Glycopeptide resistance in enterococci: first isolation of a strain harbouring the vanB gene in Belgium.
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Biomedical subjects
Publications and source records attributed to D Pierard.
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Neisseria meningitidis, a ubiquitous Gram-negative diplococcus, is responsible for a spectrum of clinical manifestations. This is illustrated by the history of three patients recently admitted to our hospital. Because of the possibly rapid and dramatic evolution, awareness for meningococcal diseases remains obligatory. Adequate antibiotic treatment instituted as soon as the diagnosis is suspected and early application of aggressive supportive care can lead to more favourable outcome.
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Shiga-like toxin (SLT)-producing Escherichia coli (SLTEC) O101 has recently been associated with hemorrhagic colitis and hemolytic-uremic syndrome in humans. In this study, SLTEC O101 strains from humans and pigs were characterized for clonal relatedness by nucleotide sequence analysis of their slt genes, DNA finger-printing of genomic DNA, and determination of virulence factors. The slt genes of five E. coli O101 strains were cloned and sequenced. For all strains, the deduced amino acid sequences of the B subunits were identical to those of the SLT-IIe present in the classical SLTEC O139 strains that cause edema disease in pigs. The A subunit revealed more than 99% homology to that of SLT-IIe. DNA fingerprinting revealed a high degree of genetic relatedness between the human and porcine O101 isolates. None of the O101 strains investigated had virulence factors frequently found in porcine (F107 fimbriae or heat-stable or heat-labile enterotoxins) or human SLTEC strains (eaeA or enterohemorrhagic E. coli hemolysin). The absence of virulence factors typical of SLT-I- and SLT-II-producing E. Coli together with the presence of SLT-IIe, a toxin previously seen only in porcine E. coli, suggests a new pathogenic mechanism for E. coli O101 infection of humans. For diagnostic purposes, we recommend the use of PCR primers and DNA probes complementary to slt-IIe to correctly identify such strains and to further evaluate their role in human diseases.
Bilateral cultures of bronchoalveolar lavage fluid were obtained from eight children with unilateral lobar pneumonia. In four patients bacterial pathogens were not isolated from lavage of the radiologically normal side but were subsequently cultured from the consolidated segment. This pattern helped to exclude contamination by oropharyngeal flora of bronchoalveolar lavage fluid. Bilateral bronchoalveolar lavage may help in the interpretation of lower respiratory tract cultures obtained by fiberoptic bronchoscopy.
DNA polymorphisms of Arcobacter butzleri outbreak-related strains and Arcobacter reference strains were determined by use of the polymerase chain reaction with primers aimed at repetitive sequences. The epidemiological relationship among 14 outbreak-related strains was substantiated, as they showed virtually no genomic variations. Their DNA amplification patterns were, however, clearly different from those of all Arcobacter reference strains studied; each reference strain was characterized by a unique DNA fingerprint.
The efficacy of cefetamet pivoxil (20 mg/kg and 10 mg/kg b.i.d.) was investigated in an open, prospective, randomized, comparative multicenter trial involving 148 children suffering from group A beta-hemolytic streptococcal (GABHS) pharyngo-tonsillitis. Phenoxymethylpenicillin given for 10 days was used as the reference drug and resulted in 15% treatment failures. After treatment with cefetamet pivoxil 20 mg/kg b.i.d., 2 failures (5.8%) were observed in 34 patients treated for 7 days and 2 (6%) in 33 patients after 10 days treatment. In 8 children treated with cefetamet pivoxil 10 mg/kg b.i.d. for 10 days, 7 were cured and 1 relapsed in the late follow-up. Recruitment for this dosage group is being continued. No serious adverse events occurred. Cefetamet pivoxil, given b.i.d., can be considered an alternative to phenoxymethylpenicillin in the treatment of GABHS pharyngo-tonsillitis.
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A Belgian multicenter trial was conducted to evaluate problems encountered with quality control results of antimicrobial disk susceptibility testing and to compare the performance of BBL disks and Rosco tablets. Over a period of four weeks 18 laboratories daily tested three reference strains against eight antibiotics. A standardised method was used by all participants. For all results together 10.4% and 7.3% of the measurements with BBL disks and Rosco tablets, respectively, were outside the recommended range. Major problems were observed for some specific strain-antibiotic combinations. Standard deviations were similar for both systems; their precision was comparable. The results suggest that cooperation between manufacturers and some reference laboratories could be improved in order to establish optimal quality control limits.
Relapsing peritonitis due to Mycobacterium xenopi developed in an 80-year-old man undergoing continuous peritoneal dialysis after appropriately treated concurrent bacterial peritonitis. The patient presented with a lymphocytic exudative peritoneal drainage fluid. The diagnosis of tuberculous peritonitis was made by identification of acid-fast bacilli in peritoneal effluent and culture of M. xenopi. Oral antituberculous drugs in combination with intraperitoneal streptomycin achieved suppression of the disease, permitting peritoneal dialysis to be continued with satisfactory clearance and ultrafiltration capacity during a follow-up period of up to 35 months. Streptomycin kinetics revealed that 75% of the intraperitoneally administered dose of streptomycin is absorbed from the dialysate.
We present a sero-epidemiological study of 190 Belgian cases of Lyme borreliosis, a multisystemic disease caused by the spirochaete Borrelia burgdorferi and transmitted by a tick bite. The whole spectrum of clinical pictures was observed in these patients, including "erythema chronicum migrans" (63%), neurological involvement (47%) and arthritis (22%), frequently in combination. Our results are compared to findings in other countries. Among the 437 Ixodes ricinus ticks collected in the Sambre and Meuse valleys around Namur, we discovered 43 ticks (9.8%) with spirochaetes in the midgut. The ecology of these arthropods explains why this infection is more prevalent in the spring and the summer. Perhaps for the same reason, the incidence ranges from low near the coast to medium in the central part and high in the wooded south-eastern part of Belgium. The main conclusions are that Lyme borreliosis is endemic in Belgium, that all the clinical pictures can be observed ant that a clear epidemiological case-definition is needed, combining clinical signs and serological results.
