Leptotrichia species in human infections II.

Leptotrichia species are non-motile facultative anaerobic/anaerobic bacteria that are found mostly in the oral cavity and some other parts of the human body, in animals, and even in ocean sediments. Valid species include L. buccalis, L. goodfellowii, L. hofstadii, L. honkongensis, L. shahii, L. trevisanii, and L. wadei. Some species require serum or blood for growth. All species ferment carbohydrates and produce lactic acid that may be involved with tooth decay. Acting as opportunistic pathogens, they are involved in a variety of diseases, and have been isolated from immunocompromised but also immunocompetent individuals. Mucositis, oral lesions, wounds, and abscesses may predispose to Leptotrichia septicemia. Because identification of Leptotrichia species by phenotypic features occasionally lead to misidentification, genetic techniques such as 16S rRNA gene sequencing is recommended. Early diagnosis and treatment of leptotrichia infections is important for positive outcomes. Over the last years, Leptotrichia species have been associated with several changes in taxonomy and new associations with clinical diseases. Such changes are reported in this updated review.

Osteoradionecrosis contains a wide variety of cultivable and non-cultivable bacteria.

BACKGROUND: Direct microscopy, anaerobic culture and DNA-DNA hybridization have previously demonstrated an association between microorganisms and osteoradionecrosis (ORN). The purpose of our study was to use culture independent molecular techniques to detect bacteria in necrotic bone lesions of the mandible after radiation therapy. DESIGN: Bacterial DNA was extracted from eight deep medullar specimens from resected mandibles (six cases), including one patient with relapse. 16S rRNA genes were PCR amplified, cloned, transformed into Escherichia coli and sequenced to determine species identity and closest relatives. RESULTS: From the analysis of 438 clones, 59 predominant species were detected, 27% of which have not been cultivated. The predominant species detected from radionecrotic mandibles were Campylobacter gracilis, Streptococcus intermedius, Peptostreptococcus sp. oral clone FG014, uncultured bacterium clone RL178, Fusobacterium nucleatum, and Prevotella spp. The study demonstrated intersubject variability of the bacteria present in ORN. In contrast to the diverse bacterial profile detected in primary infection, only a few members of the oral indigenous flora were identified from the relapse case. CONCLUSIONS: Diverse bacterial profiles in specimens of ORN in marrow spaces of the mandible were detected by culture independent molecular techniques. To better understand the pathogenesis and to improve the therapy of the infection, detection of all members of the complex bacterial flora associated with ORN is necessary.

Bacterial diversity in aortic aneurysms determined by 16S ribosomal RNA gene analysis.

BACKGROUND: Aortic aneurysms are common vascular conditions that cause considerable morbidity and mortality. Understanding of the mechanisms involved in the pathogenesis of the condition remains limited. Recently, infection has been suggested as possible contributor in the development of the disease. The aim of the present study was to examine aortic aneurysms for the presence of bacterial DNA using polymerase chain reaction (PCR) targeting the 16S ribosomal RNA (rRNA) gene, followed by cloning and sequencing. METHODS: Universal eubacterial primers were used to amplify 16S rRNA bacterial genes in 10 specimens from arterial walls of aortic aneurysms. Subsequently, PCR amplicons were cloned into Escherichia coli and sequencing of the cloned inserts was used to determine species identity or closest relatives by comparison with known sequences in GenBank. RESULTS: Sequences of Stenotrophomonas spp., including S. maltophilia (formerly Pseudomonas homology group V) were detected in six aneurysm samples. Propionibacterium acnes was identified in five samples, and Brevundimonas diminuta (formerly P. diminuta) in four samples. Other species previously assigned to the Pseudomonas genus such as Comamonas testosteroni, Delftia acidovorans, Burkholderia cepacia, Herbaspirillum sp., and Acidovorax sp. were also detected. Some clones fell into other environmental species, including Methylobacterium sp. and Bradyrhizobium elkanii, and others represented bacteria that have not yet been cultivated. DNA sequences from oral bacteria, including Streptococcus sanguinis, Tannerella forsythia, and Leptotrichia buccalis were detected. Sequences from Prevotella melaninogenica and Lactobacillus delbrueckii, which are commonly found in both mouth and gastrointestinal tract, were also detected. Additional species included Dermacoccus spp. and Corynebacterium vitaeruminis. CONCLUSIONS: A wide variety of bacteria, including oral bacteria, was found to colonize aortic aneurysms and may play a role in their development. Several of these microorganisms have not yet been cultivated. CLINICAL RELEVANCE: Although Chlamydophila pneumoniae has been detected in aneurysmal walls, its exact role in the condition remains inconclusive. Overall, there is scarce information about the role of microorganisms in aneurysmal disease. In the present study, we used molecular genetics to detect a diversity of bacteria in arterial walls of aortic aneurysms. The presence of multiple microorganisms in aneurysmal disease may have implications for chemoprophylaxis and antibiotic treatment if directed only at C.pneumoniae.

