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Biomedical subjects

G Chabanon

Publications and source records attributed to G Chabanon.

At least 19 recordsLinked to original sources
PubMed1992

Influence of nutrient media on the chemical composition of the exopolysaccharide from mucoid and non-mucoid Pseudomonas aeruginosa.

Two mucoid Pseudomonas aeruginosa strains and their non-mucoid revertants isolated from two different clinical origins (cystic fibrosis and bronchiectasis) were grown in various chemically defined media. The extracted exopolysaccharide was characterized by gas-liquid chromatography and 1H-NMR spectroscopy. The exopolysaccharide was always heterogeneous, with an alginate fraction and a neutral fraction essentially composed of glucose, galactose, rhamnose and hexosamines. The alginate composition (mannuronate/guluronate ratio and O-acetylation degree) changed according to the carbon source in nutrient media and whether the strains tested were responding differently to these environmental stimuli. In all cases, the best carbon source for the alginate production was glycerol: the two cystic fibrosis strains produced a predominantly O-acetylated alginate whereas only the mucoid bronchiectasis strain produced a polymannuronate exopolysaccharide.

Alginates↗
PubMed1991

Adherence and hemagglutination of Corynebacterium group D2.

Sixty-one strains of Corynebacterium group D2 were examined for their ability to adhere to human uroepithelial cells and to agglutinate human and guinea-pig erythrocytes. Strains were isolated from samples of two origins: urine of bacteriuric patients and healthy skin of patients without urinary infection. In addition, the isolates were examined by scanning and transmission electron microscopy. Heavy adherence to the uroepithelial cells but weak hemagglutination were noted. No statistical association was demonstrated between the adherence and the origin of the strains (65.2% of urinary isolates and 80% of healthy skin isolates were adherent). On transmission electron microscopy, a close association was observed between adherent bacteria and cells on thin sections and only few strains were piliated with negative staining. These results do not support a role of adherence as a predictor of pathogenicity of Corynebacterium group D2 which seems to act as an opportunistic pathogen in urinary tract infections.

Aged↗
PubMed1991

[Determination of factors promoting, in vitro, the expression of adhesion of Pseudomonas aeruginosa to buccal cells].

The composition of the bacterial flora in the upper respiratory tract is closely correlated with the type of pathogens recovered from the respiratory tract in patients. In intensive care patients, colonization of the oral cavity with Gram-negative organisms increases the risk of Gram-negative respiratory tract infection; the ability of bacterial cells to attach to buccal cells seems to play a central role in this correlation. Similar findings have been reported in chronic respiratory tract infections, including bronchiectasis and cystic fibrosis, with Pseudomonas aeruginosa colonization. This study was undertaken to determine the conditions best suited to in vitro detection of adhesion of P. aeruginosa to buccal cells. Use of brain-heart-infusion medium, incubation at 35 degrees C for 2 hours, and a bacterial concentration of 2 x 10(9) cells/ml were the factors correlated with improved detection of adhesion to buccal cells. Furthermore, attachment of bacteria to buccal cells was not found to vary across donors or over time in a given donor. Adhesion was independent of cell viability.

Bacterial Adhesion↗
PubMed1991

[Nosocomial infections in an urological department. Incidence and etiological factors].

The authors report a prospective study with active request of data for nosocomial infections (NI) in an urological department during six months. From 453 patients, 43 developed an NI (incidence = 9.5%): urinary tract infections (53.5%), bloodstream infections (16.3%), lower respiratory tract infections (7%), surgical wound infections (2.3%) and sepsis syndrome (20.9%). For microorganisms, most often Pseudomonas aeruginosa (22.5%) and E. coli (20%) were encountered. Other microorganisms were the next-ones: Staphylococcus aureus (15%), Staphylococcus epidermidis (7.5%), Acinetobacter baumanii (7.5%), Streptococcus group D (7.5%), Klebsiella pneumoniae (7.5%), Candida albicans (2.5%) and others (10%). Urological interventions with a high risk of NI were cystectomy with intestinal urinary diversion (68.7%), pyeloplasty for ureteropelvic junction obstruction (40%) and percutaneous nephrolitothomy (30%). Even if the last two interventions classically do not have a high risk of NI, we think that their antibioprophylaxis is recommended.

Aged↗
PubMed1990

Comparison of the incidence of Ureaplasma urealyticum in infertile men and in donors of semen.

