- Volume 62, Issue 8, 2013
Volume 62, Issue 8, 2013
- Review
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Probiotics in colorectal cancer (CRC) with emphasis on mechanisms of action and current perspectives
More LessColorectal cancer (CRC) is the third most common form of cancer. Diverse therapies such as chemotherapy, immunotherapy and radiation have shown beneficial effects, but are limited because of their safety and toxicity. Probiotic formulations have shown great promise in CRC as preventive and early stage therapeutics. This review highlights the importance of a balanced intestinal microbiota and summarizes the recent developments in probiotics for treating CRC. Specifically, this report describes evidence of the role of probiotics in modulating the microbiota, in improving the physico-chemical conditions of the gut and in reducing oxidative stress. It also discusses the mechanisms of probiotics in inhibiting tumour progression, in producing anticancer compounds and in modulating the host immune response. Even though some of these effects were observed in several clinical trials, when probiotic formulations were used as a supplement to CRC therapies, the application of probiotics as biotherapeutics against CRC still needs further investigation.
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- Pathogenicity and virulence
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Proteolytic processing of the Yersinia pestis YapG autotransporter by the omptin protease Pla and the contribution of YapG to murine plague pathogenesis
More LessAutotransporter protein secretion represents one of the simplest forms of secretion across Gram-negative bacterial membranes. Once secreted, autotransporter proteins either remain tethered to the bacterial surface or are released following proteolytic cleavage. Autotransporters possess a diverse array of virulence-associated functions such as motility, cytotoxicity, adherence and autoaggregation. To better understand the role of autotransporters in disease, our research focused on the autotransporters of Yersinia pestis, the aetiological agent of plague. Y. pestis strain CO92 has nine functional conventional autotransporters, referred to as Yaps for Yersinia autotransporter proteins. Three Yaps have been directly implicated in virulence using established mouse models of plague infection (YapE, YapJ and YapK). Whilst previous studies from our laboratory have shown that most of the CO92 Yaps are cell associated, YapE and YapG are processed and released by the omptin protease Pla. In this study, we identified the Pla cleavage sites in YapG that result in many released forms of YapG in Y. pestis, but not in the evolutionarily related gastrointestinal pathogen, Yersinia pseudotuberculosis, which lacks Pla. Furthermore, we showed that YapG does not contribute to Y. pestis virulence in established mouse models of bubonic and pneumonic infection. As Y. pestis has a complex life cycle involving a wide range of mammalian hosts and a flea vector for transmission, it remains to be elucidated whether YapG has a measurable role in any other stage of plague disease.
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Campylobacter jejuni carbon starvation protein A (CstA) is involved in peptide utilization, motility and agglutination, and has a role in stimulation of dendritic cells
More LessCampylobacter jejuni is the most frequent cause of severe gastroenteritis in the developed world. The major symptom of campylobacteriosis is inflammatory diarrhoea. The molecular mechanisms of this infection are poorly understood compared to those of less frequent disease-causing pathogens. In a previous study, we identified C. jejuni proteins that antibodies in human campylobacteriosis patients reacted with. One of the immunogenic proteins identified (Cj0917) displays homology to carbon starvation protein A (CstA) from Escherichia coli, where this protein is involved in the starvation response and peptide uptake. In contrast to many bacteria, C. jejuni relies on amino acids and organic acids for energy, but in vivo it is highly likely that peptides are also utilized, although their mechanisms of uptake are unknown. In this study, Biolog phenotype microarrays have been used to show that a ΔcstA mutant has a reduced ability to utilize a number of di- and tri-peptides as nitrogen sources. This phenotype was restored through genetic complementation, suggesting CstA is a peptide uptake system in C. jejuni. Furthermore, the ΔcstA mutant also displayed reduced motility and reduced agglutination compared to WT bacteria; these phenotypes were also restored through complementation. Murine dendritic cells exposed to UV-killed bacteria showed a reduced IL-12 production, but the same IL-10 response when encountering C. jejuni ΔcstA compared to the WT strain. The greater Th1 stimulation elicited by the WT as compared to ΔcstA mutant cells indicates an altered antigenic presentation on the surface, and thus an altered recognition of the mutant. Thus, we conclude that C. jejuni CstA is important not only for peptide utilization, but also it may influence host–pathogen interactions.
