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Volume 51,
Issue 2,
2002
Volume 51, Issue 2, 2002
- Editorial
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- Review Article
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The pneumococcus: carriage, disease and conjugate vaccines
More LessModern biotechnology has made possible the rapid development and introduction into clinical care of a wide spectrum of potent antimicrobial agents. However, the battle against Streptococcus pneumoniae (pneumococcus) has remained fierce, as acquisition of resistance is even more rapid and these antimicrobial agents are rendered ineffective. Obtaining appropriate antibiotic treatment for severe invasive pneumococcal infections is now a major challenge in many regions of the world. The ground-breaking success of Haemophilus influenzae type b (Hib) conjugate vaccine has brought hope for the conquest of other capsulate bacteria. Recent results of efficacy trials of a heptavalent pneumococcal conjugate vaccine bring hope that protein conjugate vaccines will have a similar impact on pneumococcal disease. These multivalent vaccine formulations include pneumococcal serotypes that most often acquire antibiotic resistance and there is hope that the widespread application of these vaccines will decrease the incidence of multi-drug-resistant infections. The potential reduction of pneumococcal disease could even extend to unimmunised younger siblings and the elderly residing with immunised young children, through its herd effect. However, in view of the multiplicity of serotypes and the biology of the pneumococcus, optimism must be tempered by caution.
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- Diagnostic Microbiology
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Detection of enterotoxigenic Clostridium perfringens with a duplex PCR
More LessTwo sets of primers designed to detect Clostridium perfringens phospholipase C (plc) and enterotoxin (cpe) genes in a single PCR reaction were applied to a collection of 64 predominantly food poisoning-related C. perfringens isolates. In-vitro enterotoxin synthesis was tested serologically after inducing sporulation. Of the 64 isolates, 26 were clearly enterotoxigenic; 16 were classified as potentially enterotoxigenic only as serological testing did not confirm enterotoxin production. Duplex PCR for diagnosis of enterotoxigenic C. perfringens from vegetative cultures can be a useful tool as fresh isolates often sporulate poorly or not all, giving rise to the possibility of false negative results by serological analysis.
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Evaluation of a simple and rapid dipstick assay for the diagnosis of typhoid fever in Indonesia
More LessTo support the clinical diagnosis of typhoid fever in Indonesia, where most hospitals and health centres have no facilities for culture, a rapid dipstick assay for the detection of Salmonella typhi-specific IgM antibodies was evaluated on serum samples from 127 patients clinically suspected of having typhoid fever. In a single blood sample collected on admission to hospital, the sensitivity of the dipstick assay was 69.8% when compared with bone marrow culture and 86.5% when compared with blood culture. The specificity as calculated for the group of patients with suspected typhoid fever but a negative culture result was calculated to be 88.9%. Of 80 patients with febrile illnesses other than typhoid fever, reactivity was observed in only three patients with dengue haemorrhagic fever. The assay uses stabilised components that can be stored outside the refrigerator, does not require special equipment, and may be of use in remote health facilities that have no culture facilities.
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Rapid identification of Streptococcus intermedius by PCR with the ily gene as a species marker gene
Streptococcus intermedius belongs to the anginosus group of streptococci (AGS) and is associated with endogenous infections leading to abscesses in the oral cavity and at deep-seated sites, such as the brain and liver. Two other species, S. anginosus and S. constellatus, and some presently unnamed taxa, are also classified as AGS. Recently, S. constellatus subsp. pharyngis, a new subspecies with biochemical characteristics similar to S. intermedius, was described with the potential for causing confusion when trying to identify isolates of these two species routinely with commercial identification kits, such as Rapid ID32 Strep and Fluo-Card Milleri. To correctly identify S. intermedius, this study attempted to develop an accurate PCR identification system with the ily gene as a species marker. This approach relies on amplification of an 819-bp fragment of the ily gene and its 3′-flanking region and is shown here to be specific for S. intermedius strains among all other streptococcal species. Moreover, this PCR system was applicable in direct rapid PCR with whole bacterial cells and TaKaRa Z-Taq TM (TaKaRa), a highly efficient DNA polymerase, as the template and DNA amplification enzyme, respectively.
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- Antimicrobial Resistance
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recA and glnA sequences separate the Bacteroides fragilis population into two genetic divisions associated with the antibiotic resistance genotypes cepA and cfiA
More LessThe sequences of part of the glutamine synthetase-encoding gene (glnA) and of the RecA-encoding gene (recA) were determined and aligned for 45 Bacteroides fragilis isolates from different clinical and geographical origin. The patterns of sequence divergence of glnA and recA were very similar. The sequences of a 303-bp fraction of recA showed 45 nucleotide substitutions, 40 of which allowed the separation of B. fragilis into two major divisions, which were not found when the deduced amino acid sequences were considered. The 687-bp sequences analysed for the glnA gene showed 112 nucleotide substitutions, 96 of which separated the population into the same two divisions as those described for recA. In this case, the deduced amino acid sequences showed this subdivision as well: three of the six observed amino acid substitutions were division-specific. Within the two divisions, both genes presented a high degree of sequence conservation. Each B. fragilis division was associated with the presence of a different antibiotic resistance gene: cepA encoding a serine-β-lactamase (division I) and cfiA encoding a metallo-β-lactamase (division II). No particular clusters associated with geographical or clinical origin, or with the production of an enterotoxin were observed. Sequencing of the cfiA gene allowed identification of two different alleles in division II. However, no association of these different cfiA alleles with the expression of imipenem resistance was observed. In conclusion, the phylogenetic patterns observed by sequencing recA and glnA are in agreement with those obtained previously by MLEE (multilocus enzyme electrophoresis). Thus, it appears that the evolution of recA and glnA genes is similar to that of the whole chromosome of B. fragilis. Horizontal gene transfer between divisions I and II seems to be low, at best. However, the results of the present study could not clarify definitively whether divisions I and II should be considered as two different B. fragilis genospecies.
