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Biomedical subjects

P Berche

Publications and source records attributed to P Berche.

At least 109 records · Page 6Linked to original sources
PubMed1995

Bacteremia is required for invasion of the murine central nervous system by Listeria monocytogenes.

The ability of the facultative intracellular pathogen Listeria monocytogenes to penetrate the central nervous system (CNS) was studied by following the kinetics of brain invasion and histological lesions during an acute intravenous (i.v.) infection in the mouse. CNS invasion occurred during the early phase of infection and produced severe meningoencephalitis characterized by multiple granulomatous foci predominantly located in the brainstem and associated with diffuse meningitis and an intense inflammatory reaction involving the choroid plexuses. Bacterial counts in the brain could reach 10(4.5)-10(5.8) by day 5 of infection with 1-2 x 10(6) bacteria i.v., depending upon the bacterial strain used. It was found that CNS invasion was highly dependent upon the level and the duration of bacteremia, thus indicating that persistent bacteremia is essential to induce meningoencephalitis to L. monocytogenes.

Animals↗
PubMed1995

Chronic septic arthritis and osteomyelitis in a prosthetic knee joint due to Clostridium difficile.

A case of chronic septic arthritis and osteomyelitis in a prosthetic knee joint due to Clostridium difficile is reported. A knee prosthesis was installed in a 16-year-old boy for surgical treatment of an osteosarcoma of the femur. Later, the patient suffered a traumatic closed fracture of his patella, and a sterile fluid was aspirated. One month later, the joint displayed inflammation. Culture of the articular fluid yielded a nontoxigenic Clostridium difficile strain. Despite several attempts using conservative medical treatment with penicillins and ornidazole, Clostridium difficile strains with the same antibiotic susceptibility pattern were repeatedly isolated from the joint over an eight-month period. The foreign material was then ablated, and finally, the patient's leg was amputated one year after Clostridium difficile was first isolated. The possible sources of contamination in our case and other reported cases of extraintestinal infection due to Clostridium difficile are discussed.

Adolescent↗
PubMed1995

Mercury resistance as a selective marker for recombinant mycobacteria.

The use of antibiotic-resistance markers for the selection of recombinant mycobacteria is widespread but questionable considering the development of live recombinant BCG vaccines. In contrast, vector-encoded resistance to heavy metals such as mercury may represent an interesting alternative for the development of live vaccines compatible with use in humans and in animals. The mercury resistance genes (mer) from Pseudomonas aeruginosa and from Serratia marcescens were cloned into the Escherichia coli-Mycobacterium shuttle vector pRR3. The resulting vectors, designated pMR001 and pVN2, were introduced by electroporation into Mycobacterium smegmatis, Mycobacterium bovis BCG and Mycobacterium tuberculosis. The recombinant mycobacteria were stable in vitro and in vivo, and had high-level mercury resistance, thus indicating that the mer genes can be useful as selective markers in mycobacteria.

Animals↗
PubMed1995

In vivo correlates for Streptococcus pneumoniae penicillin resistance in acute otitis media.

Eighty-four children suffering from acute otitis media caused by Streptococcus pneumoniae were treated prospectively with cefuroxime axetil suspension (30 mg/kg of body weight twice daily for 8 days). The high incidence of isolates with decreased susceptibilities to penicillin (42 of 84 isolates) allowed us to establish a relationship between clinical success and the penicillin MICs for pneumococcal isolates. It was found that cefuroxime axetil is clinically effective in the treatment of acute otitis media caused by penicillin-susceptible and penicillin-intermediate strains of S. pneumoniae. The results indicate that the risk of treatment failure with cefuroxime axetil was increased in children with otitis media caused by S. pneumoniae when the penicillin MIC were greater than or equal to 2 mg/liter.

Acute Disease↗
PubMed1995

Protective immunity induced by Bacillus anthracis toxin-deficient strains.