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- Host response
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Induction of proinflammatory cytokines in human lung epithelial cells during Rhodococcus equi infection
Rhodococcus equi is an opportunistic human pathogen associated with immunosuppressed people. While the interaction of R. equi with macrophages has been comprehensively studied, little is known about its interactions with non-phagocytic cells. Here, we characterized the entry process of this bacterium into human lung epithelial cells. The invasion is inhibited by nocodazole and wortmannin, suggesting that the phosphatidylinositol 3-kinase pathway and microtubule cytoskeleton are important for invasion. Pre-incubation of R. equi with a rabbit anti-R. equi polyclonal antiserum resulted in a dramatic reduction in invasion. Also, the invasion process as studied by immunofluorescence and scanning electron microscopy indicates that R. equi make initial contact with the microvilli of the A549 cells, and at the structural level, the entry process was observed to occur via a zipper-like mechanism. Infected lung epithelial cells upregulate the expression of cytokines IL-8 and IL-6 upon infection. The production of these pro-inflammatory cytokines was significantly enhanced in culture supernatants from cells infected with non-mucoid plasmid-less strains when compared with cells infected with mucoid strains. These results demonstrate that human airway epithelial cells produce pro-inflammatory mediators against R. equi isolates.
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Vesicle formation as a result of interaction between polymorphonuclear neutrophils and Staphylococcus aureus biofilm
More LessStaphylococcus aureus, a major opportunistic pathogen, is a leading cause of biofilm-related infections in clinical practice. Staphylococcal biofilms are highly resistant to antibacterial medicines and immune effector cells. The main result of our work is the discovery of nano-vesicles in the supernatant of the human neutrophil–S. aureus biofilm system. We also found that phospholipase C treatment causes complete destruction of these vesicles. While the addition of proteinase K led to a partial structural disorganization of the vesicles, DNase treatment did not influence the vesicle structure. These observations allowed us to conclude that phospholipids and proteins play a structure-forming role in the formation of these nano-vesicles. The vesicles demonstrated anti-biofilm activities when tested against Staphylococcus epidermidis (strains 178M and 328/5) biofilms, but were ineffective for S. aureus (strains 5983/2, 5663 and 18A) biofilms.
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- Diagnostics, typing and identification
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Evaluation of the Cobas TaqMan MTB real-time PCR assay for direct detection of Mycobacterium tuberculosis in respiratory specimens
The Cobas TaqMan MTB assay is a real-time PCR (qPCR) kit for rapid detection of Mycobacterium tuberculosis from clinical specimens. There are, however, limited studies validating its performance. We performed a prospective study in two hospitals in Taiwan on 586 respiratory specimens. By using culture as the reference method, the sensitivity and specificity of the Cobas TaqMan MTB assay were found to be 82.7 and 96.5 %, respectively. The sensitivity of the Cobas TaqMan MTB assay in acid-fast stain-negative respiratory specimens was only 34.9 %. Five specimens from five patients were positive for M. tuberculosis by the Cobas TaqMan MTB assay but were negative for M. tuberculosis by conventional culture methods. A diagnosis of pulmonary tuberculosis (TB) was made based on clinical and radiological findings as well as the response to anti-TB treatment in these five patients. Addition of data from these five specimens with discrepant results (PCR vs culture) from patients with symptoms clinically compatible with TB increased the sensitivity of the Cobas TaqMan MTB assay to 83.1 %. The Cobas TaqMan MTB assay is a rapid identification tool with a high degree of specificity for the direct detection of M. tuberculosis in respiratory specimens. The sensitivity for detecting acid-fast smear-negative respiratory specimens, however, is low.
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Successful substitution of fetal calf serum by human plasma for bulk cultivation of Leishmania donovani promastigotes
More LessThe potential of human plasma (HP) or serum (HS) as a replacement for fetal calf serum (FCS) was evaluated in a liver infusion tryptose (LIT) medium for bulk cultivation of Leishmania donovani promastigotes. The promastigote yield with the LIT-FCS standard medium was 0.4–1.8×107 ml−1, and yields of 0.5–3.4×107 (P = 0.527) and 0.4–2.4×107 (P = 0.062) were recorded for two LIT medium variants containing HP or HS as supplement instead of FCS. Significantly, higher promastigote yields of 1.3–4.9×107 ml−1 were demonstrated when LIT medium was supplemented with HP of blood group O but not A, B, AB or equally pooled ABO (P = 0.007–0.020). Matching (P = 0.56) strong positive (1 : 10 2400 to ≥1 : 262 144 00) and weak negative (1 : 5–1 : 160) direct agglutination test (DAT) titres, respectively, were demonstrated in 24 visceral leishmaniasis (VL) and 45 non-VL sera for both standard LIT-FCS and alternative LIT-HP derived antigens. Our findings indicate strong potential for sustainable production of promastigotes for important diagnostic procedures such as DAT in the VL affected areas.
