-
[show abstract]
[hide abstract]
ABSTRACT: Analysis of bacterial DNA using a polymerase chain reaction performed with broad-range eubacterial 16S rDNA primers may yield a diagnosis of bacterial meningitis in cases where Gram staining of cerebrospinal fluid (CFS), antigen detection techniques or culture fail. Since this PCR technique occasionally gives false-positive results due to contamination of samples or laboratory reagents, a study was performed to establish the diagnostic value of assaying concentrations of tumour necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) in 90 CSF samples. A high correlation was found between a positive PCR result and the concentrations of TNF-alpha and IL-10, indicating that cytokine assays may be used as a confirmatory test. The findings suggested that a combination of the PCR technique, amplicon sequencing and assay of TNF-alpha and IL-10 concentrations in CSF is a reliable and cost-effective procedure for diagnosis of culture-negative bacterial meningitis.
European Journal of Clinical Microbiology 06/2000; 19(5):388-92. · 2.86 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: An approach based on the 16 S rDNA polymerase chain reaction (16S PCR) and oligoprobe hybridization was applied to 77 cerebrospinal fluid samples submitted to the clinical microbiology laboratory for culture. Broad-range 16S rDNA primers were selected in conserved regions of the gene. Oligoprobes specific for Neisseria meningitidis, Haemophilus influenzae, Streptococcus spp., and Mycobacterium tuberculosis were selected in specific variable regions of the amplified 600 base pairs (bp) in the 16S rDNA. None of the oligoprobes cross hybridized with DNA from the other bacteria or from common contaminants. There were no false-negative results in culture-positive cerebrospinal fluid samples. Ten cases of meningitis caused by bacteria other than the four probes were not identified by any of the four probes. In culture-negative cerebrospinal fluid samples with some abnormal chemical parameters, there were 14 amplicons -- one of Haemophilus influenzae, three of Streptococcus spp., six of Mycobacterium tuberculosis, and four not identified -- while in normal cerebrospinal fluid samples there were no amplicons.
European Journal of Clinical Microbiology 06/1999; 18(5):352-7. · 2.86 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Intermittent colonization, which then becomes chronic, characterises pseudomonas lung infection in cystic fibrosis (C.F.) patients. Bacteriologic studies do not always detect this evolution, which, however, may be identified by serological examinations. The aim of this study was to apply the immunoblotting method in order to monitor the antibody response toward a Ps. aeruginosa standard antigen (St-Ag). The results were analyzed and focussed on the bacterial and clinical data. Patients with intermittent colonization were studied between 1995 and 1997. Ninety per cent of the patients were positive to total IgG and subclass IgG1 in correspondence with the bacteriological finding. Further investigation is called for regarding the presence of IgG4 in order to establish whether it could be considered an index of chronic status.
The new microbiologica: official journal of the Italian Society for Medical, Odontoiatric, and Clinical Microbiology (SIMMOC) 11/1998; 21(4):375-8. · 1.00 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The difficulty of instituting an efficacious therapy against Pseudomonas aeruginosa infections is principally due to the microorganism's antibiotic resistance. The aim of our study was to evaluate the activity of four antibacterial drugs, two penems and two quinolones, on the production of virulence factors. Our results demonstrated that the antibiotics tested have a different behaviour depending on the P. aeruginosa phenotype. Therefore it would be advisable to choose the drug on the basis of the isolated strain phenotype.
The new microbiologica: official journal of the Italian Society for Medical, Odontoiatric, and Clinical Microbiology (SIMMOC) 08/1998; 21(3):285-8. · 1.00 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A Pseudomonas aeruginosa strain (P.aeruginosa), recently isolated in clinical practice, was tested to evaluate the changes induced in the minimal inhibitory concentration (MIC) values and in the outer membrane (OM) components by a five-day exposure to sub-MIC concentrations of the quinolones ciprofloxacin and PD-131.628 and the carbapenems imipenem and meropenem. The treated strain showed a thirty two-fold increase in MIC values for quinolones and a sixteen-fold increase for carbapenems. The electrophoretic profile of the OM proteins of the strain treated with quinolones showed that ciprofloxacin induces loss of the 47 Kd protein band, whereas PD-131.628 modifies the protein pattern of the strain only after five days of exposure. The carbapenems engendered disappearance of the same protein band. Qualitative lipopolysaccaride (LPS) analysis did not reveal any change after antibiotic treatment of the strain, whereas the 2-keto-3-deoxyoctonic acid (KDO) assay showed considerable reduction in the strain treated with sub-MIC doses of meropenem. It can therefore be safely stated that the D2 protein plays an important though not exclusive role in enhancing strain resistance against the two classes of antibiotics tested in our study.