569 infertile patients and 75 fertile men (donors of semen) were included in our study from 1985 to 1987. We compared the frequency of Ureaplasma urealyticum in semen specimens in these two groups: 40 infertile men (7%) and 4 donors of semen (5.3%) had U. urealyticum in semen cultures. This difference was not statistically significant. We concluded that U. urealyticum was not more frequent in infertile than in fertile men. We also report the results of semen cultures for other bacteria and the parameters of routine semen analysis in these two groups. All infertile patients infected by U. urealyticum were treated with doxycycline: the infection was eradicated in 77.5% of them.

Humans↗
PubMed1990

[In vitro bactericidal activity of tobramycin and amikacin alone or in combination against Pseudomonas aeruginosa isolated from patients with cystic fibrosis].

The bactericidal kinetic of 60 P. aeruginosa isolates (40 from cystic fibrosis sputum and 20 from various origins) was studied. Liquid medium micromethod was performed. Bacteria were incubated with tobramycin and amikacin alone at several concentrations and combined with piperacillin, cefsulodin, ceftazidim, imipenem, and ciprofloxacin at concentrations obtained in vivo. When used alone, tobramycin showed the most rapid bactericidal activity, whatever the concentration used. The bactericidal activity (greater than or equal to 99.99% killing of the inoculum) was obtained in 5 hours, with 1 or 2 x MIC of the majority of the strains, with the 2 aminoglycosides. No difference was found between tobramycin and amikacin, when combinated with an antibiotic which provides a notable increase of the rapidity of the bactericidal activity. The combination of amikacin plus imipenem was more rapidly bactericidal: 48% of strains; 26% were synergistically inhibited by amikacin plus ciprofloxacin. When correlated with the susceptibility patterns of studied micro-organisms, the results were rather unpredictive.

Amikacin↗
PubMed1990

[Frequency and distribution of beta-lactamases in 1792 strains of Klebsiella pneumoniae in France between 1985 and 1988].

In october 1985, 1987 and 1988, all the clinical isolates of K. pneumoniae (respectively 530, 654, 590 strains) were collected in 20 hospitals. The beta-lactamases were identified by analytical isoelectrofocusing and by substrate and inhibition profiles. 76 to 81% of the strains produced only one beta-lactamase: SHV-1 type, pI 7.7 (61 to 65%) or PI 7.1 (14%). The TEM-1 betalactamase (pI 5.4) was produced in 1985 by 21% of the strains, 9% in 1987, and 11% in 1988: TEM-2, pI 5.6 by 2% in 1985-87-88. The extended broad spectrum beta-lactamases, able to hydrolyse amino-thiazol-oximino-beta-lactam antibiotics, TEM or SHV type enzymes (SHV-2, pI 7.7, SHV-3, pI 7.1; SHV-4/CAZ-5, pI 7.8; SHV-5/CAZ-4 pI 8.2; CTX-1/TEM-3, pI 6.3) were also detected: 0.75% of the strain (3 strains) in 1985, 8.4% (55 strains) in 1987, 11% (65 strains) in 1988. These extended broad spectrum beta-lactamases were found in 2 hospitals in 1985, 10 in 1987 and 9 in 1988.

France↗
PubMed1988

[Sensitivity of Pseudomonas aeruginosa and Klebsiella spp. to ceftazidime. Current status in France].

Ceftazidime was tested against 2,224 strains of Pseudomonas aeruginosa obtained from 17 hospitals in April, May and June, 1986 and against 607 strains of Klebsiella pneumoniae and 234 strains of K. oxytoca obtained from 16 hospitals in October, 1987. The MIC's of ceftazidime against P. aeruginosa were distributed normally, with an MIC50 of 2 mg/l and an MIC90 of 4 mg/l. Depending on critical concentrations, 80 per cent of strains were sensitive, 11.4 per cent were of intermediate sensitivity and 0.54 per cent were resistant. There were few differences in results between hospitals. Ninety-two per cent of resistant strains and 45 per cent of intermediate strains (as opposed to 6 per cent of all strains) produced a high-level constitutive cephalosporinase with little variations between centres. The MIC's of ceftazidime against K. pneumoniae and K. oxytoca had a bimodal distribution: 91 per cent of strains were sensitive to 0.25 mg/l, 6 per cent of strains showed intermediate sensitivity and 3 per cent were resistant. All intermediate and resistant strains produced a very broad spectrum beta-lactamase which hydrolyzed some of the third generation cephalosporins: K. pneumoniae 36 CTX-1, 5 SHV-2, and 14 strains producing a recently identified beta-lactamase "CAZ-5/SHV-4"; K. oxytoca 3 CTX-1. These strains were isolated in 10 of the 16 hospitals which took part in the 1987 study. Comparison of these results with those of studies performed in 1984 and 1985 showed a moderate increase in the number of intermediate sensitivity strains of P. aeruginosa and the occasional occurrence, of the epidemic type, in some hospitals of Klebsiella spp. producing very broad spectrum beta-lactamases which were rare in 1985.