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Pneumocystis jirovecii multilocus genotyping profiles in Northern Ireland
More LessPneumocystis jirovecii causes pneumonia, a severe opportunistic infection in immunosuppressed patients that has both person-to-person airborne transmission and environmental transmission as important routes of infection. An increasing incidence of P. jirovecii in Northern Ireland prompted a detailed epidemiological and molecular review that included enhanced surveillance on all lower respiratory specimens. Genotyping of these P. jirovecii positive specimens was undertaken using multiple locus sequence typing (MLST) targeting known variable regions of the P. jirovecii genome. Multiple circulating types were found among all patient risk categories. However, a predominance of one MLST type was found in a P. jirovecii outbreak amongst the renal transplant population. Our results demonstrate the diversity of P. jirovecii strains amongst the local immunosuppressed cohort and highlight the importance of genotyping in the investigation of common sources of P. jirovecii amongst immunosuppressed patients.
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- Antimicrobial agents and chemotherapy
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Antifungal mechanism of essential oil from Anethum graveolens seeds against Candida albicans
More LessThis work studied the antifungal mechanism of dill seed essential oil (DSEO) against Candida albicans. Flow cytometric analysis and inhibition of ergosterol synthesis were performed to clarify the mechanism of action of DSEO on C. albicans. Upon treatment of cells with DSEO, propidium iodide penetrated C. albicans through a lesion in its plasma membrane. DSEO also significantly reduced the amount of ergosterol. These findings indicate that the plasma membrane of C. albicans was damaged by DSEO. The effect of DSEO on the functions of the mitochondria in C. albicans was also studied. We assayed the mitochondrial membrane potential (mtΔψ) using rhodamine 123 and determined the production of mitochondrial dysfunction-induced reactive oxygen species (ROS) via flow cytometry. The effects of the antioxidant l-cysteine (Cys) on DSEO-induced ROS production and the antifungal effect of DSEO on C. albicans were investigated. Exposure to DSEO increased mtΔψ. Dysfunctions in the mitochondria caused ROS accumulation in C. albicans. This increase in the level of ROS production and DSEO-induced decrease in cell viability were prevented by the addition of Cys, indicating that ROS are an important mediator of the antifungal action of DSEO. These findings indicate that the cytoplasmic membrane and mitochondria are the main anti-Candida targets of DSEO.
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Evaluation of heteroresistance to polymyxin B among carbapenem-susceptible and -resistant Pseudomonas aeruginosa
One hundred and twenty-four Pseudomonas aeruginosa isolates were selected for antimicrobial susceptibility testing with anti-pseudomonal agents, MIC determination for polymyxin B and metallo-beta-lactamase detection (genes bla SPM, bla VIM-1, bla NDM-1 and bla IMP). According to the imipenem and/or meropenem susceptibility profile, a set of randomly selected isolates (12 isolates carbapenem-susceptible and 12 isolates carbapenem-resistant) were evaluated for heteroresistance to polymyxin B. Heteroresistance testing was performed by plating the isolates onto increasing concentrations of polymyxin B (from 0 to 8.0 mg l–1). The population analysis profile (PAP) was defined as the ratio of the number of colony-forming units on the plate with the highest concentration of polymyxin B at which bacterial growth occurred against the number of colony-forming units on the plate without antibiotic. Isolates presenting subpopulations that exhibited growth at polymyxin B concentrations ≥2 mg l–1 were considered heteroresistant. Isolates containing subpopulations that grew at polymyxin B concentrations at least twice as high as the original MIC but <2 mg l–1 were considered heterogeneous. Antimicrobial susceptibility testing results indicated a variable degree of susceptibility: high levels of resistance to gentamicin (30.6 %) and imipenem (29.0 %); low levels of resistance to aztreonam (1.6 %) and ciprofloxacin (4.8 %). All isolates were susceptible to polymyxin B: MIC50 and MIC90 were 1 mg l–1 and 2 mg l–1, respectively. Thirty-seven isolates (30 %) were carbapenem-resistant. Four isolates resistant to carbapenems were positive for bla IMP. There were no heteroresistant subpopulations in the carbapenem-susceptible group, but three isolates presented heterogeneous subpopulations. The PAP frequency ranged from 2.1×10−4 to 6.9×10−8. In the carbapenem-resistant group, one isolate was heteroresistant. Six isolates in this group presented heterogeneous subpopulations. In the resistant population, the PAP frequency ranged from 2.1×10−7 to 2.6×10−4. In this study, polymyxin B heteroresistance in P. aeruginosa was uncommon and occurred in only one carbapenem-resistant isolate, despite the fact that several isolates presented heterogeneous subpopulations with increased polymyxin B MICs.
