Merja Rautio

Reclassification of Bacteroides putredinis (Weinberg et al., 1937) in a New Genus Alistipes gen. nov., as Alistipes putredinis comb. nov., and Description of Alistipes finegoldii sp. nov., from Human Sources

During studies on the bacteriology of appendicitis in children, we often isolated from inflamed and non-inflamed tissue samples, an unusual bile-resistant pigment-producing strictly anaerobic gram-negative rod. Phenotypically this organism resembles members of Bacteroides fragilis group of species, as it is resistant to bile and exhibits a special-potency-disk pattern (resistance to vancomycin, kanamycin and colistin) typical for the B. fragilis group. However, the production of brown pigment on media containing haemolysed blood and a cellular fatty acid composition dominated by iso-C15:0, suggests that the organism most closely resembles species of the genus Porphyromonas. However, the unidentified organism differs from porphyromonads by being bile-resistant and by not producing butyrate as a metabolic end-product. Comparative 16S ribosomal RNA gene sequencing studies show the unidentified organism represents a distinct sub-line, associated with but distinct from, the miss-classified species Bacteroides putredinis. The clustering of the unidentified bacterium with Bacteroides putredinis was statistically significant, but they displayed > 4% sequence divergence with each other. Chromosomal DNA-DNA pairing studies further confirmed the separateness of the unidentified bacterium and Bacteroides putredinis. Based on phenotypic and phylogenetic considerations, it is proposed that Bacteroides putredinis and the unidentified bacterium from human sources be classified in a new genus Alistipes, as Alistipes putredinis comb. nov. and Alistipes finegoldii sp. nov., respectively. The type strain of Alistipes finegoldii is CCUG 46020(T) (= AHN243(T)).

Role of Porphyromonas gingivalis, Prevotella intermedia, and Prevotella nigrescens in Extraoral and Some Odontogenic Infections

Porphyromonas gingivalis, Prevotella intermedia, and Prevotella nigrescens were isolated from 138 subjects with various infections (intraabdominal, skin and soft-tissue, head and neck, pleuropulmonary, and odontogenic infections and bacteremia). The phenotypic identification of 173 isolates was completed by molecular methods. Arbitrarily primed polymerase chain reaction (AP PCR) analysis was used to determine the genetic similarity of intraindividual P. intermedia/P. nigrescens group isolates recovered from 12 subjects. All 19 P. gingivalis isolates (16 intraabdominal isolates and three odontogenic isolates) hybridized with the P. gingivalis-specific DNA probe. Of the 154 P. intermedia/ P. nigrescens group isolates, 74 were identified as P. intermedia; 78, as P. nigrescens; and 2, as P intermedia/P. nigrescens-like isolates. P. intermedia and P. nigrescens were isolated with equal frequency from patients with all other infections except those with bacteremia, from whom only P. nigrescens isolates were recovered. There were 12 cases in which multiple P. intermedia/ P. nigrescens group isolates were recovered; in nine, only one of the species was isolated, whereas in three, two different species were detected. The intraindividual isolates representing the same species always exhibited identical AP PCR genotypes.

Porphyromonas uenonis sp. nov., a Pathogen for Humans Distinct from P. asaccharolytica and P. endodontalis

ABSTRACT Three Porphyromonas species (Porphyromonas asaccharolytica, P. endodontalis, and the novel species that is the subject of the present report, P. uenonis) are very much alike in terms of biochemical characteristics, such as enzyme profiles and cellular fatty acid contents. P. asaccharolytica is distinguished from the other two species by virtue of production of α-fucosidase and glyoxylic acid positivity. The novel species is difficult to differentiate from P. endodontalis phenotypically and was designated a P. endodontalis-like organism for some time. However, P. endodontalis is recovered almost exclusively from oral sources and also grows poorly on Biolog Universal Agar, both characteristics that are in contrast to those of the other two organisms. Furthermore, P. uenonis is glycerol positive in the Biolog AN Microplate system. Both P. asaccharolytica and P. uenonis are positive by 13 other tests in the Biolog system, whereas P. endodontalis is negative by all of these tests. P. asaccharolytica grew well in both solid and liquid media without supplementation with 5% horse serum, whereas the other two species grew poorly without supplementation. Sequencing of 16S rRNA revealed about 10% divergence between the novel species and P. endodontalis but less than 2% sequence difference between the novel species and P. asaccharolytica. Subsequent DNA-DNA hybridization studies documented that the novel organism was indeed distinct from P. asaccharolytica. We propose the name Porphyromonas uenonis for the novel species. We have recovered P. uenonis from four clinical infections in adults, all likely of intestinal origin, and from the feces of six children.

