Biomedical subjects
Publications and source records attributed to P Berche.
Qualitative bacterial samples were taken from 53 appendices which were purulent, or had lymphoid hyperplasia or were normal. The results did not demonstrate a specific bacterial flora responsible for appendicular disease in childhood.
The protective antibodies obtained in mice with an acellular vaccine P2 from Pseudomonas aeruginosa have been titered in vivo by a bacterial clearance technique. The kinetics of the bacterial disappearance from the circulating blood were compared in mice which had been vaccinated or had received injection of specific serum, and in normal mice. The following results were obtained; (a) the disappearance of the bacteria from the blood is quicker in immunized animals; (b) the rate of bacteria in the blood depends on doses of injected serum; (c) the titers of protective antibodies expressed by 99% clearance dose is directly in relation with the vaccinating dose.
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Resistance to phagocytosis of Yersinia pseudotuberculosis by mouse resident macrophages was investigated using a highly virulent plasmid-bearing strain and its low-virulent plasmid-free derivative. It was found that plasmid-bearing and plasmid-less bacteria did not resist the ingestion step nor inhibit the oxidative burst and phagolysosomal fusion in the peritoneal macrophages. These in vitro data were further confirmed by the study of bacterial survival in infected mice. Bacteria from plasmid-bearing and plasmid-free strains were similarly eliminated during the first hours of infection in the liver and in the peritoneal cavity. Our results therefore suggest that plasmid-mediated virulence is not related to the resistance to the bactericidal activity of fixed macrophages of the reticuloendothelial system during the early phase of infection, and that plasmid-encoded factors are expressed after a latency period by an unknown mechanism.
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Infection with human cytomegalovirus (HCMV) has been associated with severe diseases in immunologically impaired patients. Cytomegalovirus hepatitis has been frequently described in this population, but this diagnosis is still difficult. Molecular hybridization with the V EcoRI restriction fragment of human cytomegalovirus strain AD 169 has been tested upon DNA extracted from liver samples to assess the usefulness of this technique for cytomegalovirus hepatitis diagnosis. This probe was shown by the Southern technique not to hybridize with DNA extracted from cells infected with other herpesviruses or with DNA of non-infected normal liver. The sensitivity was estimated to be 2 x 10(5) genomes. Twenty-five renal transplant recipients under immunosuppressive therapy and three patients having the acquired immunodeficiency syndrome were studied. In 9 out of 10 renal transplant recipients with normal liver, previous exposure to cytomegalovirus, as defined by serological tests, was not sufficient to allow positive detection by the probe. Out of 11 patients with abnormal liver, cytomegalovirus DNA sequences were shown in 5. In 2 patients with histological evidence of cytomegalovirus hepatitis, a very strong signal showed the presence of viral genomes. These results show that the Southern technique with the V EcoRI probe can be useful for the diagnosis of HCMV hepatitis and might be proposed for the detection of this viral genome in human tissues.
This multicentre, prospective study evaluated the efficacy and safety of 7-day oral moxifloxacin (400 mg/day) for treatment of acute maxillary sinusitis after first-line treatment failure (group 1), and acute sinusitis with high risk of complications (group 2). Two hundred and fifty-eight patients with radiologically confirmed acute sinusitis were enrolled by 52 investigators; 216 patients (83.7%) qualified for per protocol efficacy analysis (group 1, n = 175; group 2, n = 41), and 92 for bacteriological analysis. Samples were collected from the middle meatus. The clinical success rate 7-10 days post-treatment was 92.6%. Bacteriological success rates were 95.7% after 3-4 days of treatment, and 97.2% and 95.2%, in group 1 and group 2, respectively, at 7-10 days post-treatment. Drug-related adverse events, including abdominal pain (2.4%), nausea (2.4%) and diarrhoea (1.2%), were reported in 12.2% of patients. Overall, moxifloxacin therapy resulted in rapid bacteriological eradication, with a high rate of clinical success.
A performance analysis was established between three methods for testing of bacterial susceptibility to sixteen antibiotics: agar dilution or minimal inhibitory concentration (MIC) method, agar diffusion or DISK method, and semi-automatic dilution in liquid medium or ABACR method. Precision of the three methods was determined using three reference strains in repetition experiments (9 repetitions for MIC, 60 repetitions for both DISK and ABAC). The results show that MIC method was the most precise, and that the precision of DISK and ABAC methods was not sifnificantly different. Fidelity of both DISK and ABAC methods was compared in taking as reference the MIC of 200 wild strains of Gram-negative bacteria. Omitting the data concerning trimethoprim-sulfamethozoaxol, the results were found concordant between DISK and MIC methods in 68.6 percent of the cases, between ABAC and MIC methods in 73.6 percent, and between ABAC and DISK methods in 68.9 percent. With regard to MIC, ABAC method gave results slightly better than those of DISK method, especially for five antibiotics: gentamicin, minocyclin, doxycylin, chloramphenicol and polymyxin B. So, the ABAC method looks very interesting for a semi-automatic routine method in testing bacterial susceptibility to antibiotics.
