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Biomedical subjects

G Ravizzola

Publications and source records attributed to G Ravizzola.

At least 19 recordsLinked to original sources
PubMed2002

Carbapenems in the treatment of severe community-acquired pneumonia in hospitalized elderly patients: a comparative study against standard therapy.

In this open, prospective, study were enrolled 204 hospitalized elderly patients with severe (88 males, 116 females, age range 70-94). Patients were randomized to receive one of the following antibiotic treatment regimens: meropenem 500 mg i.v. t.i.d. (52); imipenem/cilastatin 500 mg i.v. t.i.d. (51), clarithromycin 500 mg + ceftriaxone 1 g i.v. b.i.d. (52), clarithromycin 500 mg + amikacin 250 mg i.v. b.i.d. (49). In 99 cases causative germs were isolated (24 meropenem, 26 imipenem, 23 clarithromycin + ceftriaxone, 26 ceftriaxone + amikacin). A satisfactory clinical, bacteriological response was achieved respectively in 86.5% 77% in meropenem; 86.3% 71% in imipenem/cilastatin; 69% 61% in ceftriaxone + clarithromycin and in 85.7% 77% in clarithromycin + amikacin. The mean total cost for each patient was $1,560; $1,620; $1,760 and $1,792 in meropenem, imipenem/cilastatin, clarithromycin + ceftriaxone and clarithromycin + amikacin respectively. This study shows that treatment with either meropenem or imipenem is as efficacious as conventional therapy in the treatment of community acquired pneumonia (CAP), and that meropenem is the most cost-effective.

Aged↗
PubMed1997

In-vitro study of the synergy between beta-lactam antibiotics and glycopeptides against enterococci.

The synergy between glycopeptides and beta-lactams was studied using different techniques such as broth macrodilution, killing curves and agar dilution combined with agar diffusion. Two glycopeptide-resistant enterococci isolated from different clinical samples were used. Results showed different effects with significant changes in MICs. Antibacterial activity was related to the concentration of glycopeptide and beta-lactam for Enterococcus faecalis 8253, while for Enterococcus faecium 8072 a paradoxical effect was observed. With this strain, the best synergic effect was detected at teicoplanin concentrations of 1-4 mg/L, but antibacterial activity was reduced at concentrations of 8, 16 and 32 mg/L. No synergic effect was observed with vancomycin. The combination of agar dilution with agar diffusion techniques may constitute a simple method for routine detection of synergic effects between glycopeptides and beta-lactams.

Anti-Bacterial Agents↗
PubMed1995

Monoclonal antibodies against antigens exposed on the surface of vegetative forms and spores of Myxococcus virescens.

Twelve monoclonal antibodies (mAbs) directed against cell-surface antigens of Myxococcus virescens cells were developed and partially characterized. All of them recognized multiple, diffuse proteic bands in Western blot and four were also reactive to living bacteria, as assessed by flow cytometry. The four latter mAbs recognized antigens common to a number of vegetative forms and spores. The selective expression of proteins recognized by mAbs on the microorganisms and the possible applications of mAbs to the study of myxobacterial cell interaction are discussed.

Antibodies, Bacterial↗
PubMed1994

Diagnosis of bronchopulmonary infections by quantification of microflora.

The quantification of bacteria and fungi in sputum or bronchoaspirate is of clinical value for the diagnosis of respiratory tract infections. We have developed an easy method to count the micro-organisms in patients with respiratory tract infections. This consists of the quantification of micro-organisms by subsequent streakings of a calibrated loop on agar. The correlation between microbiological quantitative data and the clinical status of patients with lower respiratory tract infections is discussed. The data seem to indicate that certain bacteria present in sputum or bronchoaspirate above a certain concentration may be responsible for lower respiratory tract infections. In patients with immunological disorders or chronic pathologies even lower concentrations of micro-organisms in bronchial secretions probably are enough to cause infections. The advantage of this counting method of the microbic species from the respiratory tract consists of their quantification: thus we can attribute an etiological role to a high concentration of the germs, while micro-organisms at low concentrations are probably contaminants. By this method isolated colonies are obtained after 12-18 hours. The bacterial quantification, by respiratory samples examination of the same patient in the following days, allows us to evaluate the efficacy of antibacterial therapy, producing a reduction of bacterial concentration.

