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Biomedical subjects

C Bollet

Publications and source records attributed to C Bollet.

At least 37 records · Page 2Linked to original sources
PubMed1996

Epidemiological investigation of Pseudomonas aeruginosa nosocomial bacteraemia isolates by PCR-based DNA fingerprinting analysis.

Between July 1994 and March 1995, 64 isolates of Pseudomonas aeruginosa were implicated in bacteraemia in 25 cancer patients in five wards of two hospitals. These, together with 24 environmental isolates and one isolate from a bacteraemia in a non-cancer patient were examined by three PCR-based DNA fingerprinting methods: random amplified polymorphic DNA (RAPD), enterobacterial-repetitive intergenic consensus (ERIC)-PCR, and 16S-23S spacer region-based RAPD. These methods were reproducible, discriminatory and showed close agreement; all indicated that 47 isolates that had caused bacteraemia in 19 cancer patients were indistinguishable. Seventeen other isolates that had caused bacteraemia in 10 cancer patients were discriminated into eight further groups, and the 24 environmental and non-cancer patient isolates into further distinct groups. No environmental source of the epidemic strain was found, but it was suspected that the outbreak was related to infusion implants.

Anti-Bacterial Agents↗
PubMed1996

Molecular epidemiology of Enterobacter aerogenes acquisition: one-year prospective study in two intensive care units.

To evaluate the respective contributions of patient-to-patient transmission and endogenous acquisition of Enterobacter aerogenes isolates, we conducted a prospective epidemiologic study in two intensive care units (ICUs) between May 1994 and April 1995. We collected a total of 185 E. aerogenes isolates: 130 from 51 patients in a surgical ICU (SICU), 45 from 26 patients in a medical ICU (MICU), and 10 from the environments in these two ICUs. All isolates were typed by random amplification of polymorphic DNA and enterobacterial repetitive intergenic consensus PCR. Among the 175 clinical isolate, we observed 40 different profiles by random amplification of polymorphic DNA and 36 different profiles by enterobacterial repetitive intergenic consensus PCR. We identified a ubiquitous and prevalent clone, corresponding to 58% of SICU and 41% of MICU clinical isolates. Three epidemiologically related strains were specific to each ICU and represented 17% of SICU and 24% of MICU clinical isolates; unique type strains represented 17 and 29% of SICU and MICU clinical isolates, respectively, and E. aerogenes strains which were spread to a limited degree and which were isolated less than five times during the 1-year study period represented 8 and 6% of SICU and MICU clinical isolates, respectively. Our results show that E. aerogenes is acquired in the ICU in three different ways: patient-to-patient spread of a prevalent or an epidemiologically related strain, acquisition de novo of a strain from patients' own flora, and acquisition of a nonendemic strain followed by occasional patient-to-patient transmission. The findings point out the importance of patient-to-patient transmission in E. aerogenes acquisition and suggest that changes in E. aerogenes ecology in the hospital have taken place during the past decade.

Adult↗
PubMed1995

Identification and strain differentiation of Mycobacterium species on the basis of DNA 16S-23S spacer region polymorphism.

Amplification of the region separating the genes coding for the two rRNA species 16S and 23S was performed to identify 56 mycobacterial strains, belonging to eleven species: Mycobacterium tuberculosis, M. avium, M. kansasii, M. gordonae, M. abscessus, M. fortuitum, M. xenopi, M. bovis, M. bovis/BCG, M. africanum and M. intracellulare. Reproducible amplification patterns were obtained with most species with the exception of M. kansasii which showed heterogeneity, confirming the existence of a genetically distinct subspecies within this species. In addition, we used the amplified products as target DNA for restriction endonuclease digestion and RAPD (randomly amplified polymorphic DNA) analysis to compare strains of M. abscessus, M. tuberculosis and M. avium. The discriminatory power of these two typing methods was higher than when whole genomic DNA is used as target. Our results demonstrate that the two-step approach to identification and typing on the basis of the hypervariability of 16S-23S spacer region is reliable, rapid and simple, and consequently could be an epidemiological tool in clinical laboratories.

DNA Fingerprinting↗
PubMed1995

Variations in DNA concentrations significantly affect the reproducibility of RAPD fingerprint patterns.

The influence of the DNA concentration was tested using two different primers and nine DNA samples. Major modifications in the DNA banding pattern were apparent between successive dilutions. Such differences could be explained by concomitant changes in three different molecular conditions: the presence of perfect priming sites, the amplification of rare sites and the existence of mismatch annealing events. At low DNA concentrations (less than 1 pg/microliter), molecular events occurred at random and had a direct consequence on the reproducibility of RAPD profiles. At the appropriate DNA concentration (between 100 ng/microliters and 10 pg/microliters), reproducibility was adequate at a given concentration, but RAPD profiles differed from one dilution to another. These observations demonstrate the usefulness of the bis-benzimide method for quantification of DNA extracts.