Characteristics of an Unusual Anaerobic Pigmented Gram-Negative Rod Isolated from Normal and Inflamed Appendices

During our studies of the bacterial etiology of appendicitis, we often isolated a previously undescribed anaerobic gram-negative rod. This organism resembled the Bacteroides fragilis group because it was resistant to bile and because of its special-potency-disk pattern (resistant to vancomycin, kanamycin, and colistin), but unlike the B. fragilis group, this bacterium produced brown pigment on media containing hemolysed blood. The cellular fatty acid pattern, with iso-C15:0 being the predominant acid, was most closely related to the fatty acid profile of Porphyromonas species; however, this organism differed from Porphyromonas species by being bile-resistant and by not producing butyrate as a metabolic endproduct. Enzymatic activities of 31 isolates were determined with use of the API ZYM system and Rosco diagnostic tablets. These profiles were different from those of Prevotella, Porphyromonas, and related species. This organism was isolated from 40% of appendiceal tissue samples; no obvious qualitative or quantitative difference in rates of isolation from patients with inflamed or normal appendices was observed.

Colonic methane production modifies gastrointestinal toxicity associated with adjuvant 5-fluorouracil chemotherapy for colorectal cancer.

Goals: To investigate the association of colonic methane, formed by methanogenic achaea, and pH with gastrointestinal symptoms during colorectal cancer chemotherapy. Background: Adjuvant 5-fluorouracil chemotherapy reduces recurrences in colorectal cancer, but causes severe gastrointestinal toxicity, partly related to disturbed intestinal microbiota. Study: Resected colorectal cancer patients (n=143) were analyzed for colonic methanogenesis and pH before and during the 24 weeks of 5-fluorouracil chemotherapy and for gastrointestinal symptoms during chemotherapy. This study was performed within the setting of an intervention study on the effects of Lactobacillus on chemotherapy-related gastrointestinal toxicity. The site of resected cancer, resection type, stoma, chemotherapy regimen, hypolactasia, and Lactobacillus intervention were considered as possible confounding factors, and multivariate models were constructed. Results: Baseline methane producers had less frequent diarrhea (more than or equal to moderate) during chemotherapy than nonproducers [odds ratio (OR), 0.42; 95% confidence interval (CI), 0.20 to 0.88; P=0.022] and more frequent constipation (OR, 4.56; 95% CI, 2.01 to 10.32; P<0.001). Baseline fecal pH was also associated with symptoms during chemotherapy; higher the pH, the lower the risk of diarrhea (OR, 0.56; 95% CI, 0.31 to 1.02; P=0.058) and higher the risk of constipation (OR, 2.23; 95% CI, 1.35 to 3.68; P=0.002). In multivariate stepwise models, methanogenesis was a significant explaining factor with inverse association with diarrhea and positive association with constipation. Fecal pH, which was significantly associated with methane production, was no longer a significant explaining factor when methanogensis was included in the model. Conclusions: Methane producer status has a role in determining whether patient experiences diarrhea or constipation during 5-fluorouracil therapy. This underscores the importance of intestinal microbiota in the development of intestinal toxicity during 5-fluorouracil therapy.

Colonic methanogenesis in vivo and in vitro and fecal pH after resection of colorectal cancer and in healthy intact colon.

PurposeWe compared colonic methanogenesis in vivo and in vitro as well as fecal pH in healthy subjects and in patients with resected colorectal cancer thus without the possible confounding effects of the tumor.MethodsA total of 144 subjects, 96 with resected colorectal cancer (of whom, 48 were with metastatic disease), 48 healthy subjects with intact colon, were analyzed for breath methane, fecal methanogenesis in vitro and fecal pH. In addition, the association between methanogenesis and pH with cancer site, operation technique and abdominal discomfort was investigated.ResultsIn vivo and in vitro methane measurements were in agreement. The percentage of breath methane excretors and fecal pH did not significantly differ in participants resected for colorectal cancer, either with (46%, 6.76) or without (46%, 6.77) metastatic disease, from healthy participants (40%, 6.80). Breath methane excretors had higher fecal pH than nonexcretors (7.05 versus 6.57, P < 0.001) and less abdominal discomfort (30% versus 54%, P = 0.016). Among patients with resected right-sided cancer (n = 15), there were less breath methane excretors (20%) than among those with resected left-sided cancer (51%, n = 81, P = 0.029) as well as lower fecal pH than among those with resected left-sided cancer (6.27 versus 6.86, P = 0.002) and among healthy subjects (6.80, P = 0.010).ConclusionsPatients with resected colorectal cancer were as frequently methane producers as healthy subjects with intact colon, and there was no difference in their fecal pH. Low methanogenesis was found in patients with abdominal discomfort and is a possible characteristic, along with low fecal pH, to right-sided colorectal cancer.

Screening for Enzymatic, Metabolic, and Fatty Acid Profiles to Characterize the Intestinal Microflora from Stool Specimens

Screening for Enzymatic, Metabolic, and Fatty Acid Profiles to Characterize the Intestinal Microflora from Stool Specimens. MAARIT LONNROTH, MERJA RAUTIO, URPO NIEMINEN, RIITTA KORPELA, TUULA VESA, MAIJA SAXELIN, ANJA SIITONEN, MARTTI FARKKILA, AND HANNELE JOUSIMIES-SOMER. From the Anaerobe Reference Laboratory and the Laboratory of Enteric Pathogens, National Public Health Institute; the Department of Medicine, Division of Gastroenterology, Helsinki University Central Hospital; the Valio Research Centre; and the Foundation for Nutrition Research; Helsinki, Finland