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R Fontana

Publications and source records attributed to R Fontana.

At least 37 records · Page 2Linked to original sources
PubMed2001

Molecular heterogeneity of bla(VIM-2)-containing integrons from Pseudomonas aeruginosa plasmids encoding the VIM-2 metallo-beta-lactamase.

A bla(VIM-2) metallo-beta-lactamase determinant, identical to that previously identified in Pseudomonas aeruginosa COL-1 isolate from a French hospital, was detected on a 28-kb plasmid carried by a nosocomial isolate of P. aeruginosa from Verona, Italy. In this plasmid the bla(VIM-2) determinant was inserted into a class 1 integron of original structure, named In72, that contains a partially deleted intI1 integrase gene and two gene cassettes. The first cassette carries an aacA4 aminoglycoside acetyl transferase determinant. The second cassette carries a bla(VIM-2) determinant followed by a partially deleted attC site. The structure of In72 was notably different from that of In56, the bla(VIM-2)-containing integron found in the COL-1 isolate, revealing the existence of molecular heterogeneity among bla(VIM-2)-containing integrons in clinical isolates of P. aeruginosa from Europe.

Acetyltransferases↗
PubMed2001

Epidemiological analysis of vancomycin-resistant enterococci in a large tertiary-care hospital in Northern Italy.

The epidemiology of vancomycin-resistant enterococci (VRE) was studied in a large tertiary-care hospital in northern Italy from February 1993 to December 1999. Sixteen cases of bacteraemic and 17 cases of nonbacteraemic active infections caused by VRE were recorded. Fifteen of the bacteraemic and four of the nonbacteraemic infections occurred in patients in the haematology department, while the remainder were registered in other departments of the same hospital. Active surveillance for the presence of VRE in stools led to identification of 51 noninfected carriers over the 1994-1999 period; of these, 32 were haematology patients and the remainder were patients admitted to other departments. All VRE isolates carried the vanA gene. Forty-one Enterococcus faecium isolates and eight Enterococcus faecalis isolates collected in the 1993-1996 period were typed by pulsed-field gel electrophoresis. Twenty-nine isolates of Enterococcus faecium shared either indistinguishable or strictly or possibly related patterns. Of these, 26 were isolated from patients in the haematology department. This is believed to be the first study on the epidemiology of VRE carried out in a large hospital in Italy over a period of several consecutive years. It reports an increase in VRE due to the epidemic spread of genetically related strains and sporadic infections or colonisation by unrelated VRE. It also documents the success of surveillance and of the measures adopted for preventing the spread of VRE in patients at risk.

Bacteremia↗
PubMed2001

Antimicrobial susceptibility of respiratory isolates of Enterobacteriaceae and Staphylococcus aureus in Italy: incidence and trends over the period 1997-1999.

The antibiotic susceptibility of members of the family Enterobacteriaceae and of Staphylococcus aureus strains isolated from the respiratory tract was assessed over the period 1997-1999 as part of the Italian Epidemiological Observatory survey sponsored by the Smith-Kline Foundation. A standardised method was used to determine the MICs of 22 antibiotics against isolates of Klebsiella pneumoniae (n=870), Escherichia coli (n=684), Enterobacter cloacae (n=342), Enterobacter aerogenes (n=187) and Serratia marcescens (n=135) as well as the MICs of 11 antibiotics against isolates of Staphylococcus aureus (n=1,606). Overall, the susceptibility rate of Enterobacteriaceae isolates was > or = 90% to 5 agents (meropenem, imipenem, amikacin, cefepime and gentamicin); 89-80% to 2 agents (ciprofloxacin and tobramycin); and <80% to 11 agents (cefotaxime, piperacillin-tazobactam, trimethoprim-sulfamethoxazole, cefetamet, ceftriaxone, ceftazidime, aztreonam, ticarcillin-clavulanate, tetracycline, piperacillin, cefuroxime, chloramphenicol, ticarcillin, amoxicillin-clavulanate and amoxicillin). During the 3-year monitoring period, antibiotic susceptibility increased in Klebsiella pneumoniae against amoxicillin-clavulanate, in Escherichia coli against third-generation cephalosporins and aztreonam, in Enterobacter aerogenes against amoxicillin and piperacillin-tazobactam and in Serratia marcescens against most of the antibiotics. In contrast, Enterobacter cloacae showed a tendency to develop resistance to cefetamet, amikacin and ciprofloxacin. Of the total number of Staphylococcus aureus strains, 38% were methicillin resistant. Nearly 80% of the methicillin-resistant strains displayed a multiresistance pattern (additional resistance to 2 or more non-beta-lactam antibiotics). Rates of susceptibility of particular species (Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus) were compared using strains from different geographical areas of Italy (northern, central and southern) and from different nosocomial areas (outpatients, intensive care unit [ICU] inpatients, non-ICU inpatients). Susceptibility of Klebsiella pneumoniae to several antibiotics was lower in southern Italy, whereas the incidence of methicillin-resistant strains was higher in northern and central Italy. The susceptibility of Escherichia coli was similar in all three areas. No significant differences in susceptibility of Klebsiella pneumoniae or Escherichia coli were found between strains from inpatients and outpatients or from inpatients admitted to ICU and non-ICU units. The incidence of methicillin-resistant Staphylococcus aureus was higher in ICU inpatients (52%) than in non-ICU inpatients (38%) and lower in outpatients (19%) than in inpatients.

