- Volume 53, Issue 2, 2004
Volume 53, Issue 2, 2004
- Pathogenicity And Virulence
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Lactoferricin influences early events of Listeria monocytogenes infection in THP-1 human macrophages
Bovine lactoferrin (BLf) and its derivative peptide lactoferricin B (LfcinB) are known for their antimicrobial activity towards several pathogens, including Listeria monocytogenes, a food-borne Gram-positive invasive bacterium that infects a wide variety of host cells, including professional phagocytes. To add further information on the antibacterial effects of these compounds, the influence of BLf, LfcinB and the antimicrobial centre of LfcinB, the hexapeptide LfcinB4–9, on the invasive behaviour of L. monocytogenes was analysed in IFN-γ-activated human macrophagic cells (THP-1). Significant inhibition of bacterial entry in THP-1 cells was observed at LfcinB concentrations that were unable to produce any bacteriostatic or bactericidal effect, compared with BLf and LfcinB4–9 peptide. This inhibition occurred when LfcinB was incubated during the bacterial infection step and was not due only to competition for common glycosaminoglycan receptors. Assays performed through a temperature shift from 4 to 37 °C showed that inhibition of invasion took place at an early post-adsorption step, although an effect on a different step of intracellular infection could not be ruled out.
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Chlorate: a reversible inhibitor of proteoglycan sulphation in Chlamydia trachomatis-infected cells
More LessSulphated glycosaminoglycans, such as heparan sulphate, have been shown to be essential for the infectivity of many organisms. The aims of this study were to verify the role of sulphated glycosaminoglycans in chlamydial infection and to investigate whether they are present on chlamydia or chlamydial host cells. The effect of undersulphation of host cells and chlamydial elementary bodies was examined using sodium chlorate. Also studied was whether any inhibitory effect was reversible. The results strongly suggest that Chlamydia trachomatis does not produce heparan sulphate and that heparan sulphate of the host cell is necessary and sufficient to mediate chlamydial infection. The essential role played by the sulphate constituents of the host-cell glycosaminoglycan in the infectivity of LGV serovars, and to a lesser extent of serovar E, was also confirmed.
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- Host Response
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Protective effect of ethyl-3-(3-dimethyl aminopropyl)urea dihydrochloride (EDU) against LPS-induced death in mice
Evaluation of anti-adhesive gels and bioresorbable films in animal models of intra-abdominal infection has shown that a product of the cross-linking reaction between hyaluronic acid (HA) and CM-cellulose, 1-ethyl-3-(3-dimethyl aminopropyl)urea dihydrochloride (EDU), has immunomodulatory properties. The effects of EDU were evaluated by using an endotoxin-induced shock mouse model. Pre-treatment of mice with EDU (50 mg kg−1) in DMSO resulted in a significant reduction in mortality following injection of LPS, compared to vehicle (DMSO) pre-treatment alone. Serum levels of TNF-α, IL1β and IFN-γ in EDU-treated mice were significantly lower than those in vehicle-treated mice. Nitric oxide (NO) concentrations in the sera of mice after inoculation with LPS were significantly lower in the EDU-treated group than in the vehicle-treated group at various time-points. In contrast, EDU pre-treatment was associated with an enhanced IL10 response after LPS injection, compared to vehicle pre-treatment alone. In vitro studies revealed that IL10 production by RAW 264.7 macrophages, elicited by LPS, was increased significantly when EDU was added to the culture medium. These results suggest that the protective effect of EDU during LPS-induced shock in mice is the result of inhibition of proinflammatory cytokines and NO production and an enhanced IL10 response.
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- Diagnostics, Typing And Identification
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Lack of circulating Candida mannoprotein antigen in patients with focal hepatosplenic candidiasis
More LessThe significance of Candida mannoprotein serum detection in 15 patients with haematological malignancies and proven (six cases) or probable (nine cases) hepatosplenic candidiasis was retrospectively evaluated. Circulating mannoprotein antigen was detected in three of six and in one of two serum samples from two patients with probable infection. The antigen was not detected in 38 serum samples of 13 (87 %) patients. Thus, in contrast to other deep-seated Candida infections, mannoprotein is infrequently detectable during focal hepatosplenic candidiasis and does not appear to be of diagnostic value.
