Bacteroides Caccae Sp
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INTERNATIONAL JOURNALOF SYSTEMATIC BACTERIOLOGY,OCt. 1986, p. 499-501 Vol. 36, No. 4 0020-77 13/86/WWB-O3$02.00/0 Copyright 0 1986, International Union of Microbiological Societies Bacteroides caccae sp. nov., Bacteroides merdae sp. nov., and Bacteroides stercoris sp. nov. Isolated from Human Feces JOHN L. JOHNSON, W. E. C. MOORE, AND LILLIAN V. H. MOORE* Department of Anaerobic Microbiology, College of Agriculture and Life Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 Three new saccharolytic Bacteroides species that have DIVAS with guanine-plus-cytosine contents of 40 to 46 mol%, produce maor amounts of succinate, and were isolated principally from human feces are described: BacCeroides caccae, with ATCC 43185 as the type strain; B. merdae, with ATCC 43184 as the type strain; and B. stercoris, with ATCC 43183 as the type strain. These groups previously have been referred to as the “3452A,” “T4-1,” and “subsp. a” groups, respectively. In 1978, Johnson (3) and Johnson and Ault (4) described, reaction. Strains also were characterized with the RapID- but did not name, three DNA homology groups of sac- ANA (Innovative Diagnostics Systems, Inc., Atlanta, Ga.) charolytic anaerobic gram-negative rods that grow well in panels following the directions of the manufacturer. Antibi- 20% bile and form succinate as a major product: groups otic susceptibility results were determined by the methods of “3452A,” “T4-1,” and “subsp. a.” Except for a few strains Wilkins and Thiel (6). Any reaction that was atypical af of group “3452A” from clinical specimens, all strains stud- results obtained with other strains in the group was repeated. ied were isolated from fecal samples. Because the strains are nonmotile, anaerobic, gram- RESULTS AND DISCUSSION negative rods, produce major amounts of succinate from glucose, have DNA with a guanine-plus-cytosine (G + C) Bacteroides caccae (cac’cae, pronounced kak’ke) Gr. n. content of 40 to 46 mol% (3), and cluster with Bacteroides kakke feces; NL gen. n. caccae of feces, referring to source fragilis and related species by RNA homology studies (3, of isolate. Previously referred to as “3452A” DNA homol- they are members of the genus Bacteroides (2). For them we ogy group (3, 4). propose the names Bacteroides caccae, Bacteroides Cells of the type strain from peptone-yeast extract-glucose merdae, and Bacteroides stercoris. broth cultures are 1.4 to 1.6 by 2.5 to 12 pm and occur singly or in pairs. Cells may appear vacuolated or beaded in strains MATERIALS AND METHODS from broth cultures in media with a fermentable carbohy- drate. Strains. Strains were from the Virginia Polytechnic Insti- Surface colonies on supplemented brain heart infusion tute and State University Anaerobe Laboratory collection blood agar plates (1) incubated for 48 h are 0.5 to 1 mm in and, with the exception of OC-9, are the same strains of diameter, circular, entire, convex, gray, translucent, shiny, Bacteroides homology groups (“3452A,” “T4-1,” and and smooth. Rabbit blood may be slightly hemolyzed. “subsp. a”) studied by Johnson (3) and Johnson and Ault Glucose broth cultures are turbid with a smooth sediment (4). Strain OC-9 could not be recovered from storage and and have a final pH of 5.0 to 5.2. Strains grow equally well at was omitted from this study. The type strain (3452A) and 18 30 and 37°C but less well at 25 and 45°C. The type strain other strains of Bacteroides caccae were isolated from reduces neutral red and does not produce hydrogen sulfide. human feces; one strain (PrCvot 2302) was isolated from a From peptone-yeast extract-glucose broth cultures, major blood culture. The type strain (T4-1) and eight other strains amounts of succinate and acetate, often with trace amounts of B. merdae were isolated from human feces; one was of propionate and isovalerate, are detected; only a trace of isolated from hog cecum contents. The type strain (B5-21) hydrogen is detected in headspace gas. Pyruvate is con- and 17 other strains of B. stercoris were isolated from human verted to acetate. Lactate and threonine are not utilized. feces. Other characteristics of the species are given in Table 1. Methods of characterization. Cultures for tests for fermen- Characteristics by which B. caccae can be differentiated tation of sugars, hydrolysis of esculin, digestion of gelatin, from phenotypically similar Bacteroides species are given in milk, and meat, reduction of nitrate and resazurin, growth in Table 2. 