Acquired Immunodeficiency Syndrome↗
PubMed1994

A multicentre study: Staphylococcus and Enterococcus susceptibility to antibiotics.

A multicentre study to evaluate the susceptibility of Gram-positive cocci isolated from clinical samples, was performed by six centres working in different areas of Italy. We examined 4,544 strains of Staphylococcus aureus, 4,381 strains of coagulase-negative staphylococci and 2,478 strains of enterococci. The following antibiotics were tested: penicillin G, ampicillin, amoxicillin, piperacillin, imipenem, oxacillin, ofloxacin, pefloxacin, ciprofloxacin, gentamicin, tobramycin, amikacin, netilmicin, rifampicin, clindamycin, tetracycline, cotrimoxazole, erythromycin, chloramphenicol, vancomycin and teicoplanin. Oxacillin-susceptible staphylococci confirmed their susceptibility to many other antimicrobial agents while oxacillin-resistant strains confirmed their multiple and frequent resistance to antibiotics. Resistance to oxacillin, cotrimoxazole and chloramphenicol was more frequent in coagulase-negative staphylococci than in Staphylococcus aureus. Aminoglycosides, rifampicin and quinolones were more active against coagulase-negative staphylococci than against Staphylococcus aureus. Enterococci were susceptible to penicillins and imipenem, and moderately susceptible to ciprofloxacin. Susceptibility of 70-79% was observed with high levels of aminoglycosides. Excellent results against staphylococci and enterococci were observed with vancomycin and teicoplanin.

Anti-Bacterial Agents↗
PubMed1994

In vitro antibacterial activity of the new quinolone Bay y3118 against clinical isolates.

The in vitro antibacterial activity of the new fluoroquinolone Bay y3118 against 609 clinical isolates was evaluated. Bay y3118 exhibited activity against a broad spectrum of organisms, including Gram-negative bacilli, Gram-positive cocci, mycobacteria. The activity of Bay y3118 was often superior to that of other quinolones. Against Gram-negative bacilli its activity was similar to that of ceftriaxone, cefotaxime, ceftazidime and imipenem except for Serratia marcescens, Klebsiella pneumoniae, Enterobacter spp. and Xanthomonas maltophilia, where its activity was superior. Gentamicin and piperacillin sometimes were less active. Bay y3118 was active against a large number of Gram-positive cocci. The fluoroquinolones tested were active against all the strains of Mycobacterium tuberculosis, but only Bay y3118 was effective against Mycobacterium avium.

Anti-Bacterial Agents↗
PubMed1994

Effect of subinhibitory concentrations of lomefloxacin on bacterial adherence.

We studied the effect of subinhibitory concentrations of lomefloxacin on bacterial adherence, assessing the presence of fimbriae in E. coli and the adherence to uroepithelial cells of Staphylococcus saprophyticus. The degree of inhibition of fimbriae in E. coli in the log-phase is directly proportional to subminimal inhibiting concentrations (sub-MIC). On the contrary, there is no effect when the bacteria are in a stationary phase. In the case of Staphylococcus saprophyticus the adherence to epithelial cells was observed at concentrations of 1/2 and 1/4 the MIC.

Anti-Infective Agents↗
PubMed1994

Development of a flow cytometric assay for the detection and measurement of neutralizing antibodies against human immunodeficiency virus.

Cells infected with human immunodeficiency virus type 1 (HIV-1) develop viral antigens which can be detected by immunofluorescence. We developed a flow cytometric immunofluorescence assay (FIFA) which provides a quantitative analysis of HIV-1 p24 using a monoclonal antibody (mAb) as a specific reagent. The reduction of HIV p24 antigen expression in viral infected cells was then used to determine HIV neutralizing antibody titers in human sera. Results obtained by FIFA for detecting neutralizing antibodies against HIV-1, when compared with results obtained by indirect immunofluorescence assay (IFA), showed an overall index of agreement of 94.1%. The correlation between the neutralizing antibody titers obtained with each method was found to be highly significant (ro = 0.8; p < 0.01). The simple methodology and the adaptability of this FIFA to various assay conditions make it suitable for routine purposes and for assessing the efficacy of vaccination strategies.