Genetic relatedness of oral yeasts within and between patients with marginal periodontitis and subjects with oral health.

BACKGROUND: Yeasts are found in periodontal pockets at a frequency of 15-21%. However, the genetic relatedness of oral yeasts within and between patients with marginal periodontitis is not clear. OBJECTIVES: Assay genetic relatedness of oral yeasts from marginal periodontitis patients and oral health subjects, as well as genetic relatedness of yeasts from different oral sites in these two groups of participants. MATERIAL AND METHODS: Yeast isolates were collected from 23 marginal periodontitis patients and 19 oral health subjects. Random amplified polymorphic DNA (RAPD) fingerprinting and the Dendron computer-assisted program for gel analyses were applied for estimation of genetic relatedness of yeasts. RESULTS: The similarity coefficient (S(AB)) of the marginal periodontitis group ranged from 0.49 to 1.00 with an average of 0.64 +/- 0.11, whereas the S(AB) of the oral health group ranged from 0.62 to 1.00 with an average of 0.72 +/- 0.07. Three genetic clusters and 73 genotypes were obtained from the marginal periodontitis group, whereas three genetic clusters and 55 genotypes were found in the oral health group. In the pooled dendrogram, 57% of the yeast isolates and the type strain of Candida albicans fell in a major cluster V. There were no significant differences between the frequencies of clusters from the different oral sites within the two participant groups. CONCLUSIONS: Genetically heterogeneous yeasts were found in the oral cavities of marginal periodontitis patients and oral health subjects. Similar genetic clustering patterns were obtained from the yeasts of the two groups, with cluster V being most predominant. Yeasts of the marginal periodontitis group were more genetically diverse than yeasts of the oral health group, and some yeasts of the marginal periodontitis group exhibited unique genetic patterns. There was no clear association between yeast genetic clusters and oral sites in the two participant groups.

Genetic diversity of Leptotrichia and description of Leptotrichia goodfellowii sp. nov., Leptotrichia hofstadii sp. nov., Leptotrichia shahii sp. nov. and Leptotrichia wadei sp. nov.

Sixty strains of Gram-negative, anaerobic, rod-shaped bacteria from human sources initially assigned to Leptotrichia buccalis (n=58) and 'Leptotrichia pseudobuccalis' (n=2) have been subjected to polyphasic taxonomy. Full-length 16S rDNA sequencing, DNA-DNA hybridization, RAPD, SDS-PAGE of whole-cell proteins, cellular fatty acid analysis and enzymic/biochemical tests supported the establishment of four novel Leptotrichia species from this collection, Leptotrichia goodfellowii sp. nov. (type strain LB 57(T)=CCUG 32286(T)=CIP 107915(T)), Leptotrichia hofstadii sp. nov. (type strain LB 23(T)=CCUG 47504(T)=CIP 107917(T)), Leptotrichia shahii sp. nov. (type strain LB 37(T)=CCUG 47503(T)=CIP 107916(T)) and Leptotrichia wadei sp. nov. (type strain LB 16(T)=CCUG 47505(T)=CIP 107918(T)). Light and electron microscopy showed that the four novel species were Gram-negative, non-spore-forming and non-motile rods. L. goodfellowii produced arginine dihydrolase, beta-galactosidase, N-acetyl-beta-glucosaminidase, arginine arylamidase, leucine arylamidase and histidine arylamidase. L. shahii produced alpha-arabinosidase. L. buccalis and L. goodfellowii fermented mannose and were beta-galactosidase-6-phosphate positive. L. goodfellowii, L. hofstadii and L. wadei were beta-haemolytic. L. buccalis fermented raffinose. With L. buccalis, L. goodfellowii showed 3.8-5.5 % DNA-DNA relatedness, L. shahii showed 24.5-34.1 % relatedness, L. hofstadii showed 27.3-36.3 % relatedness and L. wadei showed 24.1-35.9 % relatedness. 16S rDNA sequencing demonstrated that L. hofstadii, L. shahii, L. wadei and L. goodfellowii each formed individual clusters with 97, 96, 94 and 92 % similarity, respectively, to L. buccalis.