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Biomedical subjects

D Savoia

Publications and source records attributed to D Savoia.

At least 37 records · Page 2Linked to original sources
PubMed1995

Group A streptococci: evaluation of in vitro resistance to two macrolides.

In recent years an increase in severe group A streptococcal infections has been observed. The possible relation between the failure of therapy and an increase of resistance to antibiotics, which are often used for streptococcal infections (clarithromycin and erythromycin), has been assessed in vitro. Streptococcus pyogenes strains tested for susceptibility were isolated in different years from pharyngotonsillar swabs of symptomatic children and typed; another nine strains came from the American Type Culture Collection. The evaluation of antimicrobial activity demonstrated that the percentage of resistance of these bacteria to the two macrolides was 4, 4.4 and 15.5%, respectively, for strains isolated in 1990, 1991 and 1994. Clarithromycin showed a better antistreptococcal, above all bactericidal, activity. The presence of M protein in streptococci does not seem to modify the kinetic activity of the two drugs, while a slower bactericidal effect was observed against capsulated strains. The resurgence of severe group A Streptococcus infections may be due to an increase in the circulation of strains with a capsule expression, which is critical also for resistance to phagocytic killing.

Antigens, Bacterial↗
PubMed1995

Human PBMC proliferative response to Leishmania infantum promastigotes is inhibited by anti-IFN-gamma mAb gamma 123.

PBMC from individuals both exposed and non-exposed to leishmaniae proliferative and produce interferon-gamma (IFN-gamma) following stimulation with Leishmania antigens. We studied the kinetics of the proliferative response of PBMC from non-exposed individuals and from patients recovering from visceral leishmaniasis due to Leishmania infantum, using heat-killed stationary-phase promastigotes of L. infantum as stimulating agent. The kinetics of both groups followed a similar temporal pattern, with higher values in the patient's group. Moreover, we observed that in both groups the activation was dose-dependently inhibited following the addition of gamma 123 anti-IFN-gamma monoclonal antibody. These results indicate the need for IFN-gamma in the activation process of PBMC induced by Leishmania antigens and stress the role of IFN-gamma in the immune response to leishmaniasis. The relevance of the elucidation of the immune response mechanism in human leishmaniasis for therapy and vaccination is briefly discussed.

Animals↗
PubMed1994

Evaluation of virulence factors and the adhesive capability of Escherichia coli strains.

Escherichia coli strains recently isolated from adult women with recurrent urinary tract infection (R-UTI) were compared with strains from women with non-recurrent infections (UTI). Haemolysin and mannose-resistant (MR) haemagglutinin were more prevalent in the first group. Using a spectrophotometric technique with biotinylated bacteria, the ability of bacteria to adhere to uroepithelial cells was related to this last character. R-UTI strains are also more resistant to the phagocytic activity of U937 cells. This could relate in vivo to a resistance to mucosal phagocytes, so as to prevent host defence mechanisms.

Adult↗
PubMed1994

Proliferative response of human T cells to stimulation with Leishmania infantum and L. major promastigotes in logarithmic and stationary growth phase.

T cells from healthy donors, non-exposed to Leishmania, proliferative and produce lymphokines when cultured in the presence of killed Leishmania promastigotes. We compared the stimulative activity of L. major and L. infantum promastigotes harvested in logarithmic and stationary growth phase on human T cells by performing a proliferation kinetics during the first 5 days of culture. Stationary-phase promastigotes induced a good response at the 4th-5th day, whereas the effect of logarithmic-phase promastigotes was almost undetectable. Both species gave a similar pattern. The implications of these findings in the current model of immunologic reaction to leishmaniasis are discussed.

Animals↗
PubMed1994

Evaluation of the diagnostic accuracy of a kit for the rapid detection of group A streptococci.

A rapid immunoassay method using an Event Test Strip Strep A experimental kit (Boehringer Mannheim) was evaluated. Results obtained were compared with culture results to evaluate the accuracy of detection of group A streptococci directly from throat swabs or from artificial swabs containing various bacterial concentrations. A good diagnostic accuracy was obtained with a sensitivity of 96.9% in the assay of throat swabs which provided more than ten group A Streptococcus colonies per plate. Since a low level of micro-organisms may indicate infection, it is recommended that a culture be performed when the rapid test based on antigen detection is negative.

