Transfer of penicillin resistance between Neisseriae in microcosm.

Horizontal gene transfer between commensal and pathogenic Neisseriae is the mechanism proposed to explain how pathogenic species acquire altered portions of the penA gene, which encodes penicillin binding protein 2. These changes resulted in a moderately penicillin-resistant phenotype in the meningococci, whose frequency of isolation in Spain increased at the end of the 1980s. Little has been published about the possibility of this gene transfer in nature or about its simulation in the laboratory.

Role of the outer membrane in the accumulation of quinolones by Serratia marcescens.

Accumulation of four quinolones by Serratia marcescens was measured fluorometrically. The passage of quinolones through the outer membrane was studied in both lipopolysaccharide-deficient and porin-deficient mutants. The lipopolysaccharide (LPS) layer formed a partially effective barrier for highly hydrophobic quinolones such as nalidixic acid.

Salicylate induction of phenotypic resistance to quinolones in Serratia marcescens.

The influence of salicylic acid on the permeability and susceptibility of Serratia marcescens to both nalidixic acid and ciprofloxacin was studied, as well as the effect of salicylate on outer membrane proteins and lipopolysaccharide. As salicylic acid concentration increased, ciprofloxacin accumulation decreased with a concomitant, previously observed, reduction in the porin content of the outer membrane. Resistance to ciprofloxacin and nalidixic acid was enhanced when bacteria grew in the presence of salicylic acid.

Telecardiology: results and perspectives of an operative experience.

A telecardiology system has been established between six Italian hospitals. Four of them are connected using three ISDN lines; the remaining two are connected with only a single ISDN line. The telecardiology system was evaluated between two hospitals.

Toxigenic Escherichia coli isolated from pigs in Argentina.

The presence of porcine toxigenic E. coli (ETEC, VTEC) in 28 piggeries (5% of total) of the central and northeast region of Argentina was studied for a better understanding of the epidemiology of porcine strains. Samples were taken by rectal swabs from healthy piglets and from those with diarrhoea, in addition to their dams.

Effects of topical application of free and liposome-encapsulated lactoferrin and lactoperoxidase on oral microbiota and dental caries in rats.

Four groups of rats were inoculated with Streptococcus sobrinus ATCC 33478 and fed a cariogenic diet for 42 days. Topical treatment with either distilled water, sodium fluoride (0.2%), a solution containing lactoferrin and lactoperoxidase, or a solution containing liposome-encapsulated lactoferrin and liposome-encapsulated lactoperoxidase was applied at intervals for 35 days.

Evaluation of acquired platelet dysfunctions in uremic and cirrhotic patients using the platelet function analyzer (PFA-100 ): influence of hematocrit elevation.

Background And Objective: Patients with end-stage renal disease or advanced cirrhosis develop bleeding disorders characterized by defective interaction of platelets with damaged subendothelium. The anemia associated with both clinical entities has a negative influence on hemostasis. We evaluated alterations of platelet function in patients suffering from end-stage renal disease (n=21) or hepatic cirrhosis (n=20) using standard aggregometric techniques and the recently developed platelet function analyzer (PFA-100 ).

Interactions between pairs of bacteriocins from lactic bacteria.

Activity of pairs of crude extracts of lactic acid bacteria (LAB) containing different bacteriocins (nisin, pediocin AcH, lacticin 481, lactacin F, and lactacin B) was measured against 10 different indicator strains. Experiments were carried out both in liquid and on solid media. Both synergisms and antagonisms were observed.

Prevalence of bovine verotoxin-producing Escherichia coli in Argentina.

Faecal swabs obtained from 126 calves and 118 cows in Argentina were investigated for the presence of verotoxin-producing Escherichia coli (VTEC). VTEC strains were recovered from 10 (23%) of 43 calves with diarrhoea, from 24 (29%) of 83 healthy calves, from 40 (44%) of 91 healthy cows waiting at the slaughterhouse, and from 6 (22%) of 27 healthy grazing cattle. PCR showed that 21 (9%) of animals carried VT1+ strains, 49 (20%) VT2+ strains and 10 (4%) VT1+ VT2+ strains.

Non-typable Haemophilus influenzae from a single hospital: epidemiological markers.

A total of 51 strains of non-typable Haemophilus influenzae isolated from a single hospital were subjected to analysis of biochemical traits, outer membrane protein (OMP) profiles, lipopolysaccharide (LPS) electrophoresis and antibiotic susceptibility determination in order to establish a method for bacterial typing. Results proved that none of the methods tested were useful for typing purposes, although the data showed that (1) OMP profiles were extremely variable; (2) LPS profiles were uniform; (3) the multiresistant strains manifested different resistance patterns; and (4) biochemically, all strains were closely related.

[Functionality of von Willebrand factor present in Fanhdi: adhesion to the vascular subendothelium in vitro].

Purpose: To study the ability of VWF present in a plasma derived high purity factor VIII concentrate (> or = 100 UI FVIII/mg of protein, Fanhdi) to promote deposition and platelet adhesion on the injured vessel wall, as an indicator of the functionality of said VWF.

Material And Methods: An in vitro perfusion system was employed. Adequate proportions of platelets and red cells were suspended in a human albumin solution.

The role of outer membrane in Serratia marcescens intrinsic resistance to antibiotics.

Three different porins from Serratia marcescens were described. They were named Omp1, Omp2 and Omp3 and their molecular weights were 42, 40 and 39 kDa respectively. Omp2 and Omp3 showed osmoregulation and thermoregulation in a similar way to OmpC and OmpF of Escherichia coli.

Molecular basis of antimicrobial resistance in non-typable Haemophilus influenzae.

