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Volume 52,
Issue 2,
2003
Volume 52, Issue 2, 2003
- Pathogenicity And Virulence
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Cytolethal distending toxin B gene (cdtB) homologues in taxa 2, 3 and 8 and in six canine isolates of Helicobacter sp. flexispira
More LessThe presence of the cytolethal distending toxin B gene (cdtB) was examined in eight Helicobacter sp. flexispira reference strains, Helicobacter trogontum ATCC 700114T and 12 Finnish porcine H. trogontum strains and canine flexispira isolates. Part of the cdtB gene was amplified by PCR with degenerate primers VAT2 and DHF1, cloned and sequenced. The presence/absence of the cdtB gene as determined by PCR was confirmed by Southern hybridization and toxin production by HeLa cell-line experiments. PCR amplification resulted in approximately 700 bp fragments from Helicobacter sp. flexispira taxa 2 (ATCC 49314), 3 (ATCC 49320) and 8 (ATCC 43880, ATCC 49308, ATCC 43879), from six canine isolates as well as from the control strains Helicobacter bilis and Helicobacter hepaticus. The hybridization patterns of HaeIII-, HindIII- and AseI-digested chromosomal DNA confirmed the results of the PCR experiments. The cdtB-positive strains had effects ranging from weak to strong on HeLa cell cultures. PCR amplification from the reference strains Helicobacter sp. flexispira taxa 1 (ATCC 43968), 4 (ATCC 49310) and 5 (ATCC 43966) and H. trogontum (ATCC 700114T), and also six of the Finnish strains, was unsuccessful. No toxic effect on HeLa cells was evident when bacterial suspensions of PCR-negative strains were used for toxicity assay. Our results are in accordance with previous observations that the cdtB gene is not present in all Helicobacter species. Further, the presence/absence of the cdtB gene in Helicobacter sp. flexispira strains was in accordance with recent taxonomic analysis of the same strains, which suggests that it could serve as a useful marker in Helicobacter taxonomy.
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Role of staphylococcal enterotoxin A in a fatal case of endocarditis
More LessA young female with no identifiable risk factors developed rapid, overwhelming Staphylococcus aureus endocarditis. Despite rapid sterilization of the blood and the mitral valve with optimal antimicrobials, she had persistent septic shock. In order to investigate this, the toxin-producing capacity of the infecting strain and the patient's ability to produce antibodies were determined. The strain produced high levels of both α-toxin and staphylococcal enterotoxin A (SEA), whilst the patient responded with modestly high levels of antibodies to α-toxin and low–normal levels to SEA. The patient was most probably susceptible to the actions of SEA and developed a toxic-shock-syndrome-like disease that further aggravated her valvular dysfunction. This case illustrates that optimal antimicrobial therapy alone is not sufficient treatment in patients with persistent toxic shock and that there is a need to evaluate immunomodulatory strategies in such patients.
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Manganese-dependent regulation of the endocarditis-associated virulence factor EfaA of Enterococcus faecalis
More LessThere is increasing recognition of the emerging role of manganese regulation and acquisition in some pathogenic bacteria. Expression of the Enterococcus faecalis endocarditis-associated virulence factor EfaA is induced by growth in serum. It is demonstrated here that expression of the efaCBA operon encoding a putative ABC-type transporter is regulated by Mn2+. Transcription of efaCBA and EfaA production were repressed in Mn2+-supplemented medium. A Mn2+-responsive transcriptional regulator, EfaR, sharing 27 % identity with the Corynebacterium diphtheriae diphtheria toxin repressor (DtxR), was identified. In the presence of Mn2+, EfaR protein bound in vitro to the efaC promoter region. Analysis of the E. faecalis V583 genome revealed ten additional putative EfaR-binding sites, suggesting that manganese availability could have a broader regulatory role in infection. The results identify a new Mn2+-sensing regulator in enterococci that regulates the expression of a virulence factor implicated in enterococcal endocarditis.
