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V Falbo

Publications and source records attributed to V Falbo.

32 records · Page 2Linked to original sources
PubMed1986

Dissemination of a gentamicin resistance plasmid in the microbial population of hospital patients.

The dissemination of a gentamicin resistant plasmid, originally found in strains of Klebsiella and termed pk181, into the microbial population of patients of the Orvieto Hospital was studied during 1982. Five hundred and seventy-four strains of Gram-negative bacilli were examined, transferable gentamicin resistance being revealed in five different bacterial species. The resistance was shown to be encoded by 81-megadalton plasmids in Escherichia coli and Enterobacter cloacae, and by 93-megadalton plasmids in Serratia marcescens and Pseudomonas spp. Restriction endonuclease digestion of plasmid DNA showed that the fragment patterns of the 81-megadalton plasmids from E. coli and enterobacter cloacae were identical to one another and to the pattern of plasmid pk181. The fragment patterns of the 93-megadalton plasmids from Serratia and Pseudomonas, on the contrary, differed substantially from those of the 81-megadalton plasmids.

DNA Restriction Enzymes↗
PubMed1985

Faecal bacteria of wild ruminants and the alpine marmot.

Faecal samples from 60 red deer (Cervus elaphus), 13 roe deer (Capreolus capreolus), 7 chamois (Rupicapra rupicapra), 41 alpine marmot (Marmota marmota) and soils mixed with deer faeces from the Stelvio National Park were examined for Campylobacter sp. and Salmonella sp. with negative results. The same material, especially deer faeces, was a habitat highly suitable for Yersinia sp.: Y. enterocolitica (two biotypes) was isolated twice, Y. kristensenii (two serotypes) was isolated 19 times, Y. frederiksenii and Y. intermedia were isolated once. Antibiotic-resistant Escherichia coli were isolated from 16 specimens from wild ruminants, one from marmot and two from feeding places.

Animals↗
PubMed1985

Toxin production and haemagglutination in strains of Escherichia coli from diarrhoea in Brescia, Italy.

Two hundred and ninety-nine different strains of Escherichia coli, isolated from 172 patients with diarrhoea and 113 healthy subjects, were examined for enterotoxin, cytotoxin and haemolysin (Hly) production and for mannose-resistant haemagglutination (MRHA) and invasive properties. Three strains proved enterotoxigenic, none enteroinvasive; cytotoxin and Hly production was shown in 25 strains from patients and in 3 from controls. Ten strains produced the cytotoxic necrotizing factor (CNF), 6 released other factors which kill cell cultures. Hly production was shown in 21 strains, 9 of which were also positive for CNF. MRHA was detected in 26% of strains from diarrhoea compared with 14% of strains from healthy people. A strong association between toxin production and MRHA was demonstrated. Serotyping results showed that the strains exhibiting virulence traits mostly belonged to serogroups commonly involved in extra-intestinal infections. The possible role of strains of E. coli showing one or more virulence factors as opportunistic pathogens in diarrhoeal diseases is discussed.

Adhesiveness↗
PubMed1985

Acute childhood diarrhoea in Naples: an aetiologic study.

A potential aetiologic agent was detected in the stools of 56% of 118 children hospitalized in Naples for acute diarrhoea. Rotavirus and Salmonella were the agents most commonly associated with disease, accounting for 23 and 17 percent of cases, respectively. Campylobacter jejuni, enterotoxigenic Escherichia coli, Yersinia and Shigella were less frequently isolated (total, 11% of cases). These findings fit well with the epidemiological picture described for other developed countries, except for the isolation rate of Salmonella which widely exceeds that reported in other investigations. Cytotoxic strains of E. coli and other Gram-negative bacilli were identified in the stools of 18 children; the possible pathogenic role of these strains is unknown and needs further investigation.

Acute Disease↗
PubMed1984

A cell division-active protein from E. coli.

A purification procedure for a protein obtained from an pathogenic strain of E. coli is described. The protein-called CNF-is active in inhibiting the duplication of cultured mammalian cells. Since nuclei division is apparently normal, treatment of cultured cells with CNF leads to the formation of gigantic, polynucleated cells. The purified protein is chromatographically and electrophoretically homogeneous. A partial characterization of CNF protein is also given.

Amino Acids↗
PubMed1984

Enteric infections, cow's milk intolerance and parenteral infections in 118 consecutive cases of acute diarrhoea in children.

One hundred and eighteen consecutive cases of childhood acute diarrhoea (mean age: 10.5 months) were studied after admission to our Pediatric Unit in Naples over a 13-month period. A diagnosis was established in 92 patients (78%): 55% of patients were found to have an infectious enteritis (among them, 5 had ETEC infections and 1 had an ST-producing Klebsiella infection), 12% a parenteral infection, 11% cow's milk intolerance. The occurrence of gross blood (P less than 0.01), leukocytes, and reducing substances in the stools was more commonly associated with infectious enteritis than with diarrhoea due to all other causes. In 14 patients (8 of whom were malnourished), diarrhoea ran a prolonged course. In all, the eventual outcome was favourable. Our findings, while confirming that infectious enteritides account for most of acute diarrhoeas in children, stress the importance of parenteral infections and cow's milk intolerance in this condition. Also, the need for an accurate search for enterotoxigenicity of enterobacteria before ruling out their pathogenetic role is stressed.