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The minimal inhibitory concentration (MIC) of four betalactamins (carbenicillin, ticarcillin, piperacillin and (CGP-7174-E) against 109 clinical isolates of Pseudomonas aeruginosa was determined by an agar dilution method. CGP-7174-E was the most active (MIC 3.4 micrograms/ml), followed in descending order by piperacillin (MIC 4.9 micrograms/ml), ticarcillin (MIC 22 micrograms/ml) and carbenicillin (MIC 36 microgram/ml). High correlation was found between the MIC of these betalactamins (r greater than 0.60). In 12 strains where MIC for carbenicillin was greater than or equal to 1,024 microgram/ml, MIC for CGP-7174-E was less than or equal to 128 micrograms/ml and less than 16 micrograms/ml in four strains.
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Experiments have been established in order to study the antagonistic effect of cyclophosphamid treatment on the antibiotic activity of gentamicin in vivo. An immunodepressive state in mice (50 % reduction of neutrophil polymorphonuclear) was obtained with a 5 day treatment of cyclophosphamid, at the dose of 15 mg/kg. The mice were inoculated intraperitoneally with 10 LD50 of Klebsiella pneumoniae. Antibiotherapy was applied in 2 ways differing with the dose of gentamicin given twice a day by subcutaneous route (either 2.5 or 25 mg/kg) and with the time at which treatment was started (either at 1 or at 2 h after bacterial challenge). The gentamicin activity decreases in immunosuppressed mice when antibiotic is applied with a low dose (2.5 mg/kg), 1 h after infection challenge. This effect disappears when gentamicin is given with high doses (20 mg/kg) or when antibiotherapy is delayed (2 h after infection challenge). In this case, mortality is important and close to non immunodepressed mice.
The role of complement in the bactericidal activity of human serum against a mutant strain of Pseudomonas aeruginosa used as a model was demonstrated. The involvement of complement in the bacterial destruction of P. aeruginosa, and the contribution of the alternative and classical pathways of the complement system were directly evidenced by using sera from complement-deficient patients.
Susceptibility to bacterial infections after chronic exposure to cadmium was studied in mice. Cadmium chloride was injected intraperitoneally three times a week for 4 weeks. After this treatment, mice displayed splenomegalia, hyperplasia of the B-dependent areas of spleen. Virulence of bacteria considered as usually having extracellular sites of multiplication (Klebsiella pneumoniae, Pseudomonas aeruginosa), or intracellular (Listeria monocytogenes), was determined. Only L. monocytogenes showed an increased virulence in cadmium-treated mice.
A 20 month-old girl with Thalassemia major presented with a pseudotumoral mesenteric lymphadenitis due to Yersinia enterocolitica. The authors stress the rarity of this type of Yersinia infection. The clinical and bacteriological diagnosis is difficult and is based on the early isolation and identification of the bacterial strain, thus allowing an efficient antibiotic treatment. The frequency of such a Yersinia infection in thalassemic children is further discussed.
From a strain (72 V) of Pseudomonas aeruginosa, we have prepared an acellular vaccine P2, which showed a good efficiency against homologous experimental infection in mice. The extraction procedure is as follows: washed bacterial cells are suspended in 0,15 M NaCl and heated at 60 degrees centigrade for 1 hr; after centrifugation, the supernatant fluid is precipitated with one and five volumes of ethanol. This acellular vaccine possess the following properties: rapid efficiency (10 days) after a single or three inoculations of very small doses (ED50 = 0.014 mug per mouse); weak toxicity (LD50 = 1,148 mug per mouse, subcutaneous route); capacity for production of specific protective antibodies.
Homologous and cross-reactions were studied in 16 strains of Pseudomonas aeruginosa belonging to different O serogroups according to Habs' classification. By slide agglutination, cross-reactions were rare between the strains of two or three serogroups: O2, O5 and O16; O1 and O9; O7 and O8; O13 and O14. Experiments of cross-protection have been performed in mice inoculated with acellular vaccines prepared from the 16 studied strains. A high homologous protection was observed with all the 16 strains, which is in favour of existence of an O serogroup-specific immunity. However, it exists some cross-protective reactions between the serogroups. This cross-protection allows to reduce the numbers of strains for a polyvalent vaccine. A classification of P. aeruginosa into 8 classes of related serogroups (A to H) is proposed which could be a basis for an antigenic classification of P. aeruginosa.