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Biomedical subjects

J Bille

Publications and source records attributed to J Bille.

At least 109 records · Page 6Linked to original sources
PubMed1993

Prevalence of latent toxoplasmosis and serological diagnosis of active infection in HIV-positive patients.

The seroprevalence of latent Toxoplasma gondii infection was determined in a cohort of 715 HIV-positive patients followed up at an HIV outpatient clinic. Using indirect immunofluorescence and direct agglutination assays for detecting IgG, the prevalence of anti-Toxoplasma gondii antibodies was shown to be 50%. During a four-year period, clinically apparent acute toxoplasmosis occurred in 47 patients (43 with cerebral, 3 with ocular and 1 with bone marrow toxoplasmosis) among the 360 patients positive for anti-Toxoplasma gondii IgG and in one patient (with cerebral toxoplasmosis) among the 355 patients who were serologically negative. A significant rise in IgG levels could be shown during acute toxoplasmosis episodes in only 30% of patients, compared with 3% of patients without active toxoplasmosis. During acute toxoplasmosis, IgM antibodies were detected in only two patients (6%) by an immunosorbent agglutination assay and in one (3%) by an enzymatic immunocapture assay. Specific IgA was detected by a non-enzymatic immunocapture assay in six patients (18%) during acute episodes. The very high predictive value (99.7%) of a negative IgG test remains the best serological parameter for excluding an acute episode of toxoplasmosis in HIV-positive patients.

Acute Disease↗
PubMed1993

Correlation between in vitro susceptibility of Candida albicans and fluconazole-resistant oropharyngeal candidiasis in HIV-infected patients.

Twenty-five patients seen consecutively at an HIV outpatient clinic who had clinical evidence of oropharyngeal candidiasis and two or more oral swabs positive for yeasts on culture were studied retrospectively. For each of the 65 isolates susceptibility to fluconazole was evaluated by the disk diffusion test and determination of the minimal inhibitory concentration (MIC). A correlation was sought between clinical resistance and in vitro susceptibility data. Seven patients were non-responders and 19 were responders (one patient figuring in both groups). Significant differences were observed between the two groups with respect to the median interval after the diagnosis of AIDS (27 months in non-responders and 2 months in responders; p = 0.001), the median CD4+ cell count (6 and 21 cells/mm3 respectively; p = 0.005) and the median number of previous episodes of oropharyngeal candidiasis treated with fluconazole (13 and 2 episodes respectively; p = 0.001). Candida albicans was identified in 64 of 65 cultures. The correlation between MIC values and diameters of inhibition was good (r = 0.85; p < 0.001). The degree of in vitro susceptibility of the isolates to fluconazole showed a significant difference between non-responders and responders (mean inhibition diameters 13 and 36 mm respectively; p < 0.001) with a tentative cut-off value of 25 mm. An advanced stage of HIV infection and previous exposure to fluconazole could be risk factors for the development of fluconazole-resistant oropharyngeal candidiasis. Candida albicans strains with decreased in vitro susceptibility to fluconazole were responsible for the clinical resistance which could be predicted by a simple disk diffusion test.

AIDS-Related Opportunistic Infections↗
PubMed1993

Characterization of Listeria strains isolated from soft cheese.

Three soft cheeses were exposed to quantitative analysis for listeria and found to contain a large number of listeria. Thirty-five of the listeria strains isolated from the three cheeses were characterized by use of biochemical tests, serotyping, phagetyping and DNA restriction enzyme analysis. Seven isolates were identified as Listeria innocua and 28 as Listeria monocytogenes. Two to four different clones of L. monocytogenes could be identified from each cheese. In contrast, only one clone could be detected among the L. innocua isolates. From an epidemiological point of view the findings of different clones of L. monocytogenes in the same cheese emphasize the need for typing several listeria isolates from one and the same food sample. It is concluded that the best overview of the population of the listeria strains is obtained after direct plating of the sample followed by enumeration, isolation and extensive typing.