The two toxins secreted by Bacillus anthracis are composed of binary combinations of three proteins: protective antigen (PA), lethal factor (LF), and edema factor (EF). Six mutant strains that are deficient in the production of one or two of these toxin components have been previously constructed and characterized (C. Pezard, E. Duflot, and M. Mock, J. Gen. Microbiol. 139:2459-2463, 1993). In this work, we examined the antibody response to the in vivo production of PA, LF, and EF in mice immunized with spores of strains producing these proteins. High titers of antibody to PA were observed after immunization with all strains producing PA, while titers of antibodies to EF and LF were weak in animals immunized with strains producing only EF or LF. In contrast, immunization with strains producing either PA and EF or PA and LF resulted in an increased antibody response to EF or LF, respectively. The differing levels of protection from a lethal anthrax challenge afforded to mice immunized with spores of the mutant strains not only confirm the role of PA as the major protective antigen in the humoral response but also indicate a significant contribution of LF and EF to immunoprotection. We observed, however, that PA-deficient strains were also able to provide some protection, thereby suggesting that immune mechanisms other than the humoral response may be involved in immunity to anthrax. Finally, a control strain lacking the toxin-encoding plasmid was unable to provide protection or elicit an antibody response against bacterial antigens, indicating a possible role for pXO1 in the survival of B. anthracis in a host.

Animals↗
PubMed1994

[Recognition and identification of unknown infectious agents].

The recognition and the identification of previously unrecognized infectious agents require a multidisciplinary approach to specify the nosologic entity of the disease and the epidemiological data, especially the modes of transmission and the risk factors, as well as to discover the microorganism in the laboratory. In the past 20 years, significant breakthroughs have been achieved in cellular cultures (growth factors), in immunology (monoclonal antibodies), and moreover in molecular biology, which have been widely used in the field of infectious diseases. Whereas the classical methods used to grow microorganisms remain of major interest in many cases, innovating strategies have been recently designed to identify previously unknown pathogens. The genomic amplification by polymerase chain reaction (PCR) of highly conserved bacterial genes (as those coding for ribosomal RNA), from tissue biopsies for example, allow to recognize unknown bacteria. The evolutionary distance between a newly recognized pathogen and known microorganisms can be calculated through sequencing of these genes, as described for Rochalimaea henselae or Tropheryma whipplelii. The constitution of cDNA banks from infected tissues is also a novel approach allowing to clone and sequence viral genes, such as those from hepatitis C or from hepatitis E. In the near future, noteworthy improvements will be achieved to rapidly detect microorganisms with highly sensitive and specific tests using monoclonal antibodies, molecular probes (including branched DNA) and with PCR (including Q beta replicase and ligase chain reaction), and to determine the genetic diversity of microbial pathogens by new methods as pulse field gel electrophoresis or arbitrarily primed PCR. This will result in a better knowledge of the pathophysiology of infectious diseases, in a better recognition of a typical, previously unrecognized clinical expression of pathogenicity, and also in a more precise assessment of the actual impact of a given pathogen in human populations by highly sophisticated diagnosis tests.

Animals↗
PubMed1994

Detection of Mycobacterium paratuberculosis by polymerase chain reaction in children with Crohn's disease.

Mycobacterium paratuberculosis, the causative agent of Johne's disease (a chronic enteritis in ruminants), has been suspected to be involved in Crohn's disease. In this study, polymerase chain reaction was used to detect the presence of IS900 DNA sequences specific to M. paratuberculosis genomes in biopsies and surgical resections from 53 children with various gastrointestinal diseases and disorders. IS900 sequences were found in 13 of 18 samples from patients with Crohn's disease (72%; P < .01 vs. samples from patients without Crohn's disease), in 1 of 5 with ulcerative colitis, in 2 of 6 with severe unclassified colitis, and in 7 of 24 with other gastrointestinal illnesses. These results appear to support the hypothesis that M. paratuberculosis is involved in the pathogenesis of Crohn's disease.

Child, Preschool↗
PubMed1994

The novel epidemic strain O139 is closely related to the pandemic strain O1 of Vibrio cholerae.

A new Vibrio cholerae serogroup O139 strain of unknown origin recently emerged in India and Bangladesh, causing a major outbreak of cholera. The genetic relationship between this epidemic strain and the O1 strain responsible for the 7th pandemic of cholera was studied by analyzing the DNA polymorphism of V. cholerae by pulsed-field gel electrophoresis and arbitrarily primed polymerase chain reaction. The restriction patterns of the reference strain O139 Bengal and 10 wild O139 strains isolated early in the Indian outbreak strikingly resemble that of the pandemic O1 strain of V. cholerae El Tor, thus suggesting a close genetic relationship among these strains. This similarity contrasts with the genetic heterogeneity of sporadic non-O1 strains isolated in various parts of the world. Study results strongly suggest that the new epidemic O139 strain is closely related to and might be derived from the pandemic O1 strain of V. cholerae.