Strains of the facultative anaerobe Haemophilus influenzae, both type b and non typable strains, are frequently multiresistant. The measurement of the antibiotic permeability of Haemophilus influenzae outer membrane (OM) shows that antibiotics can cross through the OM easily. Thus, enzymatic activity or efflux pumps could be responsible for multiresistance.

The acrAB homolog of Haemophilus influenzae codes for a functional multidrug efflux pump.

Disruption of gene HI0894 or HI0895 in Haemophilus influenzae Rd, homologs of Escherichia coli acrAB multidrug efflux genes, caused hypersusceptibility to erythromycin, rifampin, novobiocin, and dyes such as ethidium bromide and crystal violet and increased accumulation of radioactive erythromycin, showing that these genes are expressed and contribute to the baseline level resistance of this organism through active drug efflux. The gene disruption did not produce detectable changes in susceptibility to several other antibiotics, possibly because rapid influx of small antibiotic molecules through the large H. influenzae porin channels counterbalances their efflux.

Perspectives on Shiga-like Toxin Infections in Argentina .

Argentina has the highest frequency of hemolytic uremic syndrome (HUS) in the world (300 cases/year). The risk of HUS in children from 6 to 48 months old is approximately 22/100,000 in Buenos Aires. In Argentina, HUS is the most frequent cause of acute renal damage and the second cause of chronic renal injury in children.

New fimbrial adhesins of Serratia marcescens isolated from urinary tract infections: description and properties.

Fimbriation, hemagglutination and adherence properties were studied in two strains of S. marcescens (ATCC 43820 and 43821) isolated from the urine of two hospitalized patients in two different hospitals. Studies were performed using electron microscopy (EM), fimbrial purification, recombinant DNA and hemagglutination techniques, hydrophobicity and tests of adherence to uroepithelial cells, catheters and glass.

Existence of a platelet-adhesion defect in patients with cirrhosis independent of hematocrit: studies under flow conditions.

A defect in hemostasis has been repeatedly reported in patients with cirrhosis. However, the nature of this defect has not been fully characterized. We explored adhesive and cohesive functions of platelets from cirrhotic patients at different stages of disease development.

Clonality of multidrug-resistant nontypeable strains of Haemophilus influenzae.

The genetic structure of a population of multidrug-resistant nontypeable (unencapsulated) Haemophilus influenzae strains isolated at a hospital in Barcelona, Spain, was investigated by using multilocus enzyme electrophoresis to determine the allelic variation in 15 structural loci. In our study we have also included some antimicrobial agent-susceptible strains isolated at the same hospital. All enzymes were polymorphic for two to eight electromorphs, and the analysis revealed 43 distinct electrophoretic types among the 44 isolates.

The effect of O-antigen on transformation efficiency in Serratia marcescens.

Serratia marcescens is an enterobacterium that exhibits very low efficiency of transformation. According to previous work, neither the bacterium restriction system nor its nuclease production accounts for this low efficiency. Differences in the efficiency of transformation from plasmid DNA were found in wild type of S.

Outer membrane permeability of non-typable Haemophilus influenzae.

The permeability to cephaloridine was studied in five Haemophilus influenzae strains (four non-typable and one type b) using the Zimmermann and Rosselet method. The beta-lactamase activity was due to a plasmid-encoded TEM-1 enzyme. High permeability coefficients were measured in all strains examined.

Modification by analgesics of the susceptibility to antibiotics in Serratia marcescens.

The influence of analgesics at low concentrations on permeability and beta-lactamase expression have been studied "in vitro". The effect of these drugs on major outer membrane proteins and the lipopolysaccharide was evaluated. Acetylsalicylate and paracetamol induced modifications in susceptibility to a large variety of antibiotics when tested at therapeutic concentrations.

Taxonomy and protein fingerprinting of halophilic Vibrio isolates from bivalves of the Ebre delta.

A total of 380 isolates of halophilic Vibrio and related bacteria isolated from shellfish bred in the Ebro delta (in northeastern Spain) were studied by biochemical characterization; this allowed the use of numerical taxonomy programs. All but 25 isolates fell into 12 phenotypes. The analysis of whole-cell electrophoretic fingerprints of 100 isolates confirmed the numerical analysis of biochemical and morphological traits.

Lipopolysaccharide recovery restores susceptibility levels towards beta-lactams in Serratia marcescens.

O-side chain-defective spontaneous mutants of Serratia marcescens, selected by phage resistance, showed lower MICs against various beta-lactams than did their parental strains. The recovery of their ability to produce O-antigen restored the original MIC values, as well as phage susceptibility. The permeability coefficients of wild-type, O- mutants, and revertants, demonstrated that O-antigen modifies the permeability of antibiotics in S.

Serratia marcescens adherence: the effect of O-antigen presence.

The presence of O-antigen affects the adhesion of Serratia marcescens cells to inert and biological surfaces. Mutants defective in the O-side chain showed significant decreases in their ability to adhere to plastic and glass surfaces and to the surfaces of Foley urinary catheters, compared with their respective parental strains. Similar results were obtained when the ability to adhere human uroepithelial cells was tested.

Outer membrane proteins from Serratia marcescens.

The outer membrane proteins (OMPs) of several strains of Serratia marcescens have been studied by sodium dodecyl sulphate - urea - polyacrylamide gel electrophoresis. Four major OMPs, named Omp1, Omp2, Omp3, and OmpA (42, 40, 39, and 37 kDa, respectively), have been visualized. The relative proportions of Omp2 and Omp3 depend on cultural conditions (temperature of incubation, osmolarity, and nutrient availability).