Marja-Liisa Väisänen

Gastrointestinal Microflora Studies in Late-Onset Autism

Some cases of late-onset (regressive) autism may involve abnormal flora because oral vancomycin, which is poorly absorbed, may lead to significant improvement in these children. Fecal flora of children with regressive autism was compared with that of control children, and clostridial counts were higher. The number of clostridial species found in the stools of children with autism was greater than in the stools of control children. Children with autism had 9 species of Clostridium not found in controls, whereas controls yielded only 3 species not found in children with autism. In all, there were 25 different clostridial species found. In gastric and duodenal specimens, the most striking finding was total absence of non-spore-forming anaerobes and microaerophilic bacteria from control children and significant numbers of such bacteria from children with autism. These studies demonstrate significant alterations in the upper and lower intestinal flora of children with late-onset autism and may provide insights into the nature of this disorder.

In Vitro Activities of OPT-80 and Comparator Drugs against Intestinal Bacteria

ABSTRACT The activities of OPT-80 against 453 intestinal bacteria were compared with those of seven other drugs. OPT-80 showed good activity against most clostridia, staphylococci, and enterococci, but streptococci, aerobic and facultative gram-negative rods, anaerobic gram-negative rods, and Clostridium ramosum were resistant. Poor activity against anaerobic gram-negative rods may maintain colonization resistance.

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.

Cetobacterium somerae sp. nov. from Human Feces and Emended Description of the Genus Cetobacterium

Phenorypic and phylogenetic studies were performed on four isolates of an unidentified gram-negative, microaerotolerant, non-spore-forming, rod-shaped bacterium isolated from the feces of children. The unknown organism was bile resistant and produced acetic acid as the major end product of metabolism of peptides and carbohydrates. It possessed a low DNA G + C content of 31 mol %. Comparative 16S rRNA gene sequencing demonstrated that the four isolates were phylogenetically identical (100% 16S rRNA sequence similarity) and represent a hitherto unknown sub-line within the genus Cetobacterium. The novel bacterium displayed approximately 5% sequence divergence with Cetobacterium ceti, and can be readily distinguished from the latter by physiological and biochemical criteria. Based on phylogenetic and phenotypic evidence, it is proposed that the unknown fecal bacterium be classified in the genus Cetobacterium, as Cetobacterium somerae sp. nov. The proposed type strain of Cetobacterium somerae is WAL 14325(T) (ATCC BAA-474(T) = CCUG 46254T).

“Bacteroides goldsteinii sp. nov.” Isolated from Clinical Specimens of Human Intestinal Origin

ABSTRACT Phenotypic and phylogenetic studies were performed on an unknown gram-negative, strictly anaerobic, rod-shaped bacterium isolated from human clinical specimens. This organism was indole negative, resistant to 20% bile, produced acetic and a lesser amount of succinic acids as the major end products of glucose metabolism, and possessed a G+C content of approximately 43 mol%. Comparative 16S rRNA gene sequencing demonstrated that the unidentified bacterium was a member of the Cytophaga-Flavobacter-Bacteroides phylum of gram-negative bacteria and formed a close association (with an average sequence similarity of 93.6%) with the second subcluster of the Porphyromonas cluster in the Bacteroides subgroup. Phylogenetically and phenotypically it resembled Bacteroides merdae; however, a 16S rRNA gene sequence divergence of approximately 5.5% between the unknown bacterium and B. merdae, as well as distinguishable biochemical characteristics, demonstrate that the unknown bacterium is genotypically and phenotypically distinct and represents a previously unknown subline within the Porphyromonas phylogenetic cluster. Furthermore, a DNA-DNA reassociation value of 17.8% between isolates WAL 12034T (the type strain of this novel taxon) and ATCC 43184T (B. merdae type strain) also documented the separateness of the unknown species and B. merdae. Based on the phenotypic and phylogenetic findings, a new species, “Bacteroides goldsteinii sp. nov,” is proposed. The G+C content of the DNA is 43 mol% for Bacteroides. The type strain of “B. goldsteinii” is WAL 12034T (= CCUG 48944T = ATCC BAA-1180T).

Beta-lactamase production in Prevotella intermedia, Prevotella nigrescens, and Prevotella pallens genotypes and in vitro susceptibilities to selected antimicrobial agents.

