Hg bioavailability and impact on bacterial communities in a long-term polluted soil.

Different soil samples characterised by a long-term Hg-pollution were studied for Hg total content, fractionation, phytotoxicity and influence on the bacterial community. Hg pollution ranged from 1 to 50 mg kg(-1) and most of it was speciated in scarcely soluble forms. In agreement with this, the biochemical quality indexes were investigated (biomass, enzyme activities) and the bacterial community (viable heterotrophic (VH) bacteria, functional diversity) apparently was not influenced by the degree of Hg pollution. In particular, the investigated soils exhibited a low percentage of Hg-resistant (Hg(R)) bacteria ranging from less than 0.001% to 0.25% of the VH and the addition of available Hg in the form of HgCl(2) induced an enrichment of resistant Hg(R) populations. The general biodiversity of the bacterial community was evaluated by denaturing gradient gel electrophoresis of DNA of Hg spiked soil microcosms and of control soils. Hg(R) bacteria capable to grow in a minimal medium containing HgCl(2) were also isolated and identified. MerA and merB gene PCR fragments were obtained from different Hg(R) strains and the range of similarities at the DNA level and at the deduced amino acid level showed that they carried mercuric reductase and lyase. Differently from bacteria, some influence of soil Hg content on seeds' germination and root elongation was observed for Lepidium sativum L. and Solanum lycopersicum L. In conclusion, most of the Hg in these long-term polluted soils was scarcely mobile and available and did not significantly influence the soil bacterial community. The risk of potential Hg remobilization over time, that could be naturally favoured by the activity of plant roots or other inorganic processes occurring in soil, can be extenuated since bacterial community was resistant and resilient to subsequent Hg stress.

Molecular and cellular signatures of human vaccine adjuvants.

Oil-in-water emulsions are potent human adjuvants used for effective pandemic influenza vaccines; however, their mechanism of action is still unknown. By combining microarray and immunofluorescence analysis, we monitored the effects of the adjuvants MF59 oil-in-water emulsion, CpG, and alum in the mouse muscle. MF59 induced a time-dependent change in the expression of 891 genes, whereas CpG and alum regulated 387 and 312 genes, respectively. All adjuvants modulated a common set of 168 genes and promoted antigen-presenting cell recruitment. MF59 was the stronger inducer of cytokines, cytokine receptors, adhesion molecules involved in leukocyte migration, and antigen-presentation genes. In addition, MF59 triggered a more rapid influx of CD11b+ blood cells compared with other adjuvants. The early biomarkers selected by microarray, JunB and Ptx3, were used to identify skeletal muscle as a direct target of MF59. We propose that oil-in-water emulsions are the most efficient human vaccine adjuvants, because they induce an early and strong immunocompetent environment at the injection site by targeting muscle cells.

Mucosal vaccines: non toxic derivatives of LT and CT as mucosal adjuvants.

Most vaccines are still delivered by injection. Mucosal vaccination would increase compliance and decrease the risk of spread of infectious diseases due to contaminated syringes. However, most vaccines are unable to induce immune responses when administered mucosally, and require the use of strong adjuvant on effective delivery systems. Cholera toxin (CT) and Escherichia coli enterotoxin (LT) are powerful mucosal adjuvants when co-administered with soluble antigens. However, their use in humans is hampered by their extremely high toxicity. During the past few years, site-directed mutagenesis has permitted the generation of LT and CT mutants fully non toxic or with dramatically reduced toxicity, which still retain their strong adjuvanticity at the mucosal level. Among these mutants, are LTK63 (serine-to-lysine substitution at position 63 in the A subunit) and LTR72 (alanine-to-arginine substitution at position 72 in the A subunit). The first is fully non toxic, whereas the latter retains some residual enzymatic activity. Both of them are extremely active as mucosal adjuvants, being able to induce very high titers of antibodies specific for the antigen with which they are co-administered. Both mutants have now been tested as mucosal adjuvants in different animal species using a wide variety of antigens. Interestingly, mucosal delivery (nasal or oral) of antigens together with LTK63 or LTR72 mutants also conferred protection against challenge in appropriate animal models (e.g. tetanus, Helicobacter pylori, pertussis, pneumococci, influenza, etc). In conclusion, these LTK63 and LTR72 mutants are safe adjuvants to enhance the immunogenicity of vaccines at the mucosal level, and will be tested soon in humans.

IEM101, a naturally attenuated Vibrio cholerae strain as carrier for genetically detoxified derivatives of cholera toxin.

