Search

The misuse of antibiotics in our daily lives has led to the emergence of antimicrobial resistance. As a result, many antibiotics are becoming ineffective. This phenomenon is linked with high rates of mortality and morbidity. Therefore, new approaches are required to address this major health issue. Leptotrichia buccalis is a Gram-negative, rod-shaped bacterium which normally resides in the oral and vaginal cavities. It is an emerging bacterial pathogen which is developing new antibiotic-resistance mechanisms. No approved vaccine is available against this pathogen, which is a cause for growing concern. In this study, an in silico-based, multi-epitopes vaccine against this pathogen was designed by applying reverse vaccinology and immunoinformatic approaches. Of a total of 2193 predicted proteins, 294 were found to be redundant while 1899 were non-redundant. Among the non-redundant proteins, 6 were predicted to be present in the extracellular region, 12 in the periplasmic region and 23 in the outer-membrane region. Three proteins (trypsin-like peptidase domain-containing protein, sel1 repeat family protein and TrbI/VirB10 family protein) were predicted to be virulent and potential subunit vaccine targets. In the epitopes prediction phase, the three proteins were subjected to B- and T-cell epitope mapping; 19 epitopes were used for vaccine design. The vaccine construct was docked with MHC-I, MHC-II and TLR-4 immune receptors and only the top-ranked complex (based on global energy value) was selected in each case. The selected docked complexes were examined in a molecular dynamic simulation and binding free energies analysis in order to assess their intermolecular stability. It was observed that the vaccine binding mode with receptors was stable and that the system presented stable dynamics. The net binding free energy of complexes was in the range of -300 to -500 kcal/mol, indicating the formation of stable complexes. In conclusion, the data reported herein might help vaccinologists to formulate a chimeric vaccine against the aforementioned target pathogen.

Gmür R, Wyss C, Xue Y, Thurnheer T, Guggenheim B. Gingival crevice microbiota from Chinese patients with gingivitis or necrotizing ulcerative gingivitis. Eur J Oral Sci 2004; 112: 33–41.© Eur J Oral Sci, 2004 The objective of this study was to quantitatively compare the bacterial population structure in plaque from the gingival margin of two groups of 21 Chinese patients with gingivitis or necrotizing ulcerative gingivitis (NUG). Subjects were recruited in four dental clinics in Eastern China. Samples were quantitatively assessed by immunofluorescence and fluorescent in situ hybridization for taxa known to be associated with periodontal diseases. The analyses showed that the fusiform taxa ( Fusobacterium nucleatum/Fusobacterium periodonticum, Leptotrichia buccalis, Tannerella forsythensis, and Capnocytophaga sp.), Campylobacter rectus, Prevotella intermedia, Prevotella nigrescens, Selenomonas sputigena, and treponemes were present in both groups with high prevalence. Porphyromonas gingivalis and Actinomyces gerencseriae were much more prevalent in the NUG group. Quantitatively, most taxa, including P. gingivalis, F. nucleatum and the treponemes, accounted, on average, for < 3% of the total bacterial cell number. Only P. intermedia/P. nigrescens, P. gingivalis, S. sputigena, A. gerencseriae, and the sum of all monitored suspected periodontal pathogens were significantly increased in the NUG group. The present study demonstrates for both groups a highly diverse plaque composition and suggests that, etiologically, the overall concentration and the concerted effects of the entire group of opportunistic pathogens thriving in NUG-associated plaque are of prime importance. [ABSTRACT FROM AUTHOR]

Phospho-β-galactosidase (P-β-gal; EC 3.2.1.85) is induced during growth of Leptotrichia buccalis ATCC 14201 on lactose and lactulose. The enzyme has been purified to electrophoretic homogeneity (Mr∼53 kDa, pI∼4.8), and kinetic parameters have been determined using the chromogenic analog o-nitrophenyl-β-D-galactopyranoside-6-phosphate as substrate. Both ATP and galactose-6-phosphate are inhibitors of P-β-gal activity. Microsequence analysis has identified the first 32 residues from the N-terminus of the protein, and by comparative sequence alignment the enzyme can be assigned to Family 1 of the glycosylhydrolase superfamily. Polyclonal antibody against the enzyme permits the highly specific immuno-detection of P-β-gal in cell-free extracts of L. buccalis. Although described previously in several Gram-positive species, this is the first reported purification of P-β-gal from a Gram-negative organism. [Copyright &y& Elsevier]

Lipopolysaccharides (LPS) from Leptotrichia buccalis, strains L11, ATCC 14201 and ATCC 19616 were partially degraded with 1% acetic acid. The acid soluble polysaccharides were subjected to gel filtration. These experiments showed that the carbohydrate moiety of LPS from ATCC 14201 and ATCC 19616 were similar, consisting of a core oligosaccharide unsubstituted by 0-side chains containing galactose, glucose and D-glycero-D-manno-heptose as neutral sugars. The core analogous fraction isolated from L11 LPS contained the same three neutral sugars, hut in different ratios. [ABSTRACT FROM AUTHOR]

We present the case of a 64-year-old previously healthy man admitted for long evoluating fever. Buccal examination showed severe parodontitis. Blood cultures were positive for Leptotrichia buccalis and computed abdominal tomography discovered a hepatic abscess. So far, only exceptional cases of systemic diseases associated with Leptotrichia buccalis infections have been described in immunocompetent patients. Thus, in cases of severe parodontitis and long evoluating fever, attention must be paid to secondary anaerobic infections even in immunocompetent subjects. [ABSTRACT FROM AUTHOR]