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Biomedical subjects

G Gialdroni Grassi

Publications and source records attributed to G Gialdroni Grassi.

At least 37 records · Page 2Linked to original sources
PubMed1989

Bactericidal activity of meropenem and interactions with other antibiotics.

MICs of meropenem for selected clinical isolates of bacteria were determined. Killing curves were performed on strains of methicillin-sensitive Staphylococcus aureus, methicillin-resistant Staph. aureus (MRSA), methicillin-resistant Staph, epidermidis, Escherichia coli, Klebsiella spp., Enterobacter cloacae, Pseudomonas aeruginosa, Citrobacter freundii and Acinetobacter spp. A reduction of greater than or equal to 3 x log10 in viable cells was observed at 4 and 6 h of exposure to 4 and 8 x MIC, and this was usually maintained at 24 h (with a few exceptions for methicillin-resistant Staph, epidermidis and Ent. cloacae). At the MIC and twice the MIC regrowth tended to occur at 24 h although this varied from strain to strain. The interaction with other antibiotics was determined by the chequerboard technique. Usually an additive or synergistic effect was observed when meropenem or imipenem was used in combination with an aminoglycoside against Gram-negative species, while in a few cases antagonism occurred in combination with beta-lactams. Against Staph, aureus, MRSA and Staph, epidermidis synergism was usually obtained with combinations with teicoplanin or vancomycin and either synergism or addition with combinations with rifampicin, co-trimoxazole or ciprofloxacin.

Anti-Bacterial Agents↗
PubMed1988

Infections by gram-positive bacteria: an overview.

Staphylococcus aureus, which has exceptional ability to cause disease in man, has responded to the introductions of antimicrobial agents by the selection and emergence of antibiotic-resistant strains. There have been cyclical changes in the prevalence of these strains in nosocomial infections. Other Gram-positive species that give rise to concern, for related reasons, are Staph. epidermidis and other coagulase-negative staphylococci, Streptococcus faecalis and the JK group of corynebacteria. These problems are discussed to provide a background for the contributions that follow.

Bacterial Infections↗
PubMed1988

Penetration of roxithromycin in bronchial secretions.

Roxithromycin sputum and serum concentrations after administration of therapeutic doses (150 mg in a single dose) were evaluated in six patients. Blood samples and pooled sputum samples were collected at corresponding time intervals up to 24 h after drug administration. Roxithromycin sputum levels were found to be almost always above serum concentrations, the highest sputum levels being 5.85 +/- 2.5 micrograms/ml in the interval ranging from 2 to 4 h after drug administration. Due to its antibacterial spectrum and favourable pharmacokinetic properties, roxithromycin, like other macrolide antibiotics, seems to be particularly indicated in the treatment of respiratory tract infections.

Age Factors↗
PubMed1987

Complement-dependent bactericidal activity for E. coli K12 in serum of preterm newborn infants.

Complement-dependent serum bactericidal activity for E. coli K12 was assessed in 12 term infants and in 16 preterm infants. In both groups of newborns, at birth, bactericidal reaction by the classical pathway of complement activation was impaired with respect to normal controls at less than 0.001 level of significance (as estimated by Student's t-test). The serum bactericidal reaction by the alternative pathway of complement activation was significantly impaired only in preterm newborns, being normal in term infants. At a time corresponding to 40 weeks' gestational age also in preterm newborns alternative pathway mediated bactericidal activity for E. coli K12 was found normal. Classical pathway mediated bactericidal activity became normal only at an age corresponding to 52 weeks' gestational age.

Blood Bactericidal Activity↗
PubMed1987

Clinical efficacy of ofloxacin in lower respiratory tract infections. A multicentre study.

A multicentre clinical trial was carried out to determine the activity and tolerability of ofloxacin in the treatment of lower respiratory tract infections. 667 patients were randomly allocated to 1 of 3 different twice daily dosage regimens: 400 mg (245 patients), 600 mg (211) or 800 mg (211). The mean duration of treatment was 8.77 +/- 2.62 days. Satisfactory overall clinical results (i.e. cured or improved) were obtained in 612 of 667 patients (91.8%). Eradication of pathogens was achieved for 279 of 354 isolated strains (78.8%). Side effects were observed in 31 patients and consisted of gastrointestinal disturbance (22), skin rash (1), neurological disturbance (3) and others (5). No significant alteration of haematological parameters was reported.

Aged↗
PubMed1987

In vitro and ex vivo influence of rifamycins on human phagocytes.

We studied the effects of rifamycin SV, rifampicin and rifapentine on human phagocyte functions. Rifamycins inhibited in vitro neutrophil chemotaxis in the range of their therapeutic levels, and they significantly affected the survival of a rifamycin-sensitive strain of Staphylococcus aureus inside human monocytes. Both effects were related to the intraphagocytic penetration of these antibiotics. For the ex vivo studies, 600 mg of rifampicin were orally administered to five subjects with defective S. aureus killing. A significant reduction of neutrophil chemotaxis and increased activity against S. aureus were shown 150 and 210 min after administration of the drug.