Two mutants of cholera toxin (CTS106 containing a Pro106-->Ser substitution and CTK63 containing a Ser63-->Lys substitution) with greatly reduced or no toxicity respectively, were expressed in the naturally attenuated IEM101 Vibrio cholerae strain (El Tor, Ogawa) which does not express cholera toxin (CT). Expression was driven by the natural promoter of CT, or by a promoter known to induce strong in vivo expression such as nirB. In the rabbit ileal loop assay, where 10(4) wild type bacteria were sufficient to induce fluid accumulation, 10(9) IEM101 expressing CTS106 bacteria were needed to induce some fluid accumulation, while IEM101 expressing CTK63 was inactive, even when 10(10) cells were used. When used to immunize mice intranasally, all bacteria induced vibriocidal antibodies; however, anti-CT antibodies were not induced by bacteria expressing low levels of CTK63 under the control of the ct promoter. Anti-CT antibodies were successfully induced by bacteria expressing high levels of CTK63 under the control of the nirB promoter, or by bacteria expressing low levels of CTS106. These data show that antibodies against cholera toxin can be induced in vivo by high level expression of a non toxic mutant, or by using a mutant with residual ADP-ribosyltransferase activity. In conclusion, we have shown that IEM101, a naturally attenuated Vibrio strain known to be safe and immunogenic in humans, can be engineered to express immunogenic levels of CTK63, and may represent a good candidate for vaccination against cholera.

[In vitro chemo-antibiotic sensitivity of gram-negative bacteria from various biological materials. Comparison between aztreonam and other agents]. / Chemioantibiotico sensibilità "in vitro" di batteri gram-negativi provenienti da diverso materiale biologico. Confronto tra aztreonam ed altri agenti.

527 Gram negative bacterial strains isolated from different biological substances were studied by chemo-antibiotic sensitivity. The examination was carried out by the agar diffusion test (Kirby-Bauer). A very good sensitivity to aztreonam (E. coli, Serratia spp., Klebsiella spp., Proteus spp.), to amikacin (Pseudomonas spp., Enterobacter spp., Citrobacter spp.) and to norfloxacin (Citrobacter spp.) was found. Even when it was not the best, aztreonam was the second (Citrobacter spp.) or the third choice (Pseudomonas spp.), always near to the drug of first choice.

[Antibiograms performed on Gram-negative bacteria isolated from urine cultures. Results and considerations]. / Antibiogrammi eseguiti su batteri Gram-negativi isolati da urinocolture. Risultati e considerazioni.

The authors have isolated 938 Gram-negative germs from 3141 urinocultures. In the work is reported the percentage of sensitivity of the single tested antibiotics and it is recommended an exact therapy, if we won't have clamorous failures.

[Reference values for the serum concentration of apolipoproteins A and B, the A/B ratio and cholesterol-HDL. Evaluation in a clinically healthy population in Amiata (Grosseto)]. / Studio dei valori di riferimento della concentrazione sierica delle apolipoproteine A E B, del rapporto A/B E del colesterolo-HDL. Valutazione in una popolazione clinicamente sana dell'amiata, versante grossetano.

The authors have studied the distribution of the Apolipoproteins A and B, the Apo A/B ratio and the HDL-cholesterol on healthy people, according to sex and age, in order to fix the reference values, considering that the literature is poor and the opinions are different.

[Identification and sensitivity of Streptococci to antibiotics]. / Identificazione e sensibilità dello streptococco agli antibiotici.

In the first part of this research, the author accentuates the quick and easy identification of the Streptococcus by means of Latex-test, testing at the same time the bacitracin. In the second part, the antibiotic sensitivity is tested on 354 strains of Streptococci.

[Pseudomonas: considerations on its in vitro sensitivity to antibiotics]. / Pseudomonas: considerazioni sulla sensibilità "in vitro" agli antibiotici.

The Pseudomonas spp. increase more and more. The chemoantibiotics tested on 187 strains result 75% no sensitive and other 25% weakly sensitive.

[Urine culture and antibiogram in 2 different populations (ambulatory and hospitalized). Considerations on 2155 tests performed consecutively]. / Urinocolture ed antibiogrammi in due diverse popolazioni (ambulatoriale ed ospedalizzata). Considerazioni su 2155 esami eseguiti consecutivamente.

The authors report a their casuistry on 2155 between urinocultures and cultures of vescical catheters, pointing out an unexpected prevalence of Gram-positive germs and of that point out the possible causes. There are represented also some tables relative to the antibiotics tested for the single germs.

[Polyresistant "Salmonella bredeney" in a general surgical ward (author's transl)]. / "Salmonella bredeney" poliresistente in una divisione di chirurgia generale.

A series of cases of postoperative gastroenteritis by Salmonella bredeney in a general surgical ward has been described. The particular serotype of Salmonella in question, the widerange of drug-resistance of the strains, the epidemiological stages of the outbreak and the kind of the ward interested have been considered of uncommon occurrence.