Objectives. The salivary level of Streptococcus mutans related to filled teeth was compared with the levels related to decayed and sound teeth, in order to establish whether the presence of restorations may increase the risk of infection of other teeth by Streptococcus mutans.Methods: The sound, decayed and filled teeth were recorded in 809, 6-7-year-old school-children. Salivary Streptococcus mutans detection (i.e. more than 1 x 10(4) CFU/ml) and counts were evaluated. Streptococcus mutans log count means and prevalence values of subjects with only sound teeth (group 1), with filled? without decayed teeth (group 2), with decayed, without filled teeth (group 3), were calculated and compared using the Student's t-test and the chi-square test. The effect of filled, decayed and sound teeth on Streptococcus mutans level was also evaluated using logistic regression.Results. Log count means and prevalence values of group 2 subjects were significantly lower than values of group 3 subjects (means, 0.92 vs 1.66; prevalence, 73.17% vs 94.63%) and statistically not-different from values of group 1 subjects (mean, 0.75; prevalence, 70.06%). The logistic regression analysis showed that the factors significantly increasing the risk of Streptococcus mutans being detected in saliva were only primary and/or permanent decayed teeth. The risk of Streptococcus mutans being detected in saliva was not affected by filled teeth more than sound teeth.Conclusions: In the present study population, the salivary Streptococcus mutans level attributable to filled teeth was low; this suggests that treatment of a carious lesion would cause a lowering of Streptococcus mutans concentration to the same levels as those shown by healthy subjects, thus reducing the risk of infection to other teeth. (C) 1997 Elsevier Science Ltd.

The aim of the present paper was to study whether sucrose consumption may affect the level of salivary Streptococcus mutans. The study was justified by the disagreement between results of ''in vitro'', animal and human experiments and results of epidemiological studies made on study-populations. According to experimental research, sucrose availability promotes Streptococcus mutans selection and development in the oral cavity. On the other hand, the results of epidemiological studies run counter to these experiments.In the present study, the main reasons for this disagreement were investigated and identified. From this, an epidemiological study was performed, taking into account these potentially confounding factors. The results show that sucrose consumption is actually able to promote Streptococcus mutans selection and development in the oral cavity, thus increasing the risk of dental caries.

Bacteriolytic enzymes secreted by log-phase cultures of enterococci (Enterococcus faecalis, Ent. faecium, Ent. durans, Ent. hirae, Ent. casseliflavus, Ent. avium, Ent. mundtii) were analysed by means of a zymogram technique to resolve activities according to the size of their polypeptide component and their specificities towards different substrates. Heterogeneous patterns of lytic activity were observed with different species. For each test substrate, homogeneous patterns of lytic activities were observed with strains of the same species, except for Ent. faecalis strains, which showed heterogeneous lytic patterns even towards the same substrate, and could be divided into at least four different groups according to their lytic pattern. No lytic activity was common to all strains tested. Results of zymogram analysis of Enterococcus bacteriolytic enzymes were consistent with current knowledge on enterococcal taxonomy, indicating that this analytical approach may be a useful tool for fine-tuned characterization of different enterococcal strains.

An acid phosphatase containing a 27-kDa polypeptide component has been identified in Escherichia coli by means of a zymogram technique. The enzyme is secreted in the periplasmic space and is able to hydrolyze several organic phosphate esters, but not diesters, showing preferential activity on p-nitrophenyl phosphate and other phenolic phosphate esters. Production of the enzyme apparently occurs only in cells growing on carbon sources other than glucose.

A novel staining procedure to demonstrate glycocalyx production by clinical isolates is presented. The short times required, specificity and sensitivity suggest that the staining could be applied to routine in vitro diagnostic procedures.