Adolescent↗
PubMed1992

Effect of fibronectin and interferon-gamma on the uptake of Leishmania major and Leishmania infantum promastigotes by U937 cells.

Uptake of Leishmania major and Leishmania infantum promastigotes by U937 cells was determined by microscopic observation and by using radiolabelled parasites. With both species we observed an increase in uptake after parasite pretreatments with fibronectin, and a decrease in uptake after cell pretreatment with interferon-gamma (IFN gamma). When both pretreatments were performed, the uptake was significantly decreased only in L. infantum experiments. These findings may be of some importance in the evaluation of IFN gamma as a leishmanicidal agent.

Animals↗
PubMed1991

Evaluation of different assay techniques to assess the interaction between Leishmania major and L. infantum promastigotes and U937 cells.

Adherence of Leishmania major and L. infantum promastigotes to U937 cells was determined by microscopic observation or by using radiolabelled parasites. With both methods L. infantum showed a greater adherence. Aspecific attachment to plastic was greater for L. major. The possible implications of these findings in connection with disease pathogenesis are briefly discussed.

Animals↗
PubMed1990

The effect of subinhibitory concentrations of some antibiotics on the hydrophobicity of gram-negative bacteria.

Cell surface hydrophobicity is currently regarded as an important factor in promoting bacterial adherence to a wide variety of surfaces. This feature was investigated in some Gram-negative bacteria isolated from urinary tract infections and the extent to which their surface characteristics were affected by subinhibitory concentrations of some antibiotics was assayed. Surface properties were evaluated using the salting-out technique (SAT) and bacterial absorption to n-hexadecane (BATH). SAT showed that all except 3 Escherichia coli strains were autoaggregating. BATH detected more hydrophobic characteristics in the stationary phase of bacterial growth. Pretreatment with antibiotics generally reduced hydrophobicity and thus affected the initial reversible phase of attachment of bacteria to eukaryotic cells.

Anti-Bacterial Agents↗
PubMed1989

Secretory hydrolases of Trichomonas vaginalis.

Supernatants of three Trichomonas vaginalis strains obtained from culture or after contact and cultivation with WISH cells were assayed to characterize the nature of the factor/s responsible for the cytotoxic activity on WISH cell monolayers. This factor, mainly secreted from the live, exponentially grown parasite, with a molecular weight higher than 10,000 daltons and heat-unstable, does not appear to be a protease. In its place, we demonstrated that the presence of some hydrolases (particularly acid phosphatase and beta-N-acetylglucosaminidase) was related to the cytotoxic activity of T. vaginalis strains. Hence, some hydrolytic enzymes may indicate the pathogenetic role of a T. vaginalis strain.

Animals↗
PubMed1988

Influence of gender in pathogenesis of trichomoniasis in congenitally athymic (nude) mice.

Evaluation of abscesses appearing in male and female euthymic and athymic (nude) Balb/c mice after subcutaneous injection of Trichomonas vaginalis in the dorsal region showed that females were more susceptible than males. Female euthymic mice, however, were more susceptible than male athymic mice, and splenectomised athymic males were more susceptible than non-splenectomised athymic males. F1 female athymic mice were the most susceptible, as their abscesses reached a peak size five days earlier than those of athymic homozygous females. F1 male athymic mice, though slightly more susceptible than athymic homozygous males, did not develop abscesses that were similar in size. These results suggest that resistance or susceptibility to T vaginalis infection depends on the gender of the host and on thymus dependent cellular populations.

Animals↗
PubMed1988

Use of a crude extract or a purified antigen of Trichomonas vaginalis for the detection of secretory antibodies by ELISA.