Drug Resistance, Bacterial↗
PubMed2001

Molecular analysis of vanA enterococci isolated from humans and animals in northeastern Italy.

A total of 53 vancomycin-resistant vanA-positive enterococci isolates from poultry farms (17 Enterococcus faecium; 8 Enterococcus durans) and from different hospitals (23 E. faecium; 5 Enterococcus faecalis) in northeastern Italy were compared on the basis of their antibiotic susceptibilities, their SmaI pulsed-field gel electrophoresis (PFGE) patterns, and the organization of their Tn1546-related elements. Ampicillin resistance was similar in both groups of isolates (52 and 60.7%, respectively), whereas human strains were more resistant to high-level gentamicin and streptomycin. A total of 52% of animal strains and 60% of human strains were resistant to tetracycline, and 56% and 46.4% to quinupristin/dalfopristin, respectively. In E. faecium and E. durans animal isolates, nine and six distinct PFGE patterns, respectively, were found: in two instances indistinguishable isolates were found from different farms. In E. faecium and E. faecalis human isolates, nine and six distinct PFGE patterns, respectively, were found; among E. faecium strains, 12 were identical or closely related and were isolates from the same hospital. Elements mediating vanA-glycopeptide resistance were characterized by PCR with primers that amplified 10 overlapping fragments of Tn1546. A total of 84.6% of animal strains and 64.2% of human strains contained elements indistinguishable from the prototype Tn1546. In addition, nine different types were identified, but none was common to animal and human strains.

Animals↗
PubMed2001

In70 of plasmid pAX22, a bla(VIM-1)-containing integron carrying a new aminoglycoside phosphotransferase gene cassette.

An Achromobacter xylosoxydans strain showing broad-spectrum resistance to beta-lactams (including carbapenems) and aminoglycosides was isolated at the University Hospital of Verona (Verona, Italy). This strain was found to produce metallo-beta-lactamase activity and to harbor a 30-kb nonconjugative plasmid, named pAX22, carrying a bla(VIM-1) determinant inserted into a class 1 integron. Characterization of this integron, named In70, revealed an original array of four gene cassettes containing, respectively, the bla(VIM-1) gene and three different aminoglycoside resistance determinants, including an aacA4 allele, a new aph-like gene named aphA15, and an aadA1 allele. The aphA15 gene is the first example of an aph-like gene carried on a mobile gene cassette, and its product exhibits close similarity to the APH(3')-IIa aminoglycoside phosphotransferase encoded by Tn5 (36% amino acid identity) and to an APH(3')-IIb enzyme from Pseudomonas aeruginosa (38% amino acid identity). Expression of the cloned aphA15 gene in Escherichia coli reduced the susceptibility to kanamycin and neomycin as well as (slightly) to amikacin, netilmicin, and streptomycin. Characterization of the 5' and 3' conserved segments of In70 and of their flanking regions showed that In70 belongs to the group of class 1 integrons associated with defective transposon derivatives originating from Tn402-like elements. The structure of the 3' conserved segment indicates the closest ancestry with members of the In0-In2 lineage. In70, with its array of cassette-borne resistance genes, can mediate broad-spectrum resistance to most beta-lactams and aminoglycosides.

