogenicity, commonly associated with B. fragilis 2. Eubacterium brachy, E. timidum, E. nodosum prevalent in periodontal infections 3. Propionibacteria normally inhabit skin and gastrointestinal tract 4. Lactobacillus part of mouth and gastrointestinal tract and sometimes predominant vaginal flora 5. Actinomyces-discussed under X. E. ANAEROBIC GRAM-POSITIVE COCCI 1. Peptococcus (corresponding to the facultative Staphylococcus) 2. Peptostreptococcus (corresponding to the facultative Streptococcus) 3. Streptococcus a. S. intermedius most common isolate b. Strains may grow in C02 incubation or air after initial anaerobic isolation 4. Sensitive to penicillin, cephalosporins, clindamycin, and metronidazole ANAEROBIC GRAM-NEGATIVE COCCI 1. Veillonella sp. 2. Acidaminococcus fermentans-normal flora of gut

ORAL MICROBIAL FLORA • • • •

TONGUE DORSAL SURFACE-Steptococcus salivarius TEETH-Streptococcus sanguis, Streptococcus mutans BUCCAL MUCOSA-Streptococcus mitior GINGIVAL CREVICE-Bacteroides melaninogenicus, oral spirochetes