DNA, Bacterial↗
PubMed1995

Demonstration of Mycobacterium kansasii species heterogeneity by the amplification of the 16S-23S spacer region.

Amplification of the region separating the genes coding for the two rRNA species 16S and 23S was performed with 56 strains of several mycobacterial species, including 21 clinical isolates of Mycobacterium kansasii and the M. kansasii type strain ATCC 12478. On the basis of PCR product profiles, the previously suggested heterogeneity of M. kansasii species was confirmed. Three subgroups were identified; members of the first subgroup showed the same PCR profile as the reference strain. Different profiles were obtained for the two other subgroups. Amplification of the 16S-23S spacer is rapid and simple and, consequently, may be a helpful tool for identification and characterisation of M. kansasii isolates in epidemiological analysis.

Base Sequence↗
PubMed1995

Efficient discrimination of Mycobacterium tuberculosis strains by 16S-23S spacer region-based random amplified polymorphic DNA analysis.

Amplification of the region separating the genes coding for 16S and 23S rRNA was performed with 15 Mycobacterium tuberculosis isolates and the type strain, ATCC 27294. Reproducible amplification patterns were obtained. PCR products were then used as target DNA for random amplified polymorphic DNA (RAPD) analysis. The discriminatory power was higher than when whole genomic DNA was used as a RAPD template. 16S-23S spacer region-based RAPD analysis was a simple and efficient method of differentiation. Consequently, it may be a useful tool for epidemiologic studies of tuberculosis.

Bacteriological Techniques↗
PubMed1995

Bronchoscopic or blind sampling techniques for the diagnosis of ventilator-associated pneumonia.

The purpose of this prospective postmortem study was to assess the diagnostic accuracy of bronchoscopic techniques (bronchoalveolar lavage [BAL] and protected specimen brush [PSB]) and nonbronchoscopic techniques (blind bronchial sampling [BBS] and mini-BAL) in the diagnosis of ventilator-associated pneumonia (VAP). The results of each technique were compared with histology and culture of lung tissue specimens obtained by surgical pneumonectomies in 38 patients who died after at least 72 h of mechanical ventilation. Histology was positive for VAP in 18 patients and negative in 20 patients. There were 12 definite VAP (positive histology and positive lung cultures) and 6 histologic VAP (positive histology and negative cultures). Clinical pulmonary infection score (CPIS) at a threshold of 6 achieved a sensitivity of 72% and a specificity of 85%. When the CPIS was combined with the logarithmic concentration of the predominant microorganism obtained from the BBS sample culture, specificity was increased to 95%, for a threshold of 10. Using 10(3) cfu/ml as the threshold of positivity for cultures obtained with PSB and mini-BAL samples and 10(4) cfu/ml for cultures obtained with BBS and BAL, the respective sensitivities of these techniques for definite VAP were 42, 67, 83, and 58%. The sensitivity of BBS was significantly higher than that of PSB (p < 0.05). The area under the receiver operator characteristic curve was significantly greater for BBS than PSB (p < 0.05). Given that it is more sensitive and noninvasive, BBS is preferable to PSB for the diagnosis of VAP.

Aged↗
PubMed1994

[Evaluation of the extra- and intracellular activity of clarithromycin against Mycobacterium chelonae].

The in vitro activity of clarithromycin alone and in combination with amikacin, ethambutol and rifabutin was tested against twelve strains of M. chelonae abscessus and eight strains of M. chelonae chelonae isolated from patients. Extracellular activity of clarithromycin was assessed by determining MICs using the 1 p. cent proportion method in Middlebrook 7H11 agar media compared to the radiometric methodology in 7H12 broth at two pHs 6.8 and 7.4. The MICs obtained at pH 7.4 were 2 to 4 more dilutions lower than those obtained at pH 6.8. By both methods, clarithromycin appeared more active against isolates of M. chelonae chelonae than against isolates of M. chelonae abscessus. Clarithromycin- amikacin combination demonstrated the most important additive effect. The use of three drugs in association resulted in syngergistic effect. Studies of intracellular bacteria showed that the most effective bactericidal combination was clarithromycin amikacin and ethambutol together.

Amikacin↗
PubMed1993

In-vitro evaluation of clarithromycin, temafloxacin, and ethambutol in combination against Mycobacterium avium complex.

The in-vitro activity of clarithromycin, temafloxacin, and ethambutol were assessed by MIC, FIC and intra-macrophage killing determinations alone and in various combinations against ten pigmented and ten non-pigmented strains of Mycobacterium avium complex bacteria. Alone, either clarithromycin or temafloxacin were found to be active against M. avium, but the best results were obtained from combinations of drugs. Clarithromycin and temafloxacin together were found to have an additive effect against two of ten pigmented variants and one of ten non-pigmented variants. Clarithromycin and ethambutol demonstrated a synergistic effect against two pigmented and one non-pigmented strain, and an additive effect against five and three pigmented and non-pigmented strains, respectively. For temafloxacin and ethambutol, additive effects were observed in four and two pigmented and non-pigmented strains, respectively. In cultures of macrophages both clarithromycin and temafloxacin alone reduced the numbers of bacteria growing intracellularly after six days, but the most effective bactericidal combination was clarithromycin, temafloxacin, and ethambutol together.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Fatal pneumonia due to Serratia proteamaculans subsp. quinovora.

