Biomedical subjects

J Top

Publications and source records attributed to J Top.

14 recordsLinked to original sources

PubMed2005

Unnoticed spread of integron-carrying Enterobacteriaceae in intensive care units.

BACKGROUND: Integrons are strongly associated with multidrug resistance in Enterobacteriaceae. Little is known about the natural history of integron-associated resistance in hospitals during nonoutbreak periods. The prevalence of integrons and the incidence of cross-transmission and horizontal gene transfer in Enterobacteriaceae with reduced susceptibility to cephalosporins (ERSC) were determined for 2 intensive care units (ICUs). METHODS: Microbiological surveillance using rectal swab samples obtained 2 times per week and genotyping using amplified fragment-length polymorphism (AFLP) were used to determine colonization with and genetic relatedness of ERSC. IntI1 integrase polymerase chain reaction (PCR), conserved-segment PCR, restriction fragment-length polymorphism, and DNA sequencing were used to determine the prevalence and contents of integrons. RESULTS: Of 457 patients, 121 patients were colonized with ERSC, and 174 isolates underwent AFLP and PCR. In 34 isolates obtained from 31 patients, 11 different integrons were identified; these integrons encoded resistance to streptomycin/spectinomycin, gentamicin/tobramycin/kanamycin, chloramphenicol, and trimethoprim. Integrons could be divided into 7 clusters of > or =2 isolates each. Compared with isolates that were negative for integrons, isolates that were positive for integrons were associated with resistance to piperacillin, cephalosporins, aminoglycosides, and quinolones. Acquisition rates of integron-carrying ERSC were 10 cases per 1000 patient-days in the first ICU and 8 cases per 1000 patient-days in the second ICU, with most cases (26 of 34) being acquired during the ICU stay. Nineteen episodes resulted from cross-transmission. In addition, 2 cases of interspecies transfer and 1 case of intraspecies transfer of integrons were recorded. Younger age was independently associated with acquisition of integron-carrying ERSC (hazard ratio, 0.953; 95% confidence interval, 0.926-0.987). CONCLUSION: Surveillance, genotyping, and integron analysis identified previously unnoticed outbreaks of integron-carrying ERSC. Cross-transmission appeared to be the dominant route of transmission. Therefore, barrier precautions are necessary to prevent further spread.

Adult↗

PubMed2005

Molecular analysis of human, porcine, and poultry Enterococcus faecium isolates and their erm(B) genes.

Fifty-nine erm(B)-positive Enterococcus faecium strains isolated from pigs, broilers, and humans were typed using multilocus sequence typing (MLST), and the coding sequence of the erm(B) gene was determined. Identical erm(B) gene sequences were detected in genetically unrelated isolates. Furthermore, genetically indistinguishable strains were found to contain different erm(B) alleles. This may suggest that horizontal exchange of the erm(B) gene between animal and human E. faecium strains or the existence of a common reservoir of erm(B) genes might be more important than direct transmission of resistant strains.

Animals↗

PubMed2002

Antibiotic resistance of faecal enterococci in poultry, poultry farmers and poultry slaughterers.

The prevalence of resistance in enterococci to antibiotics, commonly used for therapy in poultry or as antimicrobial growth promoters (AMGPs), was determined in faecal samples of two chicken populations: broilers in which antibiotic and AMGP use is common and laying-hens with a low antibiotic usage. In addition faecal samples were examined from three human populations: broiler farmers, laying-hen farmers and poultry slaughterers. MICs of an extended panel of antibiotics for a randomly chosen gentamicin- or vancomycin-resistant enterococcal isolate from each faecal specimen were also determined. The prevalence of resistance for all antibiotics tested was higher in broilers than in laying-hens. Resistance in faecal enterococci of broiler farmers was for nearly all antibiotics higher than those observed in laying-hen farmers and poultry slaughterers. The overall resistance in broilers was correlated with the resistance in broiler farmers and in poultry slaughterers. No correlation between the results obtained in the laying-hens with any of the other populations was found. The 27 gentamicin-resistant isolates all showed high-level resistance to gentamicin and two of these isolates, both Enterococcus faecium, were resistant to all antibiotics tested, except vancomycin. The 73 vancomycin-resistant enterococci (VRE) isolated from the five populations belonged to four different species and in all isolates the vanA gene cluster was detected by blot hybridization. The pulsed-field gel electrophoresis (PFGE) patterns of these vancomycin-resistant enterococci were quite heterogeneous, but Enterococcus hirae isolates with the same or a closely related PFGE pattern were isolated at two farms from the broiler farmer and from broilers. Molecular characterization of vanA-containing transposons of these isolates showed that similar transposon types, predominantly found in poultry, were present. Moreover, similar vanA elements were not only found in isolates with the same PFGE pattern but also in other VRE isolated from both humans and chickens. The results of this study suggest transmission of resistance in enterococci from animals to man. For VRE this might be clonal transmission of animal strains, but transposon transfer seems to occur more commonly.