Drugs under experimental and clinical research 02/1995; 21(4):139-44.
-
[show abstract]
[hide abstract]
ABSTRACT: Escherichia coli pre-exposed to a sub-minimal inhibitory concentration (sub-MIC) of several antibiotics elicits an enhanced humoral response which is protective against challenges with untreated homologous and heterologous bacteria. To characterise the specificity of this response we produced murine monoclonal antibodies (MAbs) to aztreonam-treated E. coli O6:K-. This resulted in the identification of MAb MT 1F, of isotype IgG1, that recognised a 12-kDa protein component of the untreated bacterial cells. After passive transfer, the MAb displayed protective activity in mice infected with lethal doses of live E. coli O6:K- and E. coli O111:B4. In ELISA experiments the MAb cross-reacted with structures located on whole cells of E. coli O6:K-, E. coli O111:B4, E. coli J5 and Salmonella minnesota Re595 and it also exerted a bactericidal activity against live E. coli O6:K-. The modifications induced by antibiotic treatment may unmask bacterial epitopes that may elicit the production of MAbs endowed with protective capacity.
Journal of Medical Microbiology 10/1994; 41(3):179-83. · 2.50 Impact Factor
-
Journal of Antimicrobial Chemotherapy 06/1994; 33(5):1039-43. · 5.07 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The Authors take in account the technical aspects of the serological tests for the diagnosis of HCV infections. Particularly they consider the better diagnostic capacity of the 2nd generation and, at the present time, 3rd generation screening tests compared to tests of 1st generation. This happens because an antigen, the c33-c, codified by a genomic sequence, specific for the non-structural proteins, NS3, of the genome of HCV virus is used in the last methodologies. This antigen induces the production of specific antibodies more quickly than the other antigenic proteins. Moreover in many cases of HCV infections it has been evidenced that the anti-c33-c are the only antibodies produced. For this reason the tests that use this antigen not only allow an early diagnosis, enclosing the "window effect", but in every case have the best diagnostic capacity. Moreover the authors evaluate also the tests defined "confirmatory tests", in which the importance of the presence of systems for the identification of both anti-c33-c and c22-3 antibodies is evidenced.
Recenti progressi in medicina 02/1994; 85(1):64-71.
-
[show abstract]
[hide abstract]
ABSTRACT: The capacity of human and murine polyclonal and monoclonal antibodies to inhibit lipopolysaccharide (LPS)-induced tumor necrosis factor-alpha (TNF-alpha) release from human monocytes was investigated. Human pooled immunoglobulin G (IVIG), human IgM monoclonal antibody (HA-1A) directed against the lipid A moiety of LPS, and murine IgG monoclonal antibody (MT-1F) raised in mice against antibiotic-treated Escherichia coli O6:K- were either added simultaneously with LPS to monocytes or preincubated for 1 h at 37 degrees C before being added to monocytes. TNF-alpha content in the monocyte supernatants was then tested. Simultaneous addition of increasing concentrations of IVIG (from 0.3 to 2.5 mg/ml) and 10 micrograms/ml of LPS to monocytes induced an enhanced release of TNF-alpha by monocytes in a dose dependent fashion. Preincubation of IVIG with LPS abolished the additive effect, but did not inhibit LPS-induced TNF-alpha release by monocytes. The simultaneous addition of LPS and HA-1A to monocytes had no additive effect nor did it inhibit TNF-alpha release. On the other hand, inhibition of TNF-alpha release was observed when HA-1A was preincubated with LPS before being added to monocytes. In all instances MT-1F inhibited TNF-alpha release when the monocytes were stimulated with smooth type LPS, but not with LPS isolated from rough mutants.