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- Host Response
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Immune response to native NadA from Neisseria meningitidis and its expression in clinical isolates in Brazil
A mAb against the NadA protein from Neisseria meningitidis strain 3006 (serosubtype B : 2b : P1.2 : P5.2,8) demonstrated strong bactericidal activity against Brazilian epidemic serogroup B strain N44/89 (B : 4,7 : P1.19,15 : P5.5,7) and a serogroup C strain, IMC 2135 (C : 2a : P1.5,2), but not against another serogroup C strain, N1002/90 (C : 2b : P1.3 : P5.8). The immunogenicity of native NadA in an outer-membrane vesicle (OMV) preparation was also tested. Serum from mice immunized with OMV from serogroup B strain N44/89, which contains the NadA protein, showed bactericidal activity against serogroup B and C strains possessing NadA. In dot-blot analysis of 100 serogroup B and 100 serogroup C isolates from Brazilian patients, the mAb to NadA recognized about 60 % of the samples from both serogroups. The molecular mass of the NadA protein from strain N44/89 determined by mass spectrometry was 37 971 Da and the peptide sequences were identical to those of NadA from N. meningitidis strain MC58.
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- Diagnostics, Typing And Identification
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Low-stringency single specific primer PCR for identification of Leptospira
Thirty-five Leptospira serovars from the species Leptospira interrogans, Leptospira borgpetersenii, Leptospira santarosai, Leptospira kirschneri, Leptospira weilii, Leptospira biflexa and Leptospira meyeri were characterized by the low-stringency single specific primer PCR (LSSP-PCR) technique. LSSP-PCR analysis was performed to detect DNA polymorphisms in a 285 bp DNA fragment amplified from genomic DNA with G1 and G2 selected primers. Similar LSSP-PCR profiles were obtained for serovars from the same genomic species, while serovars from non-related species produced distinct multiband patterns. Based on the data from sequence analysis, all genomic fragments amplified with G1 and G2 primers from distinct serovars of Leptospira were 285 bp in length, with nucleotide variation observed most frequently among different genomic species. The simplicity and accuracy of the LSSP-PCR technique were found to be suitable for identification of Leptospira species.
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Granulicatella adiacens and Abiotrophia defectiva bacteraemia characterized by 16S rRNA gene sequencing
Traditionally, the identification, epidemiology and spectrum of clinical diseases caused by Granulicatella adiacens and Abiotrophia defectiva are dependent upon their phenotypic characterization. During a 6-year period (July 1995–June 2001), seven and two α-haemolytic streptococci were identified as G. adiacens and A. defectiva, respectively, by 16S rRNA gene sequencing. Three patients with haematological malignancies and neutropenic fever had primary bacteraemia. Three patients with valvular problems or congenital heart disease had infective endocarditis. A patient with ischemic heart disease and cerebrovascular accident had infected aortic atheroma with dissection. A patient with recurrent pyogenic cholangitis had acute cholangitis and a patient with polypoid cystitis and benign prostatic hypertrophy had acute prostatitis. Four of the nine patients died, including all three with G. adiacens infective endocarditis or infected atheroma. For the seven G. adiacens isolates, the API 20 STREP system successfully identified one and five isolates as G. adiacens with >95 % and 80–90 % confidence, respectively, whereas the Vitek System (GPI) and ATB Expression system (ID32 STREP) successfully identified none and one isolate as G. adiacens. Of the two A. defectiva isolates, none of the three systems successfully identified either of them as A. defectiva. 16S rRNA gene sequencing is the technique of choice for identifying G. adiacens and A. defectiva, and early surgical intervention should be considered when G. adiacens endocarditis is diagnosed.