Agriculture↗

PubMed2001

Variant esp gene as a marker of a distinct genetic lineage of vancomycin-resistant Enterococcus faecium spreading in hospitals.

In the USA, vancomycin-resistant Enterococcus faecium (VREF) is endemic in hospitals, despite lack of carriage among healthy individuals. In Europe, however, hospital outbreaks are rare, but VREF carriage among healthy individuals and livestock is common. We used amplified fragment-length polymorphism analysis to genotype 120 VREF isolates associated with hospital outbreaks and 45 non-epidemic isolates from the USA, Europe, and Australia. We also looked for the esp virulence gene in these isolates and in 98 VREF from animals. A specific E. faecium subpopulation genetically distinct from non-epidemic VREF isolates was found to be the cause of the hospital epidemics in all three continents. This subpopulation contained a variant of the esp gene that was absent in all non-epidemic and animal isolates. Identification of the variant esp gene will be important in guiding infection-control strategies, and the Esp protein could be a new target for antibacterial therapy.

Bacterial Proteins↗

PubMed2001

Molecular analysis of Tn1546-like elements in vancomycin-resistant enterococci isolated from patients in Europe shows geographic transposon type clustering.

Resistance mechanism relatedness was studied in 18 clinical, European vanA vancomycin-resistant enterococci. Molecular analysis revealed 10 Tn1546-like elements, suggesting two evolutionary lineages. Lineage I dominated the European mainland, and lineage II dominated the United Kingdom and Israel. Geographic clustering reflected different types of meat consumption between countries, since each lineage is associated with colonization of different animals.

Adolescent↗

PubMed2000

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↗

PubMed1999

Molecular diversity and evolutionary relationships of Tn1546-like elements in enterococci from humans and animals.

We report on a detailed study on the molecular diversity and evolutionary relationships of Tn1546-like elements in vancomycin-resistant enterococci (VRE) from humans and animals. Restriction fragment length polymorphism (RFLP) analysis of the VanA transposon of 97 VRE revealed seven different Tn1546 types. Subsequent sequencing of the complete VanA transposons of 13 VRE isolates representing the seven RFLP types followed by sequencing of the identified polymorphic regions in 84 other VanA transposons resulted in the identification of 22 different Tn1546 derivatives. Differences between the Tn1546 types included point mutations in orf1, vanS, vanA, vanX, and vanY. Moreover, insertions of an IS1216V-IS3-like element in orf1, of IS1251 in the vanS-vanH intergenic region, and of IS1216V in the vanX-vanY intergenic region were found. The presence of insertion sequence elements was often associated with deletions in Tn1546. Identical Tn1546 types were found among isolates from humans and farm animals in The Netherlands, suggesting the sharing of a common vancomycin resistance gene pool. Application of the genetic analysis of Tn1546 to VRE isolates causing infections in Hospitals in Oxford, United Kingdom, and Chicago, Ill., suggested the possibility of the horizontal transmission of the vancomycin resistance transposon. The genetic diversity in Tn1546 combined with epidemiological data suggest that the DNA polymorphism among Tn1546 variants can successfully be exploited for the tracing of the routes of transmission of vancomycin resistance genes.

Animals↗

PubMed1999

Enterococci with glycopeptide resistance in turkeys, turkey farmers, turkey slaughterers, and (sub)urban residents in the south of The Netherlands: evidence for transmission of vancomycin resistance from animals to humans?

The number of vancomycin-resistant enterococci (VRE) relative to the total number of enterococci was determined in fecal samples from turkeys and three human populations in 1996, each with a different level of contact with turkeys, i.e., turkey farmers, turkey slaughterers, and (sub)urban residents. The percentage of VRE relative to the total enterococcal population (i.e., the degree of resistance) was low (2 to 4%) in all groups (except in six samples). No difference was observed between farmers who used avoparcin and those who did not. The pulsed-field gel electrophoresis (PFGE) patterns of the VRE isolates from the different populations were quite heterogeneous, but isolates with the same PFGE pattern were found among animal and human isolates, in addition to the isolates which were described previously (A. E. van den Bogaard, L. B. Jensen, and E. E. Stobberingh, N. Engl. J. Med. 337:1558-1559, 1997). Detailed molecular characterization of vanA-containing transposons from different isolates showed, that in addition to a previously reported strain, similar transposons were present in VRE isolates from turkeys and turkey farmers. Moreover, similar VanA elements were found not only in isolates with the same PFGE pattern but also in other strains from both humans and animals.

Animals↗

PubMed1998

The efficacy of a whole cell pertussis vaccine and fimbriae against Bordetella pertussis and Bordetella parapertussis infections in a respiratory mouse model.