Bangladesh↗
PubMed1994

Comparative efficacy and safety of cefprozil and amoxycillin/clavulanate in the treatment of acute otitis media in children.

Cefprozil is a new oral cephalosporin with activity against the most common pathogens isolated in acute otitis media. This randomized study enrolled 361 patients (mean age 29 months). Physical examination and culture via tympanocentesis were required less than 48 h before therapy. One hundred and ninety-one patients were evaluable for clinical efficacy; 99 received cefprozil (20 mg/kg/day bd) and 92 received amoxycillin/clavulanate (13.3 mg/kg/day tid). Duration of treatment was 7-9 days for 81 patients, 10 days for 105 patients and 11-16 days for five patients. The treatment groups were comparable with respect to demographics, severity of infection and number of previous episodes. Clinical evaluations of efficacy were based on physical examination including otoscopy within a 14 day period after therapy. Satisfactory clinical responses were achieved in 84% of cefprozil-treated patients and 87% of amoxycillin/clavulanate-treated patients. Pathogens most commonly isolated included Haemophilus influenzae (33%) and Streptococcus pneumoniae (22%). All 361 patients were evaluable for safety. Adverse clinical events were reported in 13% (24) of cefprozil-treated patients and 20% (36) of amoxycillin/clavulanate-treated patients. Cefprozil, administered twice a day, is comparable to a regimen of amoxycillin/clavulanate three times a day in the treatment of acute otitis media in children.

Acute Disease↗
PubMed1994

Inhibition of intracellular growth of Listeria monocytogenes by antibiotics.

We studied the activities of 15 antibiotics on the intracellular growth of Listeria monocytogenes in a HeLa cell line. After 24 h of contact with the infected cells, the antibiotics most effective against the intracellular growth of the 10 strains tested were amoxicillin, temafloxacin, and sparfloxacin, which nevertheless failed to totally eliminate the intracellular bacteria. Rifampin and co-trimoxazole had variable effects, depending on the isolates studied. The most active combinations were amoxicillin-sparfloxacin, co-trimoxazole-gentamicin, and sparfloxacin-co-trimoxazole. The results suggest the value of using a cell culture technique to study the activities of antibiotics against certain bacteria with intracellular sites of multiplication.

Anti-Bacterial Agents↗
PubMed1994

Lack of antibody response to invasin in humans with yersiniosis.

The Yersinia pseudotuberculosis inv gene encodes invasin, a 103-kDa outer membrane protein allowing bacteria to penetrate mammalian cells. This protein is produced in vitro at below 30 degrees C. In this work, we studied the antibody response against invasin in humans suffering from yersiniosis and in mice orally infected with a virulent strain of Y. pseudotuberculosis. Infection with enteropathogenic Yersinia strains did not induce either a systemic or a gut antibody response to invasin. Our results suggest that the inv gene is not expressed in the gut at 37 degrees C and, therefore, that invasin is not present to the immune system when microorganisms multiply in the host tissues.

Adhesins, Bacterial↗
PubMed1994

Fate of Listeria monocytogenes in murine macrophages: evidence for simultaneous killing and survival of intracellular bacteria.

The intracellular survival of the ubiquitous pathogen Listeria monocytogenes was studied in primary cultures of bone marrow-derived mouse macrophages. Bacteria were able to grow rapidly in these cells, with an apparent multiplication rate of about 40 min. Electron microscopy demonstrated that intracellular bacterial replication was the consequence of simultaneous intracellular killing and replication of bacteria in the same cells. Within the first hour following phagocytosis, most bacteria were destroyed in the phagosomal compartment to which they were confined. This was due to early transfer of hydrolytic enzymes to phagosomes, undoubtedly via phagosome-lysosome (P-L) fusion, as demonstrated by a quantitative analysis after staining for a lysosomal marker, acid phosphatase. One hour after infection, about 14% of the bacteria were free in the cytoplasm, in which they multiplied and induced actin polymerization and spreading to adjacent macrophages, as in epithelial cells. By using the 3-(2,4-dinitroanilino)-3'-amino-N-methyldipropylamine staining procedure, direct evidence is presented that all phagosomes were acidified immediately after phagocytosis, thus indicating that intraphagosomal bacteria were exposed to an acidic environment that might favor vacuolar lysis by listeriolysin O. Intracellular growth in macrophages, therefore, appears to be the result of a competition between the expression of the hydrolytic activity of these cells following P-L fusion and the capacity of L. monocytogenes to escape from the acidified phagosomal compartment before P-L fusion has occurred. The finding that concomitant intracellular killing and survival of L. monocytogenes occurs in the same macrophages might explain the high immunogenicity observed in vivo with live bacteria, as opposed to killed bacteria.

