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Biomedical subjects

I Covelli

Publications and source records attributed to I Covelli.

At least 19 recordsLinked to original sources
PubMed2001

An observational study on the epidemiology of respiratory tract bacterial pathogens and their susceptibility to four injectable beta-lactam antibiotics: piperacillin, piperacillin/tazobactam, ceftazidime and ceftriaxone.

Bacterial infections of the respiratory tract account for a large proportion of total medical consultations in general practice. In recent years, antibiotic resistance has increased alarmingly in a number of bacterial species that are common causes of these infections. The aim of this observational study was to determine the antibiotic resistance of microbial agents isolated from patients with acute or acutely exacerbated respiratory infections. Subjects recruited as potential sources of bacteria were either outpatients seen in a number of specialized clinics and hospital practices, or hospitalized patients. Overall, 648 consecutive patients (67% male, mean age 48.1+/-27.0 years) with infection of the upper or lower respiratory tract were observed during a 13-month period. A total of 551 pathogenic microbial strains were isolated and tested for their in vitro susceptibility to piperacillin, piperacillin/tazobactam, ceftazidime, and ceftriaxone. Among all isolates, the four most frequent pathogens were Pseudomonas aeruginosa (132 isolates, 24%), Streptococcus pyogenes (99 isolates, 18%), Staphylococcus aureus (93 isolates, 17%), and Klebsiella pneumoniae (46 isolates, 8%). The susceptibility of gram-positive isolates ranged from 97.5% to 95.1%, and no remarkable difference was found in the antibacterial activity of tested b-lactam antibiotics. The susceptibility of gram-negative isolates to piperacillin and piperacillin/tazobactam was also similar: 96.5% and 97.1%, respectively. In contrast, differences were found between piperacillin (or piperacillin/tazobactam) and either ceftazidime (p=0.003) or ceftriaxone (p<0.0003) in gram-negative isolates. We conclude that, despite the extensive use of beta-lactam antibiotics (piperacillin, ceftazidime, and ceftriaxone) in medical practice during the past three decades, the susceptibility of the most common pathogens involved in the etiology of upper and lower respiratory tract infections to these antibiotics is still high. In particular, bacterial resistance developed by gram-positive organisms against piperacillin is negligible and not alarming.

Adolescent↗
PubMed1999

Multicenter evaluation of the MB-Redox medium compared with radiometric BACTEC system, mycobacteria growth indicator tube (MGIT), and Löwenstein-Jensen medium for detection and recovery of acid-fast bacilli.

MB-Redox is a new manual culture system designed for the recovery of mycobacteria from clinical specimens. It consists of a liquid medium (modified Kirchner medium) containing a redox indicator, a colorless tetrazolium salt, which is reduced to colored formazan by actively growing mycobacteria. Acid fast bacilli (AFB) are easily detected in the medium as pink to purple pinhead-sized particles. We report the results of a multicenter study (involving four Italian microbiology laboratories processing 2370 clinical specimens) aiming to evaluate the recovery rates of AFB and time required for their detection by using the MB-Redox medium. Two different protocols were set up: in Protocol A (1580 specimens) the performance of MB-Redox was compared with those of the radiometric BACTEC 460 TB system (B460) and Löwenstein-Jensen medium (L-J), whereas in Protocol B (790 specimens) it was compared with those of the Mycobacteria Growth Indicator Tube (MGIT) and L-J. A total of 213 mycobacteria were recovered, including 172 Mycobacterium tuberculosis complex (MTB) isolates and 41 nontuberculous mycobacteria (NTM) isolates. In Protocol A, recovery rates were 81% for MB-Redox system, 84% for B460 system, and 77% for L-J. In Protocol B the recovery rates by individual system were 87, 83, and 76% for MB-Redox, MGIT, and L-J, respectively. Differences in both the protocols were not statistically significant. The MB-Redox system plus L-J (Combination 1) recovered 94% of the isolates in Protocol A and 93% in Protocol B, while B460 plus L-J (Combination 2) and MGIT plus L-J (Combination 3) detected 91 and 89% of all mycobacteria isolates respectively. No statistically significant differences were found among the combinations. The mean time to detection of mycobacteria was 16.3 days in Protocol A and 19.1 days in Protocol B with the MB-Redox system, 22.4 and 25.9 days with L-J, 13.2 days with B460, and 18.2 days with MGIT. The contamination rates were 2.1, 2.0, 1.9, and 3.6 for MB-Redox, B460, MGIT, and L-J respectively. The MB-Redox is a reliable, nonradiometric system for growth and detection of mycobacteria. When used in combination with a solid medium it proved to be an effective replacement for B460. The MB Redox system is a labor-intensive method requiring much handling during the visual reading procedures.