Due to local and systemic side-effects, the currently used, highly effective, whole-cell pertussis vaccines (WCVs) will be replaced by acellular vaccines (ACVs) in some countries. These ACVs contain detoxified pertussis toxin, either alone or in combination with the filamentous haemagglutinin, pertactin and fimbriae. Ongoing clinical trials show that ACVs are clearly less reactogenic than WCVs and that ACVs comprised of three to five proteins are highly efficacious in inducing protection against Bordetella pertussis infections. An important unresolved question is, what the effect will be of the switch from WCVs to ACVs on the incidence of Bordetella parapertussis infections, the second causative agent of pertussis. A comparison of the efficacy of WCVs and ACVs against B. parapertussis infection is required to answer this question. We show that the Dutch WCV, although prepared from B. pertussis strains, protects against B. parapertussis infection in a murine respiratory model, although less efficiently than against B. pertussis infection. It was shown previously that the ACV components pertussis toxin, FHA and pertactin did not protect against B. parapertussis infection in a murine respiratory model. We have investigated the efficacy of two other ACV components, B. pertussis serotype-2 and -3 fimbriae against B. parapertussis infection in the murine model. The B. pertussis fimbriae protected mice against B. parapertussis infection although less efficiently than against B. pertussis infection. This result indicates that B. pertussis and B. parapertussis fimbriae are antigenically distinct. B. pertussis fimbriae were found to be as efficacious as the WCV against B. pertussis infection. Our results are discussed in the light of the switch from WCVs to ACVs.

Animals↗

PubMed1997

A novel pathogenic taxon of the Mycobacterium tuberculosis complex, Canetti: characterization of an exceptional isolate from Africa.

In an attempt to characterize an unusual mycobacterial strain isolated from a 2-year-old Somali patient with lymphadenitis, we applied various molecular methods not previously used for the taxonomic classification of mycobacteria. This isolate, designated So93, did not differ from Mycobacterium tuberculosis in the biochemical tests and in its 16S rRNA sequence, but produced smooth and glossy colonies, which is highly exceptional for this species. This smooth phenotype was unstable and switched nonreversibly to a rough colony morphology with a low frequency. The two colony types were equally virulent for the guinea pig, exhibiting characteristic tuberculous disease. Both morphotypes had shorter generation times than the M. tuberculosis reference laboratory strain H37Rv and clinical isolates of M. tuberculosis and Mycobacterium bovis. Furthermore, the So93 isolate differed from all M. tuberculosis complex strains described thus far by having only a single copy of insertion sequence IS1081, an unusual composition of the direct repeat cluster, and a characteristic phenolic glycolipid and lipooligosaccharide. This glycolipid had previously been observed only in a smooth isolate of M. tuberculosis obtained in 1969 by Canetti in France. Analysis of the Canetti strain showed that it shared virtually all genetic properties characteristic of So93, distinguishing these two strains from the known M. tuberculosis complex taxa, M. tuberculosis, Mycobacterium africanum, M. bovis, and Mycobacterium microti. The natural reservoir, host range, and mode of transmission of the group of bacteria described in this paper are presently unknown. This study, partly based on not previously used molecular criteria, supports the idea that the established members within the M. tuberculosis complex and the newly described Canetti grouping should be regarded as a single species, which likely will be designated "M. tuberculosis".

Animals↗

PubMed1997

Role of the Bordetella pertussis minor fimbrial subunit, FimD, in colonization of the mouse respiratory tract.

Bordetella pertussis fimbriae are composed of a major subunit, Fim2 or Fim3, and the minor subunit FimD. Using immunoelectron microscopy, we provide evidence that FimD is located at the fimbrial tip. The role of FimD in colonization of the mouse respiratory tract was studied by using two fimbrial mutants: a mutant completely devoid of fimbriae (designated FimD-) and a mutant devoid of the major fimbrial subunits but still producing the minor subunit (designated FimD+). The ability of the two fimbrial mutants to colonize the nasopharynx, trachea, and lungs was compared with those of the wild type parental strain and a filamentous hemagglutinin (FHA) mutant. Of the three mutants studied, the FimD- mutant showed the greatest defect, colonizing less well in the nasopharynx, trachea, and lungs. The most pronounced defect in colonizing ability of the three mutants was observed in the trachea. However, the colonizing defect of the FHA and FimD+ mutants in the trachea was observed only during the first 3 days of infection. After 10 days, the colonization level was nearly restored to wild-type levels. The FHA and FimD+ mutants showed a slight colonization defect in the nasopharynx but no defect in the lungs. A maltose binding protein-FimD fusion protein and a peptide derived from FimD were able to bind to heparin, a member of a class of sulfated sugars which are ubiquitous in the respiratory tract. Recently it was shown (W. L. W. Hazenbos, C. A. W. Geuijen, B. M. van den Berg, F. R. Mooi, and R. van Furth, J. Infect. Dis. 171:924-929, 1995) that FimD also binds to the integrin VLA-5, and our results suggest that the binding of B. pertussis to these two molecules plays an important role in colonization of the respiratory tract of the mouse.

