A bacteriological survey of an oyster-growing area: The Oualidia Lagoon,Morocco

A 3-year bacteriological survey of an oyster-growing area in Morocco, where the Japanese oyster (Crassostrea gigas) is grown, showed that the contamination of this lagunar ecosystem was not continuous but intermittent and that animal manure and human recreational activities were important sources of pollution. The major source of contamination was of animal origin, except during the summer, when human contamination prevailed.     

Thiol-stimulated secretion of riboflavin and porphyrins by Escherichia coli

Abstract Streptococcus lactis strain IL594 contains 9 plasmids, designated pIL1 to pIL9. On the basis of protoplast-induced curing experiments we showed that derivatives containing pIL7 (31 kb) were resistant to UV-irradiation while derivatives lacking pIL7 were sensitive. The pIL7-determined UV-protection was confirmed by cotransfer of the plasmid and of the character into a plasmid-free derivative of S. lactis IL594. Moreover, prophage induction required higher UV-fluence in this derivative carrying pIL7 than in the plasmid-free strain. This is the first report of a plasmid-mediated UV-protection in group N streptococci.     

Rapid Identification of Mutans Streptococcal Species

Mutans streptococci are considered the predominant pathogens in dental caries. Three methods, i.e. dot blot hybridization analysis, PCR analysis and SDS-blue dextran-PAGE, were examined for identifying mutans streptococcal species. In dot blot hybridization, DNA probe derived from the dextranase gene (dexA) of Streptococcus mutans hybridized with different intensities under the condition of low stringency against each species of mutans streptococci although the dexA probe was specific for S. mutans under the condition of high stringency. Oligonucleotide primers for polymerase chain reaction (PCR) were designed on the basis of the dexA DNA sequence. The primers amplified species-specific PCR products in the reference species (15 strains of 5 species) of mutans streptococci. An electrophoretic profile of dextranases from the mutans streptococci on SDS-blue dextran-PAGE also showed species-specific behavior. These results suggest that the three identification methods examined here are useful for distinguishing the species of mutans streptococci and also indicate that PCR analysis is suitable for simple, rapid and reliable identification of mutans streptococcal species.     

Relationships between mutans streptococci and perceived treatment need of primary root-caries lesions.

A total of 447 primary root-caries lesions from 169 dental patients was studied to determine the relationships between mutans streptococci and the perceived treatment need of primary root-caries lesions. Samples of this altered dentine for microbiological culture were obtained. Lesions were classified into 5 treatment categories; soft and restore, leathery and restore, leathery and debride of caries, leathery and treat chemotherapeutically, and hard, to receive no treatment. The total numbers of mutans streptococci decreased significantly with decreased treatment need. The percentage of mutans streptococci from lesions requiring no treatment was significantly less than from lesions requiring treatment. The frequency of isolation of mutans streptococci was significantly greater from lesions requiring more treatment. Significantly more lesions containing > 10² mutans streptococci were distributed in the groups with a greater perceived treatment need or with larger dimensions occlusogingivally and/or mesio-distally or bucco-lingually or with a closer proximity to the gingival margin.     

Serological identification of group D streptococci using commercial antisera

Three commercial group D streptococcal antisera were tested for the serological identification of 100 group D enterococci; 20 Streptococcus bovis; 5 isolated from each of the following streptococcal groups: A, B, C and G; and 3 isolates from serological group F. Antisera from Difco Laboratories, BBL, and Wellcome Reagents Limited were used in the classic capillary tube precipitin test on extracts prepared using the Rantz and Randall procedure. No false positive precipitin reactions were observed. Of the enterococcal isolates, all 100 reacted with the Wellcome, 99 reacted with the BBL, and 96 reacted with the Difco group D antisera. However, of the 20 S. bovis isolates, only 2 reacted with the BBL, and 1 reacted with both the Difco and the Wellcome antisera. Each antiserum was then used to prepare staphylococcal coagglutination (CoA) reagents and each isolate was subsequently tested. A simple extraction procedure was performed by suspending colonies of an isolate in a loopful of salin on a microscope slide and gently heating the slide directly in the flame of a Bunsen burner. All 100 enterococci and all 20 S. bovis gave positive results with the BBL and the Wellcome CoA reagents. Using the Difco reagent, 2 S. bovis isolates failed to produce postitive results. No false positive results were observed with the non-Group D isolates. Our results indicate that the CoA technique using commercial group D antisera may provide faster and sometimes more sensitive serological identification than the classic capillary tube precipitin test.     