A modification of the procedure for O-1 phage Salmonella screening is presented. The novel method is based on the use of two media, i.e., a new medium (double sugar-tyrosine [DST]), which permits the combination of adonitol and sucrose fermentation and tyrosine clearing tests, and the previously described o-nitrophenyl-beta-D-galactopyranoside urease indole medium. In comparative trials, the new procedure and the conventional one were used to screen for Salmonella isolates from 553 lactose-negative strains of members of the family Enterobacteriaceae. The O-1 phage test, performed on DST medium, recognized the same number of phage-susceptible Salmonella strains as did the standardized method; however, it permitted the correct identification of a greater number of phage-resistant strains for discard (95.6 versus 85.3%). In particular, DST medium presented a higher efficacy than triple sugar iron agar (which is the corresponding medium in the reference procedure) in correctly identifying phage-negative cultures for discard (69.1 versus 28.5%).

In this paper, we describe a reduced sequence of identification that includes T-mod medium, a selective and differential isolation medium which allows accurate presumptive identification of the most common gram-negative bacteria encountered in urine samples. The present study, performed on bacteria isolated from 1,762 independent urine samples, has shown that a few selected tests (lysine and ornithine decarboxylase, urease and trehalose fermentation tests) improve the identification accuracy of T-mod, making it possible both to identify the less frequent species and to prevent some misidentifications of Klebsiella pneumoniae and Proteus mirabilis. The proposed work flow agreed with conventional identification protocols to a 99.3% extent and allowed identification of 87.4% of the isolates directly from the primary plate, 11.4% after 1 to 3 additional tests, and 1.2% after an identification gallery.

The usefulness of o-nitrophenyl-β-D-galactopyranoside-urease-indole (ONPG-urease-indole medium, β-GUI), coupled with triple sugar iron agar (TSI), Kligler iron agar (KIA) and lysine iron agar (LIA), respectively, for the early detection of Salmonella, Shigella and Yersinia was evaluated and compared with the LIA combined with both TSI and KIA. The study was performed on 749 selected, lactose-negative Enterobacteriaceae isolates. The most effective combination was LIA-β-GUI, which showed the highest efficiency for Shigella Yersinia presumptive recognition. It also yielded good results for Salmonella, leading to the further examination of only four cultures more than TSI-β-GUI which was the best for Salmonella screening. Moreover, out of the 749 lactose-negative isolates, it considered as a ‘suspicious enteric pathogen’ the lowest number of strains (452, 60.3%). Out of these, 416 (55.5% of the total strains and 92.0% of those yet to be tested) actually belonged to Salmonella, Shigella or Yersinia genus.

Seven Klebsiella rhinoscleromatis standard cultures and two wild isolates were examined for their responses to Api 20E (API System, S.A.) strips. Several strains yield incostant results for arabinose fermentation test in Api strips and, when positive, they were not identified. The arabinose positive test indeed, led to the numerical profiles 0004773 (not mentioned in the analytical catalogue), or 0004553 (two strains) corresponding to a Klebsiella ozaenae identification. The mathematical analysis of the biochemical results confirmed the identity of the strains as K. rhinoscleromatis.

A new selective, differential plating medium to screen the common gram-negative urinary tract pathogens is described. The medium combines adonitol fermentation, phenylalanine deaminase, and beta-glucuronidase tests and allows the indole and cytochrome oxidase tests to be performed directly from the plates. High-level agreement with individual conventional tests was recorded in comparative studies with 504 cultures of gram-negative rods. There was 100% agreement, except for the Providencia spp. indole spot test (61.6% agreement). Adonitol fermentation by Providencia species could not be determined. Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Pseudomonas aeruginosa were identified with a high efficiency (100, 85.7, 83.5, and 100% agreement, respectively) without further testing. There was 96% overall agreement for the 267 infected urine samples tested.

A new diagnostic two-steps scheme for the species identification of enterobacteria was employed with 703 strains. The diagnoses were compared with those obtained by employing Api 20 E and Enterotube II. On the basis of the reported results this new scheme is shown to be reliable (99.71% right diagnosis) and easy to perform.

The Authors propose a new two-steps key for the identification of the species belonging to the Enterobacteriaceae Family. This key can be employed both with standard tube methods and most commercial kits. The proposed method is a simple, easy and rapid one; moreover it considers each genus and species of Enterobacteriaceae Family, associated with human pathology, which has been defined within the month May, 1984.