Bacteriological Techniques↗
PubMed1998

Detection of IgG and IgA against the mycobacterial antigen A60 in patients with extrapulmonary tuberculosis.

BACKGROUND: Diagnosis of extrapulmonary tuberculosis is often difficult to establish using standard methods. Serological techniques based on detection of antibodies against mycobacterial antigen A60 have shown good sensitivity and specificity in pulmonary tuberculosis. The present study was undertaken to define the diagnostic accuracy of testing for IgG and IgA against A60 in extrapulmonary tuberculosis. METHODS: One hundred and ninety eight subjects were studied: 42 patients with extrapulmonary tuberculosis confirmed by microbiology and/or histology, 24 subjects with healed pulmonary or extrapulmonary tuberculosis, 44 patients with a defined non-tuberculous disease, and 88 healthy volunteers (44 PPD negative and 44 PPD positive). Detection of IgG and IgA against A60 antigen was carried out by enzyme-linked immunosorbent assay. Cut off values were determined by receiver operating characteristic curves. RESULTS: Sensitivity of the IgG test was 73.8% in extrapulmonary tuberculosis, while the specificity was 96.1%. The IgA test showed a sensitivity of 69.0% with a specificity of 93.6%. Combination of the IgG and IgA tests showed a sensitivity of 80.9% and a specificity of 92.3%. Patients with extrapulmonary tuberculosis showed significantly higher titres of both IgG and IgA against A60 than other groups. CONCLUSIONS: Anti-A60 IgG or IgA tests are characterised by good sensitivity and specificity. The combined use of both tests allows an increase in diagnostic accuracy of extrapulmonary tuberculosis.

Antigens, Bacterial↗
PubMed1997

Evaluation of IgA-mediated humoral immune response against the mycobacterial antigen P-90 in diagnosis of pulmonary tuberculosis.

BACKGROUND: Serologic methods for diagnosis of tuberculosis have been widely investigated owing to their low cost and rapid technical execution. Sensitivity and specificity of different tests have been reported to be largely variable. STUDY OBJECTIVES: To evaluate the IgA-mediated humoral immune response against the mycobacterial antigen P-90 as a tool for diagnosis of pulmonary tuberculosis. PARTICIPANTS: Eighty-eight patients with microbiologically confirmed diagnosis of pulmonary tuberculosis (32 with positive sputum smears and 56 with negative sputum smears), 28 patients with a definite nontuberculous lung disease, 12 subjects with healed tuberculosis, and 47 healthy volunteers (24 purified protein derivative negative and 23 positive). MEASUREMENTS AND RESULTS: Detection of anti-P-90 IgA was performed by enzyme-immunoassay. At a cutoff of 0.221 optical density, determined by a receiver operating characteristic curve, the overall sensitivity and specificity of the test were 70.4% and 91.9%, respectively. Patients with active tuberculosis showed significantly higher titers of anti-P-90 IgA compared with other groups (p < 0.05). CONCLUSIONS: The evaluation of IgA-mediated humoral immune response against the antigen P-90 might constitute a useful tool for presumptive diagnosis of pulmonary tuberculosis.

Adult↗
PubMed1994

Seroprevalence of anti-HTLV I/II and anti-HIV-1 antibodies in a sample population in the Marche Region, Italy.

A total of 1292 sera, provided by different USLs (Local Health Centers) in the Marche Region (Italy), was tested by ELISA and Western Blot for the detection of anti-HTLV I/II ad HIV-1 antibodies. It was decided not to follow any particular criterion when collecting the sera, so no protocol of admission was established in advance. Of the 1292 sera tested, 12 were found antibody positive to HTLV I/II, 18 to HIV-1 and 4 to both viruses. Of the seropositives, for HTLV I/II and HIV-1, respectively, 2 and 3 were prisoners; 2 and 4 were IVDAs, 3 and 7 were hematological patients, 3 and 2 were hospitalized subjects (not for hematological disorders), and 2 and 2 were positives belonging to a healthy population group. These data suggest that the viruses may also be spreading among groups other than the high-risk ones (homosexuals, IVDAs, prisoners, blood-transfusion recipients, promiscuous heterosexuals).