Serratia proteamaculans subsp. quinovora was isolated from several samples (blood cultures, tracheal aspirates, pleural effusion) from a patient with pneumonia. This is the first clinical isolate and the first documented human infection caused by this organism.

Adult↗
PubMed1993

A rapid DNA extraction method from culture and clinical samples. Suitable for the detection of human cytomegalovirus by the polymerase chain reaction.

We propose an one-step DNA extraction method suitable for the polymerase chain reaction. This procedure utilizes Chelex 100, a chelating in exchange resin. This technique was compared with a traditional technique (proteinase K lysis, phenol-chloroform extraction and ethanol precipitation) for isolation of human cytomegalovirus DNA from clinical samples. The procedure using Chelex 100 appeared to be a simple and fast extraction method for human cytomegalovirus DNA.

Bronchoalveolar Lavage Fluid↗
PubMed1993

Pseudomonas aeruginosa and cystic fibrosis: intrastrain variability in relation to intensity of immune response and clinical outcome.

Over periods exceeding two years, 63 Pseudomonas aeruginosa strains isolated from three children with cystic fibrosis were characterized using a 154 character auxanogram. Numerical analysis was carried out to establish intrastrain variability in relation to intensity of immune response and clinical outcome. For two patients, strains segregated in two distinct phenons. For the last patient, strains did not cluster. The degree of intrastrain variability during the infection was correlated with an increasing number of precipitins and with an unfavorable clinical outcome. This would suggest that strains which have a singular potential for antigenic variability are more likely to promote a host-bacteria conflict.

Bacterial Typing Techniques↗
PubMed1992

Serological response of tuberculosis patients to antigen 60 of BCG.

Two ELISA tests (IgG and IgM) for the serodiagnosis of tuberculosis, both based on antigen 60 (A60) of M. bovis BCG, were applied to 1,644 controls and patients to analyse the immune response in different forms of this infectious disease. Out of 200 healthy individuals, 148 being tuberculin--positive BCG-vaccinated adults, only 10 contacts--nurses of the pneumology department and laboratory technicians of the mycobacterial laboratory--were found positive for anti-A60 IgG. One quarter of hospitalized patients affected by non-tuberculous pneumopathies (194 in total) were found weakly positive for anti-A60 IgG. We suppose that these positive cases have suffered from inapperant infections and are in a "persistent state". Out of 344 cases of primary pulmonary tuberculosis, 88% were positive for anti-A60 IgG and 75% for the corresponding IgM. Among 97 cases of primary extra-pulmonary tuberculosis, 94% were found IgG positive and 33% IgM positive. The difference between active and inactive post-primary (chronic) tuberculosis was striking: about 100% of both pulmonary and extra-pulmonary cases (367 altogether) had high titers of anti-A60 IgG but IgM positivity was observed in only 15% of the cases, whereas in inactive and quiescent noncavitary tuberculosis (442 cases), 57% of the patients were weakly positive for anti-A60 IgG and none were positive for IgM. Kinetics of synthesis of anti-A60 IgG and IgM were analysed in primary and post-primary (chronic) active tuberculosis. The IgM tracing immune response to A60 was shorter and lower during primary tuberculosis as compared to post-primary tuberculosis. Our findings point to the high prognostic value of the A60- ELISA test for tuberculosis. Anti-A60 IgM mark initial stages of the disease or reactivation processes whereas anti-A60 IgG last longer than IgM and provide an evaluation of the intensity of the infectious process. Repeated serological tests allow monitoring of the course of the infection and the efficacy of therapy. The test is negative in healthy BCG-vaccinated persons (tuberculin-positive) and healed tuberculous infection cases. The combined use of both IgG and IgM tests helps in the correct diagnosis of "false positive" cases.

Adolescent↗
PubMed1992

[Identification of Mycobacterium tuberculosis and Mycobacterium avium by non-radioactive probes: evaluation of the Snap Syngene system].

We evaluated an alkaline phosphatase-labeled oligonucleotide probe for the rapid identification of Mycobacterium tuberculosis and mycobacteria belonging to the M avium and M intracellulare complex (MAIS). Sixty-two strains of mycobacteria and eight strains belonging to related genera were studied. All M tuberculosis strains hybridized with the tuberculosis probe. All M avium and M intracellulare gave a strong signal with their probes. However the 3 M xenopi strains tested hybridized with all probes for MAIS complex.

DNA Probes↗