The activity of amoxycillin/clavulanic acid (Augmentin) and ticarcillin/clavulanic acid (Timentin) was tested against 303 unselected clinical anaerobic isolates recently collected in seven Belgian university hospitals and compared with that of 11 other antimicrobial agents. Bacteroides spp. accounted for 52.1% of the isolates, Clostridium spp. for 23.4%, anaerobic cocci for 15.5%, nonsporeforming gram-positive bacilli for 4.6% and Fusobacterium spp. for 3.3%. Ticarcillin/clavulanic acid (fixed clavulanic acid concentration of 2 mg/l) was the most active drug with an overall susceptibility rate of 99.7%. Amoxycillin/clavulanic acid (fixed ratio of 2:1) and chloramphenicol inhibited 97.4% of the isolates, metronidazole 95.4%, piperacillin 92.4%, ticarcillin 91.4%, clindamycin 87.8%, cefotetan 81.2%, cefazolin 63.0%, cefuroxime 60.4%, erythromycin 57.8%, penicillin 57.1% and doxycycline 52.1%. beta-lactamases were detected exclusively in Bacteroides spp. isolates (79.1% positive).
The in-vitro activity of lomefloxacin (SC 47111, NY-198) was investigated by the determination of MICs in agar and in broth, of MBCs in broth, of killing curves and of the duration of the post-antibiotic effect. MICs measured in broth and in agar were almost identical. Lomefloxacin was two- to eight-fold less active against Gram-positive bacteria than ofloxacin. Its activity against Staphylococcus aureus was independent of resistance to penicillin and oxacillin. The activity of lomefloxacin, ofloxacin and pefloxacin was poor against JK corynebacteria. Enterobacteriaceae, Aeromonas spp., Haemophilus, influenzae, Neisseriaceae and Campylobacter jejuni were highly susceptible to the three quinolones investigated. Non-fermenting Gram-negative bacilli were less susceptible. MBCs were within one dilution of the corresponding MICs. The killing rate was very high against Gram-negative bacilli (2.5-4.0 log cfu/ml reduction in 2 h) whereas it was low against Gram-positive bacteria (0.5-1.0 log cfu/ml reduction in 2 h). Emergence of resistance was not observed. The duration of the post-antibiotic effect with Gram-negative bacilli depended on the strain and species (median: 0.9-1.5 h). The post-antibiotic effect was insignificant with Staph. aureus.
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The mechanism regulating the deposition of basement membrane components (BMCs) in a polymeric structure at the junction with the connective tissues is not yet understood. Cultures and cocultures of epithelial BMC-producing cells (L2 or PER cells) and fibroblasts were prepared in several experimental conditions and the organization of BMCs was studied by immunofluorescence. The pattern of BMCs in pure cultures of L2 or pulmonary epithelial rat (PER) cells consisted of intra- and extracellular granular deposits. At very high density, the cell contours were also underlined by a disrupted network of BMC deposits. A different fibrillar plexus--containing laminin, collagen type IV, and heparan-sulfate proteoglycan resistant to deoxycholate treatment and distant from the cell membrane--was observed in cocultures of L2 or PER cells with fibroblasts. Fibrils of fibronectin and/or collagen type I were most often dissociated from this plexus of BMCs. Similar results were obtained by adding a conditioned medium of L2 or PER cells to confluent fibroblasts, even when the cells were killed. Pure laminin also bound to the fibroblast layer. A coated film of fibronectin or polymeric collagen type I was unable to bind BMC provided by a conditioned medium. It is suggested that molecule(s) synthesized by fibroblasts and deposited in the pericellular matrix are involved in the assembly of BMCs.
In an attempt to identify the origin of cellular fragments released in the urine of patients treated with potentially nephrotoxic drugs such as cytostatics, two monoclonal antibodies were applied: monoclonal antibody PM II 9 C2, directed against an antigen in distal tubular cells; and monoclonal antibody PM II 39 H11 specific for an antigen in proximal tubular cells. The specificities of both monoclonal antibodies were elaborated in the indirect as well as in the direct immunofluorescence technique. Both antibodies were then used to identify cellular fragments obtained from the urine of patients treated with cytostatic drugs by ultracentrifugation. By application of the indirect immunogold method, it was shown that material of proximal as well as distal tubular origin was shed by the damaged cells. Whereas the proximal tubular antigenic epitope recognized by PM II 39 H11 was always found in large irregular complexes of debris-containing vesicles, the distal tubular antigenic epitope recognized by PM II 9 C2 was always found associated with filament-like regular structures. This is the first report in which excretion of components of distal tubular cells is demonstrated as a consequence of the nephrotoxic side effects of cytostatic treatment. With the help of monoclonal antibodies, it has now become possible to identify and to investigate the damage inflicted on the distal part of the tubule system in addition to the well-documented proximal tubular damage.
Five direct radio-immunoassay kits for the dosage of 17 beta-estradiol were assessed for their usefulness to monitor the serum values of 17 beta-estradiol in stimulated and natural ovarian cycles. Prerequisites included a turn-around time of 4 hours for an assay of 100 tubes and a range extended to at least 2,000 ng/l. The following parameters were evaluated: characteristics of the standard curve, sensitivity, precision profile, within- and between-assay precision, analytical drift and linearity. We found that the five tested methods are technically suitable to monitor serum 17 beta-estradiol in stimulated cycles but they all lack precision for low 17 beta-estradiol levels as seen in the early follicular phase of natural cycles.