Antimicrobial susceptibility of potentially pathogenic halophilic vibrios isolated from seafood.

Susceptibility patterns to 27 antimicrobial agents and beta-lactamase production were investigated in potentially pathogenic halophilic vibrios from seafood. The effect of salinity on the response to the drugs in vitro was also studied. All isolates were uniformly sensitive to choramphenicol, imipenem, meropenem but resistant to lincomycin. All were highly sensitive to oxolinic acid, trimethoprim-sulphamethoxazole, doxycycline, flumequine, cefotaxime, nalidixic acid and ciprofloxacin. Some strains of V. harveyi, V. alginolyticus and V. parahaemolyticus apparently had mechanisms of resistance to several beta-lactam antibiotics other than by the production of beta-lactamases. Sixty-nine strains produced penicillinase but a low correlation between beta-lactamase activity and resistance to beta-lactam antibiotics was noted. The salt concentration affected the in vitro susceptibility of halophilic vibrios and the effect of salinity depended on both the individual strains and the antimicrobial tested.

Methicillin-resistant staphylococcal strains isolated from clinical samples.

Infections caused by methicillin-resistant Staphylococcus strains (MRSS) have become an increasing problem both as community-acquired and nosocomial infections. In order to eradicate colonization as well as to cure infections, optimal antibiotic treatment is required. In this study we examined the incidence of MRSS in clinical samples and compared the antibiotic susceptibility pattern of methicillin-resistant Staphylococcus aureus with that of methicillin-resistant Staphylococcus non-aureus strains. All the MRSS were resistant to penicillin. Among them there was a variation in the percentage of strains resistant to various antimicrobial agents. Within MRSS the most frequent resistances were those to erythromycin and norfloxacin. Ciprofloxacin and teicoplanin were the most effective antibiotics tested against MRSS, followed in activity by vancomycin and imipenem. The incidence of antibiotic resistance among MRSS was significantly higher than that among methicillin-susceptibility staphylococcal species.

Microbial growth and air pollution in carbonate rock weathering. Preliminary results of a in situ experimental study.

Preliminary results on limestone weathering caused by air pollution and microbial colonization are presented in this study. Outdoor exposure experimental assays were performed on Scaglia limestone samples. Samples were exposed in two areas in Perugia (Italy) that differ for degree of urban air pollution. At different times of exposure, ranging from 1 to 12 months, microbial contamination and textural modifications of sampled surfaces were evaluated by microbiological procedures, X-ray diffraction, and scanning electron microscopy. After one year of exposure a significant fungal colonization and the presence of weathering products (i.e. gypsum) were detected on sampled surfaces.

[Immunogenic activity of hemocyanin from the hemolymph of Helix pomatia and Octopus vulgaris]. / Attività immunogena di emocianine da emolinfa di Helix pomatia e di Octopus vulgaris.

The immunogenic activity of Helix Pomatia Haemocyanin (HPH) and Octopus vulgaris Haemocyanin (OVH) has been tested in rabbits. Primary and secondary antibody response has been evaluated in sera by agar double immuno-diffusion test (Ouchterlony), counter immunoelectrophoresis and complement fixation. Bath haemocyanins proved highly antigenic: antibody titers rising up to 1/3.200 after the second antigenic challenge. The Ouchterlony test showed a partial identity between H.P.H. and O.V.H. No adverse effect was evident in injected animals.

[The use of BCG as immunoadjuvant in combination with antitumor drugs in a virus induced leukemia. II]. / L'uso del BCG come immunoadiuvante in combinazione con farmaci antitumorali in una leucemia virus indotta. II.

Various treatment schedules of BCG with respect to tumor challenge and drug administration were applied in a histocompatible tumor-host system. LSTRA, an ascitic lymphoma induced by Moloney leukemia virus in BALB/c mice, was inoculated ip in histocompatible CD2F1 mice. BCG was administered ip before and/or after (-14, +1, -14+1) the tumor challenge. The drugs used in our experiments: cyclophosphamide (CY), iphosphamide (IPHO), nitrogen mustard (NM), were given at graded doses on day +5. In our experimental system the BCG treatment schedule (-14+1) only showed synergistic antitumor effects at defined doses: only the association BCG-CY have no significant survival percentage increase. No synergistic antitumor activity was evidenced when the drugs were associated with BCG given 14 days before or 1 day after the tumor challenge. The degree of immunochemotherapy treatment efficacy was different according to various antineoplastic agents used. It was never found any treatment schedule was able to cure experimental mice with the best survival percentage increase.