Adolescent↗
PubMed1994

Netilmicin influences siderophores production and iron receptor expression in Escherichia coli.

This study investigated the effect of subinhibitory concentrations of netilmicin on the phenolate (enterochelin), hydroxamate (aerobactin) and total siderophores production and on the 81-kDa and 74-kDa receptors expression in Escherichia coli. Netilmicin at 1/40 MIC reduces total siderophores by 40%; the cathecols by 50% and the hydroxamate by 80%. Concomitant with siderophores reduction, the antibiotic induces the upregulation of the 81-kDa protein receptor. Both effects reduce the ability of the bacterium to survive in the host.

Carrier Proteins↗
PubMed1994

ELISA method for evaluation of anti-A60 IgG in patients with pulmonary and extrapulmonary tuberculosis.

Several studies on the IgG mediated humoral immune response against the mycobacterial antigen A60 are available in the literature. However extensive variability in observed responses has been reported. In the present study we measured by ELISA the titers of IgG antibodies against A60 in 50 tuberculin negative healthy subjects, (Group I); 44 tuberculin positive healthy subjects, (Group II); 13 patients with healed Tuberculosis (Group III); 22 patients with a defined acute or chronic Non Tuberculous Pulmonary Pathology (Group IV); 42 patients suffering from sputum positive Active Pulmonary Tuberculosis, (Group V); 15 patients with sputum negative Active Pulmonary Tuberculosis (Group VI) and 16 patients with Active Extrapulmonary Tuberculosis (Group VII). The assay was performed at the time of recruitment into the study, corresponding for patients of Groups IV to VII to the day of hospital admission; in patients from Groups III to VII the assay was repeated two weeks later. The cut-off point was defined as mean +2SD of values found in Groups I-IV and was 0.372 (expressed in Optical Density). By using this cut-off, the test on first blood samples was positive in 1/50 subjects from Group I, 1/44 from Group II, 0/13 from Group III, 3/22 patients from Group IV, 35/42 from Group V, 9/15 from Group VI, 9/16 from Group VII. On second blood samples, kept 9-12 days after starting anti-TB chemotherapy in Groups V, VI and VII, the test resulted positive in 0/13 patients from Group III, 3/22 from Group IV, 39/42 from Group V, 13/15 from Group VI and 14/16 from Group VII.

Adolescent↗
PubMed1994

Specific inhibition of acid proteinase secretion in Candida albicans by Lys-Nva-FMDP.

Secretion of aspartic (acid) proteinase by Candida albicans is inhibited by the action of a new anticandidal agent, L-lysyl-L-norvalyl-[N3-(4-methoxyfumaroyl)]-L-2,3-diamino pro panoic acid (Lys-Nva-FMDP), at low, even sub-minimum inhibitory concentrations. The observed phenomenon is a direct consequence of inhibition of the enzyme, glucosamine-6-phosphate synthase. As a result of this inhibition, biosynthesis of candidal mannoproteins is markedly reduced. A possible correlation between general inhibition of mannoprotein biosynthesis and acid proteinase secretion is suggested. The reported inhibition of acid proteinase secretion by Lys-Nva-FMDP is more specific than the previously described effects of methyl patricin, 5-fluorocytosine and fenticonazole.

Aspartic Acid Endopeptidases↗
PubMed1991

Microbiological profile of teicoplanin.

The in-vitro antibacterial activity of teicoplanin, a new glycopeptide antibiotic, previously named teichomycin A2, was tested against 258 gram-positive anaerobic bacterial strains, recently clinically isolated, by measuring the minimum inhibitory concentrations. Comparisons were made with other drugs, clindamycin, rifampicin, netilmicin, enoxacin, vancomycin, widely utilized for the treatment of bacterial infections. Teicoplanin was very active against the tested species and showed the highest activity against all the tested strains, with a geometric mean of MICs, a MIC 50 and MIC 90 of 0.125, 0.12 and 0.5 microg/ml, respectively.

Anti-Bacterial Agents↗
PubMed1990

Laboratory survey of Chlamydia trachomatis ocular infections.