Journal of chemotherapy (Florence, Italy) 11/1993; 5(5):317-24. · 1.08 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The release of tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6) by human monocytes stimulated with whole heat-killed Candida albicans CA3 (a clinical isolate) and CA2 (a germ tube-negative mutant) either treated or not treated with amphotericin B was investigated. The optimal release of the cytokines was observed at 24 h of incubation of the yeasts with the monocytes for both TNF-alpha and IL-6. The levels ranged from 10,500 to 19,000 U/ml for TNF-alpha and from 350 to 460 pg/ml for IL-6. Germ tube-negative mutant CA2 induced the release of TNF-alpha at levels significantly (P < 0.05) lower than those induced by clinical isolate CA3, while no major differences were observed between the two strains with regard to their capacity to induce the release of IL-6. In all instances, preincubation of the yeasts with a sublethal concentration of amphotericin significantly reduced cytokine production. These results suggest that drug-induced alterations of fungal outer structures may affect the interactions between the yeasts and the monocytes, resulting in a reduced level of secretion of cytokines.
Antimicrobial Agents and Chemotherapy 10/1993; 37(9):1958-61. · 4.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In a randomized double blind study, we analyzed the efficacy of IVIG in the infectious complications in patients at high risk of developing sepsis syndrome. Two groups of twenty patients were enrolled, one receiving 250 mg/Kg of IVIG on the first and seventh day after admission and the other receiving sterile saline as placebo. Serum samples were drawn before IVIG administration and 24, 48 and 72 hours afterwards. The same schedule was used for patients treated with placebo. Sera pooled from healthy donors served as controls. On all the samples, opsonic and bactericidal activity as well as C3, total IgG and serum TNF content were tested. IVIG did not significantly affect total IgG and C3 content. Similarly, opsonic and bactericidal activity tested against E. coli 06 :K-, E. coli 0111 and SAC I was not modified ranging within HPS values. Furthermore, IVIG administration did not change the TNF level. A lower incidence of bacteremia in IVIG treated patients was observed.
The new microbiologica: official journal of the Italian Society for Medical, Odontoiatric, and Clinical Microbiology (SIMMOC) 08/1993; 16(3):251-8. · 1.00 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The release of interleukin-6 (IL-6) by human monocytes upon stimulation with culture filtrates and heat-killed Candida albicans cells was studied. Two strains of C. albicans (a wild strain CA3 and an agerminative mutant CA2) were cultured overnight at 28 degrees C in complete medium, and 10(6) cells/ml were either filtered at different time points (6, 12, 18, 24, 30 hours) or heat-killed. C. albicans preparations were then added to monolayers of monocytes isolated from healthy donors and incubated at 37 degrees C in 5% CO2 atmosphere. Cell culture supernatants were collected at different time points (every 6 hrs for 30 hrs), and IL-6 content was then measured by immunometric assay. Monocytes stimulated with heat-killed C. albicans cells released IL-6 in the supernatants with values ranging from 59 to 460 pg/ml, that peaked at 24 hrs of incubation. Using heat-killed whole cells of C. albicans no major differences were observed between the two strains used in their capacity to induce IL-6. Culture filtrates also stimulated monocytes to release IL-6 and maximal cytokine levels were observed when the monocytes were triggered with filtrates from yeasts cultured for 24 hours. CA2 filtrate induced IL-6 levels to an extent significantly higher than did CA3 filtrate. These data add further evidence to the immunomodulatory properties possessed by structures of C. albicans.
The new microbiologica: official journal of the Italian Society for Medical, Odontoiatric, and Clinical Microbiology (SIMMOC) 08/1993; 16(3):267-74. · 1.00 Impact Factor
-
Transplantation Proceedings 07/1993; 25(3):2280-1. · 1.00 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The murine immune response to Escherichia coli O6:K-alone or pre-exposed to 0.1 x MIC of aztreonam was investigated. Relative to mice immunized with untreated bacteria, mice immunized with antibiotic-treated microorganisms presented a significantly enhanced protection towards a challenge of 100 x LD50 of viable E. coli O6:K-. Previous injection of 0.1 mL of serum drawn from mice immunized with treated and untreated bacteria protected non-immunized mice towards a challenge of 10 x LD50 of viable E. coli O6:K--. Serum from mice immunized with treated bacteria also protected non-immunized mice towards a lethal challenge of E. coli O111. The antiserum contained high titre of IgG antibodies that cross-reacted with lipopolysaccharide isolated from smooth and rough Gram-negative bacteria. Immunoblotting showed additional bands of reactivity to the untreated E. coli O6:K-. Immunization with antibiotic-treated bacteria led to the production of type specific and cross reactive antibodies that protected animals against viable homologous and heterologous lethal challenges.