Chemotaxis, Leukocyte↗
PubMed1987

In vitro activity of macrolides on human phagocytic functions.

The aim of this study was to examine the in vitro activity of erythromycin, josamycin, flurithromycin, miocamycin and roxithromycin on some leukocyte functional parameters. All tested macrolides did not interfere with the frequency and index of phagocytosis, nitroblue tetrazolium reduction to formazan deposits and candidacidal activity of human polymorphonuclear leukocytes (p greater than 0.05). Among macrolide antibiotics, only flurithromycin significantly inhibited neutrophil chemotaxis at a high concentration (greater than or equal to 50 micrograms/ml). All macrolides, at 10 and 50 micrograms/ml, reduced the survival of a susceptible strain of Staphylococcus aureus ingested by human monocytes.

Anti-Bacterial Agents↗
PubMed1986

The effect of teicoplanin on leukocytic activity and intraleukocytic micro-organisms.

The interference of teicoplanin with certain phagocyte activities was investigated in comparison with that of vancomycin. Neither teicoplanin nor vancomycin interfered with chemotaxis, adherence, phagocytosis or nitroblue tetrazolium reduction of human neutrophils. Teicoplanin, but not vancomycin, enhanced intracellular killing by neutrophils from normal donors and from a patient with chronic granulomatous disease. Human monocytes in the absence of fresh human serum did not significantly kill Staphylococcus aureus but when pre-treated with teicoplanin 90% of phagocytozed bacteria were killed during 4 h incubation.

Anti-Bacterial Agents↗
PubMed1986

In vitro activity of flurithromycin, a novel macrolide antibiotic.

Flurithromycin is an (8,S)-8-fluoroerythromycin isolated from the fermentation broth of Streptomyces erythraeus ATCC 31772, a blocked mutant of a strain producer of erythromycin. Its in vitro antibacterial activity has been determined on recent clinical isolates of respiratory pathogens. The range of MIC for Streptococcus pneumoniae and Streptococcus beta-haemolyticus group A is from 0.0015 to 0.006 microgram/ml, for Haemophilus influenzae from 0.012 to 0.4 microgram/ml, for Staphylococcus aureus from 0.1 to 3.1 micrograms/ml. Its action is bacteriostatic and increases at alkaline pH. Among anaerobes Clostridium perfringens, Bacteroides fragilis, other species of Bacteroides and Peptostreptococcus are particularly susceptible. Flurithromycin also showed some activity on Mycobacterium bovis, M. scrofulaceum and M. phley. The determination of killing curves indicated that in most cases a killing effect was obtained at 4 X MIC. A combination of flurithromycin with ampicillin or doxycycline sometimes was synergic, but more often additive and never antagonistic. The possible interference of flurithromycin on some parameters of the natural system of defense was determined. At concentrations equal to therapeutic levels in blood and tissues, flurithromycin did not influence chemotaxis, phagocytosis, metabolic activation and the killing activity of neutrophils.

Ampicillin↗
PubMed1984

Influence of ceftriaxone on natural defense systems.

The in vitro and in vivo effects of ceftriaxone, a newly developed cephalosporin, on phagocytes and T-cell subsets were studied. Ceftriaxone in vitro did not interfere with phagocytosis, phagocytosis-dependent metabolic activation, and microbicidal activity (against Staphylococcus aureus and Candida albicans) of human neutrophils at doses ranging from 10 to 320 micrograms/ml. In vitro chemotaxis was markedly inhibited both in the presence of and after 30 minutes of exposure to 40 micrograms/ml of ceftriaxone. Six normal adult volunteers were given 2 g of antibiotic intravenously every 24 hours for six days. The in vivo effects of ceftriaxone on neutrophil functions and T-cell subsets were investigated before and 30 minutes after injection on the first and third days. No change in any phagocyte function (chemotaxis, phagocytosis, phagocytosis-dependent metabolic activation, and microbicidal activity) or in the distribution of T-cell subpopulations was observed.

Cefotaxime↗
PubMed1983

In vitro activity of teichomycin against isolates of gram-positive bacteria.

The in vitro activity of teichomycin has been evaluated against 189 clinical isolates of Staphylococcus aureus, Staphylococcus epidermidis and group D streptococci. Teichomycin was as active as vancomycin, a chemically related antibiotic, on staphylococci and inhibited the in vitro growth of methicillin-resistant strains at the same concentration necessary to inhibit the sensitive ones. Against group D streptococci teichomycin was about three times more active than vancomycin (MIC50 = 0.125 mg/l, MIC90 = 0.4 mg/l). MBC:MIC ratios of both drugs against staphylococci were comparable, but teichomycin had higher bactericidal activity against group D streptococci, as shown also by killing curves. The activity of teichomycin was not significantly affected by variation of pH, even if the maximum activity was achieved at neutral pH, or by different methods of MIC evaluation. The antibiotic seemed more active when tested with a low inoculum (10(3)-10(5)/ml): a two- to threefold increase in MIC was observed at an inoculum of 10(7)/ml. A reduction of the in vitro activity could be shown when Penassay broth was used as culture medium.

Anti-Bacterial Agents↗