Alcaligenes↗
PubMed2001

Identification of 54 mycobacterial species by PCR-restriction fragment length polymorphism analysis of the hsp65 gene.

A total of 121 reference and clinical strains of both slowly and rapidly growing mycobacteria belonging to 54 species were studied for restriction fragment length polymorphism of a PCR-amplified 439-bp segment of the gene encoding the 65-kDa heat shock protein. Restriction digests were separated by 10% polyacrylamide gel electrophoresis (PAGE). By including a size standard in each sample, the restriction fragment profile was calculated using a computer-aided comparison program. An algorithm describing these 54 species (including 22 species not previously described) is proposed. We found that this assay based on 10% PAGE provided a more precise estimate than that based on agarose gel electrophoresis of the real size of restriction fragments as deduced from the sequence analysis and allowed identification of mycobacteria whose PCR-restriction fragment length polymorphism analysis patterns were unequivocally identified by fragments shorter than 60 bp.

Algorithms↗
PubMed2000

Hospital outbreak of carbapenem-resistant Pseudomonas aeruginosa producing VIM-1, a novel transferable metallo-beta-lactamase.

A total of 8 Pseudomonas aeruginosa isolates was collected from 7 different patients in different wards of the University Hospital of Verona, Italy, from February 1997 to February 1998. The high level of resistance to carbapenems (imipenem minimum inhibitory concentration was always >128 microg/mL) and other broad-spectrum beta-lactams and the rate of imipenem hydrolysis and its inhibition by ethylenediamine-tetra-acetic acid were all suggestive of production of a carbapenem-hydrolyzing metallo-beta-lactamase. A specific DNA probe derived from the recently cloned bla(VIM-1) gene hybridized to all the isolates. A genomic DNA fingerprinting profile revealed clonal relatedness for 7 of 8 isolates. A description of this hospital outbreak is reported, the occurrence of which confirms that proliferation of metallo-beta-lactamase-producing strains multiply resistant to beta-lactams is already a reality outside Japan. These findings emphasize the need for early recognition of similar isolates.

Adult↗
PubMed2000

Lung cancer mortality in the Mayo Lung Project: impact of extended follow-up.

BACKGROUND: The Mayo Lung Project (MLP) was a randomized, controlled clinical trial of lung cancer screening that was conducted in 9211 male smokers between 1971 and 1983. The intervention arm was offered chest x-ray and sputum cytology every 4 months for 6 years; the usual-care arm was advised at trial entry to receive the same tests annually. No lung cancer mortality benefit was evident at the end of the study. We have extended follow-up through 1996. METHODS: A National Death Index-PLUS search was used to assign vital status and date and cause of death for 6523 participants with unknown information. The median survival for lung cancer patients diagnosed before July 1, 1983, was calculated by use of Kaplan-Meier estimates. Survival curves were compared with the log-rank test. RESULTS: The median follow-up time was 20.5 years. Lung cancer mortality was 4.4 (95% confidence interval [CI] = 3.9-4.9) deaths per 1000 person-years in the intervention arm and 3.9 (95% CI = 3.5-4.4) in the usual-care arm (two-sided P: for difference =.09). For participants diagnosed with lung cancer before July 1, 1983, survival was better in the intervention arm (two-sided P: =.0039). The median survival for patients with resected early-stage disease was 16.0 years in the intervention arm versus 5.0 years in the usual-care arm. CONCLUSIONS: Extended follow-up of MLP participants did not reveal a lung cancer mortality reduction for the intervention arm. Similar mortality but better survival for individuals in the intervention arm indicates that some lesions with limited clinical relevance may have been identified in the intervention arm.

Algorithms↗
PubMed2000

Epidemiological survey of bacterial resistance in upper respiratory tract infections in italy.