Journal of Antimicrobial Chemotherapy 02/1993; 31(1):117-28. · 5.07 Impact Factor
-
Drugs. 01/1993; 45:190-191.
-
[show abstract]
[hide abstract]
ABSTRACT: This study's objectives were to evaluate the effects of subminimum inhibitory concentrations (MICs) of tobramycin, gentamicin, netilmicin, streptomycin, ciprofloxacin, cefotaxime and piperacillin on proteinase production, alginate and siderophore synthesis by two strains of Pseudomonas aeruginosa. One of these strains, of recent clinical isolation, was mucoid. In fact it is well known that mucoid strains are more resistant than non-mucoid; there is, moreover, evidence that in cystic fibrotic lungs the non-mucoid P. aeruginosa are invariably replaced by mucoid variants. Our results show that subinhibitory concentrations of beta-lactams and quinolones significantly reduced the amount of alginate. Protease production was affected by all antibiotics tested.
Journal of chemotherapy (Florence, Italy) 05/1992; 4(2):78-81. · 1.08 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: P. aeruginosa is highly resistant to a wide range of antimicrobial agents. This intrinsic resistance mainly depends on the rate of permeation across the outer membrane (o.m.). In order to promote antibiotic uptake across the hydrophilic channel of the o.m. porins, a permeator can be used with a hydrophilic antibiotic. In the present study we assess the o.m. electrophoretic profile of three P. aeruginosa strains cultured with and without antibiotic Aztreonam and Netilmicin (A:N) using the MIC concentration in the association (3:1). The observed increase in the band can be referred to the F porin when the strains are treated with Aztreonam.
Microbiologica 11/1991; 14(4):301-5.
-
[show abstract]
[hide abstract]
ABSTRACT: An experimental study was undertaken to assess aztreonam biliary concentrations in bile duct ligated jaundiced rats. The study proved that aztreonam biliary concentrations are sufficient to inhibit Gram-negative bacteria within the first and the second hour after antibiotic administration. The experimental model suggests that clinical conditions such as lithiasis or neoplasms of the biliary tree should not totally inhibit the antibiotic excretion.
Journal of chemotherapy (Florence, Italy) 05/1991; 3(2):98-100. · 1.08 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The activation and differentiation of resting B cells into Ig secreting cells are regulated by T cells, macrophages and their secreted factors. The present study evaluated the effect of cyclosporin A (CsA) on this process. Peripheral blood lymphomonocytes (PBMC) drawn from healthy donors were stimulated with protein A (PA) or with lipopolysaccharides plus pokeweed (LPS+PWM) in either the presence or the absence of CsA. Phenotypic B cell changes and immunoglobulin production was then analyzed. The data revealed that CsA decreased the expression of B cell surface receptors of the activation phase, and enhanced the resting phase receptors. Different effects of CsA were found on B cell differentiation, depending on its induction by PA or LPS+PWM. In the first system, CsA decreased the expression of differentiation phase receptors and the secretion of free Ig. In cultures stimulated with LPS+PWM, CsA increased the differentiated phase receptors and Ig secretion. Thus, CsA seemed to act as a blocking agent of the activation phase and as a modulator of the differentiation phase and of IgG secretion, depending upon the antigen used for stimulation.
Drugs under experimental and clinical research 02/1991; 17(10-11):493-500.
-
[show abstract]
[hide abstract]
ABSTRACT: The hypothesis of a different immunogenicity between untreated and antibiotic-treated Escherichia coli was investigated in vivo. Groups of mice were injected weekly for eight weeks with formalin-killed E. coli ATCC 25922 either exposed or not to 0.1 x MIC of aztreonam. A group of mice injected with sterile saline only served as control. IgG production towards whole bacteria was clearly enhanced in the group immunized with antibiotic-treated E. coli as shown in ELISA assays. In the same group, the appearance of additional bands of reactivity in the region of major outer membrane proteins was observed in immunoblot experiments as well as an enhanced protection towards a challenge of 10 x LD50 of live E. coli. These findings seem to support the hypothesis that sub-MICs of antibiotics modify the bacterial surface influencing host-parasite relationships.
Journal of chemotherapy (Florence, Italy) 02/1991; 3 Suppl 1:136-40. · 1.08 Impact Factor