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Genotypic analysis of multidrug-resistant Mycobacterium tuberculosis isolates from Monterrey, Mexico
Thirty-seven multidrug-resistant and 13 pan-susceptible isolates of Mycobacterium tuberculosis were analysed for the diversity of genotypes associated with known drug-resistance mechanisms. The isolates were obtained from patients attending a university tuberculosis clinic in Monterrey, Mexico. A total of 25 IS6110-RFLP patterns were obtained from the multidrug-resistant tuberculosis (MDR-TB) isolates. Approximately 65 % of the MDR-TB isolates were attributed to secondary resistance. Different drug-susceptibility patterns were seen with the clustered isolates. The percentage of isolates resistant to isoniazid (INH), rifampicin (RIF), ethambutol (EMB) and streptomycin (STR) was 100, 97.3, 48.7 and 67.6, respectively. The most common resistance-associated polymorphisms for the four drugs were as follows: INH, Ser315Thr (67.6 %) in katG; RIF, Ser450Leu (41.7 %) in rpoB; EMB, Met306Ile/Val/Leu (66.7 %) in embB; and STR, Lys43Arg (24 %) in rpsL. Drug-resistance-associated mutations were similar to changes occurring in isolates from other areas of the world, but unique, previously unreported, mutations in katG (n = 5), rpoB (n = 1) and rrs (n = 3) were also identified.
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Automation of a fluorescence-based multiplex PCR for the laboratory confirmation of common bacterial pathogens
More LessA fluorescence-based multiplex PCR was automated for the simultaneous detection of Neisseria meningitidis, Streptococcus pneumoniae and Haemophilus influenzae in clinical samples from patients with suspected meningitis. Sensitivity of one to two genome copies per 100 μl sample and specificity of 100 % for each organism were shown. Automation of DNA extraction, liquid handling, PCR and analysis are achieved on a single platform, which enables a high throughput and rapid turnaround of clinical samples that, in turn, leads to faster diagnosis. This is ultimately beneficial to the treatment of the patient and for public health management.
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Comparison of ITS and IGS1 regions for strain typing of clinical and non-clinical isolates of Pichia anomala
Pichia anomala is an emerging nosocomial pathogen and there is a need for methods that distinguish between different P. anomala strains. In the typing of several clinical as well as non-clinical P. anomala strains, the sequence variation of the internal transcribed spacer (ITS) was found to be inadequate for typing purposes. The intergenic spacer 1 (IGS1) region of the rDNA of several P. anomala strains was therefore investigated in detail. The IGS1 region (which varied from 1213 to 1231 bp in length) was interspersed with repeats and had more variation than the ITS regions. Comparative analysis in cases where analysis by the ITS was ambiguous clearly revealed the IGS1 region to be a more discriminatory tool in the typing of P. anomala strains.
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Human papillomavirus (HPV) study of 2916 cytological samples by PCR and DNA sequencing: genotype spectrum of patients from the west German area
More LessHuman papillomaviruses (HPVs) are aetiological agents for cervical cancer. More than 70 different HPV types that infect genital mucosa have been found. In order to develop a sensitive and specific detection and typing assay, a PCR/direct sequencing approach was used. Two pairs of consensus primers were used for amplification of HPV DNA and the PCR products obtained were analysed by automated sequencing. Sequences were compared with those in GenBank by using the blast program. In this study, 2916 cytological samples were screened for HPV, as well as for triage. Nine hundred and forty-eight (32.5 %) samples were positive for HPV, of which 134 harboured more than one HPV type. Of the 948 PCR-positive samples, 648 were typed. Thirty-nine different HPV types were identified by sequencing. The two most frequently found HPV types, 16 and 31, together accounted for 36.3 % of the sequences (26.2 and 10.1 %, respectively). This group was followed by HPV types 6 (5.7 %), 18 (5.3 %), 58 (4.5 %), 61 (4.5 %), 53 (4.4 %), 42 (4.3 %) and 51 (4.0 %). All other types were detected at frequencies <4 % and eight types were detected only once. PCR/direct sequencing is a reliable method for routine detection of HPV in cytological samples. The data presented here suggest a complex distribution of HPV types in the population tested. The results accentuate the importance of PCR-based techniques in HPV diagnosis, as hybridization-based methods can only detect a limited number of infections. This method can also be applied easily to the analysis of tissue samples and it therefore also allows type-specific follow-up of women who have been treated for cervical intraepithelial neoplasia.
