Dietary habits and gastrointestinal colonization by antibiotic resistant microorganisms.
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Diet, Vegetarian↗
Biomedical subjects
N van Den Braak
Publications and source records attributed to N van Den Braak.
In vitro activities of ertapenem (MK-0826) against recent clinical bacteria collected in Europe and Australia.
Ertapenem (MK-0826, L-749,345) is a 1-beta-methyl carbapenem with a long serum half-life. Its in vitro activity was determined by broth microdilution against 3,478 bacteria from 12 centers in Europe and Australia, with imipenem, cefepime, ceftriaxone, and piperacillin-tazobactam used as comparators. Ertapenem was the most active agent tested against members of the family Enterobacteriaceae, with MICs at which 90% of isolates are inhibited (MIC(90)s) of < or =1 microg/ml for all species. Ertapenem also was more active than imipenem against fastidious gram-negative bacteria and Moraxella spp.; on the other hand, ertapenem was slightly less active than imipenem against streptococci, methicillin-susceptible staphylococci, and anaerobes, but its MIC(90)s for these groups remained < or =0.5 microg/ml. Acinetobacter spp. and Pseudomonas aeruginosa were also much less susceptible to ertapenem than imipenem, and most Enterococcus faecalis strains were resistant. Ertapenem resistance, based on a provisional NCCLS MIC breakpoint of > or =16 microg/ml, was seen in only 3 of 1,611 strains of the family Enterobacteriaceae tested, all of them Enterobacter aerogenes. Resistance was also seen in 2 of 135 anaerobes, comprising 1 Bacteroides fragilis strain and 1 Clostridium difficile strain. Ertapenem breakpoints for streptococci have not been established, but an unofficial susceptibility breakpoint of < or =2 microg/ml was adopted for clinical trials to generate corresponding clinical response data for isolates for which MICs were as high as 2 microg/ml. Of 234 Streptococcus pneumoniae strains tested, 2 required ertapenem MICs of 2 microg/ml and one required an MIC of 4 microg/ml, among 67 non-Streptococcus pyogenes, non-Streptococcus pneumoniae streptococci, single isolates required ertapenem MICs of 2 and 16 microg/ml. These streptococci also had diminished susceptibilities to other beta-lactams, including imipenem as well as ertapenem. The Etest and disk diffusion gave susceptibility test results in good agreement with those of the broth microdilution method for ertapenem.
Anti-Bacterial Agents↗
Accuracy of the VITEK 2 system to detect glycopeptide resistance in enterococci.
We evaluated the accuracy of the VITEK 2 fully automated system to detect and identify glycopeptide-resistant enterococci (GRE) compared to a reference agar dilution method. The sensitivity of vancomycin susceptibility testing with VITEK 2 for the detection of vanA, vanB, and vanC1 strains was 100%. The sensitivity of vancomycin susceptibility testing of vanC2 strains was 77%. The sensitivity of teicoplanin susceptibility testing of vanA strains was 90%. Of 80 vanC enterococci, 78 (98%) were correctly identified by VITEK 2 as Enterococcus gallinarum/Enterococcus casseliflavus. Since the identification and susceptibility data are produced within 3 and 8 h, respectively, VITEK 2 appears a fast and reliable method for detection of GRE in microbiology laboratories.
Anti-Bacterial Agents↗
Host specificity of vancomycin-resistant Enterococcus faecium.
Amplified-fragment length polymorphism (AFLP) analysis was used to investigate the genetic relationships among 255 vancomycin-resistant Enterococcus faecium (VREF) strains isolated from hospitalized patients, nonhospitalized persons, and various animal sources. Four major AFLP genogroups (A-D) were discriminated. The strains of each taxon shared >/=65% of the restriction fragments. Most isolates recovered from nonhospitalized persons (75%) were grouped together with all pig isolates in genogroup A. Most isolates from hospitalized patients (84%), a subset of veal calf isolates (25%), and all isolates from cats and dogs clustered in genogroup C. Most isolates from chickens (97%) and turkeys (86%) were grouped in genogroup B, whereas most veal calf isolates (70%) clustered in genogroup D. Therefore, VREF strains are predominantly host-specific, and strains isolated from hospitalized patients are genetically different from the prevailing VREF strains present in the fecal flora of nonhospitalized persons.
Animals↗
Molecular characterization of Campylobacter jejuni from patients with Guillain-Barré and Miller Fisher syndromes.
Campylobacter jejuni has been identified as the predominant cause of antecedent infection in Guillain-Barré syndrome (GBS) and Miller Fisher syndrome (MFS). The risk of developing GBS or MFS may be higher after infection with specific C. jejuni types. To investigate the putative clonality, 18 GBS- or MFS-related C. jejuni strains from The Netherlands and Belgium and 17 control strains were analyzed by serotyping (Penner and Lior), restriction fragment length polymorphism analysis of PCR products of the flaA gene, amplified fragment length polymorphism analysis, pulsed-field gel electrophoresis, and randomly amplified polymorphic DNA analysis. Serotyping revealed 10 different O serotypes and 7 different Lior serotypes, thereby indicating a lack of serotype clustering. Two new O serotypes, O:35 and O:13/65, not previously associated with GBS or MFS were found. Serotype O:19 was encountered in 2 of 18 strains, and none was of serotype O:41. The results of all genotypic methods also demonstrated substantial heterogeneity. No clustering of GBS- or MFS-related strains occurred and no molecular marker capable of separating pathogenic GBS or MFS from non-GBS- or non-MFS-related enteritis strains could be identified in this study. Sialic-acid-containing lipopolysaccharides (LPS) are thought to be involved in the triggering of GBS or MFS through molecular mimicry with gangliosides in human peripheral nerves. Therefore, further characterization of GBS- or MFS-related C. jejuni should target the genes involved in the synthesis of LPS and the incorporation of sialic acid.
Bacterial Typing Techniques↗
The prevalence and clonal expansion of high-level gentamicin-resistant enterococci isolated from blood cultures in a Dutch university hospital.
We studied the prevalence and clonality of high-level gentamicin-resistant enterococci (HLGRE) in a Dutch university hospital. Of 238 enterococcal strains isolated from blood cultures between 1991 and 1997, 57 were HLGRE. Genomic analysis of these strains revealed 19 different genotypes, two of which were encountered more frequently [type A (12/57), type B (23/57)]. The spread of these types largely explained the rise in HLGRE incidence from 14% in 1991 to 31% in 1997. However, the contribution of unique strains to the total HLGRE burden also increased from 4% to 16%. We conclude that both clonal expansion and the emergence of unique HLGRE have contributed significantly to the increasing incidence of HLGRE.
Anti-Bacterial Agents↗