Bacterial Infections↗
PubMed1983

Partial purification and characterization of an escherichia coli toxic factor that induces morphological cell alterations.

A factor produced by several strains of Escherichia coli isolated from enteritis-affected children has been shown to produce both a necrotizing effect on rabbit skin and striking morphological alterations on CHO, Vero, and HeLa cells. The same strains were found to have hemolytic activity on sheep erythrocytes. The toxic, cell-altering factor was demonstrated to be different from both heat-labile and heat-stable enterotoxins and from Vero toxin. The main effect induced by the isolated factor on cultured cells was the formation of large multinucleated cells. The partial purification achieved suggests that the same factor (most likely a protein with a molecular weight of 70,000 to 80,000) is responsible for toxic and cell-altering activities, whereas a different molecular species is responsible for hemolytic activity.

Animals↗
PubMed1982

Antimicrobial resistance among Salmonella isolates from hospitals in Rome.

The susceptibility to antimicrobial agents of 569 salmonella isolated collected in 1977-8 from patients in hospitals in Rome was tested. Fifty-nine per cent of all isolates were resistant to one or more antimicrobials. Resistance was most common to sulphathiazole, tetracycline, streptomycin, whereas colistin, gentamicin, tobramycin, trimethoprim-sulphamethoxazole and nalidixic acid were the most active in vitro. Multiple resistance was most frequently found in strains of Salmonella wien and S. typhimurium (94% and 38% respectively). A significant change in the resistance pattern of S. wien was observed between 1977 and 1978, with a significant increase of susceptibility to some antimicrobials in 1978. Twenty-one R-plasmids transmissible to E. coli K12 were derived from 46 resistant strains of S. typhimurum.

Anti-Bacterial Agents↗
PubMed1982

Isolation of Salmonella wien heat-labile enterotoxin.

An enterotoxic activity has been identified in culture filtrates of Salmonella wien. The enterotoxin causes fluid accumulation in rabbit ligated ileal loops, firm induration and erythema in rabbit skin and morphological alteration in chinese hamster ovary (CHO) cell cultures; it was revealed by treatment with calcium phosphate gel, and purified on DEAE-Sephadex A-50 and BioGel A-1.5 m. The enterotoxic activity was eluted from the BioGel column in two peaks. Approximately 50-70% of the enterotoxic activity of the first peak, corresponding to the excluded volume, was resistant to heating at 75 degrees C for 30 min, while the activity of the second peak was completely destroyed by this treatment. From the heat-labile peak a protein, in homogeneous form, was isolated exploiting its affinity towards agarose gel filtration media. This protein, with enterotoxic activity was also present as shown by SDS-PAGE, in the first peak, eluted from the Bio-Gel column, where it appears to be closely associated with cell wall or membrane components and thus protected from heat denaturation. The isolated enterotoxin is stable in alkaline conditions but it is sensitive to acidic pH values; moreover, it stimulates adenylate cyclase in cell culture systems. Thus, it appears to possess properties similar to both cholera toxin and the heat-labile enterotoxin of Escherichia coli. These results indicate that the enterotoxin is a protein in nature and it is postulated that it may participate in the pathogenesis of S. wien infection.

Adenylyl Cyclases↗
PubMed1976

Unfolding of E. coli ribosomes: evidence for pre-existing breaks in the large subunit.

An investigation has been made on structure modifications of E. coli ribosomes following EDTA treatment. When completely deprived of magnesium, the small subunit sediments at 16S while the large one, in the same conditions, shows two components at 17S and 21S. Unfolding causes in both subunits an increase in radius of gyration without substantial change in molecular weight, as shown by light scattering measurements. The occurence of the slower 17S component besides the 21S one has to be connected with a fraction of the large subunit population which presents nucleolytic breaks in its RNA chain. These breaks do not cause fragmentation of the unfolded subunit but lead to a more open configuration sedimenting at lower velocity.

Edetic Acid↗
PubMed1974

[Determination of bacteria count by enumeration of microcolonies with an electronic counter apparatus (author's transl)].

In this paper a method is described to determine the bacteria count of samples by enumerating the microcolonies with the aid of a "Coulter Counter" automatic apparatus. Samples of bacterial cultures were incubated in a suitable medium at 32 degrees C for 12 h, then passed through a Coulter Counter aperture of 200 mu diameter to count the microcolonies. Microcolonies from cultures grown in similar conditions were also enumerated by the classical plate method. Comparison showed a good correction between the two sets of results after logarithmic transformation. Some advantages and limitations of this automatic technique are discussed, in view of its routine employment in food analysis.

Bacteriological Techniques↗