A crude aqueous extract (T2) or a gel-filtration purified antigen of T. vaginalis was utilized to detect secretory antibodies in cervico-vaginal secretions by ELISA. The test was developed under optimum conditions using a rabbit anti-Trichomonas serum. Conditions established for monitoring antibodies to trichomonas in immunized rabbits were equally effective for human secretions. The crude extract was capable of assessing secretory antibodies in 45% of women with acute trichomoniasis and 43% of healthy women. The purified antigen showed a marked antigenic activity and compared to the crude antigen, testing 6 samples from infected women, detected a false positive and reduced the O.D. value of another sample by 1/4.

Animals↗
PubMed1987

Effect of fosfomycin trometamol on bacterial adhesion in comparison with other chemotherapeutic agents.

The effect of fosfomycin trometamol in comparison with that of norfloxacin and co-trimoxazole on the hemagglutination, yeast cell aggregation and adhesive properties of both gram-positive and gram-negative microorganisms was studied. The strains were isolated from the urine of patients with urinary tract infections, or from vaginal swabs. At sublethal concentrations (1/4 and 1/8 of the minimal inhibitory concentration), the ability of the bacteria to adhere to human uroepithelial cells was reduced by any of the 3 drugs assayed. The reduction corresponded to a decrease in the agglutinating activity of the gram-negative bacteria tested, such providing further evidence for the efficacy of the different chemoantibiotics. In particular, fosfomycin trometamol and norfloxacin proved to be more effective than co-trimoxazole in affecting the adhesive properties of all the strains employed.

Bacterial Adhesion↗
PubMed1987

Modulation of the adherence of group A streptococci to murine cells.

The adherence of group A Streptococci to P388 cells increases after treatment with interferon-gamma; this enhancement is less when antifibronectin antibodies are used. In parallel, peritoneal murine elicited macrophages pretreated with fibronectin bind more bacteria. Moreover, two monoclonal antibodies obtained against group A Streptococci had different effects on the ability of microorganisms to adhere to phagocytic cells.

Animals↗
PubMed1987

Treatment of urinary infections: clinical perspectives.

The present study was carried out with the aim of comparing the microbiological and clinical efficacy of norfloxacin, cinoxacin and aztreonam in urinary tract infections. Patients were tested who had infections of the higher and/or lower urinary tracts associated with complicating factors. The microorganism most frequently isolated in these individuals was Escherichia coli. The assays carried out with the aim of testing the in vitro antibacterial activity (agar diffusion method and minimum inhibitory concentration) on the microorganisms responsible for the infections, as well as the evaluation of clinical efficacy, showed that norfloxacin has a wider antibacterial spectrum of action and inhibitory activity greater than the other two drugs tested.

Adult↗
PubMed1986

Adherence of Trichomonas vaginalis to cell culture monolayers.

The in vitro adherence to WISH cells of a pathogenic Trichomonas vaginalis strain was studied with a method utilizing thymidine-labeled protozoa. A marked dose-related adherence was observed. Glutaraldehyde fixed trichomonads were not adherent. The presence of fetal calf serum during the assay did not influence attachment. Concanavalin A inhibited adherence of protozoa. Complete or partial inhibition of adherence was achieved by preincubating WISH cells with Lactobacillus fermentum or Streptococcus agalactiae. Finally, pretreatment of cells with alpha-estradiol, beta-estradiol, progesterone and estrone influenced attachment of protozoa, whereas estriol was ineffective. These results suggest that adherence of Trichomonas vaginalis is dependent on different factors, whose manipulation may have clinical relevance in preventing recurrence of trichomonad vaginitis.

Adhesiveness↗
PubMed1986

A method for the rapid detection of streptococcal group A antigen by specific monoclonal antibody.

In this study we evaluate the efficacy of a method for the rapid detection of group A streptococci employing a hybridoma mouse antibody specific against group A streptococcal carbohydrate. Using coagglutination technique we demonstrated an absolute specificity. The sensitivity was absolute if the preparation contained greater than or equal to 5 X 10(4) cocci. This test seems therefore a valid criterion for symptomatic patients with a larger number of group A streptococci in throat specimens, more sensitive than other methods, but not sensitive enough for carriers of few bacteria.

Agglutination Tests↗