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- Epidemiology
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Presence of Clostridium difficile PCR ribotype clusters related to 033, 078 and 045 in diarrhoeic calves in Germany
More LessThis study provides data on the distribution and relationship of C. difficile PCR ribotypes in diarrhoeic calves in Germany. C. difficile was isolated from 176 of 999 (17.6 %) faecal samples or swabs of diarrhoeic calves from 603 farms collected between January 2010 and August 2012 by eight federal laboratories of six states. Strains were assigned to 17 PCR ribotypes. PCR ribotypes 033 (57 %), 078 (17 %) and 045/FLI01 (closest match to 045 in the WEBRIBO database; 9 %) were found the most frequently. Nine per cent of all culture-positive tested animals shed more than one multiple locus variable number tandem repeat analysis (MLVA) or PCR ribotype. Eight PCR ribotypes with related profiles (including 033, 078 and 045/FLI01) representing 92 % of all isolates were grouped into three clusters. Molecular relatedness was supported by the absence of the MLVA locus A6 Cd only in clustered strains and identical toxin gene profiles for strains within each cluster. Previously reported mulitilocus sequence typing analysis for PCR ribotypes that were also recovered in this study found identical sequence types and a tcdC deletion (Δ39 bp) for 033, 045, 078 and 126 (ST-11), confirming this clustering. A different geographical occurrence of PCR ribotypes was shown for cluster 033 (found more frequently in southern Germany) and 045 (found more frequently in northern Germany). This study showed that clusters of C. difficile PCR ribotypes related to 033, 078 and 045 are predominant in diarrhoeic calves in Germany. The high number of strains belonging to PCR ribotype 078 demonstrated that diarrhoeic calves are also potential reservoirs for human pathogenic C. difficile strains.
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Prevalence of fusB in Staphylococcus aureus clinical isolates
More LessFusidic acid (FA) resistance in Staphylococcus aureus markedly varied among different regions. Few data for FA resistance are available in China. In this study, FA susceptibility testing was performed, and the prevalence of fusB and fusC in 116 clinical isolates of S. aureus was investigated by PCR. Mutations in fusA were also determined by sequencing of PCR products. Molecular typing of fusB-positive strains was based on multilocus sequence typing (MLST), spa typing and pulsed-field gel electrophoresis (PFGE). A DNA fragment flanking fusB was sequenced. Transformation experiments were carried out in fusB-positive S. aureus. Of 116 S. aureus including 19 meticillin-resistant S. aureus (MRSA) and 97 meticillin-susceptible S. aureus (MSSA), four (3.5 %) were resistant to FA with MICs of 6–12 µg ml−1, including one MRSA from blood and three MSSA from wound exudates. All four FA-resistant isolates were found to be fusB gene positive. Three FA-resistant MSSA strains had the same MLST profile of ST630 and spa type of t377, whilst the MRSA strain belonged to ST630-t4549. Only one PFGE pattern was recognized for these four strains. No fusC and fusA mutations were detected in any of the isolates. FA resistance in fusB-positive clinical isolates could be transferred to S. aureus RN4220. The fusB gene was located in a transposon-like element, which had 99 % identity with that found in pUB101. In conclusion, the FA resistance rate is low in S. aureus, and the fusB gene is responsible for the resistance.