Distribution of Streptococcus troglodytae and Streptococcus dentirousetti in chimpanzee oral cavities

The aim of this study was to analyze the distribution and phenotypic properties of the indigenous streptococci in chimpanzee (Pan troglodytes) oral cavities. Eleven chimpanzees (aged from 9 to 44 years, mean ± SD, 26.9 ± 12.6 years) in the Primate Research Institute of Kyoto University were enrolled in this research and brushing bacterial samples collected from them. Streptococci were isolated from the oral cavities of all chimpanzees. The isolates (n = 46) were identified as thirteen species by 16S rRNA genes analysis. The predominant species was Streptococcus sanguinis of mitis streptococci from five chimpanzees (45%). Mutans streptococci were isolated from six chimpanzees (55%). The predominant species in the mutans streptococci were Streptococcus troglodytae from four chimpanzees (36%), this species having been proposed as a novel species by us, and Streptococcus dentirousetti from three chimpanzees (27%). Streptococcus mutans was isolated from one chimpanzee (9%). However, Streptococcus sobrinus, Streptococcus macacae and Streptococcus downei, which are indigenous to human and monkey (Macaca fasciclaris) oral habitats, were not isolated. Of the mutans streptococci, S. troglodytae, S. dentirousetti, and S. mutans possessed strong adherence activity to glass surface.     

A high molecular mass cranberry constituent reduces mutans streptococci level in saliva and inhibits in vitro adhesion to hydroxyapatite

Previous investigations showed that a high molecular mass, non-dialyzable material (NDM) from cranberries inhibits the adhesion of a number of bacterial species and prevents the co-aggregation of many oral bacterial pairs. In the present study we determined the effect of mouthwash supplemented with NDM on oral hygiene. Following 6 weeks of daily usage of cranberry-containing mouthwash by an experimental group (n = 29), we found that salivary mutans streptococci count as well as the total bacterial count were reduced significantly (ANOVA, P < 0.01) compared with those of the control (n = 30) using placebo mouthwash. No change in the plaque and gingival indices was observed. In vitro, the cranberry constituent inhibited the adhesion of Streptococcus sobrinus to saliva-coated hydroxyapatite. The data suggest that the ability to reduce mutans streptococci counts in vivo is due to the anti-adhesion activity of the cranberry constituent.     

Serological properties of Abiotrophia and Granulicatella species (nutritionally variant streptococci)

Serological variations were examined among 12 type or reference strains and 91 oral isolates of vitamin B6-dependent Abiotrophia and Granulicatella spp. Rabbits were immunized with whole cells of 12 selected strains and 10 typing antisera were obtained, which were unreactive with the Lancefield group A to G antigen preparations. The reactivity of the antisera and autoclaved cell surface antigen extracts was tested by double diffusion in agar gel and a capillary precipitin test. These typing antisera categorized all Abiotrophia defectiva strains, all except one Granulicatella elegans strain, three-quarters of the Granulicatella adiacens, and half of the Granulicatella paraadiacens into 8 serotypes and 2 subserotypes. The Granulicatella balaenopterae type strain was unserotypable. All A. defectiva strains were serotype I, some of which were divided into subserotype I-1 and/or I-5. The G. adiacens strains generally belonged to serotype II or III, and the G. paraadiacens strains to serotype IV, V or VI. All G. adiacens or G. paraadiacens serotype II strains were also subserotype I-5. The G. elegans strains were serotype VII or VIII. These Abiotrophia and Granulicatella serotypes were undetectable among 33 strains of the other 11 species including the bacteriolytic enzyme-producing but vitamin B6-independent strains of Streptococcus, Enterococcus, Dolosigranulum and Aerococcus. The proposed serotyping system for Abiotrophia and Granulicatella spp. would be helpful in the identification and classification of these unique coccal isolates in ecological and epidemiological studies.