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- Antimicrobial Agents And Chemotherapy
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Susceptibility testing of sequential isolates of Aspergillus fumigatus recovered from treated patients
Two-hundred sequential Aspergillus fumigatus isolates recovered from 26 immunocompromised patients with invasive aspergillosis or bronchial colonization were tested for their in vitro susceptibility to posaconazole, itraconazole, voriconazole, terbinafine and amphotericin B. Twenty-one patients were treated with amphotericin B and/or itraconazole. Antifungal susceptibilities of the isolates recovered before treatment were not significantly different from those of isolates recovered after the onset of antifungal therapy. The highest MICs were 0.125, 0.5, 0.5, 1 and 1 μg ml−1 for posaconazole, itraconazole, voriconazole, terbinafine and amphotericin B, respectively. It is concluded that the emergence of resistance in A. fumigatus during antifungal therapy with amphotericin B or itraconazole is an uncommon phenomenon.
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Frameshift mutations in frxA occur frequently and do not provide a reliable marker for metronidazole resistance in UK isolates of Helicobacter pylori
More LessMutations in the NAD(P)H flavin oxidoreductase gene (frxA) are thought to contribute to the development of metronidazole resistance in Helicobacter pylori. To test this further, 44 frxA sequences in 18 patient isolate sets of H. pylori were examined including a unique collection comprising separated Mtz-sensitive (MtzS) and Mtz-resistant (MtzR) subpopulations pre-treatment and matched MtzR strains post-treatment. Sequences of frxA contained frameshift mutations that led to premature protein truncation in at least one strain from most (17/18) patient sets. These mutations were present in all strains, irrespective of Mtz resistotype in 13/18 patients. Frameshift due to a single adenine deletion at nucleotide 53 was the most common mutation and was present in isolates from 11/18 patients. A novel real-time (LightCycler) PCR-based probe hybridization melting-point assay applied to a further 119 isolates confirmed that the frameshift-53 mutation occurred frequently, in 20 % of isolates, and could be present in MtzS as well as MtzR strains (42 % vs 58 %). This study demonstrates that frameshift mutations occur in MtzS strains as well as in MtzR strains, and are thus unlikely to cause Mtz resistance.
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- Epidemiology
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Parvovirus B19 infection in medical students during a hospital outbreak
From March to May 2002, a parvovirus B19 (B19) outbreak was identified at a general hospital that serves as a teaching facility for the Universidad Autónoma de San Luis Potosí, Mexico. Medical students attending the hospital presented with symptoms suggestive of B19 infection. Previous studies have suggested that apparent hospital-related B19 outbreaks may be a reflection of B19 infection in the community. A study was undertaken to assess whether exposure to the hospital was a risk factor for B19 infection and to determine to what extent medical students were infected during this outbreak. The incidence of B19 infection in medical students attending the teaching hospital during the outbreak (n = 211) was determined and compared to students not attending the hospital (n = 96). To assess if a community-wide outbreak had occurred, 80 blood donors were also evaluated for the presence of B19 antibodies. Acute B19 infection was identified in 40 of 119 (33.6 %) susceptible students attending the hospital and in 20 of 47 (42.6 %) susceptible students not attending the hospital. The frequency of acute infection among susceptible blood donors was lower (9.5 %) than in students, but higher than the rate expected during non-epidemic periods. Most infections (68.3 %) were asymptomatic. Symptoms reported by infected subjects were not specific for B19 infection. Only 11.7 % of subjects with acute infection fulfilled the clinical surveillance definition used to detect cases during the outbreak. In conclusion, hospital exposure was not associated to increased risk of B19 infection among medical students. Medical students may be at increased risk for acquiring and transmitting B19 infection during outbreaks.