The authors used immunofluorescence and immunoperoxidase tests to study a group of 101 patients with acute or chronic conjunctivitis, etiologically unrelated to conventional bacterial pathogens, and a control group of 30 healthy adults. Positive titers of IgG in serum and of IgA in lacrimal secretions against Chlamydia, detected by IPA, correlated with the identification of microorganisms by direct immunofluorescence. The use of both tests allows a precise evaluation of the stage of the infection and of its evolutive pattern.

Adult↗
PubMed1990

In vitro activity of sulbactam/ampicillin against ampicillin-resistant, beta-lactamase-producing bacteria isolated in Italian hospitals.

A multicenter study aimed at assessing the in vitro activity of sulbactam/ampicillin against a wide range of bacterial pathogens was performed using 2,209 clinical strains, all recently collected from inpatients in seven Italian centers and preliminarily screened as being ampicillin-resistant and beta-lactamase producers. In comparative disk diffusion trials using 8 large-spectrum antimicrobials, the percentage of resistance to sulbactam/ampicillin in staphylococci was similar to the percentage of resistance to netilmicin and lower than to the other antibiotics; with gram-negative bacteria, only netilmicin, ofloxacin, and, less consistently, cefotetan showed lower incidences of resistance. The minimal inhibitory concentrations (MICs) of ampicillin alone and sulbactam/ampicillin together were determined using the agar dilution method. The Enterobacteriaceae strains which shifted to ampicillin susceptibility in the presence of sulbactam averaged 68%, but values significantly above or below average were observed in some genera of this family. The percentage of strains which the presence of sulbactam rendered ampicillin-susceptible in vitro reached 97% in Haemophilus strains and 100% in branhamellae and gonococci. High percentages were also recorded in staphylococci, with a peak of 100% in oxacillin-susceptible Staphylococcus aureus strains. In general, center-to-center differences were relatively limited.

Ampicillin↗
PubMed1988

Serodiagnosis survey of tuberculosis by a new ELISA method.

In a survey study, the authors used a new Elisa test, designed by Anda Biologicals, Strasbourg, France, to detect specific IgG and IgM antibodies against A60 antigen. Blood samples from 53 subjects were tested with this serological method: 22 with no tubercular diseases and 31 affected by different tubercular lesions. The IgM titers were negative in all control group subjects, in two out of fourteen patients with progressive primary tuberculosis, in thirteen out of sixteen with secondary tuberculosis and in one patient with extrapulmonary tuberculosis. The IgG titers were positive (greater than 1.25 Elisa units) in all cases, except one, of progressive primary tuberculosis, in all cases, except two, of secondary tuberculosis and in the patient affected by extrapulmonary tuberculosis. The performance of this method and the overall results indicate its sensitivity and reliability to detect specific mycobacterial antibodies at different stages of the disease.

Adolescent↗
PubMed1986

Bacteremia caused by Peptococcus prevotii in an immunocompromised host.

A case of bacteremia caused by Peptococcus prevotii in an immunocompromised patient is described. A specific antibiotic therapy was successful. Details of the isolation procedures, biochemical pattern and Minimal Inhibitory Concentrations (MICs) related to the pathogen strain are reported.

Aged↗
PubMed1986

[Evaluation of the in vitro activity of aztreonam on 1990 gram-negative bacterial strains recently isolated in Campania hospitals].

The in vitro activity of aztreonam, leader of a new class of antibiotics, the monobactams, has been investigated. The effectiveness of the new molecule on 1990 strains of Gram-negative clinical isolates has been compared to that of some other drugs widely utilized for the treatment of nosocomial infections. Aztreonam has shown the highest activity against all the tested strains, with a geometrical mean of MICs (MG) of 0.37 and a MIC 90 of 8 micrograms/ml.

Aztreonam↗
PubMed1986

[Evaluation of the in vitro activity of flumequine on bacterial strains recently isolated in the hospital].

The in vitro activity of the quinolone derivative flumequine against 1918 bacterial strains, isolated from urinary tract infections, has been compared to the antibacterial activity of other compounds, such as pipemidic acid, oxolinic acid and cefazolin. The results are reported in terms of minimal inhibitory concentrations (MICs) and geometrical mean (MG) of MICs. Flumequine appeared to be the most effective molecule over all the clinical isolates, showing a MG of MICs of 1.12 and a MIC 90 of 32 micrograms/ml.

Bacteria↗