20% bile and 6.5% NaCl, and production of catalase, urease, Type strain: ATCC 43185 (VPI 3452A). The G + C content hydrogen, and fermentation acids were grown in prereduced of the DNA is 40 mol% for the type strain and 40 to 42 mol% anaerobically sterilized media, and tests were performed as for the 20 other strains examined (3). described in the Virginia Polytechnic Institute and State Bacteroides merdae (mer’dae) L. gen. n. merdae of feces, University Anaerobe Laboratory Manual (1). Neutral red referring to source of isolate. Previously referred to as reduction was tested in peptone-yeast extract-fructose me- “T4-1” DNA homology group (3, 4). dium containing 3 mg of neutral red per 100 ml of medium Cells of the type strain from peptone-yeast extract broth (the neutral red was added from a suspension of 100 ml of cultures are 1.6 by 3.1 to 12 pm and occur singly or in pairs neutral red in 100 ml of 60% aqueous absolute alcohol); or short chains. disappearance of the red color was interpreted as a positive Surface colonies on supplemented brain heart infusion blood agar plates (1) are 0.5 to 1.0 mm in diameter, circular to slightly irregular, entire, convex, white, shiny, and * Corresponding author. smooth. Rabbit blood is slightly hemolyzed. 499 500 JOHNSON ET AL. INT. J. SYST.BACTERIOL. TABLE 1. Reactions of B. caccae, B. merdue, and B. stercorisn B. caccae B. merdae B. stercoris 19 Other strains 9 Other strains 17 Other strains Characteristic ATCC ATCC % ATCC % % % 43185T % Weakly 43184T % Weakly 43183T Positive reactive Positive reactive Positive 2::;: Acid from: Am ygdalin - 5 21 0 33 0 0 L- Arabinose A 100 11 0 35 0 Cellobiose A 74 10 0 89 24 6 Dextrin W 42 26 100 100 Esculin W 90 10 0 67 65 24 Glycogen W 16 5 0 0 94 0 Gum arabic - 0 16 0 0 0 0 Inulin A 100 0 89 100 Larch arabinogalactan A 100 44 56 0 0 Melezitose A 68 26 100 0 0 Melibiose A 100 100 6 6 (D +)-Ranose A 100 100 100 Rhamnose A 63 0 67 33 100 D-Ribose A 100 22 44 76 12 Salicin A 42 10 78 22 6 0 Starch W 84 16 89 11 100 Trehalose A 100 100 0 0 Xylan - 0 5 0 0 47 6 Hydrolysis of esculin + 100 100 94 0 Digestion of gelatin W 5 37 0 33 0 6 Production of Indole - 5 0 0 0 loob Catalase - 0 0 11 0 0 0 Hydrogen WC 0 95" 0 11" 0 6' Phosphatase + 100 25 100 P-Galactosidase + 100 100 18 a-Glucosidase + 89 38 100 P-Glucosidase + 100 25 41 a-Galactosidase + 100 100 0 a-Fucosidase + 95 0 53 Tetrazolium reduction V 58 0 0 Arninopeptidase for: Glycine + 100 100 6 Proline V 5 0 0 Phenylalanine + 74 25 0 Arginine + 100 100 0 Serine + 74 25 0 Pyrrolidone - 0 38 0 Susceptibility tod: Chloramphenicol + 100 100 100 Clindamycin + 100 100 100 Penicillin G - 5 0 6 Tetracycline - 47 67 76 (I + , Positive reaction. pH below 5.5 (acid production), or susceptible (antibiotics). -, Negative reaction. pH 5.7 or above, or resistant (antibiotics). A, pH below 5.5. v, Different reaction in multiple tests. w, Weak reaction or pH 5.5 to 5.7 (acid production). All strains grow well in peptone-yeast extract-glucose broth with 20% bile and produce acid from D-fructose, glucose, D-galactose, lactose, maltose, (D+)-mannose, sucrose, and D-xylose; all strains hydrolyze esculin and produce N-acetylglucosamine and leucylglycine aminopeptidase. No strain produces acid from m-erythritol, glycerol, inositol, mannitol, or D-sorbitol; lecithinase or lipase on egg yolk agar; urease in peptone-yeast extract-urea broth; or acetylmethylcarbinol. No strain hydrolyzes hippurate, reduces nitrate to nitrite, digests milk or meat, or produces more than a trace amount of growth in peptone-yeast extract-glucose broth with 6.5% NaCl. Only 76% of strains are positive in the RapID-ANA panels. Trace to 0.1% hydrogen is detected. Test concentrations of antibiotics: chloramphenicol, 12 bg/ml; clindamycin, 1.6 p,g/ml; penicillin G, 2 U/ml; tetracycline, 6 Fg/ml. Glucose broth cultures are turbid with a smooth sediment gas. Pyruvate is converted to acetate and propionate. Lac- and have a final pH of 5.3. The optimum temperature for tate, threonine, and gluconate are not utilized. growth is 37°C. The type strain reduces neutral red and Other characteristics of the species are given in Table 1. resazurin and produces hydrogen sulfide after incubation for Characteristics by which B. merdue can be differentiated 5 days. from phenotypically similar Bucteroides species are given in From peptone-yeast extract-glucose broth cultures, major Table 2. a.mounts of succinate and acetate, often with trace amounts Type strain: ATCC 43184 (VPI T4-1). The G + C content of propionate, isobutyrate, or isovalerate, are detected; no of the DNA is 44 mol% for the type strain and 43 to 46 mol% hydrogen, or only a trace amount, is detected in headspace for the nine other strains examined (3).