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Characterization of class I integrons in clinical strains of Salmonella enterica subsp. enterica serovars Typhimurium and Enteritidis from Norwegian hospitals
More LessThe characterization of integrons and their promoters in 156 antibiotic-resistant clinical isolates of the important zoonotic pathogens Salmonella enterica subsp. enterica serovars Typhimurium (S. Typhimurium) and Enteritidis (S. Enteritidis) from Norwegian hospitals were performed. Integrons were found in 64 of 66 S. Typhimurium isolates (97 %) and in 20 of 90 S. Enteritidis isolates (22.2 %) with the following sizes; 650, 1000, 1200, 1500, 1600, 1700, 2000 and 2100 bp. The integrons were further sequenced and the aadA1, aadA2, aadA5, aadB, pse-1, catB3, oxa1, dfrA1, dfrA12 and dfrA17 genes, as well as a fragment of the sat1 gene, were found embedded in cassettes. An internal fragment of the purG gene was additionally found as an artefact PCR amplicon.
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Independent subsets of amplified fragments from the genome of Neisseria meningitidis identify the same invasive clones of ET37 and ET5
To determine whether fluorescent amplified-fragment length polymorphism (FAFLP) analysis is an unbiased genome sampling technique, data were analysed from three different primer combinations, amplifying three independent fragment subsets from 123 isolates of Neisseria meningitidis. Using these data, dendrograms were generated with near-identical topologies that identified the same invasive clones of ET37 and ET5 and also identified the same outbreak clusters.
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- Antimicrobial Agents And Chemotherapy
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Antibiotic resistance among verocytotoxigenic Escherichia coli (VTEC) and non-VTEC isolated from domestic animals and humans
More LessTwo hundred verocytotoxigenic and 216 non-verocytotoxigenic Escherichia coli (VTEC and non-VTEC), isolated from a variety of sources were tested for their resistances to 11 antimicrobial agents. The strains included isolates from domestic food animals and both symptomatic and asymptomatic infections in man. A much higher level of resistance was found among the non-VTEC than among the VTEC, regardless of source. The resistant VTEC isolated from animals were predominantly from specimens associated with sick animals. Antibiotic resistance was detected in only four of the 59 (6.8 %) VTEC of human origin, whereas more of the human non-VTEC possessed antibiotic resistance determinants. It was particularly noteworthy that 24/87 (28 %) strains isolated from healthy babies, who had neither contact with antibiotics nor had gastrointestinal symptoms for at least 2 weeks prior to the specimen being taken, were resistant to one or more of the antibiotics tested.
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Species prevalence and antibacterial resistance of enterococci isolated in Kuwait hospitals
More LessThis study investigated the species prevalence and antibacterial resistance among enterococci isolated in Kuwait hospitals. They consisted of 415 isolates of Enterococcus faecalis (85.3 %), Enterococcus faecium (7.7 %), Enterococcus casseliflavus (4.0 %), Enterococcus avium (1.2 %), Enterococcus durans (1.0 %), Enterococcus gallinarium (0.5 %) and Enterococcus bovis (0.2 %) isolated from urine (36.6 %), blood (10.4 %), wound swabs (11.0 %), stool samples (12.0 %), high vaginal swabs (9.0 %), endocervical swabs (3.0 %) and miscellaneous sources (18.0 %). All of them were susceptible to linezolid. Fifty-two (12.5 %) isolates were ampicillin resistant but none of them produced β-lactamase. They were resistant to erythromycin (63.3 %), tetracycline (60.5 %), ciprofloxacin (40.0 %), chloramphenicol (28.0 %), vancomycin (2.6 %), and teicoplanin (2.6 %). Fourteen, 19 and 20 % of them expressed high-level resistance to gentamicin, kanamycin and streptomycin, respectively. All of the vancomycin-resistant strains carried the vanA phenotype and genotype. There was no evidence of clonal spread of the vancomycin-resistant isolates.