ABSTRACT The present study investigated the β-lactamase production of 73Prevotella intermedia, 84 Prevotella nigrescens, and 14 Prevotella pallens isolates and their in vitro susceptibilities to six antimicrobial agents. TheP. intermedia and P. nigrescens isolates were recovered from oral and extraoral samples obtained from subjects in two geographic locations from 1985 to 1995. The clonality of the β-lactamase-positive and β-lactamase-negative isolates and the clustering of the genotypes were studied by arbitrarily primed-PCR fingerprinting. β-Lactamase production was detected in 29% ofP. intermedia isolates, 29% of P. nigrescensisolates, and 57% of P. pallens isolates. No difference in the frequencies of β-lactamase production by P. intermedia and P. nigrescens between isolates from oral and extraoral sites, between isolates obtained at different time periods, or between P. intermedia isolates from different geographic locations was observed. However, the P. nigrescens isolates from the United States were significantly more frequently (P = 0.015) β-lactamase positive than those from Finland. No association between the genotypes and β-lactamase production or between the genotypes and the sources of the isolates was found. The penicillin G MICs at which 90% of the isolates were inhibited were 8 μg/ml for P. intermedia, 8 μg/ml for P. nigrescens, and 16 μg/ml for P. pallens. For the β-lactamase-negative isolates, the corresponding values were 0.031, 0.031, and 0.125 μg/ml, and for the β-lactamase-positive isolates, the corresponding values were 16, 8, and 32 μg/ml. All isolates were susceptible to amoxicillin-clavulanate, cefoxitin, metronidazole, azithromycin, and trovafloxacin. The MICs of amoxicillin-clavulanate and cefoxitin were relatively higher for the β-lactamase-positive population than for the β-lactamase-negative population.

Physical, chemical and microbiological water characteristics associated with the occurrence of Legionella in cooling tower systems

Abstract The occurrence of Legionella in water of 30 cooling tower systems was studied, as well as the relationship of its occurrence with the physical, chemical and microbiological characteristics of the waters. The samples were concentrated by membrane filtration and one part of the concentrate was acid washed. Three types of culture media, MWY, CCVC and BCYEα were used. Fourteen (47%) of the cooling systems were Legionella -positive. Numbers of Legionella in the positive systems varied between 50 and 490,000 cfu/l. Legionella pneumophila was the dominant isolate, and the serogroups 6 and 1 were the commonest ones. There was no statistically significant difference in mean water temperature between the Legionella -positive (27°C) and -negative (24°C) systems. The total number of bacteria (AODC) was lower in the Legionella -positive than in the negative systems. Also the nutrient concentrations were generally lower in the Legionella -positive cooling systems. The results suggest that different factors regulate the occurrence of Legionella than that of overall bacterial populations in the cooling tower systems.

Porphyromonas somerae sp. nov., a Pathogen Isolated from Humans and Distinct from Porphyromonas levii

ABSTRACT Porphyromonas levii is an anaerobic, pigmented gram-negative bacillus originally isolated from bovine rumen. We describe 58 human clinical strains of P. levii-like organisms, isolated from various human clinical specimens that are phenotypically similar to the type strain of P. levii, a rumen isolate (ATCC 29147). Our biochemical, comparative 16S rRNA sequence analyses, and DNΑ-DNA relatedness studies indicate that the human P. levii-like organisms are similar to each other but genetically different from the P. levii type strain isolated from bovine rumen. We therefore propose the name Porphyromonas somerae to encompass the human P. levii-like organisms. P. somerae was predominantly isolated from patients with chronic skin and soft tissue or bone infections, especially in the lower extremities.

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.

Study of the In Vitro Activities of Rifaximin and Comparator Agents against 536 Anaerobic Intestinal Bacteria from the Perspective of Potential Utility in Pathology Involving Bowel Flora

ABSTRACT Rifaximin, ampicillin-sulbactam, neomycin, nitazoxanide, teicoplanin, and vancomycin were tested against 536 strains of anaerobic bacteria. The overall MIC of rifaximin at which 50% of strains were inhibited was 0.25 μg/ml. Ninety percent of the strains tested were inhibited by 256 μg/ml of rifaximin or less, an activity equivalent to those of teicoplanin and vancomycin but less than those of nitazoxanide and ampicillin-sulbactam.