Ceftazidime↗
PubMed1988

The frequency of Chlamydia trachomatis in acute epididymitis.

Twenty-five patients with bacteriologically proven epididymitis were studied between 1984 and 1986. Thirteen were less than 35 years old and in 11 of them Chlamydia trachomatis was isolated; of the 2 remaining patients Escherichia coli was found in 1 and Neisseria gonorrhoeae in the other. In patients more than 35 years old, gram negative bacteria were the cause of infection in 10 and only 1 case was attributable to Chlamydia trachomatis. These results suggest that Chlamydia trachomatis is much more frequent in men under the age of 35 and the difference is statistically significant.

Acute Disease↗
PubMed1988

Effects of five antibiotics on adhesion and haemagglutinating properties of Pseudomonas aeruginosa isolated from cystic fibrosis patients.

The aim of this study was to evaluate the in vitro effect of five antibiotics at sub-inhibitory concentrations on the adhesive and haemagglutinating properties of Pseudomonas aeruginosa isolated from cystic fibrosis sputa. Eleven isolates (mucoid and non-mucoid) from cystic fibrosis, and four isolates (mucoid and non-mucoid) from other chronic respiratory infections were tested. The adhesion test was performed on human lymphoblastoid cell-lines; the haemagglutination test used human O+ and guinea-pig erythrocytes. The antibiotics were tested at six sub-inhibitory concentrations, from MIC/2 to MIC/64. Among the five antibiotics, cefsulodin and pefloxacin were the most active in decreasing the adhesive properties: this effect was statistically significant at MIC/2 and MIC/4 for cefsulodin and at all sub-inhibitory concentrations for pefloxacin. No differences appeared between mucoid and non-mucoid strains, and no correlation was noted with their clinical origins. The three other antibiotics (ceftazidime, latamoxef and imipenem) had no significant effect on the adhesion of all the strains tested, but their effect was rather strain-dependent. This fact and the heterogeneity found in adherence and haemagglutinating activity of each strain suggest that the adhesins and the haemagglutinins of P. aeruginosa are very complex structures.

Animals↗
PubMed1987

Bacteriological and serological diagnosis of community-acquired acute pneumonia, specially Legionnaire's disease. Multicentric prospective study of 274 hospitalized patients.

In 1982 and 1983 a prospective study was carried out involving 274 adult patients hospitalized with community-acquired acute pneumonia. The results of the bacteriological and serological diagnoses are presented here. Conventional and standardized bacteriological methods were used. All the serodiagnoses of LD were carried out with the 13 antigens produced by the "Centre National de Référence" (L. pneumophila 1, 2, 3, 4, 5, 6; L. micdadei; L. bozemanii, L. dumoffii, L. jordanis; L. gormanii; L. longbeachae 1 and 2). Standardized criteria were used for the interpretation of results. Conventional methods were used for the other serodiagnoses. Because the laboratory results had been interpreted very rigorously, an etiological diagnosis was established only in 51% of pneumonia cases. Other reasons, such as the frequent prescription of antibiotics prior to hospitalization, may explain why no aetiology could be determined in 49% of cases. The microbial agents responsible were: S. pneumoniae, Legionella and M. pneumoniae in 62% of cases; H. influenzae, K. pneumoniae, Chlamydia and S. aureus in 21.6%; and viruses in 8.6%. 29 (10%) of the 274 pneumonia cases were caused by Legionella, being second to S. pneumoniae. The preponderance of L. pneumophila was striking (22 cases), 3 Legionella strains were isolated (L. pneumophila serogroup 1:2 strains, serogroup 6:1 strain). Three associated or successive infections were observed (influenza, Leptospirosis, Coxiella infection). As regards the other bacteria, implication of the strain isolated was based on its multiple occurrence in several samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1987

[In vitro study of the effects of oxolinic acid at sub-inhibitory concentrations on the activity of hemagglutinins and adhesion to uroepithelial cells by Escherichia coli isolated from urine].

The aim of the present study was to investigate the effects of sub-MIC doses of oxolinic acid (quinolone), widely used in the treatment of urinary tract infections, on both haemagglutinating activity and adhesion capacity of 13 Escherichia coli strains isolated from urine during acute cystitis or pyelonephritis. All these strains adhered to uroepithelial cells and showed mannose-sensitive and/or mannose-resistant haemagglutinating activity. Sub-MIC doses of oxolinic acid induced filaments in most of the bacterial cultures; however, inhibition of haemagglutination and adhesion was variable in vitro. When inhibition did take place in any one strain, both haemagglutination and adhesion were affected. These results confirm those of other authors and indicate that the effect of sub-MIC doses of a given antibiotic is strain-specific; they also indirectly show the heterogeneity of E. coli strains isolated from urine. It thus seems unlikely that, in clinical conditions, a single antibiotic is capable of reducing adhesion, given the diversity of the adhesins found in pathogenic E. coli strains.