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- Correspondence
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- Microbial Pathogenicity
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Pulmonary granulomas of guinea pigs induced by inhalation exposure of heat-treated BCG Pasteur, purified trehalose dimycolate and methyl ketomycolate
More LessThis study was designed to determine the identity of granulomatogenic substances in Mycobacterium bovis BCG Pasteur. When heat-treated BCG Pasteur bacilli were introduced into the lungs of guinea-pigs by an inhalation exposure apparatus, pulmonary granulomas without necrosis developed. Furthermore, when four kinds of mycolates derived from M. tuberculosis Aoyama B strain were introduced into the lungs by the same method, only trehalose 6,6′-dimycolate (TDM) and methyl ketomycolate induced pulmonary granulomas without central necrosis. The pulmonary granulomas consisted of epithelioid macrophages and lymphocytes. When a mixture of TDM and anti-TDM antibody was introduced into the lungs, development of granulomatous lesions was reduced. These data indicate that TDM and methyl ketomycolate are potent granulomatogenic reagents.
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Variations in 10 putative uropathogen virulence genes among urinary, faecal and peri-urethral Escherichia coli
A total of 868 isolates was screened from seven different collections of organisms from previous studies – pyelonephritis in children aged 1–24 months; first, second and recurring urinary tract infection (UTI) in women aged 18–39 years; UTI in women aged 40–65 years and peri-urethral and faecal isolates from women aged 18–39 years – for the presence of 10 potential Escherichia coli UTI virulence genes. Previously reported differences between the frequency of these genes in UTI compared with faecal isolates were confirmed and extended. A single virulence signature (strains containing aer, kpsMT, ompT, fim and papG AD) occurred in 29% of the pyelonephritic isolates, but in no more than 11% of the other collections. Peri-urethral isolates were found to have frequencies of these 10 genes that differed from those found for both UTI and faecal isolates.
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Expression of receptors for verotoxin 1 from Escherichia coli O157 on bovine intestinal epithelium
Human enterohaemorrhagic Escherichia coli (EHEC) infection most commonly arises, either directly or indirectly, from cattle, which act as a reservoir host for these bacteria. In man, EHEC disease can be severe, whereas EHEC do not normally cause disease in cattle. Verotoxins (VTs) are the main virulence factors in human disease but no role for VT has been ascribed in cattle; however, this study shows for the first time that VT receptor is expressed by the bovine intestinal tract. VT bound to crypt epithelial cells of the small (ileum and jejunum) and large (caecum and colon) intestine independently of the animals’ age. VT also bound to discrete cell subsets in the bovine kidney and to submucosal lymphoid cells but not to vasculature. Analysis of tissues for isoforms of the VT receptor, Gb3, confirmed the presence of the receptor in the bovine intestinal epithelium and kidney. A distinct pattern of Gb3 receptor isoform mixtures was observed in the bovine kidney. This, together with the general absence of receptors on vasculature, could contribute to the apparent resistance of cattle to systemic effects of VT. Expression of Gb3 on the bovine intestinal epithelium, together with previously described effects, may affect EHEC colonisation in its reservoir hosts and hence the potential for distribution to man.
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The interaction of Yersinia pestis with erythrocytes
More LessHuman and murine erythrocytes (RBC) were invaded by Yersinia pestis in vivo and in vitro during a short period and were probably used as an essential source of iron and porphyrin for survival, effective gross multiplication and rapid spread of these bacteria in the bloodstream of mammals. Both iron and porphyrin were extracted by Y. pestis from the RBC through oxidase-catalase activity which produced oxidation of the RBC glucose with generation of H2O2 in large concentration leading to oxidative transformation of haemoglobin into haemin. Furthermore, some mainly chromosomally encoded effector proteins were implicated in this process because all were synthesised by Y. pestis grown in media simulating the intracellular conditions of mammalian RBC. Damaged RBC lost the ability to transport O2 in the mammalian organism. As a result, significant oxygen deficiency developed in host tissues providing specific clinical disease features of plague which are similar to characteristic symptoms of poisoning with haemotoxic substances when the transformation of the haemoglobin Fe2+ to Fe3+ occurs.