Bacteriophage Typing↗
PubMed1993

Isolation and characterization of a secreted metalloprotease of Aspergillus fumigatus.

A metalloprotease (MEP) secreted by Aspergillus fumigatus was isolated from an alkaline protease-deficient mutant after the fungus was cultivated in the presence of collagen as the sole nitrogen and carbon source. The enzyme was purified 50-fold from the culture supernatant after adsorption to hydroxylapatite and carboxy-methyl-Sephadex and after gel filtration. The molecular mass was determined to be 40 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The isoelectric point was estimated at pH 5.5 by isoelectric focusing. Reducing agents and divalent cations strongly inhibited enzyme activity, whereas nonionic detergents had no effect. A. fumigatus MEP was totally inhibited by EDTA, 1,10-phenanthroline, and phosphoramidon but not by inhibitors specific for serine, aspartate, and cysteine proteases. MEP is not able to cleave elastin and is thermosensitive. Sera from patients suffering from aspergilloma reacted with MEP in Western blotting (immunoblotting) analyses, suggesting that MEP promotes an antigenic response in these patients.

Antibodies, Fungal↗
PubMed1992

Typing of Listeria monocytogenes by restriction polymorphism of the ribosomal ribonucleic acid gene region.

Ninety four strains of Listeria monocytogenes of different serovars and phagovars as well as of varying origins were characterized by ribosomal RNA gene restriction polymorphism. After digestion by EcoRI or HindIII, chromosomal DNAs were hybridized with a cloned rDNA probe from Bacillus subtilis that included the 16S rRNA gene. The 94 strains were divided into 14 ribovars according to the different hybridization patterns generated by cleavage with EcoRI. Less important genomic heterogeneity could be detected when DNAs were digested by HindIII. EcoRI ribovars analysis allowed to describe a new typing scheme which did not corroborate routine typings such as serotyping and phage typing. It also confirmed a new view of this species in exhibiting a clone gathering most human strains, as first inferred from multilocus enzyme analysis (Piffaretti et al., 22).

Animals↗
PubMed1992

Assessment of the Accuprobe Listeria monocytogenes culture identification reagent kit for rapid colony confirmation and its application in various enrichment broths.

The Accuprobe Listeria monocytogenes Culture Identification Reagent Kit, a nonradioactive probe, was evaluated as a colony confirmation test and in different selective or nonselective enrichment broths. The probe was 100% sensitive and 100% specific when applied to isolated colonies. The minimal detection limit in physiological saline was established to be about 10(5) CFU of L. monocytogenes. Hybridization done directly in broths seeded with L. monocytogenes showed variable results. Three nonselective broths (Todd-Hewitt broth, brain heart infusion broth, and tryptic soy broth) and one selective broth (FDA) gave positive reactions at an inoculum of 5 x 10(6) CFU, whereas two other selective broths (UVM, and PALCAMY) gave negative reactions with up to 10(8) and 10(9) CFU. In FDA broth, the level of detection of L. monocytogenes was not modified by the presence of other organisms in mixed cultures.

Bacteriological Techniques↗
PubMed1992

API Listeria, a new and promising one-day system to identify Listeria isolates.

API Listeria is a new 10-test strip for 24-h biochemical identification of Listeria isolates. With this commercial system, 85% of 646 Listeria strains, including atypical isolates selected for this study, were recognized at the species and subspecies level without a complementary test. A new test differentiates Listeria monocytogenes from L. innocua on the basis of the absence of arylamidase from the former. With this system, 97.7% (252 of 258) of the L. monocytogenes strains tested were correctly identified and differentiated from 99.4% (175 of 176) of the L. innocua strains also tested. Gram-positive bacteria other than Listeria spp. gave quite different biochemical patterns. This system considerably reduced the time needed for conventional identification, since results were available within 18 to 24 h.