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Changes in serotype prevalence and antimicrobial resistance among invasive Streptococcus pneumoniae isolates in Korea, 1996–2008
More LessWe investigated changes in serotypes and antimicrobial susceptibilities among 386 isolates of invasive Streptococcus pneumoniae collected from numerous hospitals in Korea from 1996 to 2008. Serotypes 19F (9.8 %), 23F (8.3 %), 19A (7.8 %), 6A (7.5 %), 3 (7.3 %), 9V (6.5 %), 6B (6.2 %), 14 (4.9 %), 1 (3.9 %), 11A (3.9 %) and 4 (3.1 %) represented 69.2 % of all isolates. While the overall proportion of PCV7 serotypes was stable over time, we observed modest decreases in children <5 years old and in adults ≥65 years old between 1996–1999 and 2007–2008. An increased prevalence of non-PCV7 serotypes in these age groups was primarily attributable to an increase in serotypes 3, 6A and 19A. Most invasive S. pneumoniae isolates showed high resistance rates to erythromycin (74.9 %), tetracycline (71.1 %) and clindamycin (61.7 %). Between 1996–2003 and 2004–2008, non-susceptibility rates to cefotaxime and multi-drugs (three or more classes) in PCV7 serotypes showed a declining trend, while in non-PCV7 serotypes there was an increasing trend. Non-PCV7 serotypes 6A and 19A, which mostly exhibited multidrug-resistant phenotypes (69.0 % and 76.7 % respectively), increased between 1996–2003 and 2004–2008. Although PCV7 was introduced in Korea in November 2003, pneumococcal vaccination has not been included in the national child vaccination programme. Our results provide details of serotype occurrence that will be useful when adoption of universal pneumococcal vaccination in Korea is being considered.
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Seroprevalence of Chlamydia psittaci infection in market-sold adult chickens, ducks and pigeons in north-western China
Chlamydia psittaci, the agent of psittacosis in humans, infects a wide range of avian species. To assess the risk of psittacosis posed by domestic birds in the urban environment, the prevalence of C. psittaci antibodies in 413 chickens (Gallus domesticus; 305 caged and 108 free-range), 334 ducks (Anas spp.; 111 caged and 223 free-range) and 312 pigeons (Columba livia) in Lanzhou, north-western China, was detected using the indirect haemagglutination assay. The specific antibodies were found in sera of 55 (13.32 %) chickens, 130 (38.92 %) ducks and 97 (31.09 %) pigeons. Statistical analysis showed that the seroprevalence of C. psittaci infection in chickens was significantly lower than that in ducks and pigeons (P<0.05). The C. psittaci seroprevalence in caged and free-range chickens was 7.54 % and 29.63 %, respectively, and the difference was statistically significant (P<0.05). The C. psittaci seroprevalence in caged and free-range ducks was 26.13 % and 45.29 %, respectively (P<0.05). To our knowledge, this is the first study indicating the presence of C. psittaci infection in market-sold chickens, ducks and pigeons in north-western China. Close contact with these birds is associated with a risk of zoonotic transmission of C. psittaci. Public education should be implemented to reduce the risk of avian to human transmission of such a pathogenic agent.
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Can implantable cardiac electronic device infections be defined as ‘early’ or ‘late’ based on the cause of infection?
More LessImplantable cardiac electronic device (ICED) infections are a major cause of morbidity and mortality. Understanding the pathogenesis of these infections is important in their prevention and management. We hypothesized that ICED infections could be classified as ‘early’ or ‘late’, based on differences in microbiological cause within or beyond 1 year of implantation, respectively. A comprehensive review of the literature was undertaken to test this hypothesis. Prosthetic valve endocarditis cases were included for comparison. Articles were included if the time from device implantation to infection, definite evidence of infection (pocket/bacteraemia/endocarditis) and a positive microbiological diagnosis were included. There were no statistically significant differences in microbiology to support a 1 year cut-off between early and late ICED infection. Staphylococcus aureus and coagulase-negative staphylococci were the predominant causes of ICED infection both within and beyond 1 year of ICED implantation. To further assess the microbiological causes of ICEDs and their implications for pathogenesis a large-scale multi-centre study is required.
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Increase of pneumococcal serotype 19A in Italy is due to expansion of the piliated clone ST416/CC199
The emergence of Streptococcus pneumoniae serotype 19A, following use of the heptavalent pneumococcal conjugate vaccine (PCV7), has been favoured by multiple antibiotic resistance of this serotype and by other unknown factors. The aim of this study was to examine 19A isolates from invasive pneumococcal diseases (IPD) obtained before and after PCV7 implementation to ascertain which characteristics, including the presence of pili, might have favoured the emergence of this serotype in Italy. All S. pneumoniae isolates from IPD collected at the Italian National Institute of Health in the years 2001–2003 and 2006–2009 were serotyped. The 19A isolates were submitted to antimicrobial susceptibility testing by Etest and were genotyped by a combination of pulsed field gel electrophoresis (PFGE) and Multi Locus Sequence Typing (MLST). The presence of the pilus islets PI-1 and PI-2 was detected by PCR assays targeting a marker gene in each islet. The proportion of 19A isolates from IPD significantly increased from 4 % in 2001–2003 to 12 % in 2006–2009. This was largely due to the expansion of a clone characterized by sequence type (ST) 416, clonal complex (CC) 199, already present in Italy before PCV7 implementation. This clone included isolates susceptible to penicillin and containing PI-1 genes. Other CCs contributed to the emergence of serotype 19A: CC63 and CC193, already present in 2001–2003, and new-emerging CCs or clones such as CC230, CC320 and ST5204, that include drug-resistant and/or pilus-positive isolates. The expansion of serotype 19A in Italy might have been favoured not only by antibiotic resistance, but also by other bacterial factors such as the presence of pili.