The vast majority of infections in the upper airways are caused by four bacterial species;, in Italy as elsewhere, antibiotics resistant strains are emerging. Enzymatic resistance to beta-lactams in Haemophilus influenzae is becoming more important and affects 15% of isolates. On the other hand less than 0.3% of H. influenzae strains are fluoroquinolone-resistant. The number of beta-lactamase-producing Moraxella catarrhalis strains in Italy has been thought to be lower than in other countries, but recent studies suggest 90% of strains are positive, a figure similar to figures reported in the international literature. The most recent data estimate high-level resistance to penicillin in pneumococci to be around 5%, but varies greatly in different geographical areas and with the different origins of the isolates. In spite of the low incidence of penicillin-resistant strains, the most recent figures for macrolide-resistance in Streptococcus pneumoniae range from 26.4 to 31.7%. More than 3 years after the dramatic increase in erythromycin-resistant Streptococcus pyogenes, the resistance levels in Italy are still among the highest in the world. Unlike the experience in other countries, resistance is often related not to the active efflux of antibiotic from the bacterial cell but to ribosomal methylation, thus affecting not only 14- and 15-membered macrolides, but also 16-membered compounds and lincosamides.

Anti-Bacterial Agents↗
PubMed2000

Characterization of the metallo-beta-lactamase determinant of Acinetobacter baumannii AC-54/97 reveals the existence of bla(IMP) allelic variants carried by gene cassettes of different phylogeny.

The metallo-beta-lactamase determinant of Acinetobacter baumannii AC-54/97, a clinical isolate from Italy that was previously shown to produce an enzyme related to IMP-1, was isolated by means of a PCR methodology which targets amplification of gene cassette arrays inserted into class 1 integrons. Sequencing revealed that this determinant was an allelic variant (named bla(IMP-2)) of bla(IMP) found in Japanese isolates and that it was divergent from the latter by 12% of its nucleotide sequence, which evidently had been acquired independently. Similar to bla(IMP), bla(IMP-2) was also carried by an integron-borne gene cassette. However, the 59-base element of the bla(IMP-2) cassette was unrelated to those of the bla(IMP) cassettes found in Japanese isolates, indicating a different phylogeny for the gene cassettes carrying the two allelic variants. Expression of the integron-borne bla(IMP-2) gene in Escherichia coli resulted in a significant decrease in susceptibility to a broad array of beta-lactams (ampicillin, carbenicillin, cephalothin, cefoxitin, ceftazidime, cefepime, and carbapenems). The IMP-2 enzyme was purified from an Escherichia coli strain carrying the cloned determinant, and kinetic parameters were determined with several beta-lactam substrates. Compared to IMP-1, the kinetic parameters of IMP-2 were similar overall with some beta-lactam substrates (cefoxitin, ceftazidime, cefepime, and imipenem) but remarkably different with others (ampicillin, carbenicillin, cephaloridine, and meropenem), revealing a functional significance of at least some of the mutations that differentiate the two IMP variants. Present findings suggest that the environmental reservoir of bla(IMP) alleles could be widespread and raise a question about the global risk of their transfer to clinically relevant species.

Acinetobacter↗
PubMed2000

Reliability of the MB/BacT system for testing susceptibility of Mycobacterium tuberculosis complex isolates to antituberculous drugs.

The susceptibility of 115 Mycobacterium tuberculosis complex clinical isolates to isoniazid, streptomycin, ethambutol, and rifampin was assessed by the MB/BacT and BACTEC 460TB systems. The correlation between the two tests was 98.3% for isoniazid, 100% for streptomycin and rifampin, and 95.8% for ethambutol. Turnaround times for antimicrobial susceptibility testing ranged from 5 to 11 days (median, 8.5 days) for MB/BacT and from 4 to 8 days (median, 6 days) for BACTEC 460TB.

Antitubercular Agents↗
PubMed1999

Molecular typing of erythromycin-resistant streptococcus pyogenes strains with the M phenotype isolated in Italy.

To assess the spread of the new M phenotype, various erythromycin-resistant Streptococcus pyogenes strains from three Italian cities (Verona, Monza, Florence) were characterised. Each strain was analysed for the presence of genes ermAM and mefA, for the ability to accumulate radioactive erythromycin in the absence of sodium arsenate, for the protein T serological type, and for the DNA macrorestriction profile identified by means of pulsed-field gel electrophoresis. In a number of strains, the presence of the inducible ermAM gene was demonstrated; all these strains were negative in the efflux-pump detection assay, did not possess the mefA gene, and had similar restriction profiles. The strains with the efflux mechanism and mefA gene belonged to different serotypes. Of these, only one serotype, T4, was isolated in all three cities. The restriction profile analysis with SmaI and SfiI revealed a very close correlation between strains with the same serotype.

Anti-Bacterial Agents↗