Bacteriological Techniques↗
PubMed1992

Evaluation of the Organon-Teknika MICRO-ID LISTERIA system.

The MICRO-ID LISTERIA system, designed to identify Listeria isolates to species level within 24 h, was compared with conventional biochemical identification. MICRO-ID LISTERIA used in combination with the CAMP test correctly identified 409 (98.8%) of 414 strains isolated from human, animal, food, and environmental sources belonging to the seven species currently defined within the genus Listeria. The kit was easy to use and simple to interpret. However, 8 of the 15 tests (i.e., phenylalanine deaminase, hydrogen sulfide, indole, ornithine decarboxylase, lysine decarboxylase, malonate, urease, and o-nitrophenyl-beta-D-galactopyranoside) were considered superfluous for the differentiation of Listeria spp. The CAMP test was indispensable when using the MICRO-ID LISTERIA system, in particular to differentiate CAMP test-positive L. monocytogenes from the nonhemolytic, rhamnose-positive L. innocua. The hemolytic L. seeligeri and L. ivanovii strains and the nonhemolytic, non-rhamnose-acidifying L. welshimeri strains could also be differentiated from one another only on the basis of their CAMP test results. The very few strains of L. grayi and L. murrayi were easily differentiated from the other nonhemolytic species. Catalase-negative cocci should not be tested, because 12 out of 19 catalase-negative strains (all enterococci) in our test were misidentified as Listeria spp. The MICRO-ID LISTERIA system identified strains within 18 to 24 h and is thus less time-consuming than conventional tests. The system could, therefore, be used together with correctly done CAMP tests for the rapid identification of Listeria isolates, especially food and environmental isolates, for which rapid species differentiation is important.

Animals↗
PubMed1992

Development of polymerase chain reaction assays for detection of Listeria monocytogenes in clinical cerebrospinal fluid samples.

In order to improve the diagnosis of Listeria meningitis or meningoencephalitis, especially in patients who have received antibiotics before their cerebrospinal fluid (CSF) has been examined, two assays for the detection of Listeria monocytogenes based on the polymerase chain reaction (PCR) were evaluated. After a standard PCR, the amplified DNA was detected either by a second round of PCR with internal primers followed by gel electrophoresis and ethidium bromide staining (nested PCR) or by dot blot hybridization to an internal digoxigenin-labeled probe (PCR-dot blot). For PCR, two sets of primers within the invasion-associated protein gene (iap gene) were chosen. They allowed for the highly specific detection of all L. monocytogenes reference strains tested (serotypes 1/2a, 1/2b, 1/2c, 3a, 3b, 3c, 4a, 4b, 4c, 4d, and 7). These primers did not detect amplification products from various other gram-positive or gram-negative bacterial DNAs or human DNA. The sensitivities of both assays were assessed on sterile CSF samples that were artificially seeded with serial dilutions of L. monocytogenes serotype 4b cells. By both methods the limit of detection was less than 10 cells in the initial reaction. Since the nested PCR is more prone to contamination because of manipulation of the amplified products, a standard PCR assay followed by dot blot hybridization was applied to 52 CSF samples in a retrospective study. Of 28 CSF samples which were sterile or positive for bacteria other than Listeria species, 24 were PCR negative. In contrast, from 17 patients with culture-proven Listeria meningitis, 14 of 17 initial CSF samples were PCR positive, as were 3 of 7 culture-negative followup CSF samples taken after patients received antibiotics. These results support the usefulness of this approach in the diagnosis of Listeria meningitis, in particular, when antibiotic administration precedes culture of CSF.

Anti-Bacterial Agents↗
PubMed1992

[Pneumonia: etiologic diagnosis and therapy in general practice].