[Use of BCG as an immunoadjuvant in combination with antitumor agents in virus-induced leukemia]. / L'uso del BCG come immunoadiuvante in combinazione con farmaci antitumorali in unal leucemia virus indotta.

The effect of administration of BCG in association with chemotherapy in histocompatible CD2F1 mice challenged ip with Moloney-virus-induced lymphoma LSTRA of Balb/c origin was studied. All untreated mice died with comparable median survival time (MST). Immunochemotherapy experiments were performed in histocompatible mice using BCG according to various treatment schedules with respect to tumor challenge and 3 nitrosureas of clinical interest (i.e. BCNU, MeCCNU and CCNU) administration. If recipients were subjected to ip treatment with drugs alone or in association with the non specific immunoadjuvant (IA) given after tumor challenge (on day +1); no significant antitumor effect was detected. Synergistic antitumor effects were evidenced when the antineoplastic agents were associated with IA administered on the "-14+1" regimen with respect to the tumor. The results pointed out that the antilymphoma effects of chemotherapy could be amplified by IA only when the treatment schedule included adjuvants administration prior to tumor challenge.

Antigen-specific cytolysis of infected cells in murine candidiasis.

Immune L3T4+ and Lyt-2+ lymphocytes play an important role in the acquired resistance of mice to challenge with virulent Candida albicans, and release macrophage-activating cytokines in response to yeast cells in vitro. To determine whether antigen (Ag)-specific cytotoxic T lymphocytes are generated during fungal infection, purified L3T4+ and Lyt-2+ lymphocytes from immunized mice were cultured in the presence of syngeneic accessory cells, Candida Ag, and IL-2. Yeast-infected bone marrow macrophages and peritoneal exudate neutrophils were used as target cells in a standard 51Cr release assay. Ag-specific, MHC-unrestricted lysis of infected macrophages was evident with immune Lyt-2+ cells after 5-10 days in culture. Under the same experimental conditions, the cytotoxic activity of L3T4+ cells was negligible, but its expression could be induced by the addition of anti-CD3 antibody. Culturing immune Lyt-2+ cells for shorter periods of time (1-2 days) resulted in preferential lysis of infected neutrophils. In addition, at limiting effector cell numbers, Ag-specific MHC-restricted lymphocytes with cytotoxic activity to infected macrophages could be identified. We suggest that C. albicans infection stimulates multiple cytotoxic T-cell precursors with varying recognition stringency, which may have an important role in antifungal resistance in vivo.

Protection test and early antibody response to tetanus immunization.

The Authors carried out a research work to study the dose-dependence of antibody response in BD2F, mice injected with tetanus toxoid. Experimental data show that it is possible to obtain an earlier resistance at least 14 days after immunization, increasing ten-fold the usual anatoxin dose administered in humans. The protection test toward 4 MLD i.v. injected of tetanus toxin proved a valuable tool for assessing the first appearance of acquired immunity.

Serum antibody level in rabbits submitted to antitetanus active-passive immunization with heterologous horse serum.

Serum antibody titres have been assessed in rabbits submitted to active and active-passive immunization against tetanus with AlPO4 adsorbed vaccine and horse heterologous immune serum. Heterologous antibodies survive in the blood stream no more than six days. Endogenous antibodies, with the adopted vaccination schedule, emerge fifteen days after the first vaccine inoculation. In rabbits undergoing active-passive immunization, the appearance time of endogenous antibodies is delayed, all the more so as the antiserum injected dose increases. Such data stress the opportunity to give up with the use of heterologous immune sera in tetanus prophylaxis, in association with vaccine as well.

[Pathogenicity of various species of Candida in an experimental murine system]. / Patogenicità di differenti specie di Candida in un sistema sperimentale murino.

The systemic infection induced by Candida albicans, Candida krusei and Candida viswanathii was studied in an experimental murine system. Candida albicans is able to kill outbred CD1 mice within a few days and at a very low concentration; C. krusei is not pathogenic not even when inoculated at a higher concentration; C. viswanathii is able to kill animals only a a higher concentration. The different resistances do not seem to be under genic control, in as much as the different strains of mice used (hybrid CD2F1 and B6C3HF1, inbred Balb/c) show the same degree of resistance as the CD1 mice to the three species of Candida. The colony forming units (CFU) in the kidneys of CD1 mice inoculated intravenously with 10(5) cells of the three species of Candida, collected at various intervals showed a good correlation with the median survival times: a rapid moltiplication of the C. albicans is evident in the kidneys of the animals 24 hours after the inoculation, while the C. krusei and the C. viswanathii do not moltiply.