Bacterial Adhesion↗
PubMed1987

[Bacterial adhesion: its consequences in antibiotherapy].

The aim of the present review is to analyze the influence of antibiotics on bacterial adhesion and to anticipate this approach as an alternative possibility of prophylactic or therapeutic interference with the infectious process. Adhesive interactions between bacteria and substratum including solid and cellular surfaces were briefly documented. Bacteria displays a very large variety of adhesins and this implies complex mechanisms in the adhesion process. Anti-adhesive therapy must take into account several factors: particularly interference with the colonization of mucosal surfaces by normal flora and phagocytic defense system in which adhesion plays a very important role as well.

Anti-Bacterial Agents↗
PubMed1979

Adhesion to a human cell line by Escherichia coli strains isolated during urinary tract infections.

It has been shown that some, but not all, Escherichia coli strains isolated from urine adhere, in vitro, to the surface of uroepithelial or vaginal cells. In the present study, 212 strains, isolated from urine of 212 infected patients, were tested for adhesion by using an in vitro human cell line assay. A variable degree of attachment to the cell monolayer was detected in these strains. From patients with cystitis, only 19 (9.7%) of the 195 strains examined were adherent, whereas 5 (29.4%) of the 17 pyelonephritis strains had similar properties (P less than 0.05). To investigate the incidence of adhesion in the clinical manifestations of urinary tract infection, a sample of patients was picked at random from those with cystitis. During cystitis caused by adhesive bacteria, patients suffer more often from macroscopic hematuria than from dysuria, frequency, or recurrency (P less than 0.05). This study shows that E. coli strains isolated from urine samples possess a strikingly difference in capacity to adhere to a human cell line surface as demonstrated previously with uroepithelial or vaginal cells. Moreover, according to these data, the adhesion of E. coli may be considered as a virulent factor and would play a part in the infection of the urinary tract in humans.

Adhesiveness↗
PubMedDate not supplied

Phenotypic and genotypic assays for the detection and identification of adhesins from pyelonephritic Escherichia coli.

Four different gene clusters have been characterized so far which encode adhesins involved in the specific binding of pathogenic Escherichia coli to epithelial cells of the urinary tractus: the pap, sfa, afa and bma operons. The ability to adhere to uroepithelial cells and to interact with one or several of the specific receptors identified for each of the 4 adhesins, has been studied for 102 E. coli strains isolated from patients with pyelonephritis. These receptor-binding assays are referred to as phenotypic assays. Isolates which adhered to uroepithelial cells 68.6% produced at least 1 of the previously described adhesins. In addition, we used DNA probes to detect homologous sequences of the pap, sfa, and afa operons. Genotypic assays revealed that 87.2% of pyelonephretic E. coli contain DNA sequences related to at least 1 of the 4 operons; 78.4%, 22.5% and 11.8% of the strains harboured sequences related to pap, sfa and afa operons, respectively. The afa- and sfa-adhesion determinants were commonly found associated with the presence of the pap operon (8.8% and 18.6%, respectively). Detection of adhesins using the genotypic approach appears to be reliable (all adhesins detected using the phenotypic approach were also detected with probes). Detection by colony hybridization was significantly higher than by phenotypic assay. Discrepancies may have been due to absence of expression of the detected operons and may have resulted from improper in vitro growth conditions, phase variation, and/or heterogeneity of the genes encoding the adhesins within a family of related sequences.

Adhesins, Bacterial↗
PubMedDate not supplied

The Epstein-Barr virus (EBV) in human pathology. II. Serologic profiles of EBV infections.

Antibodies to EBV induced intracellular antigens, (VCA, EA, NA) and VCA-IgM antibodies have been investigated to define EBV serologic profile of 245 individuals. This profile was a first studied in EBV primary infections. In infectious mononucleosis, the efficiency of EBV serodiagnosis is lower than Paul Bunnel Davidsohn reaction (PBD) : primary infection profile is only characterised in 80% of the positive PBD infectious mononucleosis (IM). On the other hand, EBV antibodies are preponderant for diagnosis in other clinical manifestations of EBV primary-infection were PBD is not alwasy positive (47%). EBV antibodies of patients with various diseases and antibodies of normal subjects show different profiles. By interpretation of these profiles one discuss the possibility to characterize reinfection, and either latent or active persistant infection.

Antibodies, Viral↗