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Antifungal properties of 5-hydroxytryptamine (serotonin) against Candida species in vitro
In this study the minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) of 5-hydroxytryptamine (5 HT, serotonin) against clinical isolates of Candida albicans (n = 11), Candida glabrata (n = 9), Candida tropicalis (n = 10) and Candida parapsilosis (ATCC 22019) using a broth microdilution test were investigated. In addition, it was examined whether delayed regrowth as a post-antifungal effect results following short exposure to 5 HT. 5 HT showed antifungal activity towards all isolates of Candida spp. The isolates yielded comparable MIC and MFC values of 5 HT in the range 0.91–7.34 mM and 1.83–14.68 mM, respectively. A lag in regrowth was dependent on the concentration tested. Treatment for 3 h at concentrations of 5 HT below and equipotent to the MFC resulted in a delayed regrowth of 8–12 h for isolates of Candida spp. In conclusion, these in vitro studies clearly demonstrate antifungal effects of 5 HT. Identifying the mode of action could be of great help in developing and researching new antifungal drugs.
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- Epidemiology
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Neisseria meningitidis phenotypic markers and septicaemia, disease progress and case-fatality rate of meningococcal disease: a 20-year population-based historical follow-up study in a Danish county
The incidence rate (IR) and case-fatality rate (CFR) of meningococcal disease increased during the late 1980s and early 1990s in North Jutland County, Denmark. We examined the hypothesis that phenotypic markers of Neisseria meningitidis are predictors of septicaemia with or without meningitis, rapid disease progress and fatal outcome of meningococcal disease and we studied whether changes in IR and CFR over time might be related to emergence or spread of certain phenotypes. This follow-up study was based on a complete registration of 413 cases of meningococcal disease in North Jutland County during 1980–99. Phenotypic markers included serogroup, serotype and serosubtype. A complete phenotype was available for 315 cases (76 %); 100 (32 %) strains were phenotype B : 15 : P1.7,16 and 31 (10 %) were C : 2a : P1.2,5. Septicaemia without meningitis was less common in cases with B : 15 : P1.7,16 and C : 2a : P1.2,5 strains. No association was found between phenotype and rapid disease progress. The overall CFR was 12 %. An increased CFR was associated with phenotypes B : 15 : P1.7,16 [odds ratio (OR) 2.8, 95 % confidence interval (CI) 1.2–18.5] and C : 2a : P1.2,5 (OR 5.2, 95 % CI 1.6–16.4) when compared with other phenotypes. The prevalence of B : 15 : P1.7,16 strains increased gradually during the study period and the CFR increased from 8 % during 1980–89 to 19 % during 1990–99, although the CFR for other phenotypes also increased. The CFR for C : 2a : P1.2,5 remained high (∼20 %), but the contribution of this phenotype to the overall CFR decreased during the study period. In conclusion, phenotypes B : 15 : P1.7,16 and C : 2a : P1.2,5 were predictors of an increased CFR. The high prevalence of phenotype B : 15 : P1.7,16 contributed to increased overall IR and CFR during 1990–99.
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Molecular epidemiology and characteristics of Corynebacterium diphtheriae and Corynebacterium ulcerans strains isolated in Italy during the 1990s
Five cases of diphtheria were reported in Italy between January 1990 and June 2001. Three cases were confirmed microbiologically by the isolation of toxigenic Corynebacterium diphtheriae (two cases) and Corynebacterium ulcerans (one case). Over the same period, 11 cases of non-toxigenic C. diphtheriae infection were reported to the Italian Public Health Institute, from which the causative organism was isolated from a skin infection in one case and from the throat in the other ten. Seven of the throat isolates were associated with fever, severe pharyngitis and tonsillitis and were all biotype gravis. Because there are no standardized breakpoints, the antimicrobial sensitivities of C. diphtheriae were determined in accordance with the National Committee for Clinical Laboratory Standards guidelines for Streptococcus spp. other than Streptococcus pneumoniae. MICs for penicillin ranged between 0.125 and 0.250 mg l −1 and 7 out of 11 strains had a minimal bactericidal concentration (MBC)/MIC ratio ≥ 32. All strains were sensitive to clindamycin (MIC ≤ 0.25 mg l −1), rifampicin (MIC ≤ 1 mg l −1) and tetracycline (MIC ≤ 2 mg l −1), and showed moderate susceptibility to cefotaxime (MIC 0.75–1.5 mg l −1). Molecular typing (ribotyping) demonstrated the presence of several distinct ribotypes. The ribotype designated ‘D11’ has been documented amongst strains isolated in the UK, Russia, Germany, Romania and Sweden. Ribotype ‘D75’ has only been documented in the UK. The C. ulcerans strain had a ribotype pattern identical to that found in recent isolates from the UK.