Acid Phosphatase↗
PubMed1994

Immunization with live aroA recombinant Salmonella typhimurium producing invasin inhibits intestinal translocation of Yersinia pseudotuberculosis.

The Yersinia pseudotuberculosis inv gene encodes invasin, a 103-kDa outer membrane protein that allows bacteria to enter mammalian cells. The gene was subcloned into the attenuated aroA mutant of Salmonella typhimurium SL3261. Invasin was produced by the recombinant Salmonella strain and increased the ability of microorganisms to translocate from the intestinal lumen to the mesenteric lymph nodes. Specific antibodies for invasin were detected in sera and intestinal secretions of mice following oral immunization with the live Inv+ Salmonella strain. The immunization strongly inhibited intestinal translocation of Y. pseudotuberculosis when this pathogen was inoculated to mice but failed to prevent Yersinia dissemination from the gut lymphoid tissue.

3-Phosphoshikimate 1-Carboxyvinyltransferase↗
PubMed1994

A double-blind comparison of ciprofloxacin and amoxycillin/clavulanic acid in the treatment of chronic sinusitis.

A total of 251 adults with chronic sinusitis were enrolled into this prospective multicentre, double-blind, double-placebo comparison of ciprofloxacin (500 mg twice daily) with amoxycillin/clavulanic acid (500 mg three times daily). The diagnosis of chronic sinusitis (persistence of clinical symptoms for at least 3 months) was confirmed by computerized tomography scan and/or sinusoscopy prior to therapy. Patients at inclusion had purulent or muco-purulent rhinorrhoea. Staphylococcus aureus (n = 45), Haemophilus influenzae (n = 35), Streptococcus pneumoniae (n = 32) and enterobacteriaceae (n = 31) were isolated from pre-treatment aspirates of the middle meatus. Treatment lasted 9 days, at the end of which nasal discharge disappeared in 71/118 (60.2%) patients of the ciprofloxacin group and 69/123 (56.1%) of those in the amoxycillin/clavulanic acid group. The clinical cure and bacteriological eradication rates were 58.6% versus 51.2% and 88.9% versus 90.5% for ciprofloxacin and amoxycillin/clavulanic acid, respectively. These differences were not significant, however, amongst patients who had a positive initial culture and who were evaluated 40 days after treatment. Ciprofloxacin recipients had a significantly higher cure rate than those treated with amoxycillin/clavulanic acid (83.3% vs. 67.6%, p = 0.043). Clinical tolerance was significantly better with ciprofloxacin (p = 0.012), essentially due to a large number of gastro-intestinal related side-effects in the amoxycillin/clavulanic acid group (n = 35). Ciprofloxacin proved to be at least as effective as amoxycillin/clavulanic acid. The superior safety profile, a twice daily dosage regimen, suggests that ciprofloxacin may be a useful therapeutic alternative for the treatment of chronic sinusitis.

Adolescent↗
PubMed1994

Controlled prospective study of oral ciprofloxacin versus amoxycillin/clavulanic acid in chronic suppurative otitis media in adults.

The efficacy and tolerability of ciprofloxacin (500 mg twice daily) was compared with that of amoxycillin/clavulanic acid (500 mg three times daily) in 76 patients with acute exacerbations of chronic non-cholesteatomatous suppurative otitis media enrolled in this open randomized multicentre trial. A total of 40 ciprofloxacin-treated patients and 35 amoxycillin/clavulanic acid-treated patients were evaluable for clinical efficacy following the 9-day treatment period. Pseudomonas aeruginosa was the main pathogen isolated prior to treatment. At the end of treatment, otorrhoea had disappeared in 57.5% of the ciprofloxacin group and 37.1% of the amoxycillin/clavulanic acid group (p = 0.04). Bacterial eradication rate was also significantly greater with ciprofloxacin (69.7%) than with amoxycillin/clavulanic acid (27.3%). Both treatments were well tolerated. Ciprofloxacin appears to be an effective treatment of chronic otitis media, and superior to amoxycillin/clavulanic acid.

Adult↗