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- Clinical microbiology and virology
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The involvement of Helicobacter pylori thioredoxin-1 in gastric carcinogenesis
Helicobacter pylori infection is related to the development of gastric diseases. Various virulence factors are responsible for the pathogenic mechanisms of H. pylori infection. Our previous studies using two-dimensional gel electrophoresis showed that H. pylori thioredoxin-1 (Trx1) is overexpressed in gastric carcinomas. Here, we examined whether H. pylori Trx1 is a novel virulence factor associated with gastric tumorigenesis. We found that Trx1 expression in H. pylori isolated from gastric cancer tissues was significantly higher than that from tissues exhibiting gastritis. In the gastric epithelial cell line GES-1, infection of H. pylori with high Trx1 expression significantly induced cell apoptosis, decreased the expression of cyclin D1 and upregulated p21. However, in the gastric cancer cell line BGC823, high Trx1 expression in H. pylori significantly increased cell proliferation, and upregulated cyclin D1. The effects on cell lines were confirmed using the H. pylori Trx1-knockout mutant strain. Our observations indicate that high Trx1 expression in H. pylori is associated with gastric carcinogenesis. In H. pylori, Trx1 likely participates in the pathogenesis of gastric cancer and H. pylori expressing high levels of Trx1 would be expected to be highly pathogenic in gastric diseases in China.
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High prevalence of occult hepatitis C virus infection in patients with chronic hepatitis B virus infection
More LessHepatitis C virus (HCV) infection in the absence of detectable antibodies against HCV and of viral RNA in serum is called occult HCV infection. Its prevalence and clinical significance in chronic hepatitis B virus (HBV) infection is unknown. HCV RNA was tested for in the liver samples of 52 patients with chronic HBV infection and 21 (40 %) of them were positive for viral RNA (occult HCV infection). Liver fibrosis was found more frequently and the fibrosis score was significantly higher in patients with occult HCV than in negative ones, suggesting that occult HCV infection may have an impact on the clinical course of HBV infection.
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High prevalence of VIM-4 and NDM-1 metallo-β-lactamase among carbapenem-resistant Enterobacteriaceae
The purpose of this study was to identify the mechanisms leading to carbapenem resistance among multidrug-resistant Enterobacteriaceae isolates recovered from hospitalized patients with nosocomial infections in Mubarak Al Kabeer Hospital, Kuwait. Fourteen carbapenem-resistant Enterobacteriaceae isolates were obtained from inpatients in different wards and intensive care units between April 2009 and February 2011. Antibiotic susceptibilities were determined using the E-test method. Genes encoding β-lactamases were characterized by specific PCR amplification, sequencing and conjugation assays. All isolates were identified as metallo-β-lactamase (MBL) producers using phenotypic and molecular methods. Eleven of the 14 isolates produced VIM-4 (six Klebsiella pneumoniae, three Escherichia coli, one Enterobacter cloacae and one Klebsiella oxytoca). Three K. pneumoniae isolates produced the MBL NDM-1 and co-produced the plasmid-encoded AmpC CMY-4. The VIM-4-producing isolates co-produced extended-spectrum β-lactamases including CTX-M-15 and some SHV derivatives. The VIM-4 gene was not transferable by conjugation studies of six selected strains. We demonstrated here the emergence of VIM-4- and NDM-1-producing isolates in the largest teaching hospital in Kuwait.
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- Case report
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Identification of Actinomyces meyeri actinomycosis in middle ear and mastoid by 16S rRNA analysis
Actinomycosis of the middle ear and mastoid is extremely rare. Here, we report a unique case of actinomycosis of the middle ear and mastoid caused by Actinomyces meyeri diagnosed by 16S rRNA gene sequence analysis.
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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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