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- Human And Animal Microbial Ecology
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Helicobacter pylori in cathartic stools of subjects with and without cimetidine-induced hypochlorhydria
More LessWe previously identified viable Helicobacter pylori in stools from asymptomatic hosts. We now report whether a decrease in gastric acidity enhances faecal shedding. Sixteen asymptomatic H. pylori-positive patients underwent two separate days of phosphosoda-induced diarrhoea, both with normal gastric acidity and under hypochlorhydric conditions induced with the H2-blocker cimetidine. Stool samples were collected for culture to determine the presence of viable H. pylori. Five of the 16 patients gave positive cultures with at least one stool from both normal pH and cimetidine-induced hypochlorhydria. Four were negative for all samples with both. Six gave positive stools only after cimetidine treatments, while one gave positive samples with normal pH but not with cimetidine (two-tailed P value, 0.13; McNemar test). These numbers show a trend suggesting that cimetidine-induced hypochlorhydria increases shedding of viable H. pylori.
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Volumes and issues
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Volume 74 (2025)
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Volume 73 (2024)
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Volume 72 (2023 - 2024)
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Volume 71 (2022)
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Volume 70 (2021)
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Volume 69 (2020)
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Volume 68 (2019)
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Volume 67 (2018)
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Volume 66 (2017)
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Volume 65 (2016)
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Volume 64 (2015)
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Volume 63 (2014)
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Volume 62 (2013)
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Volume 61 (2012)
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Volume 60 (2011)
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Volume 59 (2010)
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Volume 58 (2009)
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Volume 57 (2008)
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Volume 56 (2007)
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Volume 55 (2006)
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Volume 54 (2005)
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Volume 53 (2004)
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Volume 52 (2003)
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Volume 51 (2002)
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Volume 50 (2001)
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Volume 49 (2000)
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Volume 48 (1999)
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Volume 47 (1998)
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Volume 46 (1997)
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Volume 45 (1996)
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Volume 44 (1996)
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Volume 43 (1995)
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Volume 42 (1995)
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Volume 41 (1994)
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Volume 40 (1994)
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Volume 39 (1993)
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Volume 38 (1993)
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Volume 37 (1992)
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Volume 36 (1992)
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Volume 35 (1991)
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Volume 34 (1991)
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Volume 33 (1990)
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Volume 32 (1990)
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Volume 31 (1990)
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Volume 30 (1989)
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Volume 29 (1989)
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Volume 28 (1989)
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Volume 27 (1988)
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Volume 26 (1988)
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Volume 25 (1988)
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Volume 24 (1987)
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Volume 23 (1987)
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Volume 22 (1986)
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Volume 21 (1986)
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Volume 20 (1985)
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Volume 19 (1985)
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Volume 18 (1984)
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Volume 17 (1984)
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Volume 16 (1983)
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Volume 15 (1982)
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Volume 14 (1981)
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Volume 13 (1980)
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Volume 12 (1979)
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Volume 11 (1978)
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Volume 10 (1977)
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Volume 9 (1976)
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Volume 8 (1975)
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Volume 7 (1974)
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Volume 6 (1973)
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Volume 5 (1972)
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Volume 4 (1971)
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Volume 3 (1970)
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Volume 2 (1969)
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Volume 1 (1968)
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