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Induction of apoptosis of human macrophages in vitro by Legionella longbeachae through activation of the caspase pathway
More LessThe cytotoxicity of the facultative intracellular bacterium, Legionella longbeachae, an important cause of legionellosis, was characterised. Apoptosis was induced in HL-60 cells, a human macrophage-like cell line, during the early stages of infection and induction of apoptosis correlated with cytotoxicity. Apoptosis was confirmed by agarose gel electrophoresis of fragmented DNA, surface exposure of phosphatidylserine and propidium iodide labelling of host cell nuclei. The involvement of macrophage infectivity potentiator (Mip) protein, a known virulence factor of L. longbeachae, was also examined. A mip mutant of L. longbeachae induced apoptosis of HL-60 cells but failed to multiply intracellularly, suggesting that intracellular replication of L. longbeachae is not essential for the induction of apoptosis of HL-60 cells. Furthermore, induction of apoptosis of L. longbeachae-infected macrophages was mediated by activation of the caspase pathway but might be independent of tumour necrosis factor-α- and Fas-mediated signal transduction pathways.
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- Mycology
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Effect of fluvastatin and pravastatin, HMG-CoA reductase inhibitors, on fluconazole activity against Candida albicans
More LessSynergy between fluvastatin, at clinically unachievable concentrations, and fluconazole against Candida albicans has been reported. The purpose of the present study was to evaluate the in-vitro activity of fluconazole alone and in combination with clinically achievable concentrations of pravastatin and fluvastatin against C. albicans. In-vitro susceptibility and synergy testing were performed against clinical isolates of C. albicans with fluconazole, pravastatin and fluvastatin. Both checkerboard method and time-kill studies were performed. MICs for fluconazole ranged from 0.5 (susceptible) to >256 mg/L (resistant) at 24 h. All isolates had MICs >2 mg/L for both statins. No synergy or antagonism was observed with fluconazole in combination with either agent against any isolate of C. albicans by the checkerboard assay or time-kill studies. Clinically achievable concentrations of pravastatin and fluvastatin did not affect the in-vitro activity of fluconazole against C. albicans.
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Aetiology, antifungal susceptibility, risk factors and outcome in 201 fungaemic children: data from a 12-year prospective national study from Slovakia
A total of 201 cases of fungaemia in children in a 12-year national survey from seven University Paediatric Clinics in Slovakia in 1990–2001 was assessed to determine risk factors, therapy and outcome, and to compare those cases with fungaemia in 130 adult cancer patients studied in a similar survey. Four univariate analyses were performed to assess differences in aetiology, antifungal susceptibility and outcome between fungaemia in neonates and paediatric intensive care unit (ICU) patients as well as between paediatric and adult cancer patients with fungaemia. There was a significant difference in aetiology and antifungal susceptibility between the subgroups of children with fungaemia: 83.3% of neonates versus 40.2% in children with cancer were due to Candida albicans. None of the non-albicans Candida spp. (NAC) in neonates but 23.5% of NAC isolates from children with cancer were resistant to fluconazole. C. albicans caused 144 (71.1%) episodes and NAC 48 (23.7%) episodes. Trichosporon beigelii, Blastoschizomyces (Trichosporon) capitatus, Rhodotorula rubra and Cryptococcus laurentii were found less frequently in neonates than in children with cancer (18.8%). There were not many differences in risk factors between paediatric fungaemia and adult cancer fungaemia except C. albicans aetiology, corticosteroid use in therapy, breakthrough fungaemia after ketoconazole prophylaxis and meningitis as a complication, which were observed significantly more frequently among children than in adults, both with cancer and fungaemia. Thirty-three of the paediatric fungaemias were breakthrough cases and appeared frequently in children with cancer. Fifty-one (25.1%) children died with fungaemia (attributable mortality) and 25 (12.7%) due to underlying disease with fungaemia; overall mortality was 37.8% and there was no significant difference in death rates between the subgroups of paediatric patients (neonates, children in ICUs and children with cancer).
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PCR identification of dermatophyte fungi Trichophyton rubrum, T. soudanense and T. gourvilii
More LessDiagnosis of dermatophytosis employing conventional laboratory procedures has been complicated by the slow growth and varied morphological features shown by dermatophytes. After analysis of the nucleotide base sequences of a 1.2-kb fragment amplified from a dermatophyte fungus Trichophyton rubrum by arbitrarily primed PCR with random primer OPD18, a pair of primers (TR1F and TR1R) was designed and evaluated for specific identification of T. rubrum. The sensitivity of the primers TR1F and TR1R was high, as a specific PCR band of c. 600 bp was detected from as little as 7 pg of T. rubrum DNA. By examining 92 dermatophyte strains and clinical isolates, it was found that this pair of primers reacted in PCR with T. rubrum, T. soudanense and T. gourvilii through formation of the specific fragment of 600 bp, but not with any other of the dermatophyte species or varieties, fungi, yeasts or bacteria tested. As T. rubrum is one of the most frequently isolated dermatophyte fungi, and T. soudanense and T. gourvilii are relatively uncommon in many parts of the world, these primers can be used for rapid, sensitive and specific identification and differentiation of T. rubrum from other fungi and micro-organisms.
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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 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 41 (1994)
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Volume 39 (1993)
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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 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 12 (1979)
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Volume 11 (1978)
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Volume 10 (1977)
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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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