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Long-term predominance of two pan-European clones among multi-resistant Acinetobacter baumannii strains in the Czech Republic
More LessIn a recent study, a large proportion of multi-drug-resistant (MDR) Acinetobacter baumannii strains that were isolated from hospitalized patients in the Czech Republic was found to belong to two major groups (A and B). These groups appeared to be similar to epidemic clones I and II, respectively, which were identified previously among outbreak strains from north-western European hospitals. The aim of the present study was to assess in detail the genetic relatedness of Czech A. baumannii strains and those of epidemic clones I and II by using ribotyping with HindIII and HincII and by AFLP fingerprinting. The study collection included 70 MDR strains that were isolated in 30 Czech hospitals in 1991–2001, 15 susceptible Czech strains from 1991 to 1996 and 13 reference strains of clones I and II from 1982 to 1990. One major HindIII/HincIII ribotype (R1-1) was observed in 38 MDR Czech strains and eight reference strains of clone I, whereas another major ribotype (R2-2) was observed in 11 MDR Czech strains and in three reference strains of clone II. A selection of 59 Czech strains (representative of all ribotypes) and the 13 reference strains were investigated by AFLP fingerprinting. At a clustering level of 83 %, two large clusters could be distinguished: cluster 1 included all reference strains of clone I and 25 MDR Czech strains, whilst cluster 2 contained all reference strains of clone II and 11 MDR Czech strains. There was a clear correlation between the groupings by AFLP analysis and by ribotyping, as all strains with ribotype R1-1 and four strains with slightly different ribotypes were found in AFLP cluster 1, whereas all strains with ribotype R2-2 and seven strains with similar ribotypes were in AFLP cluster 2. Thus, 41 and 21 MDR Czech strains could be classified as belonging to clones I and II, respectively. The remaining eight MDR and 15 susceptible strains were highly heterogeneous and were distinct from clones I and II by both AFLP fingerprinting and ribotyping. These results indicate that the two predominant groups observed among MDR Czech A. baumannii strains from the 1990s are genetically congruent with the north-western European epidemic clones that were found in the 1980s. Recognition of these clinically relevant, widespread clones is important in infection prevention and control; they are also interesting subjects to study genetic mechanisms that give rise to their antibiotic resistance and epidemic behaviour.
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Mycobacterium tuberculosis isolates belonging to katG gyrA group 2 are associated with clustered cases of tuberculosis in Italian patients
Fifty-one consecutive isolates of Mycobacterium tuberculosis, collected during a 2-year period in the north-east of Italy, were subjected to IS6110-RFLP analysis to detect the presence of clusters and assigned to one of the three genotypic groups delineated by single nucleotide polymorphisms in the genes katG and gyrA. All the isolates collected from the local population belonged to group 2 or 3, while group 1 isolates were found only in specimens collected from African immigrants. Clustered cases of tuberculosis, which are likely to be related to recently transmitted infection, were found to be significantly associated with katG gyrA group 2. In the local situation, strains belonging to this group may therefore present a higher risk of transmission.
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- Oral Microbiology
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Clonal similarity of salivary and nasopharyngeal Fusobacterium nucleatum in infants with acute otitis media experience
More LessThe environment of an infant's nasopharynx during acute otitis media (AOM) favours the growth of anaerobic bacteria, which can be recovered frequently during infection, but hardly at all if the infant is healthy. The aim of this investigation was to identify the potential source and inoculation route of anaerobes that were present in the nasopharynx. Eleven Fusobacterium nucleatum isolates that were collected through the nasal cavity from the nasopharynx of eight infants with a history of AOM, and 161 F. nucleatum isolates from the saliva of the same infants, were typed to the clonal level by using arbitrarily primed PCR (AP-PCR). In five of the eight infants examined, identical AP-PCR types were found among nasopharyngeal and salivary isolates. As anaerobes seem to be present only transiently in the nasopharynx and salivary contamination of the nasopharyngeal samples can be excluded, this observation indicates that the source of nasopharyngeal anaerobes is the oral cavity and that saliva is their transmission vehicle.
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- Human And Animal Microbial Ecology
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Clostridium difficile colonization in healthy adults: transient colonization and correlation with enterococcal colonization
The aim of the present study was to investigate the colonization status of Clostridium difficile in healthy individuals. In total, 139 healthy adults from two study groups were examined at intervals of 3 months. Among the 18 positive subjects, the number of subjects from whom C. difficile was isolated once, twice, three times or four times was 10 (55.6 %), three (16.7 %), two (11.1 %) and three (16.7 %), respectively. In the student group, different subjects were colonized by different PCR ribotype/PFGE types. However, the same PCR ribotype/PFGE types of C. difficile were isolated from different subjects in the employee group, indicating that cross-transmission may have occurred in this group. Continuous colonization by the same PCR ribotype/PFGE type was only observed in three subjects. C. difficile-positive subjects were significantly more densely colonized by enterococci (P < 0.05) than C. difficile-negative subjects: subjects that were found to be C. difficile-positive three or four times appeared to have higher concentrations of enterococci. The present results demonstrate that, although colonization by a C. difficile strain is transient in many cases, there are healthy individuals that are colonized persistently by C. difficile. They also suggest that dense colonization of the intestine by enterococci may be associated with C. difficile colonization.
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- Correspondence
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Volumes and issues
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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)