The majority of community-acquired pneumonias are not hospitalized, have a good prognosis and a low mortality rate. In the nonimmunocompromised adult patient, pneumonias are caused by a broad array of microorganisms of which the so-called 'atypical' agents (mycoplasma, chlamydiae, viruses) are as frequently found as classical bacteria such as pneumococci and haemophilus. Generally, the mode of acquisition and the clinical picture will not allow to deduct the etiology with certainty, and the laboratory results are often nonconclusive (sputum examination) or delayed (serology). Empirical therapy should be initiated based on epidemiological grounds and on the characteristics of the patient. For patients without underlying conditions, immunosuppression or advanced age, a macrolide (erythromycin or a new macrolide) appears to constitute a good choice because of its broad spectrum of activity, comprising the classical bacterial agents of pneumonia, mycoplasma, chlamydiae, and legionella.

Anti-Bacterial Agents↗
PubMed1991

[Pneumonia: identification of respiratory pathogens].

The etiological diagnosis of pneumonia is necessary because it will condition therapy. The broad spectrum of potential pathogens is reduced when the host's condition and the events around the pneumonia episode are taken in account. Community acquired pneumonia in an immunocompetent host most often is caused by bacteria (predominantly S. pneumoniae) or by mycoplasma or respiratory viruses. Microbiological diagnosis relies on direct sputum examination and culture (for bacterial agents) and on serology (for nonbacterial agents). In a compromised host, the spectrum of etiological agents is broader; sputum examination often is unrewarding and invasive investigations are necessary. Bronchoscopy with bronchoalveolar lavage is increasingly used, allowing an abundant material to be analyzed with a battery of tests directed against the pathogens most probable in view of the clinical setting. Direct examinations with special stains for bacteria, fungi, parasites, and viruses offer a rapid diagnosis in some cases. Various cultural procedures for bacteria, viruses and fungi, particularly in the absence of previous antimicrobial therapy, will establish the etiological diagnosis in the majority of pneumonia cases and help to select specific therapy.

Bronchoalveolar Lavage Fluid↗
PubMed1991

Beta-lactam resistance mechanisms of methicillin-resistant Staphylococcus aureus.

In vitro and in vivo activity of amoxicillin and penicillin G alone or combined with a penicillinase inhibitor (clavulanate) were tested against five isogenic pairs of methicillin-resistant Staphylococcus aureus (MRSA) producing or not producing penicillinase. Loss of the penicillinase plasmid caused an eight times or greater reduction in the MICs of amoxicillin and penicillin G (from greater than or equal to 64 to 8 micrograms/ml), but not of the penicillinase-resistant drugs methicillin and cloxacillin (greater than or equal to 64 micrograms/ml). This difference in antibacterial effectiveness correlated with a more than 10 times greater penicillin-binding protein 2a affinity of amoxicillin and penicillin G than of methicillin and a greater than or equal to 90% successful amoxicillin treatment of experimental endocarditis due to penicillinase-negative MRSA compared with cloxacillin, which was totally ineffective (P less than .001). Amoxicillin was also effective against penicillinase-producing parent MRSA, provided it was combined with clavulanate. Penicillinase-sensitive beta-lactam antibiotics plus penicillinase inhibitors might offer a rational alternative treatment for MRSA infections.

Animals↗
PubMed1991

In-vitro activity of temafloxacin for gram-positive pathogens.

The antimicrobial activity of temafloxacin against aerobic Gram-positive cocci was compared to that of ciprofloxacin, ofloxacin, fleroxacin and pefloxacin using the broth microdilution technique. Temafloxacin was more active than the other four fluoroquinolones, particularly for viridans streptococci and Streptococcus pneumoniae. The MIC90 of temafloxacin was at least four-fold lower than that of ciprofloxacin and ofloxacin for viridans streptococci and penicillin-susceptible pneumococci. The MIC50s and MIC90s of temafloxacin were equal to or lower than those of the other fluoroquinolones for methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), and methicillin-susceptible and methicillin-resistant coagulase-negative staphylococci. Temafloxacin was more active against all the other Gram-positive aerobes (except Enterococcus faecalis) tested than the other fluoroquinolones.