Antibodies, Monoclonal↗
PubMed1993

Rapid methods for microbial diagnosis of mycobacterial infections.

The Authors describe their experience in rapid diagnosis of mycobacterial infections using a combination of a radiometric blood culture (Bactec 13 A) and a nucleic acid hybridization system (Gen probe, Accuprobe) to detect and identify Mycobacteria. They found out that a high number of septicaemias in HIV positive patients are due to Mycobacterium avium, while in HIV negative subjects Mycobacterium tuberculosis is the most frequent mycobacterium.

HIV Seropositivity↗
PubMed1989

Antibacterial activity of the new carbapenem meropenem (SM-7338) against clinical isolates.

The in vitro antibacterial activity of the new carbapenem antibiotic meropenem (SM-7338) against 567 clinical isolates was evaluated. SM-7338 exhibited activity against a broad spectrum of organisms, including aerobes and anaerobes, and was superior to the other beta-lactam drugs tested (piperacillin, cefotaxime, ceftazidime, ceftriaxone, cefoxitin). SM-7338 was more active than imipenem, gentamicin and amikacin against Enterobacter cloacae and Pseudomonas aeruginosa. SM-7338 was less potent than imipenem against staphylococci and enterococci, but the activity of the two antibiotics against anaerobes was similar. SM-7338 and imipenem showed a high bactericidal activity at a concentration of 2-4 x MIC.

Anti-Bacterial Agents↗
PubMed1989

In-vitro activity of meropenem against clinical isolates in a multicentre study in Italy.

A multicentre in-vitro study was undertaken to evaluate the susceptibility of bacterial pathogens isolated in different Italian hospitals to meropenem. A total of 1399 aerobic and 452 anaerobic strains was analysed. Comparative agents were imipenem, cefotaxime, ceftazidime, ceftriaxone, piperacillin, ciprofloxacin, gentamicin, amikacin, plus vancomycin when appropriate. The MIC ranges (mg/l) of meropenem were: 0.015-2 for Klebsiella spp., Proteus spp., Morganella morganii and Providencia spp.; less than 0.008-1 for Escherichia coli; 0.016-32 for Serratia spp.; 0.03-2 for Enterobacter spp. and Citrobacter spp.; 0.03- greater than 128 for Acinetobacter anitratus; 0.03-32 for Pseudomonas spp.; less than 0.008-0.5 for Haemophilus spp. and Neisseria spp.; 0.015-64 for Staphylococcus spp.; 0.06- greater than 128 for Enterococcus spp.; less than 0.008-0.25 for Streptococcus spp.; 0.016-8 for Fusobacterium spp.; 0.03-8 for Bacteroides spp.; less than 0.06-0.5 for anaerobic Gram-positive cocci; 0.08-2 for Clostridium spp. Meropenem exhibited superior antibacterial activity against the aerobic and anaerobic strains tested when compared to the other beta-lactam drugs. The new carbapenem was as active as ciprofloxacin and more active than imipenem and the aminoglycosides against Enterobacteriaceae and Ps. aeruginosa. It was also more active than ciprofloxacin against most strains of Gram-positive cocci. Meropenem was slightly less potent than imipenem against staphylococci and enterococci, with the exception of oxacillin-susceptible Staph. aureus against which meropenem and imipenem exhibited similar antibacterial activity.

Aminoglycosides↗
PubMed1989

Evaluation of BACTEC system for urine culture screening.

We compared urine culturing performed by the calibrated loop method with a screening system (BACTEC). A total of 852 urine specimens were examined by both the conventional loop method and the BACTEC system. With the loop method, 193 (22.6%) urine samples were positive, whereas with the BACTEC system, 185 (21.7%) were positive (sensitivity, 96.01%). At a breakpoint of 10(4) CFU/ml, eight false-negatives were detected (sensitivity, 87.09%), and at a breakpoint of 10(5) CFU/ml, four false-negatives were observed (sensitivity, 97.6%). The specificity of the BACTEC system was 100%. We propose the BACTEC method as an effective alternative to the other growth-dependent screening tests for bacteriuria.

Bacteria↗