[Pathogenicity of various species of Candida in mice immunodepressed with cyclophosphamide]. / Patogenicita' di specie differenti di Candide in topi immunodepressi con ciclofosfamide.

The resistance of outbred CD1 mice immunodepressed with cyclophosphamide to the systemic infection induced by the three species of Candida: C. albicans, C. krusei and C. viswanathii was studied. The administration of cyclophosphamide, three days before the challange of the Candida species causes a degree of immunodepression in relation to the dose of drug: decrease of leucocytes of the peripheral blood and decrease of the weight and of the cellularity of the spleens. The CD1 mice were immunodepressed with cyclophosphamide (150mg/Kg) three days before the intravenous challange with graded doses of cells of the three species of Candida. They are much more susceptible, compared to normal mice, to the systemic infection induced by C. albicans and also by C. viswanathii but in this case only when inoculated at the highest concentration. They are resistant, like normal mice, towards the C. krusei even in the case in which the degree of immunodepression of the animal is furtherly increased (with stronger doses of the drug). The number of colony forming units (CFU) from the kidneys of the immunodepressed mice with cyclophosphamide correlates the median survival times.

A comparison of experimental pathogenicity of Candida species in cyclophosphamide-immunodepressed mice.

The experimental pathogenicity of Candida albicans, C. krusei, C. guilliermondii, C. parapsilosis, C. tropicalis and C. viswanathii was tested in normal and in cyclophosphamide-(Cy) immunodepressed mice. In unpretreated CD1 mice only C. albicans, C. tropicalis and C. viswanathii were pathogenic on intravenous challenge, with LD50 of 1.0 X 10(6), 4.8 X 10(6), 7.2 X 10(8) cells, respectively, per kg. Three days after a single intraperitoneal injection of Cy (150 mg kg-1) mice had a marked decrease in spleen weight and cellularity as well as reduced numbers of circulating leukocytes. Under these conditions, there was a significant, proportional increase in pathogenicity of C. albicans, C. tropicalis and C. viswanathii but the animals were still resistant to challenge with C. krusei, C. guilliermondii and C. parapsilosis. This pattern of susceptibility was not influenced by higher doses of Cy. Only C. albicans and C. tropicalis were capable of rapid and extensive multiplication in target organs such as kidney and brain in normal and Cy-treated mice and for both these species of Candida, there was a 'rebound' effect of increased resistance to experimental infection after 12 days from Cy administration. This study shows that the strong immunodepression provoked by Cy does not modify significantly the susceptibility of the animal to those species of Candida which were endowed with low or no pathogenicity for normal mice, but it greatly increases the susceptibility to those species of Candida that are already pathogenic for unmodified host.

[New heterocyclic derivatives of benzimidazole with germicidal activity. III. Synthesis and activity of derivatives of (formyl-5'-furyl-2')-2-benzimidazole with different substitutions at position 5]. / Nouveaux dérivés hétérocycliques du benzimidazole à activité germicide. III--Synthèse et activité de derivés du (formyl-5'-furyl-2')-2-benzimidazole, différemment substitués en position 5.

The synthesis and germicidal properties of 28 new derivatives of furyl-2-benzimidazole are described. The compounds are substituted both in position 5 of the benzene moiety and in position 5' of the heterocycle moiety. The germicidal properties of the new molecules were tested using 9 strains of bacteria and Candida albicans. Some of them exhibited germicidal properties versus Gram + bacteria and versus Candida. Some derivatives were also tested using Mycobacterium aurum: two isonicotinoylhydrazones derivatives exhibited tubercolostatic activity comparable to that of streptomycin and not much lower than that of isoniazide.

Correlation between medium acidification and pathogenicity in environmental halophilic non-cholera vibrios.

AIMS: The metabolic characterization and pathogenicity of vibrios isolated from seafood were studied. METHODS AND RESULTS: Strains of halophilic vibrios, grown in the presence of 0.5% glucose, induced high medium acidification and were non-culturable after 24 h, while moderately acidifying strains were culturable, produced cytotoxins, and remained lethal when inoculated intraperitoneally in mice. Highly acidifying strains failed to elicit pathogenicity in vivo and in vitro. CONCLUSION: The high acidification of the medium and the self-killing activity of NCVs might be considered a significant phenotypic marker of virulence and/or cytotoxicity. SIGNIFICANCE AND IMPACT OF THE STUDY: We suggest the medium acidification test as possible screening method for pathogenic NCVs in food microbiology.