Anti-Infective Agents↗
PubMed1990

[In-vitro activity of cefuroxime-axetil against pathogens of bacterial infections of the respiratory tract].

Cefuroxime-Axetil is an ester of cefuroxime, which can be used as an oral antimicrobial agent. The prodrug is hydrolysed by esterases of the gut mucosa, setting free the active cefuroxime. This second generation cephalosporin is well known since more than a decade as a cephalosporin possessing high stability against gram positive and gram negative beta-lactamases. Due to its pharmacokinetic properties and its wide spectrum of activity, cefuroxime-axetil was recommended to be used as an oral agent in bacterial infections of the respiratory tract. This paper describes the in vitro activity of cefuroxime against respiratory tract pathogens and compares it with that of ampicillin and amoxicillin, amoxicillin/clavulanic acid, cefaclor, chloramphenicol, tetracycline, erythromycin and trimethoprim/sulphamethoxazole. Cefuroxime had good activity against beta-lactamase-producing and beta-lactamase-negative H. influenzae and M. catarrhalis. As expected, the aminopenicillins showed reduced activity against beta-lactamase-producing strains of these organisms. Amoxicillin/clavulanic acid and, to a lesser degree, cefaclor also showed good activity against these bacteria. Cefuroxime was highly active against penicillin-susceptible pneumococci, but showed impaired activity against penicillin-resistant strains. Therefore, this drug should not be used in infections caused by penicillin-resistant pneumococci. Resistance to penicillin in pneumococci isolated in Switzerland is not a problem at the present time. For many years, such strains were isolated only sporadically. Cefuroxime showed also a high in vitro activity against streptococci of serogroups A, B, C and G, which are encountered as respiratory tract pathogens. Against beta-lactamase-positive and -negative staphylococci, cefuroxime showed good activity. The drug was inactive, however, against methicillin-resistant strains.

Anti-Bacterial Agents↗
PubMed1990

Comparative efficacy of daptomycin, vancomycin, and cloxacillin for the treatment of Staphylococcus aureus endocarditis in rats and role of test conditions in this determination.

The in vivo efficacy of daptomycin, a new cell wall-active anti-gram-positive-bacterial agent, was compared to those of cloxacillin and vancomycin in a rat model of Staphylococcus aureus endocarditis. Both methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains were used. When therapy was initiated early (8 h) after infection, at the time when valvular bacterial counts were relatively low (approximately 10(6) CFU/g of vegetation), 3 days of therapy was found to be effective against the MSSA strains whatever the antibiotic regimen. In contrast, when the onset of therapy was delayed up to 15 h after infection, so that higher bacterial counts could develop on the valves (approximately 10(9) CFU/g of vegetation), a longer period of treatment (6 days) was required to cure infection. Under these conditions after 3 days of therapy, daptomycin was more effective than cloxacillin and vancomycin against the MSSA strains. Similarly, daptomycin showed a greater activity than vancomycin against the MRSA strain after 3 days of treatment, but after 6 days both antibiotics were equally effective. Decreasing doses of daptomycin showed decreasing activity: 10 mg/kg of body weight every 12 h (q12h) was better than 5 mg/kg q12h, whereas 5 mg/kg q24h (providing drug levels in blood detectable only during the first 12 h) failed to cure infection. In vitro, daptomycin was highly bactericidal at high concentrations (25 and 60 micrograms/ml, corresponding to peak levels in serum after doses of 5 and 10 mg/kg, respectively) and bacteriostatic at lower concentrations (0.5 to 2.5 micrograms/ml, corresponding to trough levels in serum). In conclusion, against low-bacterial-count S. aureus endocarditis, daptomycin showed an efficacy similar to those of vancomycin and cloxacillin. Against high-bacterial-count S. aureus endocarditis, daptomycin showed a higher bactericidal activity than cloxacillin (against the MSSA strains) and vancomycin (against both the MSSA and MRSA strains).

Animals↗