Adhesins, Bacterial↗

PubMed1994

Rapid typing of group A streptococci by the use of DNA amplification and non-radioactive allele-specific oligonucleotide probes.

Because of the allelic variations within the M protein gene (emm gene) of group A streptococci, reliable typing of this important human pathogen can be accomplished by the use of emm gene-specific oligonucleotide probes. Two technical modifications (a reverse dot blot and a reverse line blot hybridization assay) of a novel approach for the type-specific identification of emm genes have been developed. Both procedures involved amplification of an emm gene by polymerase chain reaction. The non-radioactively labeled amplicon was subsequently hybridized to a membrane carrying an array of immobilized emm gene-specific oligonucleotide probes, thus allowing the simultaneous analysis of the gene polymorphism in a single hybridization reaction. The feasibility of these rapid and easy to perform methods was shown for the unequivocal identification of reference strains and clinical isolates belonging to 16 different M serotypes.

Alleles↗

PubMed1989

Sensitivity and specificity of an enzyme-linked immunosorbent assay using the recombinant DNA-derived Treponema pallidum protein TmpA for serodiagnosis of syphilis and the potential use of TmpA for assessing the effect of antibiotic therapy.

The recombinant DNA-derived Treponema pallidum membrane protein TmpA, purified from Escherichia coli K-12, was used in an enzyme-linked immunosorbent assay (ELISA) to evaluate its suitability in a screening test for syphilis and to monitor the effect of antibiotic treatment. The sensitivity of the TmpA ELISA was 76% for primary syphilis, 100% for secondary syphilis, and 98% for early latent syphilis. All except 1 of 15 serum samples positive for yaws were positive in this test. A specificity of 99.6% was found by testing more than 938 donor samples. The sensitivity and specificity of the TmpA ELISA are comparable to that of the T. pallidum hemagglutination assay, and therefore the test may be useful for the diagnosis of untreated syphilis. After antibiotic treatment, the level of anti-TmpA antibodies in sera of syphilis patients dropped sharply within 1 year. Thus, TmpA might be a useful antigen for monitoring successful treatment of syphilis.

Acute Disease↗

PubMed1989

Development and evaluation of a monoclonal antibody inhibition enzyme linked immunosorbent assay to diagnose syphilis.

A highly specific inhibition enzyme linked immunosorbent assay (ELISA) using murine monoclonal antibodies to treponemes has been developed to diagnose syphilis. The monoclonal antibodies used in this study were reactive to antigens of both Treponema pallidum and Treponema pertenue and not to antigens of non-pathogenic treponemes. Inhibition of the binding of monoclonal antibody to the treponemal antigens was successful with serum antibodies of patients with syphilis in an inhibition ELISA using monoclonal antibodies raised against T pallidum antigens with molecular weights of 42 and 47 kilodaltons. In contrast, the binding of monoclonal antibodies obtained by immunising mice with treponemal membrane protein TmpB, derived from recombinant DNA was not inhibited by serum antibodies from patients with syphilis. The sensitivity of the inhibition ELISA using monoclonal antibody against the 47 kilodalton T pallidum antigen was 93% in 58 serum samples from patients with untreated syphilis. The sensitivity was 79% if the monoclonal antibody against the 42 kilodalton T pallidum antigen was used. By a combination of the test results obtained in these two inhibition assays a sensitivity of 97% in the 58 serum samples from untreated patients and 64% in 64 from treated patients was obtained. The specificity of the inhibition ELISA performed with either monoclonal antibody was 100% in 500 serum samples from non-infected people. The specificity in 432 non-infected patients attending a sexually transmitted disease clinic was 98.8% for the monoclonal antibody against the 42 kilodalton antigen, 99.5% for the monoclonal antibody against the 47 kilodalton antigen, and 98.4% for the combined antibodies. The sensitivity and specificity of the inhibition ELISA using the combination of test results obtained by the application of the monoclonal antibodies against the 42 kilodalton treponemal membrane protein, TmpA, and against the 47 kilodalton T pallidum antigen were comparable with those of the Treponema pallidum haemagglutination assay (TPHA) and the fluorescent treponemal antibody absorption (FTA-ABS) test for diagnosing early untreated disease. The inhibition ELISA offers the potential for additional confirmation of early untreated syphilis. Its use for confirming late untreated syphilis is still under investigation. The test is highly specific for pathogenic treponemes and does not need sorbens.

Animals↗